New Papers for Schmucks

[Dann Pigdon <dannj@alphalink.com.au>]

Brusatte, Nied?wiedzki & Butler 2010 "Footprints pull origin and 
diversification of dinosaur stem 
lineage deep into Early Triassic". Proceedings of the Royal Society B

Abstract:

The ascent of dinosaurs in the Triassic is an exemplary evolutionary radiation, 
but the earliest 
phase of dinosaur history remains poorly understood. Body fossils of close 
dinosaur relatives are 
rare, but indicate that the dinosaur stem lineage (Dinosauromorpha) originated 
by the latest 
Anisian (ca 242?244 Ma). Here, we report footprints from the Early?Middle 
Triassic of Poland, 
stratigraphically well constrained and identified using a conservative 
synapomorphy-based 
approach, which shifts the origin of the dinosaur stem lineage back to the 
Early Olenekian (ca 249?
251 Ma), approximately 5?9 Myr earlier than indicated by body fossils, earlier 
than demonstrated 
by previous footprint records, and just a few million years after the 
Permian/Triassic mass 
extinction (252.3 Ma). Dinosauromorph tracks are rare in all Polish 
assemblages, suggesting that 
these animals were minor faunal components. The oldest tracks are quadrupedal, 
a morphology 
uncommon among the earliest dinosauromorph body fossils, but bipedality and 
moderately large 
body size had arisen by the Early Anisian (ca 246 Ma). Integrating trace 
fossils and body fossils 
demonstrates that the rise of dinosaurs was a drawn-out affair, perhaps 
initiated during recovery 
from the Permo-Triassic extinction. 

http://rspb.royalsocietypublishing.org/content/early/2010/10/06/rspb.2010.1746

The paper itself isn't free, but the supplemental info is extensive.

-- 
_____________________________________________________________

Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
_____________________________________________________________