Saturday, October 27, 2012

Who was eating aetosaurs?

Desmatosuchus encounters Postosuchus. Artwork by Douglas Henderson in Dawn of the Dinosaurs: Life in the Triassic by Nicholas Fraser (Plate 7.5A)
Postosuchus 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.

However, the discovery of a particular aetosaur osteoderm from Petrified Forest National Park may be able to add some weight to our assumptions that Postosuchus was preying on aetosaurs. The osteoderm belonged to Typothorax, 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 Postosuchus, and the bite matches perfectly with the front teeth of Postosuchus kirkpatricki.
So, who was eating aetosaurs? It looks like Doug Henderson and other paleoartists were right. Postosuchus was a daunting top predator in the Triassic of North America and we can now say that this large rauisuchid had equally daunting prey.

Tuesday, August 28, 2012

New from JVP - A new poposaur and vertebrate fauna from Poland

Li et al presented on this new poposaur at last year's SVP (as I discuss here) 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. Qianosuchus) may suggest a strange beginning for Poposauroidea.

Chun Li, Xiao-Chun Wu, Li-Jun Zhao, Tamaki Sato & Li-Ting Wang (2012): A new archosaur (Diapsida,
Archosauriformes) from the marine Triassic of China, Journal of Vertebrate Paleontology, 32:5, 1064-1081

A new Middle Triassic archosaur, Diandongosuchus fuyuanensis, 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. D. fuyuanensis 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 Qianosuchus 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 Qianosuchus. On the basis of current information, the discovery of Diandongosuchus does not firmly underscore the affinity of the semiterrestrial vertebrate faunas between the eastern and western regions along the northern coastline of the Tethys.
Also from the new JVP is a report on a new, although rather typical, Late Triassic vertebrate fauna, which includes several archosaurs.

Tomasz Sulej, Grzegorz Niedźwiedzki & Robert Bronowicz (2012): A new Late Triassic vertebrate fauna
from Poland with turtles, aetosaurs, and coelophysoid dinosaurs, Journal of Vertebrate Paleontology, 32:5, 1033-1041

We report a new site with an occurrence of isolated bones of a Palaeochersis-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.

Monday, July 16, 2012

Phytosaurs - Some Are Real and Some Are Just Dinosaurs

Phytosaurs 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 Protome batalaria 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.

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." Journal of Vertebrate Paleontology 32(3): 573-586
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.

Barrett, P. M., and X. Xu. 2012. "The enigmatic reptile Pachysuchus imperfectus Young, 1951 from the lower Lufeng Formation (Lower Jurassic) of Yunnan, China." Vertebrata PalAsiatica 50:151-159. [Free download here]
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. 

Saturday, July 14, 2012

Recent Papers on Triassic Archosaurs (and Archosauriforms) and Other News

Several papers regarding Triassic archosaurs have come out recently. The first is a re-evaluation of Proterochamspia, including genera (specifically Proterochamspa) within the clade and a look at its evolutionary history. The second is an interesting look at bipedality and cursoriality in archosaurs. And finally, we have Smok, 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.

In other news, there is a new paleo blog out there looking at the coevolution between plants and animals - Antediluvian Salad. Check it out! And while you are checking things out, head over to the Pictures tab of The Forgotten Archosaurs for some great shots of work going on in Petrified Forest National Park this summer, including the Revueltosaurus Quarry and other PEFO paleo field work.

Dilkes, D., and A. Arcucci. 2012. "Proterochampsa barrionuevoi (Archosauriformes: Proterochampsia) from the Late Triassic (Carnian) of Argentina and a phylogenetic analysis of Proterochampsia." Palaeontology (online)
Restudy of skulls and available postcrania of the proterochampsian archosauriform Proterochampsa barrionuevoi 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. Proterochampsa nodosa is a valid species distinguished from P. barrionuevoi 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 Proterochampsa, Chanaresuchus bonapartei, Gualosuchus reigi, Tropidosuchus romeri and Cerritosaurus binsfeldi. A temporal separation between the two basal proterochampsians with earliest records in the Late Triassic (Proterochampsa and Cerritosaurus) and Chanaresuchus, Gualosuchus and Tropidosuchus in the Middle Triassic indicates hidden proterochampsian diversity in the Middle Triassic.

Kubo, T., and M. O. Kubo. 2012. "Associated evolution of bipedality and cursoriality among Triassic archosaurs: a phylogenetically controlled evaluation." Paleobiology 38: 474–485. (online)
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.

Niedźwiedzki, G., T. Sulej, and J. Dzik. 2012. "A large predatory archosaur from the Late Triassic of Poland." Acta Palaeontologica Polonica 57 (2): 267-276. (online)
We describe a new large predatory archosaur, Smok wawelski 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 S. wawelski 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 S. wawelski difficult at this time.

Sunday, July 8, 2012

Revueltosaurus Quarry- The Evolution of A Jacket

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.

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 Revueltosaurus 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.

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.
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".
Jacketing some parts of the block as Bill continues to define the edges.
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).

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.

With the smaller jacket flipped, Bruce chisels out some excess rock.
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!

Sunday, June 3, 2012

Summer at Petrified Forest National Park

I 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 Revueltosaurus quarry.

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 (view park map). 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.

Hatch Ranch - Expansion Area (2011)

Bill Parker was quoted as saying the following in the NPS news article about the expansion of the park:

Revueltosaurus quarry 2012
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.-Bill Parker, paleontologist, 2011.
The Revueltosaurus 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 in situ individuals of what they later discovered to be Revueltosaurus callenderi. Revueltosaurus 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 Revueltosaurus as the sister taxon to aetosaurs.

Reconstruction of R. callenderi by Jeff Martz, winner of the 2011 Lanzendorf PaleoArt Prize in Scientific Illustration

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, 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. 

This should be a pretty great field season.

Parker, W. G., R. B. Irmis, S. J. Nesbitt, J. W. Martz, and L. S. Browne. 2005. "The Late Triassic pseudosuchian Revueltosaurus callenderi and its implications for the diversity of early ornithischian dinosaurs." Proceedings of the Roayal Society B 272: 963-969

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.

Nesbitt, S. J. 2011. "The Early Evolution of Archosaurs: Relationships and the Origin of Major Clades." Bulletin of the American Museum of Natural History, Number 352

Monday, March 26, 2012


Last week, I got a chance to visit the North Carolina Museum of Natural Sciences. 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 Postosuchus alisonae and Dromicosuchus grallator, as well as many great specimens of Deinosuchus.

Postosuchus alisonae 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 Postosuchus they found a partially articulated skeleton of a crocodylomorph, Dromicosuchus grallator, 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.
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 Nature Research Center 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.

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 (link to job listing). Fair warning, that Triassic mudstone is tough stuff.

Dromicosuchus - Sues, Hans-Dieter, Paul E. Olsen, Joseph G. Carter, & Diane M. Scott. 2003. "A new crocodylomorph archosaur from the Upper Triassic of North Carolina" Journal of Vertebrate Paleontology 23(2): 329-343 DOI:10.1671/0272-4634(2003)023[0329:ANCAFT]2.0.CO;2

Postosuchus - Peyer, Karin, Joseph G. Carter, Hans-Dieter Sues, Stephanie E. Novak, & Paul E. Olsen. 2008. "A new suchian archosaur from the Upper Triassic of North Carolina" Journal of Vertebrate Paleontology 28(2): 363-381 DOI:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2

Wednesday, February 1, 2012

Shield Croc - Aegisuchus

"Shieldcroc" (aka. Aegisuchus witmeri 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 Aegisuchus 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.

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) doi:10.1371/journal.pone.0030471

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 Aegyptosuchus, 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.

Thursday, January 19, 2012

A New Aetosaur

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" Zootaxa 3166: 1–33

We describe the new aetosaur Aetobarbakinoides brasiliensis 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. Aetobarbakinoides 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 Aetosauroides (late Carnian-early Norian) and Neoaetosauroides (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. Aetobarbakinoides 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. Aetobarbakinoides is among the oldest known aetosaurs together with Aetosauroides 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 Aetobarbakinoides, 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.

Friday, January 13, 2012

First Symposium on the Evolution of Crocodyliforms

It seems the special issue of the Zoological Journal of the Linnean Society, "1st Symposium on the Evolution of Crocodyliforms", 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.

The volume presents six new species (five new genera), bringing the count for new crocs of 2011 up to 17. Pol & Powell describe Lorosuchus nodosus gen. et sp. nov., a basal mesoeucrocodylian (Sebecidae) from the Paleocene of Argentina. Two new notosuchians from the Upper Cretaceous of Brazil are described: Caryonosuchus pricei gen. et sp. nov. (Spageosauridae) (Kellner et al. a.)  and Labidiosuchus amicum gen. et sp. nov. with its bizarre dentition (a symphyseal dental battery) (Kellner et al. b.). Andrade et al present Goniopholis kiplingi sp. nov. (Lower Cretaceous, England) with a review of the genus and an updated definition, restricting Goniopholis 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 Fruitachampsa callisoni ge. nov., sp. nov.. The last new croc of the issue is Pieraroiasuchus ormezzanoi gen. nov., sp. nov., based on two fully articulated individuals from the Cretaceous of Italy, belonging to the Hylaeochamsidae (Buscalioni et al).

The volume also includes discussions of existing taxa, some with descriptions of new specimens. Riff et al look at the features of Stratiotosuchus maxhechti that support the view of baurusuchids as active terrestrial predators and their convergence with theropod dinosurs. The cranial anatomy of Baurusuchus albertoi 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 Stratiotosuchus maxhechti revealing bone pathologies from two distinct injuries and insect boring marks (Cabral et al). Soto et al describe a new specimen of Uruguaysuchus aznarezi from the type locality. Brochu describes cranial fragments of Necrosuchus ionensis, revealing caimanine affinities, also providing a review of Paleocene-Eocene caiman biogeography. The issue includes a redescription of Meridiosaurus vallisparadisi 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 Susisuchus anatoceps, revealing it as a basal neosuchian.

Thursday, January 12, 2012

New Jersey Borealosuchus

The 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.

Christopher A. Brochu, David C. Parris, Barbara Smith Grandstaff, Robert K. Denton Jr. & William B. Gallagher. 2012. "A new species of Borealosuchus (Crocodyliformes, Eusuchia) from the Late Cretaceous–early Paleogene of New Jersey." Journal of Vertebrate Paleontology 32(1): 105-116 DOI:10.1080/02724634.2012.633585

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, Borealosuchus threeensis. Although one of the oldest known species of Borealosuchus, phylogenetic analysis supports a closer relationship to Borealosuchus 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 Borealosuchus material from the Paleocene of western Texas, though conspecificity cannot be demonstrated at present. A close relationship with the basal alligatoroids Leidyosuchus 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 Borealosuchus) 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 Borealosuchus to the Western Interior during the Paleocene, and they indicate the presence of several unsampled lineages crossing the Cretaceous-Paleogene boundary.