. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. of "replacements," so that as the teeth in use were worn they were pushed out, until they wore away completely, to be replaced by new teeth. It is a complex structure and a difficult process to describe, but the ad- vantage of such an arrangement is obvious. Adaptations to diet were not only re- flected in the structure of the teeth of the dinosaurs, but also extended to the develop- ment and the articulation of the jaws. This follows the principle that biting and chew- ing among the vertebrat
. The dinosaur book : the ruling reptiles and their relatives. Dinosaurs; Reptiles, Fossil. of "replacements," so that as the teeth in use were worn they were pushed out, until they wore away completely, to be replaced by new teeth. It is a complex structure and a difficult process to describe, but the ad- vantage of such an arrangement is obvious. Adaptations to diet were not only re- flected in the structure of the teeth of the dinosaurs, but also extended to the develop- ment and the articulation of the jaws. This follows the principle that biting and chew- ing among the vertebrates are not alone functions of the teeth, but are dependent upon the structure of the skull, the strength of various muscles, and the movements of the jaws. In the Saurischia the jaws worked on what might be called the "scissor ; This may be explained by saying that the articulation or fulcrum for the jaws was on a line with the edges of the jaws and UTING IN DINOSAURS. rnithhchut, as illustrated by Trachodon, the hinge of the jaw is below the line of the tooth sockets, and the jaws are closed by a "nutcracker" action, with the teeth clamping together almost all at the same time Drawing* by John C. Germans the teeth, so that the mouth was closed by a scissor-like action, whereby the sharp teeth of the lower jaw were sheared past those of the skull. In this manner, the car- nivorous theropods were able to tear and cut their unfortunate victims into sizable chunks that might be swallowed. It is interesting to see that the giant carnivores had an expansion of the back part of the lower jaw, which afforded in- creased attachments for the powerful muscles that activated the bite in these fierce hunters. It is interesting to see, also, that in the toothless, fruit-eating "ostrich dinosaurs," such as Struthiomimus, the typical theropod method of jaw articulation was retained, even though these animals had departed from the ancestral car- nivorous
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Keywords: ., bookcentury1900, bookpublishernewyork, booksubjectreptilesfossil
