Dino buddy

The first dinosaurs appear in the fossil record about 230 million years ago, showing up in South America and Madagascar fauna around the same time. They coexisted with a number of other reptile groups for perhaps 30 million years before rising to dominance at the close of the Triassic Period about 200 million years.

Among the reptilian groups that bumped shoulders with the budding dinosaurs during this time were the aetosaurs, a group of Triassic herbivores armored with heavy bony plates. The early aetosaurs were fairly small - less than a meter - but some of the later forms got quite large. They included Typothorax, which has been known from fragmentary New Mexico fossils for over 100 years. A new paper in the Journal of Vertebrate Paleontology (summarized here at Science Daily) describes two new, very complete fossils that have shed new light on this animal, one of the last of the large herbivores that existed prior to the rise of the dinosaurs.

The new specimens, representing a species known as Typothorax coccinarum, reveal an animal about 2.5 meters in length, half that of the largest aetosaurs. They were completely encased in bony armor, even down to the overlapping plates that ran down the legs onto the feet. They were quadrupeds, but the front half of the body was considerably lighter and more delicate than the rear. The front legs splayed out to the side of the body, while the hind legs were held beneath the body pillar-like. Their anatomy suggests that might have fed by grubbing in the soil in much the same fashion as modern-day armadillos. In fact, Dr. Andy Heckert, one of the study's authors suggests that T. coccinarum looks like an animal "designed by a committee combining a cow with a crocodile and an armadillo."