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Scutarx, the newly-named aetosaur. Art by Jeffrey Martz.

Paleo Profile: The Shield Fortress

One of the stumbling blocks in writing about prehistory is the lack of familiar names for many of the strange creatures that came before us. Or, at least, there’s a lack of patience in sounding out anything that’s not a dinosaur. To totally bastardize a quote from Mayor Vaughn in JAWS, “You yell ‘pseudosuchian’, everybody says ‘Huh? What?’ You yell ‘dinosaur’, we’ve got schoolchildren swarming the exhibit hall.”

But not every obscure group suffers from getting lost in translation. One family of ancient oddities has gained a title that playfully sums up what they were by mashing up two more familiar critters. I’m talking about the armadillodiles.

Paleontologists know these reptiles as aetosaurs. They were herbivores and omnivores that thrived during the Triassic, between 252 and 200 million years ago, and while they share an ancient kinship with crocodiles they looked and possibly behaved something like armadillos. Hence the popular name. These bizarre animals are also favorites among Triassic experts. Case in point, Petrified Forest National Park paleontologist Bill Parker has just published a major revision of aetosaur relationships in which he describes a brand new armadillodile that was masquerading as a different species.

While it’d be wonderful if every vertebrate fossil were a complete and easily-identifiable skeleton, the fact of the matter is that paleontologists are often working with bits and pieces. Sometimes those parts get referred to already-existing species as a working hypothesis, as happened with Triassic bones found in Arizona that experts suspected belonged to an aetosaur named Calyptosuchus wellesi which had been found in other spots through the southwest. When Parker took another look at these bones, however, he found that the fossils from Arizona had a raised triangular knob on the scutes running along the animal’s side that are not present in the holotype – or name-bearing specimen – of Calyptosuchus. The different ornamentation meant that the material from Arizona, as well as some pieces from Texas with identical decorations, must belong to something new. Parker named this new armadillodile Scutarx deltatylus, the latest creature to shuffle into the Triassic spotlight.

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The partial skull of Scutarx. From Parker, 2016.

Fossil Facts

Name: Scutarx deltatylus

Meaning: Scutarx means “shield fortress”, while deltatylus translates to “triangular protuberance.”

Age: Around 230 million years ago.

Where in the world?: The Late Triassic rock of Arizona and Texas.

What sort of critter?: An aetosaur, or a heavily-armored and more herbivorous cousin of crocodiles.

Size: Cited as a “medium-sized aetosaurian.”

How much of the creature’s body is known?: A partial skull, osteoderms, and several postcranial skeletons.

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