Um....Some extinct mammals to pick from I guess:
Some Animals You Can Make with the Wolf/Canine Model
http://en.wikipedia.org/wiki/Andrewsarchus -gaint carnivorous wolf-like animal with hoofed feet that was related to whales oddly enough.
http://en.wikipedia.org/wiki/Mesonyx -smaller hoofed wolf-like creature that was also related to whales.
http://en.wikipedia.org/wiki/Borhyaenidae- A group of prehistoric dogs that were like a cross between wolves and hyenas.
http://en.wikipedia.org/wiki/Bear_dogs-A group of prehistoric animals that were dogs which resembled bears in structure.
http://en.wikipedia.org/wiki/Mesonychidae-The family of hooved wolf-like creatures related to whales.
http://en.wikipedia.org/wiki/Canis_edwardii-Edward's Wolf. A small coyote-like,jackal-like, or red wolf-like relative of gray wolves.
http://en.wikipedia.org/wiki/Dire_Wolf-Very simliar to the gray wolf but with slightly larger size.
http://en.wikipedia.org/wiki/Canis_lepophagus-Hare-eating wolf. Small prehistoric "wolf" that was probably more like a coyote or jackal than a wolf.
http://en.wikipedia.org/wiki/Canis_armbrusteri -The larger and more imposing ancestor of the Dire Wolf.
http://en.wikipedia.org/wiki/Hokkaido_Wolf-A small Japanese subspecies of the gray wolf that was driven to extinction by humans.
http://en.wikipedia.org/wiki/Honshu_Wolf- An even smaller Japanese subspecies of gray wolf that was driven to extinction by humans. It's nickname is the "dwarf wolf".
http://en.wikipedia.org/wiki/Florida_Black_Wolf-An extinct subspecies of red wolf. It looked simliar to the other subspecies except it had black fur instead of red fur.
http://en.wikipedia.org/wiki/Newfoundland_Wolf-a large northern gray wolf subspecies that used to roam Newfoundland,Canada. The only known musuem specimen has a tannish colored coat mixed with some brown,white, and gray.
http://en.wikipedia.org/wiki/Texas_Wolf-An extinct subspecies of gray wolf from Texas. Thought to look simliar to the Mexican Gray Wolf but darker in color.
http://en.wikipedia.org/wiki/Canis_lupus_bernardi-An extinct subspecies of gray wolf from Canada. It was white with a black stripe down its back.
http://en.wikipedia.org/wiki/Manitoba_Wolf-Another extinct gray wolf subspecies from Canada.
http://en.wikipedia.org/wiki/Cascade_Mountain_Wolf- An extinct cinnamon or brownish colored gray wolf subspecies from the United States.
http://en.wikipedia.org/wiki/Kenai_Peninsula_Wolf-An extinct gray wolf subspecies from Alaska. It was the largest subspecies of gray wolf to ever exsist.
http://en.wikipedia.org/wiki/Mogollon_Mountain_Wolf -An extinct gray wolf subspecies that was simliar to the Mexican Gray Wolf.
http://en.wikipedia.org/wiki/Southern_Rocky_Mountains_Wolf-An extinct gray wolf subspecies from the United States.
http://en.wikipedia.org/wiki/Cave_Hyena-A prehistoric hyena.
http://en.wikipedia.org/wiki/Pachycrocuta- "Giant hyena". A large prehistoric hyena.
http://en.wikipedia.org/wiki/Chasmaporthetes-A prehistoric hyena family.
http://en.wikipedia.org/wiki/Hemicyonidae-"Dog-Bears". Prehistoric bears that looked simliar to dogs.
http://en.wikipedia.org/wiki/Ictitherium-A prehistoric hyena.
http://en.wikipedia.org/wiki/Hesperocyon-A prehistoric animal that is thought be one of the first true canines. It's sometimes depicted as looking like a weasel-sized fox.
http://en.wikipedia.org/wiki/Cynodictis-One of the most dog-like bear-dogs. It was once thought to be an ancestor of all canines,but this was later disproven.
http://en.wikipedia.org/wiki/Borophagus_diversidens-One species of bone-crushing dog.
http://en.wikipedia.org/wiki/Warrah-Also called the Falkland Island Wolf or Falkland Island Fox. An small fox-like animal that was actually more closely related to the maned wolf than to either true wolves or foxes. It lived on an island where it was hunted to extinction by humans, unable to escape. They were known for being unusually friendly to humans which made them more vunerable to being hunted.
http://en.wikipedia.org/wiki/Tasmanian_Wolf-Also known as the Tasmanian Tiger or Thylacine. An carnivorous marsupial that looked somewhat simliar in appearance to a wolf. It was not related to canines though because it was a marsupial. It hopped and had pouch. It was hunted to extinction by government bounties supported by ranchers in Tasmania.
and more canine or canine-like extinct and prehistoric species you can think of.
Felines coming soon.