When did the first multicellular creatures appear? How did flowering plants evolve? Did T. Rex have feathers? Paleontology doesn’t lack for interesting questions. But there’s one topic that can’t help but be especially compelling: the origin and development of our own kind.
In studying the evolution of primates, Big Bend National Park might seem an unlikely destination. But the park has a rich fossil record of these ancient mammals. Now, a leading expert in the field has turned his attention to West Texas.
Dr. Christopher Beard is a Kansas University professor and MacArthur “Genius” Award recipient.
“We still have a giant gap in the fossil record,” Beard said, “between things that everybody says, oh yeah, that's a primate, and things that are kind of like maybe approximating primates, but they're certainly not there.”
In studying primate origins, Beard has worked in Turkey and Libya, Myanmar and China, and, now, Big Bend. The park, he said, abounds in fossils of early primates, and primate-like predecessors known as plesiadapiforms.
With their grasping hands and forward-facing eyes, early primates were built for life in the trees. Plesiadapiforms were likewise forest creatures. It’s uncanny to imagine them in our region. But in the transition between the Paleocene and Eocene epochs, 55 million years ago, global temperatures rose by 15 degrees. In that greenhouse world, these mammals spread across the globe, moving back and forth between Asia and North America.
“I mean, it's shocking for people,” Beard said. “We have fossil palm trees from Alaska. You could go literally across the Bering Land Bridge, and not only would it be forested, it would be warm, temperate forest, possibly even almost subtropical.”
Beard has examined fossils collected by pioneering UT scientist Jack Wilson, and LSU researcher Judith Schiebout. Last November, he and his students hunted fossils on Tornillo Flat, north of Panther Junction, and they plan to return this fall.
The Big Bend fossils reveal strange and wondrous creatures. That includes a primate predecessor called Chiromyoides.
“I would guess that the oldest Chiromyoides that we know about anywhere in the world is in Big Bend National Park,” Beard said. “I don't know what's going on in Big Bend, they seem to like it down there.”
Chiromyoides were similar to aye-aye lemurs found today in Madagascar. These nocturnal primates that use their teeth and long fingers to eat grubs out of tree trunks. Chiromyoides could likewise chew through bark. It was the size of a “very large squirrel,” Beard said.
Big Bend not only contains the oldest evidence of these types of animals. It’s also the southernmost place in North America where such fossils are found.
Primates are unique not only for their grasping hands and forward-facing eyes, but for their larger brains, and the earliest known true primate fossil is from China. Beard believes Asia is where primates emerged. But other paleontologist argue for North America as the origin. If that’s the case, Big Bend is a promising place to look for the evidence.
One group of fossils here are particularly intriguing in this regard. They’re creatures called microsyopids, and primates could be their descendants.
“If we're trying to say which plesiadapiforms are closest to primates, I think microsyopids have a real shot,” Beard said. “They've got a lot of features that, in my opinion, look very, very primate-like.”
Beard and his students have also identified the fossils of a true primate, of a previously unknown species.
Gazing out at Big Bend’s desert wilderness, it’s stunning to consider: This land was once home to the ancestral kin of lemurs and tarsiers, of monkeys and apes, and of our own kind.
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