Extinct American Lion (Panthera atrox) Fact Sheet: Reproduction & Development

Clues to stages of development in a growing animal come from tooth replacement patterns and timing of suture closure in skull and limb bones.

Growth patterns

•  Juvenile Panthera atrox have canine teeth not yet used to kill prey; they feed on adults' kills
  • The two halves of the lower jaws are not yet reinforced at the midline symphysis to withstand the force of a killing bite (Therrien 2005)
• Growth rates for canine teeth of Panthera atrox were about 2-3 mm (.08 to 1.2 in)/month (Feranec 2004)

Mortality and extinction

• No know predators on adult American Lions
• Accidents, fights, hunting by Paleolithic humans
• Extinction of Panthera atrox around 13,000 years ago

Feranec (2004)
Therrien (2005)