Check out these extinct animal images:
Saber-Toothed Cat Skull
Image by Travis S.
This is the lateral view of a saber-toothed cat skull without the muscle display. The sagittal crest down the back of the top of the skull can be seen. This extension of the skull is to add more surface area for larger jaw muscles.
Also note the incomplete orbit of the cat's skull. This is a common feature in carnivores such as the big cats and www.flickr.com/photos/baggis/2558237108/, a prosimian related to lemurs, were the first of its kind to have a complete orbit. This was probably to protect the orbit of the brachiating animals.
DWARF CAMEL
Image by Fool-On-The-Hill
Camels evolved in North America, but went extinct about 10,000 years ago like many other native animals. This one was a tiny, fast one. see en.wikipedia.org/wiki/Stenomylus
