Monday, November 14, 2011

SVP 2011 Roundup - Crocodylomorph Edition Part 1

General Crocodylomorph Ecology and Evolution
(in order of presentation)
"Campanian crocodyliforms of Laramidia: new insights from the Kaiparowits Basin of southern Utah." Irmis, R., Sertich, J., Hutchison, J. H., And Titus, A.
  • comprehensive survey of Kaiparowits crocodyliforms
    • large, goniopholidid-like mesoeucroc.
    • basal alligatorids: Deinosuchus hatcheri and Brachychampsa
    • small alligatoroid lacking globidont teeth
  • clear biogeographic relationship with the San Juan Basin (New Mexico) - some regionality but also endemic taxa
  • supports the hypothesis of a distinct southern biogeographic province
"Direct evidence of crocodyliform predation on small dinosaurians from the Kaiparowits Formation of Utah." Drumheller, S. and Boyd, C.
  • predation by a small crocodyliform on a juvenile basal ornithopod (new Hypsolophodont)
    • several bite marks characteristic of crocs
    • partial tooth embeded in femur (distal tip had been broken off previously)
"The myth of the living fossil: basal crown group relationships, reversing polarities, and restoration of the ancestral crocodylian." Brochu, C., Turner, A., Allen, E., and Wilberg, E.
  • outgroups of Crocodylia predominantly small bodied (less than 2 meters)
  • the crocodylian ancestral condition was likely equivalent to the small durophagous alligatorines of the Paleogene
  • living crocodylians are not generalized but independently highly specialized (NOT LIVING FOSSILS!!!!)

"Freshwater niche competition between choristoderes and crocodiles in the Mesozoic and Paleogene." Matsumoto, R.
  • Early Cretaceous of Asia - high diversity of choristoderes, no aquatic crocs
  • Middle Jurassic thru Eocene of Europe - only small lizard-like choristoderes, co-occuring with larger crocs
  • Cretaceous thru Paleogene of Euramerica - neochoristoderes co-occur with similar sized crocs, but neochoristoderes are the only strongly longirostrine reptiles
  • long-snouted crocs diversify in freshwater after the extinction of neochoristoderes (Oligo-Miocene)
"Late Neogene Alligator evolution and a description of specimens from the Gray Fossil Site, southern appalachians, USA." Schubert, B., Mead, J., and Stout, J.
  • abundant Alligator material
    • osteroderms and other fragmentary material
    • mostly complete juvenile
    • pathological adult skull
    • two adult partial post-cranial skeletons
  • Alligator of Gray Fossil Site posses a mixture of characters found in A. olseni, A. mefferdi, and A. mississippiensis
"Crocs not theropods were likely top predators on the Cretaceous dinosaur freeway: implications of a large track census." Lockley, M. and Lucas, S.
  • at least 1380 individual trackmakers
  • mostly ornithopods (71%)
  • only small theropods present (not large enough to prey on ornithopods)
  • abundant crocodylian tracks (walking and swimming), including large individual (around 4 meters)
"A taphonomic and paleoecological comparison of isolated crocodyliform teeth from the Woodbine Formation of Texas and the Hell Creek Formation of Montana." Bennett, G., Main, D., Peterson, R., and Anderson, B.
  • 4 different crocodyliforms in the Woodbine Formations, including Woodbinesuchus and a new genus
  • 2 different crocodyliforms in the Hell Creek (Brachychampsa montana and Borealosuchus sternbergi), showing similar population structure to A. mississippiensis.

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