Oldest Coelurosaurian Found

[MKIRKALDY@aol.com]

The July 16, 1998 issue of Nature announces a new therizinosaur (no 
name given) (Nature 394, 234-235) "The Oldest Coelurosaurian" - Xijin 
Zhao, Xing Xu.

"This discovery extends the age range of these unusual animals, 
previously known only from the Cretaceous period (Albian-Maastrichtian
stage1), back by another 94 million years. This is the oldest definitive 
record of a coelurosaurian theropod, which therefore minimizes the 
divergence time for members of the group. Most important, it contradicts
the theory that the non-avian Coelurosauria occur too late in the fossil 
record to be related to birds."
<SNIP>
"This specimen (V11579, held at the Institute of Vertebrate 
Paleontology and Paleoanthropology, Beijing), consisting of most 
of the left dentary and part of the splenial, was collected from 
the bottom of dull, purplish beds of the Lower Lufeng Formation of 
Eshan County, Yunnan."
<SNIP>
"The therizinosauroid affinities of the specimen are indicated by the 
presence of a broad and flat shelf lateral to the tooth row and the 
few, large nutrient foramina below it; the downturned anterior end of 
the dentary; the decrease in the size of teeth posteriorly; the large 
number and small size of the teeth; and the morphology of the
teeth."
<SNIP>
"The new specimen is therefore the oldest fossil definitively referable 
to Coelurosauria, extending the record of this group back by roughly 
30 million years."

Mary
mkirkaldy@aol.com