Page 215 - The Evolution Impasse 2

Theropod Dinosaurs 213

hole, which is unique to them, in the
front of the skull. Another prob lem
is that a great many ther o pods
emerged aft er Archaeopteryx. 247
Another ma jor dis tin guish ing
fea ture be tween ther o pod di no saurs
and birds is the struc ture of these di -
no saurs' hip bones. Dinosaurs are di -
vid ed in to two kinds, de pend ing on
their hip bone struc ture: Saurischian
(with rep tile-like hip bones) and
Ornithischian (with bird-like hip
bones). In members of the
Ornithischian group, the hip bones
re al ly do close ly re sem ble those of
birds, hence their name. However, in
oth er re spects they bear no re sem -
blance to birds what so ev er. For
that rea son, ev o lu tion ists are
forced to re gard Saurischian
di no saurs (those with rep -
tile-like hip bones),
which in clude the ther o -
pods, as the an ces tors of

It is im pos si ble for birds
to have evolved from
ther o pod di no saurs, be -
cause there is no mech -
a nism ca pa ble of over -
com ing the enor mous
dif fer en ces be tween the
two life forms.