The front ends of the jaws had grooves that indicate the presence of a keratinous sheath . " Nigersaurus " is the only known tetrapod animal to have had jaws wider than the skull and teeth that extended laterally across the front.
42.
""'Amargasaurus " "'(; " La Amarga lizard " ) is a genus of sauropod dinosaur from the Early Cretaceous epoch ( 129.4 122.46 skin sails or stuck out of the body as solitary structures supporting a keratinous sheath.
43.
The discovery of partial diplodocid skin impressions in 1990 showed that some species had narrow, pointed keratinous spines, much like those on an iguana and up to long, on the " whiplash " portion of their tails, and possibly along the back and neck as well, as in hadrosaurids.
44.
There is a large diastema, or gap, between the keratinous beak on the front of the mouth and the main chewing teeth in the side of the mouth, which would allow the two sections to work independently, so " Altirhinus " could crop with its beak while simultaneously chewing with its teeth.
45.
They grow from a permanent outgrowth of the frontal bone called the pedicle and can be branched, as in the white-tailed deer ( " Odocoileus virginianus " ), or palmate, as in the moose ( " Alces alces " ) . " Ossicones " are permanent bone structures that fuse to the frontal or parietal bones during an animal's life and are found only in the Giraffidae . " Pronghorns ", while similar to horns in that they have keratinous sheaths covering permanent bone cores, are deciduous.
