While Shuvosaurus was unusual, it paled in comparison to the controvery stirred up by Chatterjee's other discovery, Protoavis. Protoavis was described as a fossil Triassic bird by its discoverer, a creature about 35 centimeters tall. Even more unusual, several features that Chatterjee described in Protoavis would suggest that it is more advanced than the earliest definite known bird, Archaeopteryx, despite living 75 million years earlier. One of these features is that Protoavis has a very bird-like skull, with teeth even more reduced than in Archaeopteryx. Some scientists have called the validity of Protavis into serious question, but Chatterjee has stood by his claim.
Enter the drepanosaurids. Drepanosaurids, more informally known as monkey lizards, were a group of arboreal reptiles that have been found across the world during the Triassic period (for more info on drepanosaurs see the excellent post at the Hairy Museum of Natural History here http://www.hmnh.org/galleries/monkeylizards/index.html). Some species appear to have taken the place of squirrels or primates, others may have lived a life like the modern tamandua, and still others may have even been aquatic or flying squirrel-like animals. But most importantly, these animals had a very bird-like skull, to the point where one of their "other" names is avicephalans (bird heads). The best specimens of these animals have been found in the Eastern U.S. (Hyperonector) or Italy (Drepanosaurus and Megalancosaurus), but there is a species of drepanosaurid known from the American Southwest, Dolabrosaurus, found in the sediments of Petrified Forest National Park.