Top Ten Ice Age Mammals of Southern Arizona


The San Pedro Valley, local caves and public lands are excellent sources of the remains of extinct large mammals. 

Giant Bison

Giant Bison
Giant Bison

– The national mammal, the bison, has a long history in this country. They experienced near extinction from over exploitation by European settlers followed by recovery. 

Though many may not know of this species that was once a resident of Southern Arizona and had a horn spread over 10 feet. 

Camel – The setting of camels today may make one think of a sea of sand in the Middle East. However, camels originated in North America about 50 million years ago.

Camelops were the end of camels in the Americas. Though camelops are more closely related to llamas than modern camels, it shows the diversity of Ice Age mammals. Over a dozen general of camels were calling North America home about 15 million years ago.     



– Remains of tapirs have been found at the Lehner Mammoth Kill site by Hereford. The odd-toed beasts are part ungulates, a group that includes tapirs, horses and rhinos was once much more diverse and widespread than today.  

Shasta Ground Sloth – Their living relatives are tree dwellers in South America. This bulky hairy animal was ill suited to such a life. Ground sloths in Arizona have given a massive dump of information about their Ice Age ecosystems. Sloth dung preserved in caves in Arizona is a record of both their diet and what plant life was available. 

Horse – Horses over geological time had a long history in North America. The White River Badlands of the Dakotas from about 30 million years ago has some of the first examples of several species on this list camels, dogs and horses.

Horses in North America went extinct around the same time as all the other species on this list.

Their latter successful reintroduction by Europeans often is viewed as evidence that early people on the continent played a role in these extinctions. If it was solely environmental factors wild horses shouldn’t be successful.        

American Lion – Being 25 percent larger than the living African lion it was one of the largest cats to ever have lived on the planet.

But there’s no evidence that true lions ever moved into the continent. 

Columbian Mammoth – This eclipses it’s more famous relative the Wooly Mammoth in size. In likelihood, it required 150,000 calories a day, an indication that Southern Arizona had greater rainfall.   

American Mastodon – Mastadons are an even older lineage than their cousins the mammoths. They originated about 30 million years ago and lived primarily in North and Central America.  

Shrub ox – With dung described as the shape of a Hershey Kiss it gives similar insights as the ground sloth according to the journal Quaternary Research. “The retrieval of spring and fall pollen suggests” that it was also a resident of the Colorado Plateau throughout.

Dire Wolf

Dire Wolf

– The largest species in the genus canis to have ever lived the dire wolf wasn’t a creature just limited to fantasy books. Large number of remains from different individuals often found together suggests that they lived in packs. They were calculated to have 129 percent the bite force of modern gray wolves.   


*All photos from Wikipedia

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