200 Years. 200 Stories. Story 69: “Set in Stone ”

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photo of the Joseph Leidy statue
In this statue, Joseph Leidy holds the fossil jaw of Panthera atrox. This statue was created by Samuel Murry in 1929.

Set in Stone

In 1853 Academy naturalist Joseph Leidy found an interesting specimen in a collection of mammal fossils loaned by the American Philosophical Society to the Academy of Natural Sciences of Philadelphia. Leidy identified the fossil, which was a fragment of a lower left jaw containing four teeth (three molars and a canine), as that of very large cat. In fact, it was larger than the extinct European cave lion, which until then had been the largest known member of the cat family. Leidy named the new American lion Felis atrox.

Today we call the American lion Panthera atrox, as most large cats, including the American lion, African lion, tiger, and European cave lion, are now assigned to the genus Panthera. Some modern authorities also consider Panthera atrox to be a subspecies of the African lion (Panthera leo atrox). American lions were the largest members of the cat family. The males were about 25 percent larger than their modern African relatives. American lions probably entered North America by way of Siberia and became isolated from their Asian relatives during the Wisconsinan Glaciation (80,000–10,000 years ago). Their fossils have been found in numerous locations from Alaska to Peru.

A copy of the fossil jaw of Panthera atrox can be seen in the left hand of the Joseph Leidy statue that stands in front of the Academy on the Benjamin Franklin Parkway. Learn more about it, and check it out today!

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