Crocodiles and their kin command respect — whether it’s an alligator in the Everglades, a caiman in the Amazon, or a sea croc ambushing a shark off the Australian coast. But as impressive as these creatures are, their stature pales compared to that of their ancestors. More than 200 million years ago, in the Triassic Period, ancient “Pseudosuchians,” or proto-crocs, dominated the planet. They flourished in diverse forms, confining dinosaurs, not to mention the earliest mammals, to the ecological margins.
West Texas is an important source of their fossils. And now a new species has been added to the roster. Behold Garzapelta muelleri, an ancestral crocodilian of the West Texas Triassic.
Bill Mueller was a longtime paleontologist at Texas Tech University.
“It's amazing what we're finding,” Mueller said in a 2016 interview. “We're very fortunate to live very close to our research areas. We can run out almost any day and go do fieldwork. Who knows, this weekend we might find another new species.”
Mueller died in 2019. But his work continues to bear fruit.
One site he frequented is in Garza County, near Post, Texas. Red rocks in caprock canyons here abound in Triassic fossils, and in 1989 Mueller found the fossils of a 215-million-year-old reptile. Its precise identity remained mysterious.
Will Reyes is a UT-Austin doctoral student.
“I had heard stories about it,” Reyes said. “A lot of people have seen it, and they've all kind of cracked their heads trying to figure out what it was. So we decided to tackle it and let me lead it. And I just went crazy with it.”
Reyes set out to identify Mueller’s find.
He knew it was an aetosaur, a type of reptile that flourished in the late Triassic. Some 30 species were known. But, through careful analysis, Reyes and his colleagues confirmed this was a new species. They named it Garzapelta muelleri, honoring the site of its discovery, and Mueller himself.
The main clues were the creature’s osteoderms, bony deposits, like those of an armadillo, that formed a heavy armor.
All aetosaurs were thus armored, because compared to the Triassic, our world is warm and fuzzy.
“It kind of goes to highlight the intensity of living in the Triassic,” Reyes said. “Everything wants to eat you. Everything has teeth. So you need to develop some armor. So there's an arms race.”
Would-be predators included phytosaurs, which, like their modern crocodile kin, were long-snouted and semiaquatic. There was Postosuchus, a fierce proto-croc that reached lengths of 20 feet and stood upright, like a T. Rex. And there were threats beyond the reptilian. Ten-foot-long predatory amphibians called metoposaurs plied the streams.
Yet Garzapelta muelleri itself probably wasn’t easy pickings. It was a “girthy creature,” Reyes said, more than 3-feet wide, and 10 feet long.
Reyes is now focused on another remarkable West Texas find. In Howard County, near Big Spring, a palm-sized chunk of rock preserved a cluster of aetosaur babies, each about an inch and a half long.
It’s not known whether they emerged from eggs or were live-born. But even these newborn aetosaurs had emerging armor.
“I’ve got a micro CT scan and everything to digitally segment out the anatomy,” Reyes said. “It's just bones on bones on bones, just kind of wrapping each other. So I've been tediously segmenting out every single bone that I can, and it's starting to really look like something.”
Aetosaurs and other great proto-crocs vanished as the Triassic Period gave way to the Jurassic. Crocodilians, of course, endured. But West Texas fossils reveal that their kind once ruled the planet.
Nature Notes is produced by Marfa Public Radio with the Sibley Nature Center. The program can be heard each Tuesday and Thursday, at 7:45 a.m. and 4:44 p.m. This episode was written by Andrew Stuart.
