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

Abstract

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.

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

Abstract
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.

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.

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

Abstract

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.

The Year In Crocs

Each 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  9 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:

• Theriosuchus grandinaris - a Late Jurassic/Early Cretaceous neosuchian from Thailand - in 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." Paläontologische Zeitschrift 85(1): 37-47. DOI: 10.1007/s12542-010-0071-z

• Decuriasuchus quartacolonia - a Triassic rauisuchian from Brazil - in Franca, M. A. G. and J. Ferigolo. 2011. 'Associated skeletons of a new middle Triassic "Rauisuchian" from Brazil' Naturwissenschaften 98 (5): 389-395 DOI: 10.1007/s00114-011-0782-3 

• Neptunidraco ammoniticus - a Jurassic metriorhynchid from Italy - in Cau, A. & F. Fanti. (2011) "The oldest known metriorhynchid crocodylian from the Middle Jurassic of North-eastern Italy, Neptunidraco ammoniticus gen. et sp. nov." Gondwana Research 19(2): 550-565. doi:10.1016/j.gr.2010.07.007

Andrea Cau, study co-author, posing with the counter top and a reconstruction of Neptunidraco (from Nat Geo)

• Campinasuchus dinizi - a Cretaceous baurusuchid from Brazil - in 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. "Campinasuchus dinizi gen. et sp. nov., a new Late Cretaceous baurusuchid (Crocodyliformes) from the Bauru Basin, Brazil" Zootaxa 2871: 19-42 Open access online.

Life reconstruction (by Rodolfo Nogueira) of Campinasuchus dinizi from Carvalho et al 2011

• Arenysuchus gascabadiolorum - a Cretaceous crocodyloid from Spain - in 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." PLoS ONE 6(6) doi:10.1371/journal.pone.0020011

• Pissarrachampsa sera -a Cretaceous baurusuchid fro Brazil - in 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." PLoS ONE 6(7). doi:10.1371/journal.pone.0021916

From Figure 3 of Montefeltro et al 2011

• Archerontisuchus guajiraensis -a Paleocene dyrosaurid from Colombia - in 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." Palaeontology, 54: 1095–1116. doi: 10.1111/j.1475-4983.2011.01092.x

• Caipirasuchus paulistanus - a Cretaceous sphagesaurid from Brazil - in Fabiano V. Ioria and Ismar S. Carvalhoa. 2011. "Caipirasuchus paulistanus, a new sphagesaurid (Crocodylomorpha, Mesoeucrocodylia) from the Adamantina Formation (Upper Cretaceous, Turonian–Santonian), Bauru Basin, Brazil" Journal of Vertebrate Paleontology 31(6): 1255-1264 DOI:10.1080/02724634.2011.602777  

Reconstruction of Caipirasuchus by D. Silva in Fabiano et al.

[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 English Wealden Fossils 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 Tetrapod Zoology.

• Goniopholis willetti - an Early Cretaceous goniopholidid from England
• Anteophthalmosuchus hooleyi - an Early Cretaceous goniopholidid from England
• Leiokarinosuchus brookensis - an Early Cretaceous neosuchian from England

in Salisbury, S. W. & Naish, D. 2011. "Crocodilians." In Batten, D. J. (ed.) English Wealden Fossils. The Palaeontological Association (London), pp. 305-369