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Small theropod dinosaurs from Morrison Formation of Como Bluff, Wyoming (free pdf)

Ben Creisler

A new paper in open access:

Sebastian G. Dalman (2014)
New data on small theropod dinosaurs from the Upper Jurassic Morrison
Formation of Como Bluff, Wyoming, USA
Volumina Jurassica 12 (2):  181-196
DOI : 10.5604/17313708 .1130142

In 1879, Othniel C. Marsh and Arthur Lakes collected in the Upper
Jurassic Morrison Formation Quarry 12 at Como Bluff, Wyoming, USA,
several isolated axial and appendicular skeletal elements of small
theropod dinosaurs. Since the discovery the specimens remained
unnoticed for over a century. The skeletal remains of small theropods
are rare at Como Bluff and throughout the Morrison Formation. Their
bones are delicately constructed, so they are not as well-preserved as
the bones of large-bodied theropods. The bones of small theropods
described here were found mixed with isolated crocodile teeth and
turtle shells. Comparison of the skeletal materials with other known
theropods from the Morrison Formation reveals that some of the bones
belong to a very small juvenile Allosaurus fragilis and Torvosaurus
tanneri and also to a new ceratosaur taxon, here named Fosterovenator
churei, whereas the other bones represent previously unidentified
juvenile taxa of basal tetanuran and coelurid theropods. The discovery
and description of these fossil materials is significant because they
provide important information about the Upper Jurassic terrestrial
fauna of Quarry 12, Como Bluff, Wyoming. The presence of previously
unidentified theropod taxa in the Morrison Formation indicates that
the diversity of basal tetanuran and coelurid theropods may have been
much greater than previously expected. Although the fossil material
here described is largely fragmentary, it is tenable that theropods of
different clades co-existed in the same ecosystems at the same time
and most likely competed for the same food sources.