The members of this order of paleodinosaurs are not only the very first predatory dinosaurs, they are the very first of any dinosaurs. (Realistic dinosaur costume)Often considered thecodonts-which is why their names commonly end with the -suchus usually reserved for thecodonts- their S-curved neck, highly erect gait, completely mesotarsal ankle, and digitigrade foot make them truly dinosaurian. (walking dinosaur costume)Along with the even more primitive thecodont ornithosuchians, lagosuchians can be regarded as protodinosaurs, the base of the great radiation to come. Discovered only recently, they have told us a lot about the beginnings of dinosaurs. So far, good remains are known only from 235-million-year-old Argentina, but they probably lived elsewhere too.
Lagosuchians are small predators, in fact, downright tiny. They, and their small ornithosuchid relatives also, went through much the same size squeeze that accompanied the evolution of birds and mammals. This size squeeze probably marked the evolution of a fully avian-mammalian physiology. (Animatronic dinosaur)Lagosuchians were the first erect-gait, high-endurance runners of earth history, since high metabolic rates would have allowed the latter. Because the forelimbs were still long enough and suitable for locomotion, they may have run with a bounding gallop as well as a birdlike run. (Animatronic dinosaur for sale)Their small size, partial quadrupediality, and rabbit-like hind limbs are responsible for their names, which usually began with a derivation of Classic Greek for rabbit,Iogo.