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Extinct Short-faced Bear (Actodus spp.) Fact Sheet: Behavior & Ecology

How Do We Know This?

Since direct observation of a fossil animal's behavior isn't possible, paleontologists use comparison and contrast with living animals for guidance. Tracks can sometimes reveal further clues.

Social Behavior

Like all bears today, presumed solitary except for females with cubs

Locomotion

Not adapted for fast running locomotion as often asserted in literature. (Figueirido et al 2010)

Pleistocene tracks of Arctodusmay be preserved at a site in Lakeview, Oregon.

  • Right legs move forward at the same time, then left legs move forward together.
  • Camels have this same energy efficient gait.

Rather than having a waddling, pigeon-toed walking gait seen in other bears, walked with feet pointing frontward, no waddling.

A sesamoid bone in the wrist suggests some capacity for tree-climbing (and plant grasping); pandas have this adaptation.

Interspecies Interactions

Studies of Pleistocene Arctodus fossils from Beringia (Siberia, Alaska and the Bering Straight) indicate that competition with brown bears may have been a factor in the extinction of Arctodus. (Barnes et al 2002)

  • The two species coexisted for 10,000 years between 45 to 35,000 years ago.
  • Arctodus fossils are mostly found later when brown bears were absent.
  • The last Arctodus fossils date to the same time when brown bears are again present.

Arctodus may have competed for carcasses of hoofed animals killed by saber-toothed cats, American lions, dire wolves (Figueirido et al 2009) and possibly humans.

Page Citations

Barnes et al (2002)
Figueirido et al (2009)
Figueirido et al (2010)
Richards et al (2008)

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