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DeSantis is a vertebrate paleontologist in the Department of Biological Sciences at Vanderbilt University. She earned degrees from the University of California, Berkeley (B.S.), Yale University (M.E.M.), and the University of Florida (Ph.D.). By studying mammal teeth and bones, she determines how they responded to ancient climate change, potential reasons why they went extinct, and the long-term consequences of both climate change and large animal extinctions on a diversity of plants and animals—including saber-tooth cats, killer wombats, and Tasmanian wolves.

DeSantis is the recipient of a National Science Foundation CAREER Award which is the most prestigious award in support of “early-career faculty who have the potential to serve as academic role models in research and education.” When DeSantis is not in the laboratory, field, or classroom, she is involved in scientific and public outreach in her local community and as the Society of Vertebrate Paleontology Distinguished Lecturer for North America.  She enjoys engaging in science outreach as part of her courses and in conjunction with local science and/or historical centers, schools, movie theaters, and even breweries, and hopes to help change the face of science via these outreach events and other mentoring activities.

DeSantis has published more than 50 papers and book chapters, and her work has been featured on National Geographic Wild, the Discovery Channel, numerous radio shows, and has received global news coverage.  DeSantis dreams big to answer questions of broad relevance to society.  It is therefore no coincidence that her research lab is also named the DeSantis DREAM Lab—which stands for Dietary Reconstructions and Ecological Assessments of Mammals.

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Associate Professor of Biological Sciences

The most detailed study to date of ancient predators trapped in the La Brea Tar Pits is helping Americans understand why today we’re dealing with coyotes dumping over garbage cans and not saber-toothed cats ripping our arms off.

Larisa DeSantis, a Vanderbilt University paleontologist, grew up visiting the one-of-a-kind fossil site in Los Angeles, which contains fossils of predators that tried to eat horses, bison and camels stuck in the tar over the past 50,000 years and themselves became trapped, offering thebest opportunity to understand Ice Age animals facing climate change. The Pleistocene Epoch spanned 2.6 million years ago to about 10,000 years ago, encompassing multiple glacial and interglacial periods and the arrival of humans, one or both of which forced predators to adapt their diets or die.

DeSantis spent the last decade visiting La Brea, studying the teeth of extinct species such as American lions, saber-toothed cats and dire wolves; and teeth from ancient animals whose offspring are still alive today, such as gray wolves, cougars and coyotes. Her work revealed that competition for prey among carnivores wasn’t a likely cause of the Pleistocene megafaunal extinction as formerly believed, because, like dogs and cats of today, one preferred running after herbivores in the open fields, while the other preferred stalking them in forested areas.

“Isotopes from the bones previously suggested that the diets of saber-toothed cats and dire wolves overlapped completely, but the isotopes from their teeth give a very different picture,” said DeSantis, an associate professor of biological sciences at Vanderbilt. “The cats, including saber-toothed cats, American lions and cougars, hunted prey that preferred forests, while it was the dire wolves that seemed to specialize on open-country feeders like bison and horses.  Whilethere may have been some overlap in what the dominant predators fed on, cats and dogs largely hunted differently from one another.”

 To study these ancient predators, she employs dentistry — taking molds of the teeth and shaving off tiny bits of enamel for chemical analysis. Information about everything the animal atelies within the isotopes, she said. Further, the microscopic wear patterns on teeth can clarify who was eating flesh or scavenging on bones.

It’s likely that those giant predators went extinct due to climate change, the arrival of humans to their environment or a combination of the two, she said, and her team is working to clarify the cause of the extinction with multiple colleagues across six institutions as part of a separate on-going study.

What they know is predators alive today in the Americas were better able to adapt their diets. Instead of only feeding on large prey, they could effectively hunt small mammals, scavenge what they could from carcasses or do both.

“The other exciting thing about this research is we can actually look at the consequences of this extinction,” DeSantis said. “The animals around today that we think of as apex predators in North America — cougars and wolves — were measly during the Pleistocene. So when the big predators went extinct, as did the large prey, these smaller animals were able to take advantage of that extinction and become dominant apex-predators.” 

An even more detailed picture of ancient life at La Brea is contained in the paper “Causes and consequences of Pleistocene megafaunal extinctions as revealed from Rancho La Brea mammals,” published today in the journal Current Biology.

The work was supported by National Science Foundation grant EAR1053839.

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Intense look at La Brea Tar Pits explains why we have coyotes, not saber-toothed cats

Paleontologist Larisa DeSantis studies the teeth of ancient and modern mammals to determine how their diets changed across the millennia and, by extension, to clarify biotic responses to climate change.
But the question lingered: Is the wear on teeth an indicator of what those kangaroos and koalas ate or just how much gritty dust and dirt they consumed?
The Vanderbilt University professor’s latest research, published today in the peer-reviewed journal PLOS ONE, confirms that mesowear best indicates what they were eating, not what was on it.
“We can investigate the teeth in modern animals, begin to understand exactly what they’re recording and then take that information – a kind of Rosetta Stone – back into the fossil records and interpret the ecology of fossil animals,” said DeSantis, assistant professor of earth and environmental science. “While we eventually aim to look at how diets have changed over long periods of climate change, this study focused on whether these teeth were recording diet or aridity. They’re recording diet.”
The shape of tooth wear, also termed dental mesowear, is related to the diet of these animals and not the dryness of their local environment, she said.
DeSantis targeted Australia for her work because that continent has been drying out over millions of years, making it a rich environment to study how changing climate prompts animal evolution. For this particular study, she and a team of Vanderbilt graduate and undergraduate students based in Tennessee analyzed casts and photographs of teeth from modern koalas and kangaroos that had died over the past few decades to compare with modern climate and dietary data.
The journal article is titled Effects of climate on dental mesowear of koalas and two broadly distributed kangaroos throughout their geographic range, and the research is funded by an NSF CAREER grant. 

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Wear on koala teeth indicates what they ate, not the dirt on it

Vanderbilt paleontologist Larisa DeSantis' 1989 meeting with Pres. George H. W. Bush instilled in her a sense of responsibility to achieve and be a role model for others

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A  life-changing meeting with then Pres. George H. W. Bush

Climate change is one of society's grandest challenges. To best understand how future climate change will impact biotic organisms, we can use fossil and historic records to clarify the effects of past climate change and human activities on plants and animals. Most notably, being highly adaptable and opportunistic is a key to the success of ancient mammals. The study of our ancient past can provide critical lessons regarding climates role in stressing biotic organisms. Dr. Larisa R.G. DeSantis is a vertebrate paleontologist in the Department of Earth and Environmental Sciences at Vanderbilt University.  She earned degrees from the University of California, Berkeley (B.S.), Yale University (M.E.M.), and the University of Florida (Ph.D.).  By studying mammal teeth and bones, she determines how they responded to ancient climate change, potential reasons why they went extinct, and the long-term consequences of both climate change and large animal extinctions on a diversity of plants and animals. DeSantis is the recipient of a National Science Foundation CAREER Award which is the most prestigious award in support of “early-career faculty who have the potential to serve as academic role models in research and education.” When DeSantis is not in the laboratory, field, or classroom, she is involved in scientific and public outreach in her local community and as the Society of Vertebrate Paleontology Distinguished Lecturer for North America. This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at https://www.ted.com/tedx

Our Ancient Past is the Key to Our Future | Dr. Larisa R.G. DeSantis | TEDxVanderbiltUniversity

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