Epicyon: The Bone-Crushing Dogs

Overview

• Epicyon: A massive canid that lived in North America from 16 million to 7 million years ago ( Miocene epoch).
• Physical Traits: Powerful jaws and teeth capable of cracking bones.
• Lineage: Part of Borophaginae, known as "bone-crushing dogs".

Borophaginae

• A diverse subfamily of dogs patrolled North America for over 30 million years.
• Eventually declined and went extinct.

Canidae Family

• Includes all modern dogs, wolves, foxes, etc.
• 34 species currently exist.
• Earliest potential canid: Prohesperocyon (~36 million years ago).

Subfamilies of Canidae

1. Hesperocyoninae
   • Small, nimble, late Eocene carnivores.
   • Founding species: Hesperocyon (~37 million years ago).
   • Traits: Small prey diet, retractable claws.
2. Borophaginae
   • Emerged with Archaeocyon (~30 million years ago).
   • Various species including Epicyon haydeni, possibly the largest canid ever.
   • Traits: Powerful build, bone-crushing teeth.
3. Caninae
   • Only surviving subfamily.
   • Early species: Leptocyon.
   • Traits: Long legs and reduced toes for endurance running ("marathon runners").

Hesperocyoninae Adaptation and Extinction

• Climatic changes transitioned forests to grasslands.
• Shift in prey species led some to adapt to grasslands, e.g., Archaeocyon.
• Eventually went extinct about 13 million years ago.

Borophaginae Characteristics

• The genus Epicyon includes the largest canid, Epicyon haydeni.
• Distinctive features: Domed foreheads, large cheek teeth, wide palates.
• Bone-crushing ability for accessing bone marrow.
• Possible pack hunters and pounce-pursuit predators.
• Decline due to competition with newer canids and cats.
• Last genus: Borophagus, extinct around 2 million years ago.

Caninae’s Rise and Adaptation

• Emerged during the Late Miocene.
• Developed longer legs and reduced toes for long-distance hunting.
• First species: Leptocyon (~early Oligocene).
• Survived due to efficient endurance hunting.

Rise of Cats and Competition

• Cats evolved in Eurasia and migrated to North America ~19 million years ago.
• Competed with bone-crushing dogs for prey.
• More efficient ambush predators.

Caninae Expansion

• Spread beyond North America, reaching South America, Eurasia, Africa, and Australia.
• Examples: Maned wolf, dingo.

Conclusion

• The story of the bone-crushing dogs illustrates the precarious position of large predators.
• Adaptive strategies (e.g., endurance running) helped canines survive against new competitors.
• Cats played a significant role in the decline of Borophaginae.
• Being a top predator often means facing significant challenges when environments change.