Living in the Southwestern and South Central United States during the late Triassic, about 221-210 million years ago, Desmatosuchus measured around 4.5m long (14’9″) and was covered in thick interlocking bony osteoderms that protected its back, sides, belly, and tail, with longer spines over its neck and shoulders.
It had a triangular skull with a few blunt teeth at the back of its jaws and a toothless snout at the front. Its pointed lower jaw probably had a keratinous beak, while its upper jaw had an odd upturned flared tip. What exactly was going on with that snoot is uncertain, but it may have anchored a shovel-shaped upper keratinous beak – or, since there was a little bit of flexibility between its snout bones, possibly even a pig-like nose!
It probably mostly ate soft vegetation, using its shovel-like snout to dig up roots and tubers, although similarities with the skulls of modern armadillos suggest it may also have fed on insect grubs.
Peltephilus ferox, an armadillo from the Early Miocene of Argentina (~17-16 mya) that was similar in size to a large dog, probably around 1.5m long (5′). It had less solid armor than its modern relatives, with its bony osteoderms being arranged more like chain mail, loosely connected to each other and slightly overlapping, creating a much more flexible body covering.
Its most unusual features were the horns on its snout, convergently resembling the later horned gophers of North America. But unlike other mammals Peltephilus‘ horns were actually modified plates of its face armor, enlarged pointed osteoderms that were only connected to its skull by soft tissue membranes – meaning that after death they tended to fall off, and the exact number and position of them is still a little uncertain.
Its unusually broad snout and large teeth were originally interpreted as evidence of it being an active carnivore, but more recent studies of its anatomy have suggested that it was much more likely to have been a herbivorous or omnivorous digger, mainly feeding on underground plant matter like roots and tubers.
Boverisuchus magnifrons*, a crocodilian from the early Eocene of Germany (~50-40 mya). Reaching about 3m long (9′10″) it was much more heavily armored than its modern cousins, with an interlocking “exoskeleton” of bony osteoderms covering its body and limbs – leading to it being given the nickname “panzer croc”.
It was adapted for walking and running on land, with relatively long legs and surprisingly hoof-like claws. It may even have carried its weight directly on these hooves similar to mammalian ungulates.
And if that’s not unusual enough, its hind leg musculature suggests it also might have been capable of short bursts of bipedal sprinting.