Redefining Relationships

October 21, 2014

Michelle Stocker (Ph.D. ’13), former graduate student in the University of Texas at Austin’s Jackson School of Geosciences, dramatically rearranged the evolutionary tree for several extinct crocodile-like animals that lived over 200 million years ago in present-day Texas, Wyoming and Germany. Based on this new understanding, she renamed one of the specimens Wannia scurriensis in honor of the paleontologist who first described it in 1949, Wann Langston, Jr., an internationally renowned professor at UT-Austin who died in 2013.

Since the first of these crocodile-like specimens was described in 1904, they were sometimes assigned to one species and sometimes to three or four distinct species, yet always within a single genus called Paleorhinus. According to Stocker’s analysis, the Paleorhinus specimens represent at least four distinct species in three genera. This work, which appears in a special volume honoring Langston published online in several installments in September and October 2013 in the journal Earth and Environmental Science Transactions of the Royal Society of Edinburgh, has important implications for dating several fossil sites.

“Specimens from a wide geographic range and potentially a wide time range were all lumped into the same group,” said Stocker. “That means those sites were all thought to be about the same age. But now we see they might not be.”

Stocker said this work demonstrates the importance of preserving and maintaining fossil collections. Even when a specimen like Wannia scurriensis has been carefully analyzed and described in the scientific literature, new technologies, methodologies and comparative specimens allow scientists to continue to glean new insights.

“It’s a historic specimen—Langston described it back in 1949,” said Stocker. “And we’re still finding out new things about it today.”