Based upon the skeletal reconstruction available online. [link]
The protofeathers have been added assuming that the integumentary structures found in ornithischians are homologous to that of saurischians, making “feathers” a synapomorphy of the clade “Dinosauria”, if not Ornithodira (assuming the structures of pterosaurs are homologous too).
This was entirely made on Adobe Photoshop CS4, in order to try an experiment: to see if I was capable of drawing a “close enough” dinosaur only by digital means.
It has proven to be a quick way to draw, though I still prefer the results of combining freehand pencil drawing and coloring in Photoshop.
A simple diagram demonstrating the differences in Saurischian and Ornithischian hips. A.Eoraptor, an early Saurischian; note the forward-pointing pubis B.Lesothosaurus, a primitive Ornithischian; note the reversed pubis C. Staurikosaurus (Saurischian) pelvis D.Lesothosaurus pelvis
Staurikosaurus is yet another early basal Theropod, originating from the Upper Santa Maria Formation in Brazil. It lived about 225 million years ago, in the Carnian stage of the Late Triassic. It was a carnivorous dinosaur, however it might not necessarily have been even a Saurischian. The Herrerasauridae are interesting because they might not be really Saurischians at all, but ancestors to both the saurischian and ornithischian lines. It was lightly built and very similar to its contemporary and cousin Herrerasaurus, but had a longer neck and a larger head. After new research in 2011, however, it is supposed that the Herrerasauridae actually are early Theropods, though it was a primitive member of the group nonetheless due to it having five toes on each foot, rather than the later-common three. It appears to be an active bipedal predator, preying on small and medium-sized terrestrial vertebrates. It was a large early dinosaur, 2 meters long, showing the early diversification of dinosaurs and the trend towards bigger size starting from the beginning.
Known from a single fossil specimen found in South America in 1970, Staurikosaurus is one of the earliest dinosaurs, the immediate descendants of the two-legged archosaurs of the early Triassic period. Unlike its slightly bigger South American cousin, Herrerasaurus, it seems that Staurikosaurus was a true theropod–that is, it evolved after the ancient split between ornithischian and saurischian dinosaurs.
One odd feature about Staurikosaurus was a joint in its lower jaw that seemed to allow it to chew its food backwards and forwards, as well as up and down. Since later theropods didn’t have this adaptation, it’s likely that Staurikosaurus lived in an stark environment that forced it to extract the maximum nutrition from its wriggling meals.