A new dinosaur find is shedding light on the history of bone-headed dinosaurs, while at the same time reminding scientists of the shortcomings of the fossil record.

The fossil record represents a skewed version of ancient ecosystems. Of those organisms that have been lucky enough to stand the test of time, only a small fraction will be found by paleontologists and studied thoroughly enough to make a lasting impression on our knowledge of prehistoric times.

We all know dinosaurs were enormous beasts. But they get this reputation partially because paleontologists primarily discover large dinosaurs—the larger the bones, the more easily preserved their fossils are. The record of small-bodied dinosaurs may be lacking due to the tendency of their delicate bones to get destroyed or otherwise not become preserved over time.

Dr. David Evans from the Royal Ontario Museum and the University of Toronto recently conducted an analysis published in the journal Nature Communications of a new, small-bodied dinosaur discovered in Alberta, Canada. The new species, named Acrotholus audeti, belongs to the clade Pachycephalosauria —bone-headed dinosaurs—a group of dinosaurs with thick strong skulls.

A. audeti lived 85 million years ago, making it the oldest pachycephalosaur yet discovered in North America. This creature was 6 feet long and weighed about 90 pounds—relatively small compared to other dinosaurs (Sauropods, for instance, grew to be 120 feet long and weighed up to a whopping 200,000 pounds).

The dome formation on top of Acrotholus’ head was probably used to fight potential competitors or to attract mates. Bone-headed dinosaurs from later times had well-developed head domes, but a skull formation as advanced as A. audeti’s is unusual for how early the species lived.

In modern ecosystems, smaller organisms are much more diverse than larger ones. The discovery of Acrotholus indicates that perhaps a similar pattern was occurring million of years ago. Small-bodied dinosaurs may have been far more diverse than previous paleontological studies have shown.

The complete study can be found in the journal Nature Communications.

The Paleontological Research Institution, Ithaca, New York, is pleased to sponsor Paleontology content for This View of Life. Founded in 1932, PRI has outstanding programs in research, collections, and publications, and is a national leader in development of informal Earth science education resources for educators and the general public.

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Published On: May 26, 2013

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