Dinosaur senses primitive birds like "Archaeopteryx" and "Hesperornis". The optic nerve was large in "Carcharodontosaurus". Among dinosaurs, theropods had exceptionally large eyes. Deinonychosaurians, especially troodontids, had forward-facing eyes, suggesting stereoscopic vision and improved depth perception. Tyrannosauroid snouts allowed for a 55˚ binocular field of view, less than a modern human but more than their hadrosaurid prey. Dinosaur senses Dinosaur senses are difficult subjects of study for paleontologists since soft tissue anatomy rarely fossilizes. The three semicircular canals of the inner ear of "Allosaurus fragilis", when viewed from the side, had a subtriangular outline. This subtriangular inner ear configuration is present in "Carcharodontosaurus",
Archaeopteryx are limited to a sort of "proto-down" not dissimilar to that found in the dinosaur "Sinosauropteryx": decomposed and fluffy, and possibly even appearing more like fur than feathers in life (although not in their microscopic structure). These occur on the remainder of the body—although some feathers did not fossilize and others were obliterated during preparation, leaving bare patches on specimens—and the lower neck. There is no indication of feathering on the upper neck and head. While these conceivably may have been nude, this may still be an artefact of preservation. It appears that most "Archaeopteryx" specimens became embedded in anoxic