Paleo Profile: The Shield Fortress

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

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.

The partial skull of Scutarx. From Parker, 2016.
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.


Parker, W. 2016. Revised phylogenetic analysis of the Aetosauria (Archosauria: Pseudosuchia); assessing the effects of incongruent morphological character sets. PeerJ. doi: 10.7717/peerj.1583

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face
Alcide d’Orbigny’s Dawn Beast

One thought on “Paleo Profile: The Shield Fortress

  1. Geologic age is incorrect – Scutarx is from sediments (lower Sonsela Member of the Chinle Fm) radioisotopically dated to between 220 and 215 million years ago

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