Mastodons were the most common proboscideans in Diamond Valley, but they weren’t the only ones there. Columbian mammoths (Mammuthus columbi) were also present, although in much smaller numbers. The most complete Columbian mammoth from DVL is Xena, whose partial skeleton is on permanent exhibit at the Western Science Center.
Xena’s remains include the left femur (thigh bone), shown above in anterior view with the proximal end on the left. As is typical of Columbian mammoths, the femur is relatively long and slender when compared to mastodons. While adult mammoths and mastodons were probably pretty comparable in terms of weight, mammoths were quite a bit taller because of their long legs, which were proportioned more like those of modern elephants than the relatively short, thick legs of mastodons. Xena was not particularly tall for a Columbian mammoth, but was at least as tall as Max, the biggest mastodon known from California.
While Xena’s femur is well preserved, it is missing both the proximal and distal ends.These were lost because they had not yet fused to the rest of the femur, indicating that Xena was still growing (even at 3 m tall!). This is also borne out by her teeth; Xena’s 1st molars were in wear, but the 2nd molars were completely unerupted, suggesting that she was probably only about 18-20 years old.