The team's analysis of stegosaur plates lends support to a growing consensus among paleontologists that the weird adornments of many dinosaurs - the horns of triceratops, the helmet-like domes of the pachycephalosaurs, and the crests of the duck-billed hadrosaurs - likely served no function other than to differentiate species, akin to birds' colorful feather ornamentation.

"Our studies of bone histology are telling us a lot about dinosaur social behavior and lifestyle," said Kevin Padian, professor of integrative biology at the University of California, Berkeley, and a curator in the campus's Museum of Paleontology. "We cut up and compared the internal structures of stegosaur plates and the smaller scutes of their ancestors, and found that a functional explanation for these plates doesn't make sense for all the stegosaurs. So we think that they're more likely involved in some type of species recognition, as with many African antelopes - you have to be different from all animals in the area so you don't get mixed up with other species."

"When people see bizarre structures, they always want to give them bizarre functions," said co-author Russell Main, a former UC Berkeley undergraduate now in graduate school in Harvard University's Department of Organismic and Evolutionary Biology. "But in the case of stegosaurs or even ceratopsians, like triceratops, and also in modern bovids and some other artiodactyls, where you see a number of different types of horn or antler arrangements, you don't necessarily need to apply functional explanations. They can be relatively easily explained by talking about species or mate recognition."

Padian, Main and coautho
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Contact: Robert Sanders
rsanders@berkeley.edu
510-643-6998
University of California - Berkeley
16-May-2005