yrannosaurus_ group for the
Cretaceous Dinosaur Hall.]

"The fourth pose or study, for the proposed full sized mount, is that
of two reptiles of the same size attracted to the same prey. One
reptile is crouching over its prey (which is represented by a portion
of a skeleton). The object of this depressed pose is to bring the
perfectly preserved skull and pelvis very near the ground within easy
reach of the visiting observer. The second reptile is advancing, and
attains very nearly the full height of the animal. The general effect
of this group is the best that can be had and is very realistic,
particularly the crouching figure. A fifth study will embody some
further changes. The upright figure is not well balanced and will be
more effective with the feet closer together, the legs straighter and
the body more erect. These reptiles have a series of strong abdominal
ribs not shown in the models. The fourth position places the pelvis in
an almost impossible position as will be noted from the ischium and
pubis.

"The lateral view of this fourth pose represents the animals just
prior to the convulsive single spring and tooth grip which
distinguishes the combat of reptiles from that of all mammals,
according to Mr. Ditmars.

"The rear view of the standing skeleton displays the peculiarly avian
structure of the iliac junction with the sacral plate, characteristic
of these very highly specialized dinosaurs, also the marked reduction
of the upper end of the median metatarsal bone, which formerly was
believed to be peculiar to _Ornithomimus_."

This model of the group is on exhibition with the mounted skeleton.

As compared with its predecessor _Allosaurus_, the _Tyrannosaurus_ is
much more massively proportioned throughout. The skull is more solid,
the jaws much deeper and more powerful, the fore limb much smaller,
the tail shorter, the hind limb straighter and the foot bones more
compacted so that the animal was more strictly "digitigrade,"
approaching the ostriches more closely in this particular.

[Illustration: Fig. 16.--SKELETON OF TYRANNOSAURUS IN COMPARISON
WITH HUMAN SKELETON.]

This animal probably reached the maximum of size and of development of
teeth and claws of which its type of animal mechanism was capable. Its
bulk precluded quickness and agility. It must have been designed to
attack and prey upon the ponderous and slow moving Horned and Armored
Dinosaurs with which its remains are found, and whose