tag:blogger.com,1999:blog-72570284038968210732024-03-18T14:49:11.306-04:00The Forgotten ArchosaursOriginating approximately 250 million years ago, the Archosauria ("Ruling Reptiles") became one of the most diverse and successful clades of vertebrates on earth. However, many of the amazing creatures that are a part of that diversity are often overshadowed by the poster children of the archosaurs - the dinosaurs. This blog looks at those often forgotten archosaurs, focusing especially on the croc-line, but occasionally looking at the bird-line and even outside of crown-group Archosauria.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.comBlogger86125tag:blogger.com,1999:blog-7257028403896821073.post-5133537791126740522016-10-18T21:19:00.000-04:002016-10-18T21:19:08.664-04:00Not ForgottenI'm back! The Forgotten Archosaurs is not forgotten!<br />
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I'm making some changes, but I'm working on making this an active blog once more. Things to look forward to in the coming months: guest posts by archosaur workers, interviews, "forgotten archosaurs" in the news, and more!<br />
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In the meantime, here's <i>Dromicosuchus</i>.<br />
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<a href="https://2.bp.blogspot.com/-HgVEHCeJU6c/WAbH4QS4xLI/AAAAAAAAEBQ/FwLzkLKSLLACcBtKo6um1sxQOYLICFuJACLcB/s1600/Dromicosuchus.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="251" src="https://2.bp.blogspot.com/-HgVEHCeJU6c/WAbH4QS4xLI/AAAAAAAAEBQ/FwLzkLKSLLACcBtKo6um1sxQOYLICFuJACLcB/s400/Dromicosuchus.png" width="400" /></a></div>
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<i>Dromicosuchus grallator </i>was first named and described by Sues et al in 2003. It is a "spenosuchian"-grade crocodylomorph - a fleet-footed, fox-like little croc - from the Late Triassic of North Carolina. I've been working with this specimen quite a bit recently. Thanks to additional prep work, CT scanning, and new comparative material I've been discovering new aspects of the anatomy of <i>Dromicosuchus</i>, especially details of the braincase and forelimb. I hope to be publishing on this in the next year or 2, so stay tuned.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com216tag:blogger.com,1999:blog-7257028403896821073.post-45989238596115794212012-10-27T17:15:00.002-04:002012-10-27T17:18:59.950-04:00Who was eating aetosaurs?<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-_YtQq_FWr9E/S9dYJ_csFnI/AAAAAAAAALE/ovd-MjDt3iA/s1600/postosuchus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://2.bp.blogspot.com/-_YtQq_FWr9E/S9dYJ_csFnI/AAAAAAAAALE/ovd-MjDt3iA/s320/postosuchus.jpg" width="233" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: xx-small;"><i>Desmatosuchus</i> encounters <i>Postosuchus</i>. Artwork by Douglas Henderson in <a href="http://www.amazon.com/gp/product/0253346525?ie=UTF8&tag=forgotarchos-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0253346525">Dawn of the Dinosaurs: Life in the Triassic</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=forgotarchos-20&l=as2&o=1&a=0253346525" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; margin: 0px;" width="1" /> by Nicholas Fraser (Plate 7.5A)</span></td></tr>
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<i>Postosuchus </i>is often depicted preying on aetosaurs, but how do we know that this we really the case? With their heavy armor, aetosaurs were likely a very difficult animal to take down. Once the aetosaur was dead, it would still be fairly difficult to get around that armor, which covered the back, neck, tail, and abdomen.<br />
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However, the discovery of a particular aetosaur osteoderm from Petrified Forest National Park may be able to add some weight to our assumptions that <i>Postosuchus </i>was preying on aetosaurs. The osteoderm belonged to <i>Typothorax</i>, a medium sized aetosaur living in the Late Triassic of Arizona. Bite-marks cover the osteoderm, but the most striking evidence lies on the underside of the armored plate. Four perfect punctures, formed from a single bite, adorn the smooth ventral surface. All the evidence points towards a large predator like <i>Postosuchus</i>, and the bite matches perfectly with the front teeth of <i>Postosuchus kirkpatricki</i>.<br />
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So, who was eating aetosaurs? It looks like Doug Henderson and other paleoartists were right. <i>Postosuchus </i>was a daunting top predator in the Triassic of North America and we can now say that this large rauisuchid had equally daunting prey.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com16tag:blogger.com,1999:blog-7257028403896821073.post-58594220050477798572012-08-28T15:36:00.002-04:002012-08-28T15:38:31.771-04:00New from JVP - A new poposaur and vertebrate fauna from PolandLi et al presented on this new poposaur at last year's SVP (as I discuss <a href="http://forgottenarchosaurs.blogspot.com/2011/11/svp-2011-roundup-triassic.html">here</a>) but I'm very excited to finally see the paper, giving it a name with a full description and phylogenetic analysis. It was pretty interesting to hear that this specimen was found in marine sediments and that it possesses characters suggesting at least a semi-aquatic way of life. This new species and other like it (i.e. <i>Qianosuchus</i>) may suggest a strange beginning for Poposauroidea.<br />
<br />
<div style="color: #45818e; text-align: center;">
Chun Li, Xiao-Chun Wu, Li-Jun Zhao, Tamaki Sato & Li-Ting Wang (2012): A new archosaur (Diapsida,<br />
Archosauriformes) from the marine Triassic of China, Journal of Vertebrate Paleontology, 32:5, 1064-1081</div>
<br />
<u>Abstract</u><br />
A new Middle Triassic archosaur, <i>Diandongosuchus fuyuanensis</i>,
gen. et sp. nov., is described on the basis of a skeleton from the
Zhuganpo Member (Ladinian) of the Falang Formation, eastern Yunnan
Province, China. It is primarily characterized by the nasal process of
the premaxilla extending posteriorly well beyond the external naris, the
super-sized coracoid foramen laterally bordered by the scapula, the
ischium with a strongly expanded medial portion anteroposteriorly longer
than the proximodistal height of the bone, and anteriorly notched
cervical osteoderms. <i>D</i>. <i>fuyuanensis</i> is a pseudosuchian on
the basis of the crocodile-normal tarsal joint and other features, such
as the distal end of the ulna in posterolateral view squared off,
osteoderms with a distinct anterior process, the presacral vertebrae
dorsally covered by more than one osteoderm, dorsal osteoderm alignment
dorsal to presacrals 10–24 staggered, the pubis-ischium contact reduced
to a thin proximal contact, and the medial contact of the ischia
extensive but the dorsal margins separate. It is from a marine deposit
but shows few morphological adaptations of the postcranial skeleton for a
semiaquatic way of life when compared with <i>Qianosuchus</i> from the
Anisian limestone of the same area. A phylogenetic analysis derived from
an existing data matrix suggests that the new archosaur occupies the
basal-most position in Poposauroidea and further confirms the
poposauroid status of <i>Qianosuchus</i>. On the basis of current information, the discovery of <i>Diandongosuchus</i>
does not firmly underscore the affinity of the semiterrestrial
vertebrate faunas between the eastern and western regions along the
northern coastline of the Tethys.<br />
________<br />
Also from the new JVP is a report on a new, although rather typical, Late Triassic vertebrate fauna, which includes several archosaurs.<br />
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<div style="color: #45818e; text-align: center;">
Tomasz Sulej, Grzegorz Niedźwiedzki & Robert Bronowicz (2012): A new Late Triassic vertebrate fauna<br />
from Poland with turtles, aetosaurs, and coelophysoid dinosaurs, Journal of Vertebrate Paleontology, 32:5, 1033-1041</div>
<br />
<u>Abstract</u><br />
We report a new site with an occurrence of isolated bones of a <i>Palaeochersis</i>-like
turtle in Norian-Rhaetian fluvial sediments from southern Poland. The
turtle remains are associated with bones of a medium-sized aetosaur, a
coelophysoid dinosaur, and a larger carnivorous archosaur, as well as a
hybodontid shark, ganoid and dipnoan fishes, and a large temnospondyl.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com238tag:blogger.com,1999:blog-7257028403896821073.post-38592895881651250062012-07-16T00:20:00.000-04:002012-07-16T00:20:04.609-04:00Phytosaurs - Some Are Real and Some Are Just DinosaursPhytosaurs may not be crown group archosaurs (according to Nesbitt 2011), but they are definitely important in archosaur evolutionary history as well as Triassic ecology. Stocker's new paper increases the known diversity of phytosaurs with the description of the new species <i>Protome batalaria</i> and reinforces the importance of apomorphy-based identifications. Some recent accounts of partial skeletons have suggested that phytosaurs may have survived into the Early Jurassic, but Barrett and Xu re-affirm their end-Triassic demise and urge caution in identifying poorly preserved, partial remains, which tend to belong to dinosaurs. <br />
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<b style="color: #134f5c;">Stocker,
M. R. 2012. "A new phytosaur (Archosauriformes, Phytosauria) from the Lot’s
Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of
Petrified Forest National Park, Arizona." <i>Journal of Vertebrate Paleontology
</i>32(3): 573-586</b><a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.649815"><b></b></a></div>
<u><b>Abstract </b></u></div>
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<b></b>A
new phytosaur taxon from Petrified Forest National Park, Arizona, is here
described based on cranial material from a single individual. This specimen
previously was included in an extensive phylogenetic analysis, and it was found
to possess a combination of character states that differs from all known
phytosaur taxa in addition to two autapomorphies within the braincase and an
autapomorphy of the mandible. The new taxon adds to the taxonomic diversity
recognized from the Sonsela Member of the Chinle Formation. The continued
increase in phytosaur diversity emphasizes the need to more accurately
characterize and identify taxa within a phylogenetic systematic context in
order to produce a more refined signal for biostratigraphic correlations,
biochronologic inferences, and faunal dynamics during the Late Triassic.</div>
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<b>Barrett, P. M., and X. Xu. 2012. "The enigmatic reptile<i> Pachysuchus imperfectus</i> Young, 1951 from the lower Lufeng Formation (Lower Jurassic) of Yunnan, China." Vertebrata PalAsiatica 50:151-159. [<a href="http://english.ivpp.cas.cn/sp/PalAsiatica/vp_list/201202/t20120209_81207.html">Free download here</a>]</b></div>
<u><b>Abstract </b></u></div>
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<b></b>Phytosaurs are generally
considered to have become extinct at the end of the Triassic Period, but
several records have suggested that they survived into the basal Jurassic in
Europe and Asia. The Asian record consists of Pachysuchus imperfectus from the
lower Lufeng Formation (?Hettangian-Sinemurian) of Yunnan, China. However, this
specimen differs from phytosaurs in numerous aspects and is more likely a
poorly preserved, indeterminate sauropodomorph dinosaur skull. The referred
specimens of this species are also regarded as indeterminate, thereby removing
the post-Triassic record of phytosaurs from Asia. The European records of
Jurassic phytosaurs are also shown to be doubtful, suggesting that this clade
was restricted to the Late Triassic.<span style="font-size: 7.5pt;"> </span></div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com3tag:blogger.com,1999:blog-7257028403896821073.post-75123247346697600232012-07-14T16:26:00.001-04:002012-07-14T16:28:02.544-04:00Recent Papers on Triassic Archosaurs (and Archosauriforms) and Other News<br />
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<span style="color: black;">Several papers regarding Triassic archosaurs have come out recently. The first is a re-evaluation of Proterochamspia, including genera (specifically <i>Proterochamspa</i>) within the clade and a look at its evolutionary history. The second is an interesting look at bipedality and </span><span style="font-family: inherit; font-size: small;">cursoriality in archosaurs. And finally, we have <i>Smok</i>, a new archosaur from Poland. The paper does not commit to which archosaur branch this new animal belongs to (since this is a topic of the author's in-progess PhD), but I would bet money that it's NOT a dinosaur.</span><br />
<br />
<span style="font-family: inherit; font-size: small;">In other news, there is a new paleo blog out there looking at the coevolution between plants and animals - <a href="http://antediluviansalad.blogspot.com/">Antediluvian Salad</a>. Check it out! And while you are checking things out, head over to the <a href="http://www.forgottenarchosaurs.blogspot.com/p/pictures.html">Pictures tab</a> of The Forgotten Archosaurs for some great shots of work going on in Petrified Forest National Park this summer, including the<a href="http://www.flickr.com/photos/sdrymala/sets/72157630486501290/"> Revueltosaurus Quarry</a> and other <a href="http://www.flickr.com/photos/sdrymala/sets/72157630565233244/">PEFO paleo field work</a>.</span><b style="color: #134f5c;"> </b></div>
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<span style="font-size: small;"><span style="color: #134f5c;">Dilkes, D., and A. Arcucci. 2012. "<i>Proterochampsa barrionuevoi</i> (Archosauriformes: Proterochampsia) from the Late Triassic (Carnian) of Argentina and a phylogenetic analysis of Proterochampsia." <i>Palaeontology </i></span><span style="color: #134f5c;">(<a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01170.x/abstract">online</a>)</span></span></div>
<div class="MsoNormal" style="font-family: inherit;">
<span style="font-size: small;"><u>Abstract</u></span></div>
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<span style="font-size: small;">Restudy of skulls and
available postcrania of the proterochampsian archosauriform <i>Proterochampsa barrionuevoi</i> from the
Ischigualasto Formation (Upper Triassic, Carnian) in the San Juan Province,
Argentina, confirms that the genus is diagnosed by autapomorphies that include
dermal sculpturing consisting of prominent ridges and nodular protuberances, a
large hook-like lateral projection on the quadratojugal, an antorbital fossa
restricted to a depression along the maxilla, lateral expansion of the
premaxilla anterior to the premaxilla–maxilla contact, absence of a
supratemporal fossa, exclusion of jugal from suborbital fenestra, basal tubera
of parabasisphenoid facing ventrally and reaching laterally beyond the
basipterygoid process, and a ventral lamina on the angular. <i>Proterochampsa nodosa</i> is a valid species
distinguished from <i>P. barrionuevoi</i> by
fewer cranial ridges with larger protuberances, relatively smaller
supratemporal fenestrae and width of frontals between orbits less than that of
the nasals. A phylogenetic analysis supports the monophyly of Proterochampsia
consisting of <i>Proterochampsa,
Chanaresuchus bonapartei, Gualosuchus reigi, Tropidosuchus romeri</i> and <i>Cerritosaurus binsfeldi</i>. A temporal
separation between the two basal proterochampsians with earliest records in the
Late Triassic (<i>Proterochampsa</i> and <i>Cerritosaurus</i>) and <i>Chanaresuchus, Gualosuchus</i> and <i>Tropidosuchus</i>
in the Middle Triassic indicates hidden proterochampsian diversity in the
Middle Triassic.</span></div>
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<span style="font-size: small;"><br /></span></div>
<div class="MsoNormal" style="color: #134f5c; font-family: inherit; text-align: center;">
<span style="font-size: small;">Kubo, T., and M. O. Kubo. 2012. "Associated
evolution of bipedality and cursoriality among Triassic archosaurs: a phylogenetically
controlled evaluation." <i>Paleobiology </i>38: 474–485. (<a href="http://www.bioone.org/doi/full/10.1666/11015.1">online</a>)</span></div>
<div class="MsoNormal" style="font-family: inherit;">
<span style="font-size: small;"><u>Abstract</u></span></div>
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<span style="font-family: inherit; font-size: small;">Bipedalism evolved more
than twice among archosaurs, and it is a characteristic of basal dinosaurs and
a prerequisite for avian flight. Nevertheless, the reasons for the evolution of
bipedalism among archosaurs have barely been investigated. Comparative analysis
using phylogenetically independent contrasts showed a significant correlation
between bipedality (relative length of forelimb) and cursoriality (relative
length of metatarsal III) among Triassic archosaurs. This result indicates
that, among Triassic archosaurs, bipeds could run faster than quadrupeds.
Bipedalism is probably an adaptation for cursoriality among archosaurs, which
may explain why bipedalism evolved convergently in the crocodilian and bird
lineages. This result also indicates that the means of acquiring cursoriality
may differ between archosaurs and mammals.</span><span style="font-family: inherit; font-size: small;"> </span></div>
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<span style="font-size: small;"><br /></span></div>
<div class="MsoNormal" style="font-family: inherit; text-align: center;">
<span style="font-size: small;"><span style="color: #134f5c;">Niedźwiedzki,
G., T. Sulej, and J. Dzik. 2012. "A large predatory archosaur from the Late
Triassic of Poland." <i>Acta Palaeontologica Polonica</i> 57 (2): 267-276. (<a href="http://dx.doi.org/10.4202/app.2010.0045">online</a>) </span></span></div>
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<span style="font-size: small;"><u>Abstract</u> </span><br />
<span style="font-size: small;">We
describe a new large predatory archosaur, <i>Smok
wawelski </i>gen. et sp. nov., from the latest Triassic (latest
Norian–early Rhaetian; approximately 205–200 Ma) of Lisowice (Lipie Śląskie
clay−pit) in southern Poland. The length of the reconstructed skeleton is 5–6 m
and that of the skull 50–60 cm, making <i>S.
wawelski </i>larger than any other known predatory archosaur from the
Late Triassic and Early Jurassic of central Europe (including theropod
dinosaurs and “rauisuchian” crurotarsans). The holotype braincase is associated
with skull, pelvic and isolated limb−bones found in close proximity (within 30
m), and we regard them as belonging to the same individual. Large, apparently
tridactyl tracks that occur in the same rock unit may have been left by animals
of the same species. The highly autapomorphic braincase shows large attachment
areas for hypertrophied protractor pterygoideus muscles on the lateral surface
and a wide, funnel−like region between the basal tubera and basipterygoid
processes on the ventral surface. The skeleton (cranial and postcranial)
possesses some features similar to those in theropod dinosaurs and others to
those in large crocodile−line archosaurs (“rauisuchians”), rendering phylogenetic
placement of <i>S.
wawelski </i>difficult at this time.</span></div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com5tag:blogger.com,1999:blog-7257028403896821073.post-15641820676734817362012-07-08T18:07:00.001-04:002012-07-08T18:07:21.057-04:00Revueltosaurus Quarry- The Evolution of A Jacket<div class="separator" style="clear: both; text-align: center;">
<a href="http://1.bp.blogspot.com/-rxPO2A_wTy8/T-pp1H-FVcI/AAAAAAAADkI/rltue3JL0N0/s1600/Paleo+by+Jeff+Martz.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="126" src="http://1.bp.blogspot.com/-rxPO2A_wTy8/T-pp1H-FVcI/AAAAAAAADkI/rltue3JL0N0/s640/Paleo+by+Jeff+Martz.jpg" width="640" /></a></div>
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In field paleontology, one of the most important things you do once you find bone is create a proper field jacket. Jeff Martz recently created a nice little cartoon that describes the typical steps involved in jacketing bone once it's found (above), although he does leave out a very important final step - carrying the jacket out of the field. Here I'll show you what these steps look like in real life - an example from the Revueltosaurus Quarry - as we go from finding bone to bringing it home.<br />
<br />
Step 1 was complete in 2004, when Bill Parker and his interns discovered this site while prospecting. In anticipation of finding more bone, we've been excavating (Step 2) since the beginning of the summer. A little over two weeks ago (June 22nd, 2012), we removed the first two big jackets from the <i>Revueltosaurus </i>Quarry here at PEFO. One weighed around 100 lbs, the other over 300 lbs. The 300 lb jacket contained what is likely an entire individual revueltosaur.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-YFnBezMNMPM/T_nqBpmgUFI/AAAAAAAADkU/YIHx64JkS38/s1600/IMG_4497.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://2.bp.blogspot.com/-YFnBezMNMPM/T_nqBpmgUFI/AAAAAAAADkU/YIHx64JkS38/s400/IMG_4497.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slowly outlining where the bone is. It's hard to see, but the bone is a faint orange color in the middle of the photo.</td></tr>
</tbody></table>
We first encountered bone in the general area on June 2nd when Frankee Sena pulled out a big chunk of overburden with bone on it. Since it came from a hole, we all had to start bringing things down to that level in the surrounding area. I found a few isolated vertebrae, but then on June 4th, we found the jackpot. The bone just wouldn't stop. This is the point when, even though we just spent days (if not weeks) hoping to find bones, we started cursing each new bone that we found. It's starts to get overwhelming. And in the back of our minds, as we watched the area of bone expand, we were all thinking "this is going to be a really heavy jacket".<br />
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<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-dySCP4evSss/T_nsLsdl36I/AAAAAAAADkc/dkYIo3-NS10/s1600/IMG_4527.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://1.bp.blogspot.com/-dySCP4evSss/T_nsLsdl36I/AAAAAAAADkc/dkYIo3-NS10/s400/IMG_4527.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Jacketing some parts of the block as Bill continues to define the edges.</td></tr>
</tbody></table>
We managed to define a few edges (Step 3) before the end of the day, so I started to jacket (Step 4) part of the block. It's important to protect the bone as best you can when excavating, so if you can start to jacket something, you should. First I put down a separator (toilet paper) then started adding plaster (small plaster medical bandages).<br />
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<a href="http://2.bp.blogspot.com/-G1BeYRSmjnU/T_nzYSE9egI/AAAAAAAADk4/SXJmjbe8csI/s1600/IMG_4558.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="262" src="http://2.bp.blogspot.com/-G1BeYRSmjnU/T_nzYSE9egI/AAAAAAAADk4/SXJmjbe8csI/s400/IMG_4558.JPG" width="400" /></a></div>
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The block continued to expand, until we were finally able to define all the edges (Step 3) by June 12. By June 15, we had a complete, jacketed block. We also had the second block starting to take shape right beside it. Bill managed to recruit some help to haul these two jackets out of the quarry and up out of the badlands, so by June 21, we were ready to flip them both (Step 5). A testament to good jacketing, both blocks flipped perfectly, with no signs flexing. <br />
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<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-aRakilYut48/T_oB1GnRdCI/AAAAAAAADlI/f3lKjNVHmKE/s1600/IMG_4590.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://2.bp.blogspot.com/-aRakilYut48/T_oB1GnRdCI/AAAAAAAADlI/f3lKjNVHmKE/s400/IMG_4590.JPG" width="265" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">With the smaller jacket flipped, Bruce chisels out some excess rock.</td></tr>
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After flipping them, we cleaned some rock off the bottom (to lighten the jacket a bit) and plastered the underside. And on Friday, June 22, the Youth Conservation Corp (YCC) kids arrived to help us carry them out. This post is dedicated to them (and the two park rangers, Lauren and Desmond, who were in charge of wrangling all those teenagers). It took about 2 hours to carry those jackets almost a mile, up and down badlands, including a very steep hill at the end. And all without one word of complaint. Way to go YCC!Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com2tag:blogger.com,1999:blog-7257028403896821073.post-6295599146034905082012-06-03T18:05:00.000-04:002012-06-03T22:10:06.768-04:00Summer at Petrified Forest National ParkI have once again arrived at Petrified Forest National Park (PEFO) for the summer, doing paleontological field work with Bill Parker and several others. This year, we will be prospecting the new tract of land that was added to the park as well as reopening the <i>Revueltosaurus </i>quarry.<br />
<br />
Shortly after leaving the park last year, it expanded by 26,000 acres through the purchase of the Hatch Ranch. This area encompasses a large area to the east and northeast of Blue Mesa (including Ninemile Wash) as well as a smaller area to the west (<a href="http://www.nps.gov/pefo/planyourvisit/upload/PEFO_park_map_2006_large.pdf">view park map</a>). Most importantly, it includes strata of the Chinle Formation that are not exposed in the rest of the park, increasing the potential for important finds in the park. I got to spend some time in the expansion area last summer and it is definitely a great resource for paleontologists. This summer, we will start to explore these lands for vertebrate fossils.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-xdJRn4qt1v4/T8vJWxVopqI/AAAAAAAADjM/MYJsQbEVHqk/s1600/IMG_2266.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="265" src="http://1.bp.blogspot.com/-xdJRn4qt1v4/T8vJWxVopqI/AAAAAAAADjM/MYJsQbEVHqk/s400/IMG_2266.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hatch Ranch - Expansion Area (2011)</td></tr>
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<br />
Bill Parker was quoted as saying the following in the <a href="http://www.nps.gov/pefo/parknews/park-boundary-expansion.htm">NPS news article</a> about the expansion of the park:<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-TnooM1RZFjU/T8vUYHOBm0I/AAAAAAAADjk/UFu4olnMVLU/s1600/IMG_4463.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="http://2.bp.blogspot.com/-TnooM1RZFjU/T8vUYHOBm0I/AAAAAAAADjk/UFu4olnMVLU/s400/IMG_4463.JPG" width="265" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Revueltosaurus </i>quarry 2012</td></tr>
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<div style="color: #134f5c; text-align: center;">
<i>Historically the park has been expanded south to north, while the
main resource rich exposures run east to west. Acquisition of these
lands by the park brings some of the most fossil rich areas into the
park for protection and future paleontological research. The fossils on
these lands will add greatly to our understanding of life on earth
during the Late Triassic and provide research opportunities for years to
come.</i>-Bill Parker, paleontologist, 2011.</div>
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<div style="color: #134f5c; text-align: left;">
<span style="color: black;">The <i>Revueltosaurus </i>quarry was discovered in 2004 in the north end of the park, not far from Lacey Point. Bill Parker and crew found several bones weathering out of the side of a hill, which upon further investigation, revealed multiple<i> in situ </i>individuals of what they later discovered to be R<i>evueltosaurus callenderi</i>. <i>Revueltosaurus </i>was originally described by Hunt (1989) based on several isolated teeth from New Mexico. It has long been thought to be an ornithiscian dinosaur, but the skeletons found by Parker et al (initially discussed by Parker et al 2005) places these animals squarely in the pseudosuchian side of the archosaur tree. Furthermore, Nesbitt (2011) was able to place <i>Revueltosaurus </i>as the sister taxon to aetosaurs.</span></div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://2.bp.blogspot.com/-M3Mi0Y77O7k/T8vNvomduJI/AAAAAAAADjY/QWg8WoHfi8o/s1600/revueltosaurus.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="http://2.bp.blogspot.com/-M3Mi0Y77O7k/T8vNvomduJI/AAAAAAAADjY/QWg8WoHfi8o/s1600/revueltosaurus.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Reconstruction of <i>R. callenderi</i> by Jeff Martz, winner of the 2011 Lanzendorf PaleoArt Prize in Scientific Illustration</td></tr>
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<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-kWXjVeebtXk/T8vV8X-vZXI/AAAAAAAADjw/lXVWctEU3WQ/s1600/IMG_4476.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="133" src="http://4.bp.blogspot.com/-kWXjVeebtXk/T8vV8X-vZXI/AAAAAAAADjw/lXVWctEU3WQ/s200/IMG_4476.JPG" width="200" /></a></div>
<div style="color: #134f5c; text-align: left;">
<a href="http://4.bp.blogspot.com/-yWWyrAWEZoc/T8vX8rL13lI/AAAAAAAADj4/38DCUOeCVY8/s1600/IMG_4477.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="132" src="http://4.bp.blogspot.com/-yWWyrAWEZoc/T8vX8rL13lI/AAAAAAAADj4/38DCUOeCVY8/s200/IMG_4477.JPG" width="200" /></a><span style="color: black;">The quarry was closed in 2006 after recovering material from at least 8 individuals, but there was evidence that more bone was still there to be found. This year, Bill Parker, Bruce Bailey</span>,<span style="color: black;"> and we interns are reopening the quarry. Overburden has already been removed and we have just begun excavating. Things are looking promising already; as of yesterday, we have begun to uncover bone in 3 different areas of the quarry. Bill Parker found the first bone - an osteoderm and vertebra (pictured to the left, top) - while Franceska (a.k.a. Frankie) found several elements fused together while slowly removing overburden towards the middle of the quarry (pictures to the left, bottom). I started trying to remove rock from the quarry floor to get down to the level where Frankie found her bones and ended up running into several vertebrae and a rib. </span></div>
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<span style="color: black;">This should be a pretty great field season.</span></div>
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<div style="color: #134f5c; text-align: left;">
_____________</div>
<div style="color: #134f5c; text-align: left;">
Parker, W. G., R. B. Irmis, S. J. Nesbitt, J. W. Martz, and L. S. Browne. 2005. "The Late Triassic pseudosuchian <i>Revueltosaurus callenderi</i> and its implications for the diversity of early ornithischian dinosaurs." <i>Proceedings of the Roayal Society B</i> 272: 963-969</div>
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<div style="color: #134f5c; text-align: left;">
Hunt, A. P. 1989 A new ornithischian dinosaur from the Bull Canyon Formation (Upper Triassic) of east-central New Mexico. In Dawn of the age of dinosaurs in the American Southwest (ed. S. G. Lucas & A. P. Hunt), pp. 355–358. Albuquerque, NM: New Mexico Museum of Natural History.</div>
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<div style="color: #134f5c; text-align: left;">
Nesbitt, S. J. 2011. "The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades." <i>Bulletin of the American Museum of Natural History,</i> Number 352</div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-44772006172955631802012-03-26T20:53:00.000-04:002012-03-26T20:53:47.893-04:00NCMNS Visit<div class="separator" style="clear: both; text-align: center;"><a href="http://naturalsciences.org/"><img border="0" height="147" src="http://naturalsciences.org/profiles/ncmns/themes/naturalsciences/img/global/footer-logo.gif" width="200" /> </a></div><div class="separator" style="clear: both; text-align: left;"><br />
</div>Last week, I got a chance to visit the <a href="http://naturalsciences.org/">North Carolina Museum of Natural Sciences</a>. Next fall, I will be joining the NC State Biology Department as a grad student and a lot of my research will be done at the museum. My visit included a tour of the collections where I got to see many amazing crurotarsan specimens including the holotypes of <i>Postosuchus alisonae</i> and <i>Dromicosuchus grallator</i>, as well as many great specimens of <i>Deinosuchus</i>.<br />
<br />
<a href="http://3.bp.blogspot.com/-DXiS_S3oV_U/T3EAgs-1vTI/AAAAAAAADi8/l-spjbYi6Gk/s1600/0320NC27.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="213" src="http://3.bp.blogspot.com/-DXiS_S3oV_U/T3EAgs-1vTI/AAAAAAAADi8/l-spjbYi6Gk/s320/0320NC27.JPG" width="320" /></a><i>Postosuchus alisonae</i> was discovered in 1994 in a brick quarry in the Deep River Basin of the Newark Supergroup. The abdominal region included stomach contents preserving remains of at least four different taxa. Underneath <i>Postosuchus </i>they found a partially articulated skeleton of a crocodylomorph, <i>Dromicosuchus grallator,</i><b> </b>bearing teeth marks on its skull and neck. These specimens provide a unique window into the ecology of the Newark and have the potential to tell us much more. <br />
<div class="separator" style="clear: both; text-align: center;"></div>A replica of Postosuchus is on display in the main fossil hall of the museum, but a new wing that will feature some of the amazing real specimens is nearing completion. The <a href="http://naturesearch.org/">Nature Research Center</a> will open next month (April 20th), helping to make scientific research more accessible to the public, and will be featuring a lot of the exciting work that the museum is doing with the Triassic. Postosuchs and Dromicosuchus are just the start.<br />
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<br />
<a href="http://2.bp.blogspot.com/-AciZNmQjlcM/TrlePo6TmOI/AAAAAAAADf4/QFQtKeSEPsw/s1600/raleigh2012.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="200" src="http://2.bp.blogspot.com/-AciZNmQjlcM/TrlePo6TmOI/AAAAAAAADf4/QFQtKeSEPsw/s200/raleigh2012.jpg" width="151" /></a>For those of you who are members of the Society of Vertebrate Paleontology, I hope to see you all at the annual meeting in October, since it is being hosted by the NC Museum of Natural Sciences. I highly recommend that all my other readers make an effort to visit the museum as well. Admission is free and you'll get to see all the exciting research being done on Triassic archosaurs (and other critters). Also, to all the preparators out there, the museum is looking for a curatorial technician/ assistant lab manager (<a href="https://jobs.ncsu.edu/postings/5660">link to job listing</a>). Fair warning, that Triassic mudstone is tough stuff.<br />
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<i><u>Dromicosuchus</u></i> - Sues, Hans-Dieter<span style="color: black;">, </span>Paul E. Olsen<span style="color: black;">, </span>Joseph G. Carter<span style="color: black;">, & </span>Diane M. Scott. 2003. "A new crocodylomorph archosaur from the Upper Triassic of North Carolina" Journal of Vertebrate Paleontology 23(2): 329-343 <a href="http://www.tandfonline.com/doi/abs/10.1671/0272-4634%282003%29023%5B0329%3AANCAFT%5D2.0.CO%3B2">DOI:10.1671/0272-4634(2003)023[0329:ANCAFT]2.0.CO;2</a><br />
<br />
<u>Postosuchus</u> - Peyer, Karin<span style="color: black;">, </span>Joseph G. Carter<span style="color: black;">, </span>Hans-Dieter Sues<span style="color: black;">, </span>Stephanie E. Novak<span style="color: black;">, & </span>Paul E. Olsen. 2008. "A new suchian archosaur from the Upper Triassic of North Carolina" Journal of Vertebrate Paleontology 28(2): 363-381 <a href="http://www.tandfonline.com/doi/abs/10.1671/0272-4634%282008%2928%5B363%3AANSAFT%5D2.0.CO%3B2">DOI:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2</a><br />
<span style="color: black;"></span>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com3tag:blogger.com,1999:blog-7257028403896821073.post-45792350128934830792012-02-01T08:42:00.002-05:002012-02-02T09:36:33.624-05:00Shield Croc - Aegisuchus<div class="separator" style="clear: both; text-align: center;"><a href="http://www.abc.net.au/reslib/201202/r887648_8873808.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://www.abc.net.au/reslib/201202/r887648_8873808.png" /></a></div> <br />
"Shieldcroc" (aka. <i>Aegisuchus witmeri</i> gen. et sp. nov.) has just been published by Casey Holiday and Nick Gardner at PLoS One. The large (approx. 2-3 meter skull, 15-22 meter body) eusuchian is a member of Aegyptosuchidae from the Late Cretaceous of northern Africa (Kem Kem Formation, Morocco). Holiday and Gardner find Aegyptosuchidae to be the sister taxon to Crocodylia, challenging the biogeographic hypothesis that crown-group crocodylians originated in Laurasia. The most striking feature of <i>Aegisuchus </i>is its unique skull. It is extremely flat (shaped like a shield), with adaptations for strong jaw opening and a novel vascular integumentary structure, suggesting use for thermoregulation and/or display.<i> </i><br />
<div style="color: #134f5c;"><i><br />
</i></div><div style="color: #134f5c; text-align: center;">Holliday C.M., and N. M. Gardner. 2012. "A New Eusuchian Crocodyliform with Novel Cranial Integument and Its Significance for the Origin and Evolution of Crocodylia." PLoS ONE 7(1) <a href="http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0030471">doi:10.1371/journal.pone.0030471</a></div><div style="text-align: center;"><br />
</div><div style="text-align: left;"><u>Abstract</u></div><div style="text-align: left;">Crocodyliforms were one of the most successful groups of Mesozoic tetrapods, radiating into terrestrial, semiaquatic and marine environments, while occupying numerous trophic niches, including carnivorous, insectivorous, herbivorous, and piscivorous species. Among these taxa were the enigmatic, poorly represented flat-headed crocodyliforms from the late Cretaceous of northern Africa. Here we report a new, giant crocodyliform from the early Late Cretaceous (Cenomanian) Kem Kem Formation of Morocco. Represented by a partial braincase, the taxon has an extremely long, flat skull with large jaw and craniocervical muscles. The skull roof is ridged and ornamented with a broad, rough boss surrounded by significant vascular impressions, likely forming an integumentary structure unique among crocodyliforms. Size estimates using endocranial volume indicate the specimen was very large. The taxon possesses robust laterosphenoids with laterally oriented capitate processes and isolated epipterygoids, features allying it with derived eusuchians. Phylogenetic analysis finds the taxon to be a derived eusuchian and sister taxon to <i>Aegyptosuchus</i>, a poorly understood, early Late Cretaceous taxon from the Bahariya formation. This clade forms the sister clade of crown-group Crocodylia, making these taxa the earliest eusuchian crocodyliforms known from Africa. These results shift phylogenetic and biogeographical hypotheses on the origin of modern crocodylians towards the circum-Tethyean region and provide important new data on eusuchian morphology and evolution.</div><div style="text-align: center;"><br />
</div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com6tag:blogger.com,1999:blog-7257028403896821073.post-89882698093158873362012-01-19T15:35:00.000-05:002012-01-19T15:35:42.463-05:00A New Aetosaur<div style="color: #0c343d; text-align: center;">Julia B. Desojo, Martin D. Ezcurra, and Edio E. Kischlat. 2012. "A new aetosaur genus (Archosauria: Pseudosuchia) from the early Late Triassic of southern Brazil" <a href="http://www.mapress.com/zootaxa/content.html"><i>Zootaxa </i>3166: 1–33</a></div><br />
<b>Abstract</b><br />
We describe the new aetosaur <i>Aetobarbakinoides brasiliensis</i> gen. et sp. nov. from the early Late Triassic (late Carnian - early Norian) Brazilian Santa Maria Formation. The holotype is composed of a partial postcranium including several cervical and dorsal vertebrae and ribs, one anterior caudal vertebra, right scapula, right humerus, right tibia, partial right pes, and anterior and mid-dorsal paramedian osteoderms. <i>Aetobarbakinoides </i>is differentiated from other aetosaurs by the presence of cervical vertebrae with widely laterally extended prezygapophyses, mid-cervical vertebrae with anterior articular facet width more than 1.2 times wider than the posterior one, anterior caudal vertebrae with extremely anteroposteriorly short prezygapophyses, elongated humerus and tibia in relation to the axial skeleton, and paramedian osteoderms with a weakly raised anterior bar. A cladistic analysis recovered the new species as more derived than the South American genera <i>Aetosauroides </i>(late Carnian-early Norian) and <i>Neoaetosauroides </i>(late Norian-Rhaetian), and it is nested as the sister-taxon of an unnamed clade, composed of Typothoracisinae and Desmatosuchinae, due to the absence of a ventral keel in the cervical vertebrae. <i>Aetobarbakinoides </i>presents a skeletal anatomy previously unknown among South American aetosaurs, with the combination of presacral vertebrae with hyposphene, anteroposteriorly short and unkeeled cervical vertebrae, gracile limbs, and paramedian osteoderms with a weakly raised anterior bar. <i>Aetobarbakinoides </i>is among the oldest known aetosaurs together with <i>Aetosauroides </i>from Argentina and Brazil and Stagonolepis robertsoni from Scotland, indicating a widely distributed early record for the group. In addition, the recognition of a suite of derived features in <i>Aetobarbakinoides</i>, which is one of the oldest known aetosaurs, is in agreement with an older origin for the group, as it is expected by the extensive ghost lineages at the base of the main pseudosuchian clades.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-59302158953223115602012-01-13T12:42:00.000-05:002012-01-13T12:42:59.161-05:00First Symposium on the Evolution of Crocodyliforms<div class="separator" style="clear: both; text-align: center;"><a href="http://onlinelibrary.wiley.com/doi/10.1111/zoj.2011.163.issue-s1/issuetoc"><img border="0" src="http://onlinelibrary.wiley.com/store/10.1111/zoj.2011.163.issue-s1/asset/cover.gif?v=1&s=ce70c3c6f49fffdb5182803df4fb595fdc99ace6" /></a></div><br />
It seems the special issue of the Zoological Journal of the Linnean Society, "<a href="http://onlinelibrary.wiley.com/doi/10.1111/zoj.2011.163.issue-s1/issuetoc">1st Symposium on the Evolution of Crocodyliforms</a>", has finally appeared online. It introduces several new species and focuses on the great diversity of the lineage in an attempt to remove the stigma of crocodiles being considered living fossils. You can read the issue and get the details by following the above link, but I will give you the highlights.<br />
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The volume presents six new species (five new genera), bringing the count for new crocs of 2011 up to 17. Pol & Powell describe <i style="color: #0c343d;">Lorosuchus nodosus</i><span style="color: #0c343d;"> gen. et sp. nov.</span>, a basal mesoeucrocodylian (Sebecidae) from the Paleocene of Argentina. Two new notosuchians from the Upper Cretaceous of Brazil are described: <i style="color: #0c343d;">Caryonosuchus pricei</i><span style="color: #0c343d;"> gen. et sp. nov.</span> (Spageosauridae) (Kellner et al. a.) and<span style="color: #0c343d;"> </span><i style="color: #0c343d;">Labidiosuchus amicum</i><span style="color: #0c343d;"> gen. et sp. nov.</span> with its bizarre dentition (a symphyseal dental battery) (Kellner et al. b.). Andrade et al present <i style="color: #0c343d;">Goniopholis kiplingi</i><span style="color: #0c343d;"> sp. nov.</span> (Lower Cretaceous, England) with a review of the genus and an updated definition, restricting <i>Goniopholis </i>to the Upper Jurassic-Lower Cretaceous of Europe. Clark describes several partial skeletons of a basal crocodyliform (Shartegosuchidae) from the Late Jurassic of Colorado (USA), naming it <i style="color: #0c343d;">Fruitachampsa callisoni</i><span style="color: #0c343d;"> ge. nov., sp. nov.</span>. The last new croc of the issue is <i style="color: #0c343d;">Pieraroiasuchus ormezzanoi</i><span style="color: #0c343d;"> gen. nov., sp. nov.</span>, based on two fully articulated individuals from the Cretaceous of Italy, belonging to the Hylaeochamsidae (Buscalioni et al).<br />
<br />
The volume also includes discussions of existing taxa, some with descriptions of new specimens. Riff et al look at the features of <i>Stratiotosuchus maxhechti</i> that support the view of baurusuchids as active terrestrial predators and their convergence with theropod dinosurs. The cranial anatomy of <i>Baurusuchus albertoi</i> is described and a phylogenetic analysis of baurusuchids is presented with the new data (Nascimento & Zaher). Moraes-Santos et al provide a brief report describing a new specimen of gavialoid from Brazil. Another review article examines abnormalities in the type specimen of <i>Stratiotosuchus maxhechti</i> revealing bone pathologies from two distinct injuries and insect boring marks (Cabral et al). Soto et al describe a new specimen of <i>Uruguaysuchus aznarezi</i> from the type locality. Brochu describes cranial fragments of <i>Necrosuchus ionensis</i>, revealing caimanine affinities, also providing a review of Paleocene-Eocene caiman biogeography. The issue includes a redescription of <i>Meridiosaurus vallisparadisi</i> with a phylogenetic analysis confirming the monophyly of Pholidosauridae, including a new definition (Fortier et al). Also, Figueiredo et al discuss a new specimen, comprised of postcranial remains, of <i>Susisuchus anatoceps</i>, revealing it as a basal neosuchian.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-7269419154909025452012-01-12T16:05:00.003-05:002012-01-12T20:55:56.039-05:00New Jersey BorealosuchusThe first new croc of 2012 - Borealosuchus threeensis. Yes, that's three-ensis, so named because it was found near exit 3 of the New Jersey turnpike.<div style="color: #0c343d; text-align: center;"><br />
</div><div style="color: #0c343d; text-align: center;">Christopher A. Brochu, David C. Parris, Barbara Smith Grandstaff, Robert K. Denton Jr. & William B. Gallagher. 2012. "A new species of <i>Borealosuchus </i>(Crocodyliformes, Eusuchia) from the Late Cretaceous–early Paleogene of New Jersey." Journal of Vertebrate Paleontology 32(1): 105-116 <a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.633585">DOI:10.1080/02724634.2012.633585</a></div><div style="color: black;"><br />
</div><div style="color: black;"><u>Abstract</u></div><div style="color: black;">A lower jaw and associated postcranial remains from the Late Cretaceous–early Paleocene Hornerstown Formation of New Jersey form the basis of a new crocodyliform species, <i>Borealosuchus threeensis</i>. Although one of the oldest known species of <i>Borealosuchus</i>, phylogenetic analysis supports a closer relationship to <i>Borealosuchus</i> from the early Eocene than with other Late Cretaceous or early Paleocene forms. This is based on the shared presence of a short mandibular symphysis excluding the splenial, a small external mandibular fenestra, and ventral osteoderms composed of two sutured ossifications. It is also similar to <i>Borealosuchus</i> material from the Paleocene of western Texas, though conspecificity cannot be demonstrated at present. A close relationship with the basal alligatoroids <i>Leidyosuchus</i> or Diplocynodontinae is not supported. The distribution of lower jaws with very small slit-like external mandibular fenestrae, or no fenestrae at all, among basal crocodylian lineages (including <i>Borealosuchus</i>) and close crocodylian relatives suggests the fenestrae may have been ancestrally absent in Crocodylia and regained two or more times. Current phylogenetic hypotheses are consistent with dispersal of more-derived species of <i>Borealosuchus</i> to the Western Interior during the Paleocene, and they indicate the presence of several unsampled lineages crossing the Cretaceous-Paleogene boundary.</div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com2tag:blogger.com,1999:blog-7257028403896821073.post-55252139902742488082011-12-31T14:00:00.003-05:002012-01-02T19:40:08.021-05:00The Year In CrocsEach year, thanks to the hard work of a lot of great paleontologists, we get to add some new members to our favorite clade. In 2011, a total of <strike>9</strike> 11 crurotarsans were named (and by this I mean they were named in a peer-reviewed paper with a publication date in 2011). Check out the list below:<br />
<ul><li><u><i><b style="color: #134f5c;">Theriosuchus grandinaris</b></i> - a Late Jurassic/Early Cretaceous neosuchian from Thailand</u> - in <span style="color: #0c343d;">Lauprasert, K., C. Laojumpon, W. Saenphala, G. Cuny, K. Thirakhupt, and V. Suteethorn. 2011. "Atoposaurid crocodyliforms from the Khorat Group of Thailand: first record of Theirosuchus from Southeast Asia." </span><i style="color: #0c343d;">Paläontologische Zeitschrift</i><span style="color: #0c343d;"> 85(1): 37-47. </span><a href="http://www.springerlink.com/content/b28737j414063982/" style="color: #0c343d;"><span class="doi"><span class="label">DOI:</span> <span class="value">10.1007/s12542-010-0071-z</span></span></a> </li>
</ul><ul><li><u><b style="color: #134f5c;"><i>Decuriasuchus quartacolonia</i></b> - a Triassic rauisuchian from Brazil</u> - in <span style="color: #0c343d;">Franca, M. A. G. and J. Ferigolo. 2011. 'Associated skeletons of a new middle Triassic "Rauisuchian" from Brazil' </span><i style="color: #0c343d;">Naturwissenschaften </i><span style="color: #0c343d;">98 (5): 389-395 </span><a href="http://www.springerlink.com/content/431nmk50220u113q/" style="color: #0c343d;">DOI: 10.1007/s00114-011-0782-3</a><span style="color: #0c343d;"> </span></li>
</ul><div class="separator" style="clear: both; text-align: center;"><a href="http://3.bp.blogspot.com/-CettDzjwoSc/TaXrEZ4oj_I/AAAAAAAADFw/RpSY4iXKOxw/s1600/Decuriasuchus.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="107" src="http://3.bp.blogspot.com/-CettDzjwoSc/TaXrEZ4oj_I/AAAAAAAADFw/RpSY4iXKOxw/s400/Decuriasuchus.png" width="400" /></a></div><ul><li><u><b style="color: #134f5c;"><i>Neptunidraco ammoniticus</i></b> - a Jurassic metriorhynchid from Italy</u> - in <span style="font-size: small;"><span class="messageBody" style="color: #0c343d;">Cau, A. & F. Fanti. (2011) "The oldest known metriorhynchid crocodylian from the Middle Jurassic of North-eastern Italy, <i>Neptunidraco ammoniticus</i> gen. et sp. nov." Gondwana Research 19(2): 550-565. </span><a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7XNB-50R236P-1&_user=10&_coverDate=03%2F31%2F2011&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=1658f864e15510ce2d7febf242228059&searchtype=a" style="color: #0c343d;">doi:10.1016/j.gr.2010.07.007</a> </span></li>
</ul><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://images.nationalgeographic.com/wpf/media-live/photos/000/307/cache/crocodile-fossil-kitchen-counter_30763_600x450.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="246" src="http://images.nationalgeographic.com/wpf/media-live/photos/000/307/cache/crocodile-fossil-kitchen-counter_30763_600x450.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Andrea Cau, study co-author, posing with the counter top and a reconstruction of <i>Neptunidraco </i>(from <a href="http://news.nationalgeographic.com/news/2010/12/101230-new-prehistoric-crocodile-science-paleontology/">Nat Geo</a>)</td></tr>
</tbody></table><ul><li><u><b style="color: #134f5c;"><i>Campinasuchus dinizi</i></b> - a Cretaceous baurusuchid from Brazil</u> - in <span style="color: #0c343d; font-family: inherit;">Carvalho, I. D. S., V. D. P. A. Teixeira, M. L. D. F. Ferraz, L. C. B. Ribeiro, A. G. Martinelli, F. M. Neto, J. J. W. Seritch, G. C. Cunha, I. C. Cunha, and P. F. Ferraz. 2011. "</span><span style="color: #0c343d; font-family: inherit; font-size: small;"><i>Campinasuchus dinizi </i>gen. et sp. nov., a new Late Cretaceous baurusuchid (Crocodyliformes) from the Bauru Basin, Brazil"</span><span style="color: #0c343d; font-family: inherit;"> </span><i style="color: #0c343d; font-family: inherit;">Zootaxa </i><span style="color: #0c343d; font-family: inherit;">2871: 19-42 </span><a href="http://www.mapress.com/zootaxa/2011/f/zt02871p042.pdf" style="color: #0c343d; font-family: inherit;">Open access online</a><span style="color: #0c343d; font-family: inherit;">.</span></li>
</ul><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://3.bp.blogspot.com/-t8FHeSjg3X4/TchNRdtChII/AAAAAAAADSE/Jm87eth6ixo/s1600/campinasuchus.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="227" src="http://3.bp.blogspot.com/-t8FHeSjg3X4/TchNRdtChII/AAAAAAAADSE/Jm87eth6ixo/s320/campinasuchus.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Life reconstruction (by Rodolfo Nogueira) of <i>Campinasuchus dinizi</i> from Carvalho et al 2011</td></tr>
</tbody></table><ul><li><u><span style="font-size: small;"><b style="color: #134f5c;"><i>Arenysuchus gascabadiolorum</i></b></span> - a Cretaceous crocodyloid from Spain</u> - in <span style="color: #0c343d;">Puertolas, E., J. I. Canudo, P. Cruzado-Caballero. 2011. "A New Crocodylian from the Late Maastrichtian of Spain: Implications for the Initial Radiation of Crocodyloids." </span><i style="color: #0c343d;">PLoS ONE</i><span style="color: #0c343d;"> 6(6) </span><a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020011">doi:10.1371/journal.pone.0020011</a></li>
</ul><ul><li><u><i style="color: #134f5c;"><b>Pissarrachampsa sera</b></i> -a Cretaceous baurusuchid fro Brazil</u> - in <span style="color: #0c343d;">Montefeltro, F. C., H. C. E. Larsson, and M. C. Langer. 2011. "A New Baurusuchid (Crocodyliformes, Mesoeucrocodylia) from the Late Cretaceous of Brazil and the Phylogeny of Baurusuchidae." </span><i style="color: #0c343d;">PLoS ONE</i><span style="color: #0c343d;"> 6(7). </span><a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0021916">doi:10.1371/journal.pone.0021916</a></li>
</ul><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-F92qdzrHUFc/Tv9USirPKHI/AAAAAAAADgk/ZXuCgoGXSUw/s1600/pissarrachampsa.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://1.bp.blogspot.com/-F92qdzrHUFc/Tv9USirPKHI/AAAAAAAADgk/ZXuCgoGXSUw/s320/pissarrachampsa.png" width="285" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">From Figure 3 of Montefeltro et al 2011</td></tr>
</tbody></table><ul><li><u><i style="color: #134f5c;"><b>Archerontisuchus guajiraensis</b></i> -a Paleocene dyrosaurid from Colombia</u> - in <span style="color: #0c343d;">Hastings, A. K., J. I. Bloch, and C. A. Jaramillo. 2011. "A new longirostrine dyrosaurid (Crocodylomorpha, Mesoeucrocodylia) from the Paleocene of north-eastern Colombia: biogeographic and behavioural implications for New-World Dyrosauridae." </span><i style="color: #0c343d;">Palaeontology</i><span style="color: #0c343d;">, 54: 1095–1116. </span><a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2011.01092.x/abstract" style="color: #0c343d;">doi: 10.1111/j.1475-4983.2011.01092.x</a><span style="color: #0c343d;"> </span></li>
</ul><ul><li><u><b style="color: #134f5c;"><i>Caipirasuchus paulistanus</i></b> - a Cretaceous sphagesaurid from Brazil</u> - in <span style="color: #0c343d;">Fabiano V. Ioria and Ismar S. Carvalhoa. 2011. "</span><i style="color: #0c343d;">Caipirasuchus paulistanus</i><span style="color: #0c343d;">, a new sphagesaurid (Crocodylomorpha, Mesoeucrocodylia) from the Adamantina Formation (Upper Cretaceous, Turonian–Santonian), Bauru Basin, Brazil" Journal of Vertebrate Paleontology 31(6): 1255-1264 </span><a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.602777" style="color: #0c343d;">DOI:10.1080/02724634.2011.602777</a><span style="color: #0c343d;"> </span></li>
</ul><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://1.bp.blogspot.com/-JREbBWnO5qI/Tv0nK7JJEiI/AAAAAAAADgM/Leg7C0KW-0w/s1600/caipirasuchus.png" style="margin-left: auto; margin-right: auto;"><img border="0" height="248" src="http://1.bp.blogspot.com/-JREbBWnO5qI/Tv0nK7JJEiI/AAAAAAAADgM/Leg7C0KW-0w/s320/caipirasuchus.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Reconstruction of <i>Caipirasuchus </i>by D. Silva in Fabiano et al.</td></tr>
</tbody></table><br />
[Edit] I have been informed that there are three additional new crocs for this year. I overlooked them because they are named in a massive volume published by the Palaeontological Association, number 14 in their Field Guide to Fossils series. The contents of <a href="http://www.palass.org/beta/eps/shop/product/english-wealden-fossils/"><i>English Wealden Fossils</i></a> <em></em>are not available in any digital format, so reading about the new crocs requires purchasing the book. Fortunately, some brief comments are available over at <a href="http://blogs.scientificamerican.com/tetrapod-zoology/2011/12/02/english-wealden-fossils/">Tetrapod Zoology</a>.<br />
<ul><li><u><i style="color: #0c343d;"><b>Goniopholis willetti </b></i>- an Early Cretaceous goniopholidid from England</u></li>
<li> <u><i style="color: #0c343d;"><b>Anteophthalmosuchus hooleyi </b></i>- an Early Cretaceous goniopholidid from England</u></li>
<li><u><i style="color: #0c343d;"><b>Leiokarinosuchus brookensis</b></i> - an Early Cretaceous neosuchian from England</u></li>
</ul>in <span style="color: #134f5c;">Salisbury, S. W. & Naish, D. 2011. "Crocodilians." In Batten, D. J. (ed.) </span><em style="color: #134f5c;">English Wealden Fossils</em><span style="color: #134f5c;">. The Palaeontological Association (London), pp. 305-369</span><br />
<span style="color: #0c343d;"><br />
</span>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com5tag:blogger.com,1999:blog-7257028403896821073.post-84744788456944851182011-12-29T21:33:00.000-05:002011-12-29T21:33:33.756-05:00SVP 2011 Roundup - American Alligator Special EditionOops! Looks like I forgot to post my summaries of the remaining 8 crurotarsan-themed abstracts from this year's SVP. In my defense though, several of them were focused on making inferences about dinosaurs, so my subconscious mind may have let things slip. Better late than never.<br />
<br />
The American alligator (<i>Alligator mississippiensis</i>) seemed to be particularly popular this year, with a total of 8 abstracts dedicated to discussing aspects of the species' anatomy. Considering the alligator's availability for research and usefulness in studying extinct archosaurs, it's no surprise that these animals are such popular subjects for study.<br />
<br />
<u>Talks</u><br />
<div style="color: #134f5c;">"<b>An intra-skeletal bone microanalysis of <i>Alligator mississippiensis</i> and its application to non-avian dinosaur osteohistology</b>." Woodward, H.</div><ul><li>Osteohistologic analysis of <i>Alligator mississippiensis</i>. Results:</li>
<ul><li>each bone in an individual forms the same growth marks</li>
<li>femur, humerus, and tibiae have the highest growth rates</li>
<li>captive individuals show higher periodic growth than wild individuals = eco-phenotypic plasticity</li>
</ul><li>Used results to infer aspects of ornithiscian dinosaur growth. Results:</li>
<ul><li>basal ornithopods: rapid mineral deposition (tibia and femur) for only 2-3 growth cycles followed by slow deposition</li>
<li><i>Maiasaurus </i>shows high growth rates throughout ontogeny</li>
</ul></ul><div style="color: #134f5c;">"<b>Development of the lung in <i>Alligator mississippiensis</i> (Archosauria: Crocodylomorpha) and the evolution of the Archosaurian respiratory system</b>." Schachner, E., Metzger, R., and Farmer, C. G.</div><ul><li>description of the development of <i>Alligator mississippiensis</i> bronchi (and comparison with those of chickens)</li>
<li>investigation of the effects on oxygen tension morphogenesis during development</li>
<li>formation of bronchial chambers by branching morphogenesis with striking similarities in formation between alligators and birds</li>
<li>data suggest that lung development in extant archosaurs is determined by similar molecular and genetic programs </li>
</ul><div style="color: #134f5c;">"<b>Microstructure of the femoral growth plate in the American alligator: effects of growth rate, locomotor activity and circulatory pattern.</b>" Owerkowicz, T., Yang, J., Blank, J., Eme, J., and Hicks, J.</div><ul><li>Are growth plates with a highly irregular border at the chondro-osseous junction a synapomorphy of dinosaur? Can growth plate thickness be used to determine skeletal growth rate?</li>
<li>Alligator growth plates show highly irregular chondro-osseous borders</li>
<li>Alligator growth plate height shows significant correlation with longitudinal growth rate</li>
<li>data suggest that growth plates are sensitive to systemic arterial oxygen tension and that an irregular chondro-osseous junction is an ancestral character of archosaurs</li>
<li>"propose a thicker growth plates appeared concurrently with the origin of in-series circulation, and may thus have set the stage for later acquisition of fast growth and endothermic metabolism in birds."</li>
</ul><div style="color: #134f5c;">"<b>Pelvic anatomy of <i>Alligator mississippiensis</i> and its significance for interpreting limb function in fossil archosaurs</b>." Tsai, H., Holliday, C., and Ward, C.</div><ul><li>test the hypothesis that accurately predicting in-vivo range of motion in the hip of the American alligator cannot be done using hard tissue manipulation alone</li>
<li>first description of American alligator acetabular anatomy</li>
<li>data show that the bone-only model enabled for more movement than the soft-tissue model</li>
<li>"this study provides new insight into soft tissue structures and their osteological correlations in the archosaur hip joint."</li>
</ul><br />
<u>Posters</u><br />
<div style="color: #134f5c;">"<b>Skeletochronology of the American alligator (<i>Alligator mississippiensis</i>): the utility of various elements for determining growth patterns and longevity</b>." Garcia, B.</div><ul><li>histological analysis of every bone type in American alligators</li>
<li>shows that, aside from long bones, elements like ribs and phalanges exhibit LAG deposition</li>
<li>developed a "map" of the alligator skeleton showing the best areas for finding unobstructed LAG deposition, helping determine which bones are best for analysis and where information is best preserved along those bones</li>
<li>information will allow researchers to make more informed sampling decisions given the destructive nature</li>
</ul><div style="color: #134f5c;">"<b>Variation in hindlimb muscle attachment sites in the American alligator (<i>Alligator mississippiensis</i>) and implications for paleobiological reconstructions</b>." Taylor, E., Schachner, E., and Farmer, C.G.</div><ul><li>examined hindlimb musculature in 19 specimens of <i>Alligator mississippiensis</i></li>
<li>found high degrees of individual variation in most muscle attachments</li>
<li>suggests a need for caution when using osteological correlates in myological reconstruction</li>
</ul><div style="color: #134f5c;">"<b>Trigeminal nerve morphology in <i>Alligator mississippiensis</i>: implications for inferring sensory potential in extinct crocodyliforms</b>." George, C.</div><ul><li>cross-sectional study (histology, morphometrics, and 3D imaging) to identify patterns in neural and bony structures in <i>Alligator mississippiensis</i> and comparison with similarly-sized fossil crocodyliforms</li>
<li>"data suggest that trigeminal nerve morphology can be accurately inferred among living crocodilians."</li>
<li>extinct taxa:</li>
<ul><li><i>Leidysuchus </i>(eusuchian) and <i>Phabdognathus </i>(dyrosaur) have trigeminal ganglia similar to alligators</li>
<li><i>Hamadasuchus </i>(peirosaur) had a much smaller ganglion (dome-pressure system not as well developed)</li>
</ul><li>"these findings suggest that neural osteological correlates of the trigeminal system are informative features useful for investigation of crocodyliform as well as archosaur somatosensory evolution."</li>
</ul><div style="color: #134f5c;">"<b>Structure and function of a protosuchian mandibular symphysis using anatomical insights from <i>Alligator mississippiensis</i></b>." Skiljan, R., Gant, C., and Holliday, C.</div><ul><li>comparison of the structure and function of the jaws (especially the mandibular symphysis) of protosuchians with <i>Alligator mississippiensis</i></li>
<li>data suggest a transitional form of the symphysis is present in protosuchians, compared to the derived condition in crocodyliforms</li>
</ul>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-46885136403837147282011-11-26T21:05:00.000-05:002011-11-26T21:05:10.233-05:00Metriorhynchid Body Size<div style="color: #134f5c; text-align: center;">Young, M. T., Bell, M. A., De Andrade, M. B. and Brusatte, S. L.. 2011. "Body size estimation and evolution in metriorhynchid crocodylomorphs: implications for species diversification and niche partitioning." <i> Zoological Journal of the Linnean Society</i>, 163: 1199–1216. <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.2011.00734.x/abstract">doi: 10.1111/j.1096-3642.2011.00734.x</a></div><br />
<u>Abstract</u><br />
Metriorhynchids were a peculiar group of fully marine Mesozoic crocodylomorphs, some of which reached large body size and were probably apex predators. The estimation of their total body length in the past has proven problematic. Rigorous size estimation was provided using five complete metriorhynchid specimens, by means of regression equations derived from basicranial and femoral length against total body length. The use of the <em>Alligator</em> femoral regression equation as a proxy to estimate metriorhynchid total body length led to a slight underestimation, whereas cranial regression equations of extant genera resulted in an overestimation of body length. Therefore, the scaling of crania and femora to total body length of metriorhynchids is noticeably different from that of extant crocodylians, indicating that extant crocodylians are not ideal proxies for size reconstruction of extinct taxa that deviate from their semi-aquatic morphotype. The lack of a correlation between maximum, minimum, or the range of generic body lengths with species richness demonstrates that species diversification is driven by factors other than just variation in body size. Maximum likelihood modelling also found no evidence for directionality in body size evolution. However, niche partitioning in Metriorhynchidae is mediated not only by craniodental differentiation, as shown by previous studies, but also by body size variation.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-58451535145713311452011-11-26T20:52:00.000-05:002011-11-26T20:52:01.901-05:00Reassessment of Some Middle Triassic Rauisuchians<div style="color: #134f5c; text-align: center;">Stephan Lautenschlager and Julia Brenda Desojo. 2011. "Reassessment of the Middle Triassic rauisuchian archosaurs <i>Ticinosuchus ferox</i> and <i>Stagonosuchus nyassicus</i>." <i>Paläontologische Zeitschrift</i> 85 (4): <span class="pagination">357-381</span><span class="doi">, <a href="http://www.springerlink.com/content/ck762418u571474v/"><span class="label">DOI:</span> <span class="value">10.1007/s12542-011-0105-1</span></a></span></div><div class="floatLeft productGraphicContainer"> </div><br />
<u>Abstract</u><br />
The Middle Triassic (Anisian) rauisuchian archosaurs <i>Ticinosuchus ferox</i> and <i>Stagonosuchus nyassicus</i> are two of the earliest representatives of this group and therefore of special importance for our understanding of the evolution and early diversification of Rauisuchia. Both taxa are well preserved and, in the case of the holotype of <i>Ticinosuchus ferox</i>, nearly complete and articulated. However, the original descriptions and recent revisions of the material do not sufficiently cover all aspects of their osteology. We identify new skull elements previously unknown for <i>Ticinosuchus ferox</i> and present new reconstructions of the pectoral and pelvic girdle elements. Vertebral laminae and fossae are described for the first time in both <i>Ticinosuchus ferox</i> and <i>Stagonosuchus nyassicus.</i> Newly recognised character states of <i>Stagonosuchus nyassicus</i> include the presence of additional infraprezygapophyseal and infrapostzygapophyseal laminae in the cervical vertebrae, a hyposphene-hypantrum articulation in the dorsal vertebrae and a fibula with a posteromedial depression. Furthermore, we provide a revised and emended diagnosis for both taxa, including several autapomorphies for <i>Stagonosuchus nyassicus</i> (e.g. a boss-like protuberance on the postacetabular process of the iliac blade and a marked short dorsolateral crest on the proximal ischium). We review the taxonomic status of a further specimen of <i>Ticinosuchus ferox</i>, as well as material related to <i>Stagonosuchus nyassicus</i> from the Manda Beds of Tanzania. Additionally, we discuss the distribution and possible function of rauisuchian characters, such as accessory neural spines in the caudal vertebrae, in these and other rauisuchian taxa.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-27891268961427725602011-11-26T20:36:00.000-05:002011-11-26T20:36:28.231-05:00Pelvic and Hindlimb Myology in Poposaurus<div style="color: #134f5c; text-align: center;">Emma R. Schachner, Phillip L. Manning, and Peter Dodson. 2011. "Pelvic and hindlimb myology of the basal archosaur<i> Poposaurus gracilis </i>(archosauria: Poposauroidea)" <i>Journal of Morphology</i> 272 (12): <span id="issuePages">1464–1491 </span><a href="http://onlinelibrary.wiley.com/doi/10.1002/jmor.10997/abstract">DOI: 10.1002/jmor.10997</a></div><div style="color: #134f5c; text-align: center;"><br />
</div><u>Abstract</u><br />
The discovery of a largely complete and well preserved specimen of <em>Poposaurus gracilis</em> has provided the opportunity to generate the first phylogenetically based reconstruction of pelvic and hindlimb musculature of an extinct nondinosaurian archosaur. As in dinosaurs, multiple lineages of basal archosaurs convergently evolved parasagittally erect limbs. However, in contrast to the laterally projecting acetabulum, or “buttress erect” hip morphology of ornithodirans, basal archosaurs evolved a very different, ventrally projecting acetabulum, or “pillar erect” hip. Reconstruction of the pelvic and hindlimb musculotendinous system in a bipedal suchian archosaur clarifies how the anatomical transformations associated with the evolution of bipedalism in basal archosaurs differed from that of bipedal dinosaurs and birds. This reconstruction is based on the direct examination of the osteology and myology of phylogenetically relevant extant taxa in conjunction with osteological correlates from the skeleton of <em>P. gracilis</em>. This data set includes a series of inferences (presence/absence of a structure, number of components, and origin/insertion sites) regarding 26 individual muscles or muscle groups, three pelvic ligaments, and two connective tissue structures in the pelvis, hindlimb, and pes of <em>P. gracilis</em>. These data provide a foundation for subsequent examination of variation in myological orientation and function based on pelvic and hindlimb morphology, across the basal archosaur lineage leading to extant crocodilians.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-67082644589623947922011-11-20T13:32:00.000-05:002011-11-20T13:32:07.621-05:00SVP 2011 Roundup - Crocodylomorph Edition Part 3<div style="text-align: center;"><u>Crocodylomorph Morphology and Systematics</u></div><div style="text-align: center;">(in order of presentation)</div><u>Talks</u><br />
<div style="color: #134f5c;">"<b>Comparative morphometrics and phylogenetic perspectives on the morphospace of the crocodyliform skull</b>." Wilberg, E.</div><ul><li>presents a quantitative approach for assessing skull shape in Crocodyliformes (helping to avoid subjective intermediate assignments) </li>
<li>compared multiple methodologies for comparing skull shape</li>
<ul><li>2D geometric morphometrics (homologous landmarks and sliding semi-landmarks) - results suggest 3 or 8 shape categories</li>
<li>Eliptical Fourier Analysis (EFA) of skull outlines - results suggest 3 shape categories</li>
</ul><li>overall skull shape should not be used as a discrete character in phylogenetic analyses, but can help in evaluating ecological and functional trends within claes</li>
</ul><span style="color: #134f5c;">"</span><b style="color: #134f5c;">Evolution of the otic region of fossil Crocodyliformes</b><span style="color: #134f5c;">." Montefeltro, F. and Larsson, H.</span><br />
<ul><li>terrestrial taxa - large, more vertical otic apertures and recess, relatively large tympanic membranes</li>
<ul><li>notosuchians show the most extreme expansion of the otic region and well developed scar for the attachment of the tympanic membrane = very good hearing </li>
</ul><li>semi aquatic and aquatic taxa - reduced otic apertures and tympanic membranes</li>
<ul><li>extreme reductions in Metriorhynchidae = hearing may have been insignificant </li>
</ul><li>quadrate fenestra may have played a role in hearing</li>
</ul><br />
<u>Posters</u><br />
<span style="color: #134f5c;">"</span><b><span style="color: #134f5c;">Crocodyliform aquatic locomotion and axial flexibility: comparative vertebral anatomy of</span> <span style="color: #134f5c;">mesoeucrocodylians</span></b><span style="color: #134f5c;">." Felice, R. and O'Connor, P.</span><br />
<ul><li>quantified vertebral metrics to evaluate whether crocodylians possess specialized skeletal morphology associated with a semi-aquatic lifestyle</li>
<li>terrestrial taxa - dorsal centra are about as wide as they are tall</li>
<li>semi-aquatic taxa - dorsal centra are wider than tall</li>
</ul><div style="color: #134f5c;">"<b>Jaw mechanics of crocodiles reveal their fast mastication</b>." Suzuki, D., Hayashi, S., Chiba, K., and Tanaka, K.</div><ul><li>observed movement of the cartilago transiliens (CT) in the musculus pterygoideus anterior (MPA) in extant crocs using CAT scans</li>
<li>the CT retains a rough surface on the lateral wing of the pterygoid, making it useful for studying fossil taxa</li>
<li>MPA moves the CT anteriorly = rapid jaw closure</li>
</ul><div style="color: #134f5c;">"<b>Phylogenetic patterns, homoplasy, and the evolution of the antorbital fenestra in Crocodyliformes</b>." Leardi, J., Pol, D., and Fernandez, M.</div><ul><li>phylogenetic analysis to evaluate the pattern of character evolution of the antorbital fenestra</li>
<li>closure of the antorbital fenestra occurred independently up to 8 times within Crocodyliformes (mostly in Mesoeucrocodylia)</li>
<li>antorbital fenestra independently reappears in some notosuchians (possibly in basal thalattosuchians)</li>
<li>suggests that the antorbital fenestra in Crocodyliformes is extremely homoplastic</li>
</ul><div style="color: #134f5c;">"<b>Fleshing out the neosuchian tree: a reevaluation of the crocodyliform <i>Shamosuchus </i>from the Cretaceous of Asia</b>." Turner, A. and Brochu, C.</div><ul><li><i>Shamosuchus </i>is important in understanding the character changes occurring at the origin of Eusuchia</li>
<li>reevaluation of <i>Shamosuchus </i>species reveals only three valid species: <i>S. djadochtaensis</i>, <i>S. gradilifrons,</i> and <i>S. ancestralis</i></li>
<li>results suggest a diverse <i>Shamosuchus </i>clade in the Cretaceous of eastern Asia</li>
</ul><div style="color: #134f5c;">"<b>Cranial anatomy and osteology of <i>Gavialis gangeticus</i> using computerized axial tomography: implications for gavialoid phylogeny</b>." Gold, M.</div><ul><li>ontogenetic changes in gharials are likely obscuring data </li>
<li>description of the cranial anatomy of a hatchling <i>G. gangeticus</i> based on CT data</li>
<li>reveals numerous ontogenetic of the skull and braincase</li>
<li>morphological data seem to support the molecular data, that certain plesiomorphiuc states in <i> </i> are secondarily reversed</li>
</ul><div style="color: #134f5c;">"<b>A geometric morphometric analysis of <i>Crocodylus niloticus</i>: osteological evidence for a cryptic species complex.</b>" Nestler, J.</div><ul><li>geometric morphometric analysis of the variation in the skull of <i>C. niloticus</i></li>
<li>variation in population in broadly based on river basins</li>
<li>at least 3 distinct populations within the species with at least 2 being more distinct from each other than from other members of the species (and at least one may be endangered) = cryptic species complex, supporting molecular data from previous studies</li>
<li> paleontology can inform on conservation and issues of diversity</li>
</ul><div style="color: #134f5c;">"<b>The evolution of exoskeletal ossifications in notosuchian crocodyliformes</b>." Hill, R. and O'Connor, P.</div><ul><li>most notosuchians show a general trend toward the reduction of dorsal osteoderms along with the expansion of the caudal osteoderm shield</li>
<li>general trend towards the reduction of surface ornamentation in favor of increased internalization</li>
<li><i>Pakasuchua </i>- most extreme reduction of osteoderms; robust articulating shield of osteoderms surrounding the tail; reduced osteoderms around the dorsosacral transition; presence of ossified tendons (first reported in Crocodyliformes)</li>
<li>osteoderm reduction trend in notosuchians may be associated with decreased body size and terrestrial habitat</li>
</ul>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-12931661606167170192011-11-17T17:46:00.000-05:002011-11-17T17:46:04.586-05:00Form and Function in the Metriorhychid Skull<div style="color: #134f5c; text-align: center;">Mark T. Young, Mark A. Bell and Stephen L. Brusatte. 2011. "Craniofacial form and function in Metriorhynchidae (Crocodylomorpha: Thalattosuchia): modelling phenotypic evolution with maximum-likelihood method." <i>Biology Letters</i> 7(6): 913-916 <a href="http://www.blogger.com/goog_1314168995"><span class="slug-metadata-note ahead-of-print">DOI: <span class="slug-doi" title="10.1098/rsbl.2011.0357">10.1098/rsbl.2011.0357</span></span></a></div><div style="color: black;"><span class="slug-metadata-note ahead-of-print"><span class="slug-doi" title="10.1098/rsbl.2011.0357"><br />
</span></span></div><div style="color: black;"><u><span class="slug-metadata-note ahead-of-print"><span class="slug-doi" title="10.1098/rsbl.2011.0357">Abstract</span></span></u></div><div style="color: black;">Metriorhynchid crocodylomorphs were the only group of archosaurs to fully adapt to a pelagic lifestyle. During the Jurassic and Early Cretaceous, this group diversified into a variety of ecological and morphological types, from large super-predators with a broad short snout and serrated teeth to specialized piscivores/teuthophages with an elongate tubular snout and uncarinated teeth. Here, we use an integrated repertoire of geometric morphometric (form), biomechanical finite-element analysis (FEA; function) and phylogenetic data to examine the nature of craniofacial evolution in this clade. FEA stress values significantly correlate with morphometric values representing skull length and breadth, indicating that form and function are associated. Maximum-likelihood methods, which assess which of several models of evolution best explain the distribution of form and function data on a phylogenetic tree, show that the two major metriorhynchid subclades underwent different evolutionary modes. In geosaurines, both form and function are best explained as evolving under ‘random’ Brownian motion, whereas in metriorhynchines, the form metrics are best explained as evolving under stasis and the function metric as undergoing a directional change (towards most efficient low-stress piscivory). This suggests that the two subclades were under different selection pressures, and that metriorhynchines with similar skull shape were driven to become functionally divergent.<span class="slug-metadata-note ahead-of-print"><span class="slug-doi" title="10.1098/rsbl.2011.0357"></span></span></div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-62870088192920150562011-11-16T13:32:00.000-05:002011-11-16T13:32:19.826-05:00SVP 2011 Roundup - Crocodylomorph Edition Part 2<div style="text-align: center;"><u>New Crocodylomorph Species and Specimens</u></div><div style="text-align: center;">(in order of presentation)</div><u>Talks</u><br />
<div style="color: #134f5c;">" <b>A new basal crocodylomorph from the Late Jurassic of Patagonia and its implications for the evolution of the crocodyloform braincase</b>." Pol, D., Rauhut, O., Lecuona, A., and Leardi, J.</div><ul><li>Late Jurassic Canadon Caleareo Formation, Patagonia</li>
<li>posterior region of the skull, fragmentary remains of the rostrum, palate, mandible, and postcranium</li>
<li>unique combination of autapomorphies, crocodylomorph plesiomorphies, and crocodyliform apomorphies</li>
<li>taxa found to be the closest to (just outside of) Crocodyliformes, closer than <i>Junggarsuchus</i></li>
<li>suggests that the braincase articulation with the palate and quadrate occured before Crocodyliformes</li>
</ul><div style="color: #134f5c;">"<b>A new eusuchian crocodyliform with novel cranial integument and the origin of Crocodylia</b>." Holiday, C. and Gardner, N.</div><ul><li>found in the coastal deposits of the Early Late Cretaceous Kem Kem Beds, Morocco</li>
<li>cranial remains - long, flat skull, possibly over 2 meters</li>
<li>novel integumentary display structure (possible thermoregulatory function as well)</li>
<li>new taxon found to be a derived eusuchian and the sister taxon to crown Crocodylia</li>
<li>earliest eusuchian from Africa - biogeographic implications for the origin of modern crocodylians (circum-Tethys vs. North America)</li>
</ul><div style="color: #134f5c;">"<b>New remains of <i>Miadanasuchus oblita</i> from the Late Cretaceous of Madagascar and a reevaluation of Trematochampsidae</b>." Sertich, J.</div><ul><li>Upper Cretaceous Maevarano Formation, Madagascar</li>
<li>well preserved partial skull, numerous isolated cranial and postcranial elements, allowing for a comprehensive assessment of morphology</li>
<li><i>Miadanasuchus </i>compares closely with other trematochampsids</li>
<li>a reevaluation of Trematochampsidae and Peirosauridae shows that there are 12 valid genera within a monophyletic Trematochamsidae and that Peirosauridae is synonymous with Trematochampsia. Trematochamsidae was found to be closely related to Mahajangasuchidae and <i>Araripesuchus</i>.</li>
</ul><div style="color: #134f5c;">"<b>New primitive caimanine (Crocodylia, Alligatoridae) from the Miocene of Panama</b>." Hastings, A., Bloch, J., Rincon, A., MacFadden, B., and Jaramillo, C.</div><ul><li>Culebra Formation, early Miocene, Panama</li>
<li>complete skull of a new taxon</li>
<li>found to be just outside of Caimaninae</li>
<li>important biogeographic implications, suggesting that caimans originated in the New World Tropics, entered North and South America in the Paleogene and persisted in the tropics into the Miocene after disappearing from higher latitudes</li>
</ul><br />
<u>Posters</u><br />
<div style="color: #134f5c;">"<b>A new specimen of <i>Araripesuchus </i>(Mesoeucrocodylia) with soft tissue preservation from the Lower Cretaceous Romualdo Formation (Araripe Basin), Brazil</b>." Figueiredo, R. and Kellner, A.</div><ul><li>nearly complete skeleton (skull, limbs, vertebral column, 2 rows of osteoderms)</li>
<li>the orbit size and proportions are consistent with <i>A. gomesii</i> while the long, slender limbs are consistent with <i>A. gomesii</i>, <i>A. wegeneri</i>, and <i>A. tsangatsangana</i></li>
<li>significant soft tissue preservation (white substance, likely phosphatized) consisting mostly of muscle fibers but also epidermis </li>
</ul><div style="color: #134f5c;">"<b>A new crocodyliform from the middle Cretaceous Woodbine Formation of Texas</b>." Allen, E., Main, D., and Noto, C.</div><ul><li>Arlington Archosaur Site of the Woodbine Formation (delta plain deposits)</li>
<li> disarticulated partial skull and significant postcranial material of one individual along with disarticulated material of several other individuals</li>
<li>about 5 meters long, short dentary symphysis, paired dentary pseudocanines, and a robust triangular snout</li>
<li>new taxon is a mesoeucrocodylian, possibly a basal goniopholidid or thalattosuchian</li>
</ul><div style="color: #134f5c;">"<b>A new, small-bodied alligatoroid from the Hell Creek Formation (Late Maastrichtian) of Montana</b>." Householder, M., Williams, S., and Tremaine, K.</div><ul><li>small-bodied (about 1 meter), mature or nearly mature individual (based on fused neurocentral sutures)</li>
<li>bears some similarities to <i>Brachychampsa montana</i> and other small-bodied alligatoroids, but is a distinct taxon</li>
<li>represents the southern-most occurrence of a small-bodied alligatoroid within the Western Interior Basin during the Late Cretaceous</li>
</ul><div style="color: #134f5c;">"<b>The palate and braincase in goniopholidid crocodyliforms: insights from a new skull of <i>Eutretauranosuchus</i> <i>delfsi</i></b>." Pritchard, A. and Turner, A.</div><ul><li>well-preserved, complete skull with CT scans revealing the palate and braincase</li>
<li>dorsoventral crushing distorted some braincase elements, although the anatomical positions are preserved</li>
<li>incorperation of the new skull data into a phylogenetic analysis unites <i>Amphicotylus</i>, <i>Calsoyasuchus</i>, <i>Eutrerauranosuchus</i>, and <i>Sunosuchus </i>into a clade of derived goniopholidids, all sharing a unique palatal morphology</li>
</ul>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-3342626421239462142011-11-14T11:42:00.000-05:002011-11-14T11:42:57.363-05:00SVP 2011 Roundup - Crocodylomorph Edition Part 1<div style="text-align: center;"><u>General Crocodylomorph Ecology and Evolution</u></div><div style="text-align: center;">(in order of presentation)</div><u>Talks</u><br />
<div style="color: #134f5c;">"<b>Campanian crocodyliforms of Laramidia: new insights from the Kaiparowits Basin of southern Utah</b>." Irmis, R., Sertich, J., Hutchison, J. H., And Titus, A.</div><ul><li>comprehensive survey of Kaiparowits crocodyliforms</li>
<ul><li>large, goniopholidid-like mesoeucroc.</li>
<li> basal alligatorids: <i>Deinosuchus hatcheri</i> and <i>Brachychampsa</i></li>
<li>small alligatoroid lacking globidont teeth</li>
</ul><li>clear biogeographic relationship with the San Juan Basin (New Mexico) - some regionality but also endemic taxa</li>
<li>supports the hypothesis of a distinct southern biogeographic province</li>
</ul><div style="color: #134f5c;">"<b>Direct evidence of crocodyliform predation on small dinosaurians from the Kaiparowits Formation of Utah</b>." Drumheller, S. and Boyd, C.</div><ul><li>predation by a small crocodyliform on a juvenile basal ornithopod (new Hypsolophodont)</li>
<ul><li>several bite marks characteristic of crocs</li>
<li>partial tooth embeded in femur (distal tip had been broken off previously)</li>
</ul></ul><div style="color: #134f5c;">"<b>The myth of the living fossil: basal crown group relationships, reversing polarities, and restoration of the ancestral crocodylian.</b>" Brochu, C., Turner, A., Allen, E., and Wilberg, E.</div><ul><li>outgroups of Crocodylia predominantly small bodied (less than 2 meters)</li>
<li>the crocodylian ancestral condition was likely equivalent to the small durophagous alligatorines of the Paleogene</li>
<li>living crocodylians are not generalized but independently highly specialized (NOT LIVING FOSSILS!!!!)</li>
</ul><br />
<u>Posters</u><br />
<div style="color: #134f5c;">"<b>Freshwater niche competition between choristoderes and crocodiles in the Mesozoic and Paleogene</b>." Matsumoto, R.</div><ul><li>Early Cretaceous of Asia - high diversity of choristoderes, no aquatic crocs</li>
<li>Middle Jurassic thru Eocene of Europe - only small lizard-like choristoderes, co-occuring with larger crocs</li>
<li>Cretaceous thru Paleogene of Euramerica - neochoristoderes co-occur with similar sized crocs, but neochoristoderes are the only strongly longirostrine reptiles</li>
<li>long-snouted crocs diversify in freshwater after the extinction of neochoristoderes (Oligo-Miocene)</li>
</ul><div style="color: #134f5c;">"<b>Late Neogene Alligator evolution and a description of specimens from the Gray Fossil Site, southern appalachians, USA.</b>" Schubert, B., Mead, J., and Stout, J.</div><ul><li>abundant <i>Alligator </i>material</li>
<ul><li>osteroderms and other fragmentary material</li>
<li>mostly complete juvenile</li>
<li>pathological adult skull</li>
<li>two adult partial post-cranial skeletons</li>
</ul><li><i>Alligator </i>of Gray Fossil Site posses a mixture of characters found in <i>A. olseni</i>, <i>A. mefferdi</i>, and <i>A. mississippiensis</i></li>
</ul><div style="color: #134f5c;">"<b>Crocs not theropods were likely top predators on the Cretaceous dinosaur freeway: implications of a large track census</b>." Lockley, M. and Lucas, S.</div><ul><li>at least 1380 individual trackmakers</li>
<li>mostly ornithopods (71%)</li>
<li>only small theropods present (not large enough to prey on ornithopods)</li>
<li>abundant crocodylian tracks (walking and swimming), including large individual (around 4 meters)</li>
</ul><div style="color: #134f5c;">"<b>A taphonomic and paleoecological comparison of isolated crocodyliform teeth from the Woodbine Formation of Texas and the Hell Creek Formation of Montana</b>." Bennett, G., Main, D., Peterson, R., and Anderson, B.</div><ul><li>4 different crocodyliforms in the Woodbine Formations, including <i>Woodbinesuchus </i>and a new genus</li>
<li>2 different crocodyliforms in the Hell Creek (<i>Brachychampsa montana</i> and <i>Borealosuchus sternbergi</i>), showing similar population structure to <i>A. mississippiensis</i>.</li>
</ul><div style="text-align: center;"><br />
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</div>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-1162110548324308392011-11-09T16:50:00.000-05:002011-11-09T16:50:20.611-05:00SVP 2011 Roundup - Triassic Crurotarsan/Pseudosuchian Edition<u>Talks</u><br />
<div style="color: #134f5c;">"<b>A new archosaur (Diapsida: Archosauriformes) from the marine Triassic of China</b>." Wu, X., Li, C., Zhao, L., Sato, T., and Wang, L.</div><ul><li>a new, nearly complete (except for some of the tail) crurotarsan archosaur from the Falanf Formation (Middle Triassic - Ladinian) of China </li>
<ul><li>likely a basal poposauroid (sensu Nesbitt 2011), about 1.5 meters in length </li>
</ul><li>snout more than twice the length of the rest of the skull (about 24 cm total)</li>
<li>although found in marine sediments, it has few anatomical modifications toward an aquatic lifestyle but still not likely fully terrestrial (fish gut contents, posteriorly positioned external naris)</li>
<li>sister-group relationship with Qianosuchus (only other Middle Triassic archosaur found in marine sediments of China), but with a poor bootstrap value</li>
</ul><div style="color: #134f5c;">"<b>An enigmatic archosauriform from the Manda Beds (Middle Triassic) of Southwestern Tanzania: character conflict at the base of Pseudosuchia.</b>" Nesbitt, S., Sidor, C., Angielczyk, K., Smith, R., and Tsuji, L.</div><ul><li>a new archosaur with an unusual mix of character states</li>
<li>basal pseudosuchian, closely related to/ just outside of Paracrocodylomorpha</li>
<li>new data produces little change in relationships but a drastic change in character optimization (overall data is still obscured by high rates of homoplasy and incomplete specimens)</li>
<li>shows that the plesiomorphic bauplan of archosaurs was likely "rauisuchian"</li>
</ul><br />
<u>Posters</u><br />
<div style="color: #134f5c;">"<b>Comparative paleohistology of Triassic rauisuchian and aetosaurian osteoderms (Archosauria:Pseudosuchia).</b>" Scheyer, T., Desojo, J., and Cerda, I.</div><ul><li>sampled 8 rauisuchian, 10 aetosaurs, and <i>Revueltosaurus</i></li>
<li>rauisuchians had compact bone, showed high growth rates early, and reduced growth rates later in development</li>
<li>in aetosaurs, a few taxa showed rapid growth, but most showed slow growth (parallel-fibered/ lamellar-zonal bone)</li>
<li><i>Revueltosaurus </i>showed mostly densely remodeled parallel-fibered bone</li>
</ul><div style="color: #134f5c;">"<b>A newly recognized specimen of the phytosaur <i>Redondasaurus </i>from the Upper Triassic Owl Rock Member (Chinle Formation) and its biostratigraphic implications</b>." Parker, W., Martz, J., and Dubiel, R.</div><ul><li>a phytosaur specimen from the Owl Rock Member (Chinle Fm) has been identified as <i>Redondasaurus</i>, not <i>Pseudopalatus</i></li>
<li>this puts mush of the Owl Rock in the Apachean Biozone, drastically changing biostratigraphic correlations of the upper Chinle and Dockum</li>
<li>shows that there is no basis for the Tr-5 unconformity (no faunal turnover or depositional hiatus) </li>
</ul><div style="color: #134f5c;">"<b>The relationships and type locality of <i>Heptasuchus clarki</i>, Chugwater Group (Middle to Upper Triassic), Southeastern Big Horn Mountains, Wyoming, USA</b>." Zawiskie, J., Dawley, R., and Nesbitt, S.</div><ul><li>type locality is poorly constrained, but likely equivalent to the Popo Agie Formation</li>
<li><i>Heptasuchus </i>is the sister taxon to <i>Batrachotomus</i></li>
<li>minimum of four <i>Heptasuchus </i>individuals at the type locality, further suggesting that loricatans may have lived in groups (like <i>Decuriasuchus</i>)</li>
</ul><div style="color: #134f5c;">"<b>The trackmaker of the Late Triassic tetrapod footprint ichnotaxon <i>Brachyirotherium </i>was an aetosaur</b>." Lucas, S., Heckert, A., and Lockley, M.</div><ul><li> aetosaurs have the appropriate manus/pes morphology, were capable of a nearly over-stepped stride, and have the appropriate geographic/stratigraphic distribution to be consistent with <i>Brachyirotherium</i></li>
<li>rauisuchians and spenosuchians excluded by manus/pes morphology</li>
</ul><span style="color: #134f5c;">"</span><b style="color: #134f5c;">Diversity of aetosaurs (Archosauria: Stagonolepidae) in the Upper Triassic Pekin Formation (Deep River Basin), North Carolina</b><span style="color: #134f5c;">." Schneider, V., Heckert, A., and Fraser, N</span>.<br />
<ul><li> new specimen of a partial aetosaur carapace, composed of the first ten rows of osteoderms (including a full, articulated row of cervicals)</li>
<li>shows character states of both <i>Longasuchus </i>and <i>Lucasuchus</i></li>
<li>at least three genera of aetosaur in the Pekin Formation (<i>Lucasuchus</i>, <i>Coahomasuchus</i>, and whichever genus is represented by the new specimen), correlating it with the lower Dockum Group</li>
</ul><span style="color: #134f5c;">"</span><b style="color: #134f5c;">A virtual phytosaur (Archosauria: Crurotarsi) endocast and its implications for sensory system evolution in archosaurs</b><span style="color: #134f5c;">." Holloway, W. and O'Keefe, R</span>.<br />
<ul><li>cranial endocast (CT scan) of a complete <i>Smilosuchus adamanensis</i> skull</li>
<li>endocranial morphology very similar to <i>Crocodylus johnstoni</i> except for enlarged pineal body in <i>Smilosuchus</i></li>
<li>"This highly conserved cranial endocast morphology is consistent throughout Crurotarsi, regardless of overall body morphology or ecology, with a trend of pineal body size reduction from the enlarged basal condition to a reduced crown condition." (quoted from the abstract)</li>
</ul>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-3815057285934625512011-11-08T15:53:00.000-05:002011-11-08T15:53:40.672-05:00A New Upper Cretaceous Sphagesaurid<div style="color: #134f5c;">Fabiano V. Ioria and Ismar S. Carvalhoa. 2011. "<i>Caipirasuchus paulistanus</i>, a new sphagesaurid (Crocodylomorpha, Mesoeucrocodylia) from the Adamantina Formation (Upper Cretaceous, Turonian–Santonian), Bauru Basin, Brazil" Journal of Vertebrate Paleontology 31(6): 1255-1264 - (Online November 8th) <a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.602777">DOI:10.1080/02724634.2011.602777</a></div><br />
<u>Abstract</u><br />
A skull and mandible of a new species of notosuchian, <i>Caipirasuchus paulistanus</i>, belonging to the Sphagesauridae, were discovered in the rocks of the Adamantina Formation (Bauru Basin: Late Cretaceous). The main autapomorphies are external naris bordered only by premaxillae; very high pterygoids and ectopterygoids; palatines contacting maxillae by a cuneiform process; well-developed oval antorbital fenestra; premaxilla with four teeth; dentary with ten teeth and two diastemata; and one diastema in the premaxilla and another between the fourth alveolus of the premaxilla and the first of the maxilla. Morphological analysis and experimental data suggest an animal with a powerful bite and a dentition with specific regions of action, one adapted to apprehension and the other to food processing.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-72239375725052858732011-11-08T15:48:00.000-05:002011-11-08T15:48:57.617-05:00Osteohistology of Triassic Archosauromorphs<span style="color: #134f5c;">Jennifer Botha-Brink and Roger M. H. Smith. 2011. "</span><span style="color: #134f5c; font-size: small;">Osteohistology of the Triassic archosauromorphs <i>Prolacerta</i>, <i>Proterosuchus</i>, <i>Euparkeria</i>, and <i>Erythrosuchus</i> from the Karoo Basin of South Africa</span><span style="color: #134f5c;">." </span><i style="color: #134f5c;">Journal of Vertebrate Paleontology</i><span style="color: #134f5c;"> 31(6): 1238-1254 - (Online November 8th) </span><a href="http://www.tandfonline.com/doi/abs/10.1080/02724634.2011.621797" style="color: #134f5c;">DOI:10.1080/02724634.2011.621797</a><br />
<br />
<u>Abstract</u><br />
The South African non-archosauriform archosauromorph <i>Prolacerta</i> and the archosauriforms <i>Proterosuchus</i>, <i>Erythrosuchus</i>, and <i>Euparkeria</i> were important constituents of the Early to early Middle Triassic Karoo ecosystem following the end-Permian mass extinction. We present new data on the osteohistology of these stem archosaurs and provide insight into their paleobiology. Bone tissues of the Early Triassic <i>Prolacerta</i> contain a poorly defined fibro-lamellar complex, with parallel-fibered bone in some regions, whereas the contemporaneous <i>Proterosuchus</i> exhibits rapidly forming uninterrupted fibro-lamellar bone early in its ontogeny, which becomes slow forming lamellar-zonal bone with increasing age. The early Middle Triassic <i>Erythrosuchus</i> deposited highly vascularized, uninterrupted fibro-lamellar bone throughout ontogeny, whereas the growth of the contemporaneous <i>Euparkeria</i> was relatively slow and cyclical. When our data are combined with those of previous studies, preliminary results reveal that Early and Middle Triassic non-crown group archosauromorphs generally exhibit faster growth rates than many of those of the Late Triassic. Early rapid growth and rapid attainment of sexual maturity are consistent with life history expectations for taxa living in the unpredictable conditions following the end-Permian mass extinction. Further research with larger sample sizes will be required to determine the nature of the environmental pressures on these basal archosaurs.Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com0tag:blogger.com,1999:blog-7257028403896821073.post-22949684051553087572011-11-08T14:38:00.000-05:002011-11-08T14:38:00.283-05:00SVP 2011 Roundup - Archosauromorph Edition<div style="text-align: center;"><u>Archosauromorphs and General Archosaur Evolution</u> </div><div style="text-align: center;">(in order of presentation)</div><u>Talks</u><br />
<div style="color: #134f5c;"><b>"Archosauromorph bone histology reveals early evolution of elevated growth and metabolic rates."</b> Werning, S., Irmis, R., Smith, N., Turner, A., and Padian, K.</div><ul><li> extant and extinct ornithodirans show high metabolic rates, but not extant crocodylians</li>
<li>study of evolution of growth rate in archosauromorphs through an expanded histological database and using much more rigorous methods for collecting data</li>
<li>characters associated with high metabolic rates appear in a short, stepwise accumulation along the archosauriform tree</li>
<li>a reversal likely occured along the pseudosuchian line</li>
<ul><li>Aetosaurs and relatives show early rapid growth, but slow growth later on</li>
<li>Shuvosaurs show fast growth throughout life</li>
</ul></ul><div style="color: #134f5c;"><b>"Postcranial skeletal pneumaticity and the evolution of archosaur respiratory systems."</b> Barrett, P., Butler, R., Gower, D., and Abel, R.</div><ul><li>unidirectional airflow present in extant archosaurs</li>
<li>soft tissue associated with unidirectional airflow/ postcranial skeletal pneumaticity (PSP) not preserved by fossil record but fossae, foramina, and laminae are preserved</li>
<li>pseudosuchians (phytosaurs, aetosaurs, poposaurs) posses many vertebral laminae and fossae, but no internal features </li>
<li>no conclusive evidence in extinct archosaurs other than saurischians and pterosaurs but still likely that they had less well-developed avian-like respiratory systems with non-invasive air sacs and unidirectional air flow</li>
</ul><div style="color: #134f5c;"><b>"Phylogenetic congruence between cranial and postcranial characters in archosaur systematics."</b> Mounce, R. and Wills, M.</div><ul><li> showed a significant incongruence of cranial and postcranial signals (cranial characters appear to be significantly less homoplastic)</li>
<li>results may indicate different evolutionary rates between cranial and postcranial characters</li>
</ul><div style="color: #134f5c;"><b>"Osteohistology of Triassic archosauromorphs from the Karoo Basin of South Africa."</b> Botha-Brink, J. and Smith, R.</div><ul><li><span style="color: black;">looked at <i>Prolacerta</i>, <i>Proterosuchus</i>, <i>Erythrosuchus</i>, and <i>Euparkeria </i></span></li>
<li><span style="color: black;">Early/Middle Triassic archosauromorphs (non-crown group) show fast growth early in their life</span></li>
<li><span style="color: black;">early rapid growth and early onset of sexual maturity are consistent with the life history expected from harsh, unpredictable conditions after the Permian/Triassic extinction </span> </li>
</ul><b style="color: #134f5c;">"New information on the Triassic vertebrate faunas of Antarctica."</b><span style="color: #134f5c;"> Sidor, C., Smith, R., Huttenlocker, A., Peecook, B., and Hammer, W.</span><br />
<ul><li> small <i>Prolacerta</i>-like archosauromorph found under a <i>Lystrosaurus </i>and a <i>Proterosuchus</i>-like archosauriform</li>
<li>vertebrates of the lower Fremouw Formation likely correspond to the post-extinction recovery fauna of South Africa (Karoo Basin)</li>
<li>faunas of the two continents differentiate in the Middle Triassic</li>
<li>using network science for faunal analysis</li>
</ul><div style="color: #134f5c;"><b>"Uniting microevolution and macroevolution in deep time: the zone of variability in Archosauromorpha."</b> Bhullar, B., Bever, G., Merck, J., Lyson, T. and Gauthier, J.</div><ul><li> a phylogenetic "zone of variability" (ZOV) occurs before apomorphies become fixed</li>
<li>detected indirectly - stem members of a clade show lots of variability in character states before they become fixed in crown group members</li>
<ul><li>derived archosauriforms show an absence of a parietal foramen, an absence of supratemporals, and a complete lower temporal bar</li>
<li>stem archosauriforms show a ZOV of these characters </li>
</ul><li>detected directly - in a single taxon, variation in such character states occur between individuals</li>
<ul><li>in <i>Prolacerta broomi,</i> the three characters listed above in derived archosaurs are variably present and absent (in almost all permutations) in fossil individuals</li>
</ul></ul><u>Posters</u><br />
<div style="color: #134f5c;"><b>"Anatomy and affinities of large archosauromorphs from the lower Fremouw Formation (Early Triassic) of Antarctica."</b> Crandall, J., Hellert, S., Smith, N., Hammer, W., and Makovicky, P.</div><ul><li>first evidence of Archosauriformes in the Early Triassic of Antarctica</li>
<li> found a partial presacral vert and distal end of the left humerus of a large archosauriform from just after the P/Tr</li>
<ul><li>large size is contra the "lilliput effect" of mass extinctions</li>
</ul></ul><div style="color: #134f5c;"><b>"New data on the archosaur fauna of the Middle Triassic (Anisian) Ntawere Formation of Zambia."</b> Peecook, B., Sidor, C., Nesbitt, S., Angielczyk, K., and Steyer, S.</div><ul><li>first diagnostic remains of archosaurs from the Ntawere Formation - teeth, large pseudosuchian vertebra, pelvic and vertebral material of a silesaurid</li>
<li>Ntawere Formation (and Manda beds) shows a higher diversity of archosaurs than the ealier Karoo Basin</li>
</ul>Susanhttp://www.blogger.com/profile/00692585678285662795noreply@blogger.com1