Move over dinosaurs, there’s a new prehistoric titan in town. Aetosaurs, crocodile cousins clad in impressive bony armor, ruled the Triassic period long before the reign of the T-Rex. These fascinating creatures, once widespread across the globe, met their demise roughly 200 million years ago.
Fossil hunters rely on the aetosaurs’ distinct armor plates, called osteoderms, to identify different species. Complete skeletons are a rarity. However, a recent discovery at The University of Texas at Austin has paleontologists excited. They’ve unearthed a remarkably well-preserved aetosaur carapace, a nearly complete suit of armor encompassing most major body regions.
“This is an exceptional find,” said William Reyes, a doctoral student at UT Jackson School of Geosciences who led the research. “Usually, we only have fragments to work with. Here, we have armor tracing all the way from the neck to the tip of the tail.”
The near-intact carapace belonged to a new species, named Garzapelta muelleri. “Garza” honors the Texas county where the fossil was unearthed, and “pelta” is Latin for shield, a fitting tribute to the creature’s heavily armored form. The species name honors Bill Mueller, the paleontologist who first discovered the specimen.
Imagine a modern crocodile, but decked out in armadillo-like armor – that’s Garzapelta. These bony plates, embedded directly in its skin, interlocked to create a formidable mosaic defense system. Additionally, Garzapelta boasted curved spikes along its flanks for extra predator protection. Interestingly, while modern crocs are carnivorous, scientists believe aetosaurs were primarily omnivores.
One surprising revelation – the spikes on Garzapelta closely resembled those found on another aetosaur species. Further investigation showed these creatures were only distantly related. This similarity exemplifies convergent evolution, where unrelated species develop similar traits due to facing similar environmental pressures. The evolution of flight in insects, birds, and pterosaurs is a classic example of this phenomenon.
Reyes emphasized the unique features on Garzapelta’s plates that distinguished it as a new species. These included the way the plates fit together and the presence of distinctive bumps and ridges. However, determining Garzapelta’s place in the aetosaur family tree proved challenging. Analyzing different sections of the armor yielded conflicting results. The back armor resembled one species, while the midsection spikes mimicked another.
By recognizing the independently evolved spikes, the researchers were finally able to pinpoint Garzapelta’s position among other aetosaur species. This discovery highlights how convergent evolution can introduce complexities in classifying prehistoric creatures.
“Convergence of osteoderms has been observed before, but Garzapelta muelleri showcases the most extreme example we’ve seen,” said Reyes. “It emphasizes the potential pitfalls this phenomenon can pose in our analyses.”
The Garzapelta fossil resides in the Texas Tech University collections. It sat unnoticed for decades before Reyes brought it back to life through his research. Bill Parker, an aetosaur expert, emphasizes the crucial role university and museum collections play in such discoveries.
“These fossils aren’t new finds,” he explains. “They’ve been patiently waiting in museums for someone like Will to come along, recognize their significance, and bring their stories to light.”
Reyes’ work doesn’t end here. He’s now delving into the possibility that armor variations might be linked to an animal’s age or sex. He’s utilizing the Jackson School’s extensive aetosaur fossil collection, most of which originated from Works Progress Administration excavations in the 1940s.
This new aetosaur discovery sheds light on the diversity and adaptations of these Triassic titans. As paleontologists continue to analyze these fascinating creatures, we can expect even more remarkable revelations about their armored past.
The paper is published in The Anatomical Record.
Source: University of Texas at Austin