Short-Faced Bears of North America

Overview

• Genus: Arctodus
• Species:
  • Arctodus pristinus (Lesser short-faced bear)
  • Arctodus simus (Giant short-faced bear)
• Era: Pleistocene

Physical Characteristics

• Size:
  • Giant short-faced bear:
    • Weight: Up to 950 kg (2,000 lbs)
    • Shoulder height: 1.6 meters (5.2 feet)
    • Standing height: 4 meters (13 feet)

Habitat and Distribution

• Arctodus pristinus: Found in early Pleistocene, largely in Florida, open grassland habitats.
• Arctodus simus: Range included grasslands, tropical thorn shrub, and woodlands (Mexico, California).
• Ice-free corridors allowed migration; fossils found in northern Canada and Beringia.

Climate Adaptations

• Pleistocene Climate: Cooler and drier; glaciers covered much of North America.
• Adaptations: Thick shaggy coats, substantial fat reserves.
• Modern Climate: Bears might shift to cooler northern regions to avoid overheating.

Diet and Feeding Habits

• Omnivorous:
  • Likely ate berries, plants, meat.
  • Debate between active predators vs. scavengers.
  • Evidence suggests more herbivorous diet: broad, flat molars.
• Fossil Evidence: Tooth marks on prey like ground sloths, proboscideans.
• Modern Food Supply: Vegetation and prey like moose, elk, fish.

Extinction Factors

• Climate Change: Shift in vegetation led to less nutritional plant matter.
• Genetic Diversity: Very low, made the species vulnerable.
• Demise: Low population densities, environmental changes.

Survival Today

• Possible: Due to adaptable nature and similar lifestyle to modern bears.
• Challenges: Rapidly changing environments today.

Conclusion

• Possibility of survival in today's world, but unlikely due to rapid environmental changes.

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End of Lecture