West Texas was once home to rainforests, ancient primates

Andrew Kirsop

While West Texas today is dominated by sprawling deserts, 50 million years ago the area contained lush tropical rainforests with unique species of monkeys and apes.

On Friday, the Environmental Science Institute hosted its 103rd “Hot Science — Cool Talks” lecture and outreach program titled “Some Like It Hot, Hot, Hot: When Primates Roamed Texas’ Rainforests.”

Presenter Christopher Kirk, anthropology professor and inductee to UT’s Academy of Distinguished Teachers , based the talk on his research of primate evolution. He studies fossils for the purpose of reconstructing the evolutionary timeline.

Kirk has done most of his fossil hunting near Big Bend at Devil’s Graveyard, which is part of the Dalquest Research Site. He said that 45 million years ago, humid, tropical forests cloaked the slopes of active volcanoes there.

“What you have on the other side of the Rocky Mountain front is something called the Torneo Basin,” said Kirk. “This was a topographic low [area] that was between two mountain ranges … and what’s great is you think about these basins as traps for sediment and it’s sedimentary rocks where you find fossils.”

Kirk said the fossil record paints a picture of the various animals roaming the region during the Eocene era. During his presentation, he showed pictures of fossils and artistic renderings of what the living animals may have looked like. These ranged from small horse-like mammals about the size of a miniature doberman, to large herbivores related to the rhinoceros, to carnivores that, like spotted hyenas, had teeth capable of crushing bones.

Kirk said even more than these extinct mammals, he is looking for fossilized primates in the region.

“Primates are our order of mammals, and in addition to humans, [the order] includes things like monkeys and apes,” Kirk said, “These Eocene tropical forests in Big Bend were like most tropical forests today in having primates. That is what I study and that is what gets me out of my tent in the morning when I’m looking for fossils out there.”

In 2011, Kirk and his team were able to describe an extinct species of primate based on fossils collected at Devil’s Graveyard. This primate, which they called Mescalerolemur horneri, would have resembled a present-day lemur.

Kirk also explained why non-human primates are not seen around Big Bend now.

“The Eocene was much warmer than the present day, but it ends with the single biggest, most precipitous, drop in global temperature of the last 66 million years,” Kirk said. “When you lose the tropical forests at the end of the Eocene, you lose the primates that depend on those tropical forests and you see a complete shift in the community of animals you find on the landscape.”

Environmental science sophomore Georgia Varvarezos volunteered at the talk and said she enjoyed listening to Kirk’s lecture.

“I definitely enjoyed his enthusiasm of the topic,” Varvarezos said. “It was just a really cool talk, especially because he defined his own species.” 

Varvarezos explained that she is in the geology track of environmental science and hopes to explore paleontology further and possibly take one of Kirk’s courses. 

“I’m sure I’d learn a lot from him, and I definitely wouldn’t fall asleep in class,” she said.