Wednesday, November 16, 2011

SVP 2011 Roundup - Crocodylomorph Edition Part 2

New Crocodylomorph Species and Specimens
(in order of presentation)
" A new basal crocodylomorph from the Late Jurassic of Patagonia and its implications for the evolution of the crocodyloform braincase." Pol, D., Rauhut, O., Lecuona, A., and Leardi, J.
  • Late Jurassic Canadon Caleareo Formation, Patagonia
  • posterior region of the skull, fragmentary remains of the rostrum, palate, mandible, and postcranium
  • unique combination of autapomorphies, crocodylomorph plesiomorphies, and crocodyliform apomorphies
  • taxa found to be the closest to (just outside of) Crocodyliformes, closer than Junggarsuchus
  • suggests that the braincase articulation with the palate and quadrate occured before Crocodyliformes
"A new eusuchian crocodyliform with novel cranial integument and the origin of Crocodylia." Holiday, C. and Gardner, N.
  • found in the coastal deposits of the Early Late Cretaceous Kem Kem Beds, Morocco
  • cranial remains - long, flat skull, possibly over 2 meters
  • novel integumentary display structure (possible thermoregulatory function as well)
  • new taxon found to be a derived eusuchian and the sister taxon to crown Crocodylia
  • earliest eusuchian from Africa - biogeographic implications for the origin of modern crocodylians (circum-Tethys vs. North America)
"New remains of Miadanasuchus oblita from the Late Cretaceous of Madagascar and a reevaluation of Trematochampsidae." Sertich, J.
  • Upper Cretaceous Maevarano Formation, Madagascar
  • well preserved partial skull, numerous isolated cranial and postcranial elements, allowing for a comprehensive assessment of morphology
  • Miadanasuchus compares closely with other trematochampsids
  • 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 Araripesuchus.
"New primitive caimanine (Crocodylia, Alligatoridae) from the Miocene of Panama." Hastings, A., Bloch, J., Rincon, A., MacFadden, B., and Jaramillo, C.
  • Culebra Formation, early Miocene, Panama
  • complete skull of a new taxon
  • found to be just outside of Caimaninae
  • 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

"A new specimen of Araripesuchus (Mesoeucrocodylia) with soft tissue preservation from the Lower Cretaceous Romualdo Formation (Araripe Basin), Brazil." Figueiredo, R. and Kellner, A.
  • nearly complete skeleton (skull, limbs, vertebral column, 2 rows of osteoderms)
  • the orbit size and proportions are consistent with A. gomesii while the long, slender limbs are consistent with A. gomesii, A. wegeneri, and A. tsangatsangana
  • significant soft tissue preservation (white substance, likely phosphatized) consisting mostly of muscle fibers but also epidermis
"A new crocodyliform from the middle Cretaceous Woodbine Formation of Texas." Allen, E., Main, D., and Noto, C.
  • Arlington Archosaur Site of the Woodbine Formation (delta plain deposits)
  • disarticulated partial skull and significant postcranial material of one individual along with disarticulated material of several other individuals
  • about 5 meters long, short dentary symphysis, paired dentary pseudocanines, and a robust triangular snout
  • new taxon is a mesoeucrocodylian, possibly a basal goniopholidid or thalattosuchian
"A new, small-bodied alligatoroid from the Hell Creek Formation (Late Maastrichtian) of Montana." Householder, M., Williams, S., and Tremaine, K.
  • small-bodied (about 1 meter), mature or nearly mature individual (based on fused neurocentral sutures)
  • bears some similarities to Brachychampsa montana and other small-bodied alligatoroids, but is a distinct taxon
  • represents the southern-most occurrence of a small-bodied alligatoroid within the Western Interior Basin during the Late Cretaceous
"The palate and braincase in goniopholidid crocodyliforms: insights from a new skull of Eutretauranosuchus delfsi." Pritchard, A. and Turner, A.
  • well-preserved, complete skull with CT scans revealing the palate and braincase
  • dorsoventral crushing distorted some braincase elements, although the anatomical positions are preserved
  • incorperation of the new skull data into a phylogenetic analysis unites Amphicotylus, Calsoyasuchus, Eutrerauranosuchus, and Sunosuchus into a clade of derived goniopholidids, all sharing a unique palatal morphology

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