mmon during all the Age
of Reptiles, much as the smaller quadrupeds are today, but skulls or
skeletons are rarely found in the formations known to us. The
_Anchisaurus_, _Podokesaurus_ and other genera of the Triassic Period
have left innumerable tracks upon the sandy shales of the Newark
formation, but only two or three skeletons are known. A cast of one
of them is exhibited here. The original is preserved in the Yale
Museum. In the succeeding Jurassic Period we have the _Compsognathus_,
smallest of known dinosaurs, and this _Ornitholestes_ some six feet
long. A cast of the _Compsognathus_ skeleton is shown, the original
found in the lithographic limestone of Solenhofen is preserved in the
Munich Museum. The _Ornitholestes_ is from the Bone-Cabin Quarry in
Wyoming. The forefoot with its long slender digits is supposed to have
been adapted for grasping an active and elusive prey, and the name
(_Ornitho-lestes_ = bird-robber) indicates that that prey may
sometimes have been the primitive birds which were its contemporaries.
In the Cretacic Period, there were also small and medium sized
carnivorous dinosaurs, contemporary with the gigantic kinds; a
complete skeleton of _Ornithomimus_ at the entrance to the Dinosaur
Hall finely illustrates this group. In appearance most of these small
dinosaurs must have suggested long-legged bipedal lizards, running and
walking on their hind limbs, with the long tail stretched out behind
to balance the body. From what we know of their tracks it seems that
they walked or ran with a narrow treadway, the footsteps almost in the
middle line of progress. They did not hop like perching birds, nor did
they waddle like most living reptiles. Occasionally the tail or fore
feet touched the ground as they walked; and when they sat down, they
rested on the end of the pubic bones and on the tail. So much we can
infer from the footprint impressions. The general appearance is shown
in the restorations of _Ornitholestes_, _Compsognathus_ and
_Anchisaurus_ by Charles Knight.

[Illustration: Fig. 17.--Skeleton of _Ornitholestes_ a small
carnivorous dinosaur of the Jurassic period. American Museum No.
619.]

[Illustration: Fig. 18.--Restoration of _Ornitholestes_, by C.R.
Knight under direction of Professor Osborn. _After Osborn_]

_Ornithomimus._ The skeleton of this animal from the Cretacic of
Alberta was found by the Museum expedition of 1914. It is
exceptionally complete, and has been mount