From: Ben Creisler
bh480@scn.org
For anyone who was holding his/her breath, you can
breathe again. The paper is officially out, so if someone
else has not mentioned it yet:
Ricardo N. Martinez, Paul C. Sereno, Oscar A. Alcober,
Carina E. Colombi, Paul R. Renne, Isabel P. Montañez and
Brian S. Currie (2011)
A Basal Dinosaur from the Dawn of the Dinosaur Era in
Southwestern Pangaea
Science 331 (6014): 206-210 (14 January 2011)
DOI: 10.1126/science.1198467
http://www.sciencemag.org/content/331/6014/206.abstract
Abstract
Upper Triassic rocks in northwestern Argentina preserve
the most complete record of dinosaurs before their rise
to dominance in the Early Jurassic. Here, we describe a
previously unidentified basal theropod, reassess its
contemporary Eoraptor as a basal sauropodomorph, divide
the faunal record of the Ischigualasto Formation with
biozones, and bracket the formation with 40Ar/39Ar ages.
Some 230 million years ago in the Late Triassic (mid
Carnian), the earliest dinosaurs were the dominant
terrestrial carnivores and small herbivores in
southwestern Pangaea. The extinction of nondinosaurian
herbivores is sequential and is not linked to an increase
in dinosaurian diversity, which weakens the predominant
scenario for dinosaurian ascendancy as opportunistic
replacement.
Also
Michael Balter
Pint-Sized Predator Rattles The Dinosaur Family Tree
Science 331 (6014): 134 (14 January 2011)
DOI: 10.1126/science.331.6014.134
http://www.sciencemag.org/content/331/6014/134.short
Summary
On page 206 of this week's issue of Science, a team
working in Argentina reports the discovery of a very
early dinosaur—possibly a distant ancestor of
Tyrannosaurus rex—that lived about 230 million years ago,
during what paleontologists call the dawn of the
dinosaurs. The researchers say the new finds—two
specimens that together make up a nearly complete
skeleton of a diminutive, 1-meter-long dinosaur—and
neighboring fossils show that dinosaurs didn't outcompete
other reptiles, but rather gradually replaced them as
their predecessors died out for other reasons. More
controversially, the team says the fossils show that one
of the most well-known early dinosaurs, Eoraptor, long
considered an ancestor of meat eaters like T. rex, was
actually an ancestor of gigantic plant-eating dinosaurs
like Apatosaurus.
There's a cool video also at:
http://news.discovery.com/videos/dinosaurs-dawn-runner-
sheds-light-on-dino-evolution.html