The recent discovery of remains from a strongly armored prehistoric crocodile ancestor species known as aetosaurs provides insight into our environment from 215 million years ago.
Garzapelta Muelleri Discovery
The discovery, led by University of Texas at Austin academics and published in the journal The Anatomical Record earlier this year, identifies a new aetosaur species: Garzapelta muelleri.
The name "Garza" refers to Garza County in northwest Texas, where the aetosaur was discovered, and "pelta" is Latin for shield, alluding to the aetosaur's well-reinforced body. The species name "Muelleri" honors Bill Mueller, the paleontologist who first discovered it.
Scientists identify various species using the bony plates that make up aetosaur armor, yet they rarely have many fossil skeletons to work with.
However, the new study focuses on an aetosaur suit of armor that maintains most of its major components intact.
The suit, known as a carapace, is approximately 70% complete and covers all major body regions.
According to the researchers, aetosaurs are a species similar to current crocodiles that lived during the Triassic Period, which occurred between 229 million and 200 million years ago and predates the Jurassic Period. Aetosaur fossils have been discovered on every continent except Antarctica and Australia.
Garzapelta and other aetosaurs were covered by bony plates known as osteoderms. They were inserted directly into the skin and combined to make a suit of armor, much like a mosaic.
Garzapelta's body was coated with bony plates, and his flanks were flanked by curving spikes that would have provided further protection against predators. Although modern crocodiles are carnivorous, scientists believe that aetosaurs were mostly omnivores.
The species' spikes are remarkably similar to those of another aetosaur species, but researchers discovered that the two are only distantly related.
The commonalities they identified are an example of convergent evolution, which is the independent evolution of similar traits across species. The evolution of flight in insects, birds, mammals, and now-extinct pterosaurs is a prime illustration of this process.
Read Also: Giant Dwarf Crocodiles: Newly Discovered Reptile Species Once Hunted our Human Ancestors
Distinguishing Characteristics of New Species
According to William Reyes, a doctoral student at the UT Jackson School of Geosciences who led the research, a number of distinguishing characteristics of Garzapelta's plates plainly identified it as a new species.
They range from the way the plates fit together to the distinctive bumps and ridges on the bones. However, determining Garzapelta's position in the greater aetosaur family tree was more difficult.
Depending on which aspect of the armor the researchers prioritized in their examination, Garzapelta would wind up in very different places. The armor along its back resembled that of one species, while the spikes at its stomach resembled that of another.
After determining that the spikes evolved independently, the researchers were able to figure out where Garzapelta placed best among other aetosaur species. However, Reyes stated that the study demonstrates how convergent evolution may complicate things.
Garzapelta is part of Texas Tech University's fossil collection. It had spent the majority of the last 30 years on a shelf before Reyes discovered it during a visit.
Bill Parker, an aetosaur expert and park paleontologist at Petrified Forest National Park, believes that university and museum collections play an important role in enabling this type of research.
"They've been sitting in the museum for decades and it just takes someone like Will to come along and finally decide to study them and make them come to life," he added.
Related Article: Ancient DNA Reveals Horned Crocodile From Madagascar Is Closely Related to Today's Crocodile
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