Which came first: Grass or the teeth to eat it with?

High-crowned teeth in South America: A solution to a different problem

In contrast to their hypothesis, Burke researchers did not find evidence of grasslands in the fossil record of southern Argentina. Instead, their research shows that South American herbivores with high-crowned teeth lived in subtropical forests with abundant palm trees.

This means that South American plant eaters evolved the same adaptation as grass eaters elsewhere, but not in response to grasslands. In other words, a particular functional characteristic in animals can evolve for several, very different reasons. South American herbivores’ teeth might have adapted in response to other grit in their diet, such as dirt or volcanic ash.

“No one looked in detail at evidence in the plant record before,” Dr. Strömberg said. “Our findings show that you shouldn’t assume adaptations always came about in the same way; that the trigger is the same environment every time.”

What’s next?

Test a new hypothesis! Did high-crowned teeth evolve in South America because of volcanic ash? Stay tuned!

See it for yourself!

Visitors can learn more about this study and the Burke Museum’s paleobotany collections in a new “Why Study Evolution?” display, on view now through 2015. Included in the display are 28-million-year-old fossilized mammal teeth from the Burke Museum’s paleontology collection, up-close views of microscopic phytoliths, and more.

Plan your visit.

Study Information

Caroline A.E. Strömberg, Regan E. Dunn, Richard H. Madden, Matthew J. Kohn, and Alfredo A. Carlini. Decoupling the spread of grasslands from the evolution of grazer-type herbivores in South America. Nature Communications, published February 12, 2013.

The exhibit was developed by Caroline Strömberg, Regan Dunn, and Winifred Kehl with help from Richard Madden, Matthew Kohn, Alfredo Carlini, and Burke staff. It is based on work supported by the National Science Foundation under Grant No. 0819910. Any opinions, findings, and conclusions or recommendations expressed here are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Article Source: Burke Museum