Bison antiquus Hoof Core Fossil

I fished this bison hoof core fossil out of the Kansas River while hanging out on a sandbar today.

(At first glance, I thought it was some sort of giant shark tooth...I still kind of do.)















This hoof originally belonged to a member of the Bison antiquus (aka 'ancient bison') species--the direct ancestor to the modern American bison.












B. antiquus frolicked in North America during the Pleistocene Epoch between about 18,000 years ago up until 10,000 years ago.

Figure 1.  A comparison between the modern American bison (left) and B. antiquus (right).

Compared to the modern American bison, B. antiquus was taller, had larger bones and horns, and was about 15-25% larger overall (see Figure 1 above).[1]

The bison hoof core is more formally known as an ungual phalanx.  (Ungual = highly modified distal toe bone that ends in a hoof, claw, or nail.)[2]

Bison and other even-toed ungulates like deer and sheep have cloven hooves.

This means that they have two main hooves on each foot.  The hoof core fossil I found is just one half of the original set of two hooves.

The hoof fossil I found measures 3.50" long by 2.25" wide (or 8.89 cm long by 5.72 cm wide).








In order to be identified as a bison hoof core fossil, the bone in question must have the following qualities (see Figure 2 below)[3]:

Figure 2.  A bison hoof model.

1 - Asymmetrical (one of a pair of hooves), narrow-tipped hoof.

2 - Flat undersurface.

3 - Slight ridge on articulating surface.













References:

[1]Bison antiquus.  Wikipedia: the Free Encyclopedia,  21 September 2013.  <http://en.wikipedia.org/wiki/Bison_antiquus>.

[2]Downs, Theodore.  Fossil Vertebrates of Southern California.  University of California Press, 1968.  <http://books.google.com/books?id=roQCuVmIBN4C&lpg=PP1&pg=PA2#v=onepage&q&f=false>

[3]DeRouin, Ed.  Fossilweb Museum of Paleontology Specimen List.  Fossilweb, 2001.  <http://www.fossilweb.com/fw_specimen_list.shtml>.