Stegomosuchus

The holotype and only known specimen of Stegomosuchus (AM 900) was discovered at what was then known as the Hines Quarry, east of East Longmeadow, Massachusetts, just before the turn of the 20th century. It was found below the surface, in red sandstone used for building material. This site is now called the Hoover Quarry; it has also yielded invertebrate trace fossils and dinosaur tracks (Eubrontes). The rocks are now known to belong to the Portland Formation. While thought to be Triassic when Stegomosuchus was originally described, (approximately 200 to 190 million years ago). Its discoverer, G. B. Robinson, took home the blocks containing the specimen and placed them in his door yard, where they were exposed to the elements for "about seven years." The fossil was then found and obtained by Mr. and Mrs. E. D. White, and the specimen was then described by B. K. Emerson and F. B. Loomis in 1904. At that point, the specimen was in three blocks. The bones had been largely preserved as impressions, and the two main blocks had upper and lower impressions of the skull, twenty-eight pairs of armor plates situated along the spine up to the pelvis, right arm (minus the hand) and shoulder blade, and left foot. AM 900 was a small animal, with a skull estimated at long and across, and a body length from snout to pelvis of . Emerson and Loomis described the specimen as a new species of Stegomus (S. longipes), an aetosaur known from slightly older rocks. ==Classification==

The assessment of the material as belonging to a species of the aetosaur Stegomus held for about twenty years, until Friedrich von Huene reclassified it, giving the species the new genus Stegomosuchus and new family Stegomosuchidae, in the Pseudosuchia. Its classification was further reassessed by Alick Walker over forty-five years later, who reinterpreted Stegomosuchus as a close relative of Protosuchus, a crocodile-like reptile of similar age. In making this change, he noted that Stegomosuchidae should have priority over Protosuchidae. He also regarded AM 900 as a juvenile. although Alfred Romer recommended passing over Stegomosuchidae for the more familiar Protosuchidae. ==Paleobiology==

By comparison to other protosuchids, Stegomosuchus was probably a terrestrial carnivore. In the same issue of The American Journal of Science that contained the description of Stegomus longipes, Richard Swann Lull published a short article in which he proposed that S. longipes had produced previously known tracks named Batrachopus gracilis, also from the Connecticut River Valley. This assessment has been followed, although the ichnospecies assigned to Batrachopus have since been consolidated; B. deweyi is now the name for the tracks in question. ==Paleoenvironment==

tracks, made by an animal like Stegomosuchus'' The Hoover Quarry may represent a playa, or dry lake, a shallow lake, or a river setting. The Portland Formation as a whole is composed of reddish shallow–water and gray or black deeper water rocks in the lower part of the formation, and coarser red rocks from river or alluvial settings in the upper part of the formation. It has yielded fossils of algal structures, pollen, trees and smaller plants, bivalves, clam shrimp, ostracodes, beetles, invertebrate traces, several genera of fish (Acentrophorus, Redfieldius, Semionotus, and the coelacanth Diplurus), the theropod dinosaur Podokesaurus, the sauropodomorph dinosaur Anchisaurus, vertebrate coprolites (fossilized droppings), and several vertebrate track genera (Batrachopus, the theropod tracks Anchisauripus, Eubrontes, and Grallator, the prosauropod tracks Otozoum, and the ornithischian dinosaur tracks Anomoepus). ==References==