JOHNSON CITY (March 21, 2014) – An East Tennessee State University faculty member’s expertise on dung recently helped scientists confirm the early presence of bighorn sheep on a Mexican island.
The discovery is discussed in an article published this week in the open-access journal PLOS ONE.
A team of University of California-Riverside researchers – initially looking for fossil plants – discovered the dung mat in a small cave in the Sierra Kunkaak, a rugged mountain range on the eastern side of the Tiburón Island, located in the Gulf of California.
The dung sample was sent to Dr. Jim Mead, who chairs the ETSU Department of Geosciences and is an internationally recognized authority on the study of dung.
“The first thing I did with the sample was to smell it,” Mead said. “Smells can indicate the age of the sample, and with this particular one I knew the sample was younger than 5,000 years old.”
“That and the morphology of the dung pellets made me think it was from a bighorn sheep.”
Mead said the scientists used an “ancient DNA analysis” process to examine the biologic chemicals in the dung and confirmed that it belonged to bighorn sheep similar to those found today in northern Mexico, southern Arizona and California.
Prior to this study, researchers had no proof that bighorn sheep inhabited Tiburón Island – which is the largest island in the Gulf of California – prior to 1975 when, according to the article, wildlife biologists introduced bighorn sheep to the island for hunters.
Mead has been studying dung for over 30 years and provides consultation to researchers around the world.
“I developed an interest in dung when I was a graduate student and found these remains in a cave,” he said. “Other than my mentor, not many people were looking at dung. ‘But it is a fossil, just like a skull,’ I thought, and from there my interest continued to build. It is a unique fossil resource.
“Dung tells you a lot about diet,” he said. “True, a skull and teeth can reveal some information about the diet of a species, but with dung we know with certainty what the animal ate.”
Mead’s curated collection of dung is one of the largest in the world and contains “a couple of thousand specimens,” some of which were given to him by his late mentor, Dr. Paul S. Martin.
The PLOS ONE article was written by researchers at UC-Riverside, the U.S. Geological Survey, Oregon State University and ETSU. Authors are Benjamin T. Wilder, Julio L. Betancourt, Clinton W. Epps, Rachel S. Crowhurst, Mead, and Exequiel Excurra.