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New Papers of the Ya-Ya Sisterhood

Two new papers available free on-line at http://pubs.usgs.gov/of/2007/1047:

Smith, N.D., Makovicky, P.J., Pol, D., Hammer, W.R., and Currie, P.J. 2007. The dinosaurs of the Early Jurassic Hanson Formation of the central Transantarctic Mountains: phylogenetic review and synthesis; pp. 1-5 in Cooper, A., Raymond, C., and Team, I.E. (eds.), Antarctica: a Keystone in a Changing World -- Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. U.S. Geological Survey Open-File Report 2007-1047, SRP 003. U.S. Geological Survey, Washington, D.C.

ABSTRACT: The Hanson Formation of the Central Transantarctic Mountains has yielded a diverse Early Jurassic terrestrial fauna, which includes the nearly complete theropod dinosaur, Cryolophosaurus ellioti, and a fragmentary basal sauropodomorph dinosaur. The Hanson Formation dinosaurs are important for understanding early dinosaur evolution because: 1) they preserve a mosaic of morphological traits that render them useful for interpreting poorly known parts of the dinosaur evolutionary tree; 2) they are from the Early Jurassic, a critical period in early dinosaur evolution about which knowledge is scant; and 3) they are the only known Early Jurassic dinosaurs from Antarctica, making them particularly valuable for understanding patterns of biotic interchange during this time. Recent research suggests that Cryolophosaurus belongs to a geographically widespread clade of mid-sized, Early Jurassic theropods with cranial crests that includes Dilophosaurus wetherilli, 'Dilophosaurus' sinensis, and Dracovenator, and renders Coelophysoidea sensu lato non-monophyletic. The Antarctic sauropodomorph represents a distinct taxon that is a member of a similarly diverse massospondylid clade. This taxon shares a number of features with more derived sauropodomorphs, and provides additional evidence for the paraphyly of Prosauropoda. The phylogenetic relationships of the Antarctic dinosaurs are also consistent with a pattern of worldwide faunal homogeneity between Early Jurassic continental biotas. Furthermore, these analyses support a "ladder-like" arrangement for basal theropod and basal sauropodomorph phylogeny, suggesting that these groups passed through "coelophysoid" and "prosauropod" stages of morphological organization early in their respective evolutionary histories.

Case, J.A., Martin, J.E., and Reguero, M. 2007. A dromaeosaur from the Maastrichtian of James Ross Island and the Late Cretaceous Antarctic dinosaur fauna; pp. 1-4 in Cooper, A., Raymond, C., and Team, I.E. (eds.), Antarctica: a Keystone in a Changing World -- Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. U.S. Geological Survey Open-File Report 2007-1047, SRP 083. U.S. Geological Survey, Washington, D.C.

ABSTRACT: The recovery of material of a small theropod from the Early Maastrichtian, Cape Lamb Member of the Snow Hill Island Formation is an unusual occurrence from primarily marine sediments. The pedal morphology of the specimen that includes a Metatarsal II with a lateral expansion caudal to Metatarsal III, a third metatarsal that is proximally narrow and distally wide, a Metatarsal III with a distal end that is incipiently ginglymoidal and a second pedal digit with sickle-like ungual are all diagnostic of a theropod that belongs to the family of predatory dinosaurs, the Dromaeosauridae. Yet this Antarctic dromaeosaur retains plesiomorphic features in its ankle and foot morphology. As new dromaeosaur species are being recovered from the mid-Cretaceous of South America and the retention of primitive characters in the Antarctic dromaeosaur, a new biogeographic hypothesis on dromaeosaur distribution has been generated. Gondwanan dromaeosaurs are not North America immigrants into South America and Antarctica; rather they are the relicts of a cosmopolitan dromaeosaur distribution, which has been separated by the vicariant break up of Pangea and created an endemic clade of dromaeosaurs in Gondwana.

In the same volume, for those interested, a paper on a Late Cretaceous flora from the Shetland Islands (paper 081) and a juvenile Antarctic elasmosaurid (paper 066). Some papers concerning mostly Permian stuff, too.

Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
and     dinogami@gmail.com


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