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Geologic Timeline: The last 144 million years of Earth's 4.6 billion year history.
Extinct American lion.

FOSSIL FIELD GUIDE

Panthera atrox
American Lion
Family: Felidae

Time
Pleistocene Epoch


Panthera atrox, skull and mandible
UCMP catalog no. 20049

Panthera atrox
Fossil Mysteries exhibit

Description
Panthera atrox is the scientific name of the extinct American lion that lived throughout much of North America during the later part of the Pleistocene (approximately 120,000 to 10,000 years ago). Fossil remains of this species have been found in the American Southwest, Midwest, Southeast, and Alaska, as well as parts of Mexico. The American lion closely resembled the modern African lion, but was about 25% larger and heavier than the living species. Paleontologists hypothesize that Panthera atrox lived and hunted in open grassland savannah habitats. Whether this extinct species was gregarious and lived in social groups like the modern African lion is not known, but some studies suggest that it was.

The important Ice Age fossil deposits at Rancho La Brea in Los Angeles have yielded well-preserved bones of Panthera atrox, including several beautiful skulls. Fossil remains of Smilodon fatalis (the saber-toothed cat) are much more abundant than those of Panthera atrox in the asphalt deposits at Rancho La Brea suggesting perhaps that the American lion was more intelligent in avoiding the tar traps



Text: Dr. Tom Deméré
Illustration: William Stout
Fossil photograph: Dr. Tom Deméré

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Pleistocene Epoch 1.8 million-10,000 years ago.
Pliocene Epoch 5-1.8 million years ago.
Miocene Epoch 24-5 million years ago.
Oligocene Epoch 34-24 million years ago.
Eocene Epoch 53-34 million years ago.
Paleocene Epoch 65-55 million years ago.
Cretaceous/Tertiary Boundary Rock, 65 million years ago.
Cretaceous Period 144-65 million years ago.
Earth's history began 4.6 billion years ago.
MYA = million years ago.