A new genus and species of large-bodied aetosaur that lived some 218 million years ago has been described from a significant portion of carapace found in Texas, the United States.
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Life restoration of the aetosaur Typothorax coccinarum. Image credit: Smokeybjb.
Aetosaurs are quadrupedal, heavily-armored reptiles of the extinct order Aetosauria.
Their name means ‘eagle lizard,’ and comes from the fact that their skulls somewhat resemble that of a bird.
These creatures were up to 6 m (20 feet) long and widely distributed geographically during the Late Triassic epoch.
“Aetosauria is a group of quadrupedal, armored reptiles whose terrestrial ecology is inferred as including both herbivory and omnivory,” said University of Texas at Austin paleontologist William Reyes and his colleagues.
“They achieved a nearly global geographic distribution, whereas they are stratigraphically restricted to the Late Triassic.”
“Most species of aetosaurs reach a total body length between 2 and 6 m (6.6-20 feet).”
Dubbed Garzapelta muelleri, the newly-identified species grew up to 3.5 m (11.5 feet) in length.
The extinct animal lived in what is now the United States during the middle Norian age of Triassic, approximately 218 million years ago.
Hypothetical reconstruction of Garzapelta muelleri: (a) carapace in dorsal view and (b-f) cross-sections of the carapace in posterior view; cross-sections of the (b) posterior-cervical and anterior-trunk, (c) mid-trunk, (d) posterior-trunk and sacral, (e) anterior-caudal, and (f) mid-caudal regions. Arrows indicate anatomical direction. A – anterior, D – dorsal, L – lateral, M – medial. Image credit: Jeffrey Martz / Reyes et al., doi: 10.1002/ar.25379.
Its fossilized skeleton was found in the Cooper Canyon Formation in Garza County, Texas.
It was recovered with an associated carapace that includes elements from both the left and right sides of the body.
“The discovery of Garzapelta muelleri provides new insight into the interspecific variation of the dorsal carapace within the Aetosauria,” the paleontologists said.
“It is evident that the morphology of the lateral osteoderms is driving the final topological position of Garzapelta muelleri, recovering it as a sister taxon of the Desmatosuchini.”
“The similarities between Garzapelta muelleri, Rioarribasuchus chamaensis, and the paratypothoracin from the Eagle Basin in Colorado do suggest that we are likely dealing with the emergence of a new group of aetosaur that exhibits a biostratigraphical range that is likely confined to the Revueltian estimated holochronozone (215 to 207 million years ago) but may be as old as latest Adamanian.”
The team’s paper appears in The Anatomical Record.
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William A. Reyes et al. Garzapelta muelleri gen. et sp. nov., a new aetosaur (Archosauria: Pseudosuchia) from the Late Triassic (middle Norian) middle Cooper Canyon Formation, Dockum Group, Texas, USA, and its implications on our understanding of the morphological disparity of the aetosaurian dorsal carapace. The Anatomical Record, published online January 11, 2024; doi: 10.1002/ar.25379
