Arboreal hypothesis

Definition

Arboreal hypothesis suggests that the evolution of certain physical traits in vertebrates, particularly birds, was driven by an adaptation to life in trees. This includes the development of wings and other features facilitating gliding or flight.

5 Must Know Facts For Your Next Test

1. The arboreal hypothesis posits that early bird ancestors developed flight from tree-dwelling behaviors.
2. Key anatomical adaptations supporting this hypothesis include strong grasping limbs and elongated forelimbs.
3. This theory contrasts with the cursorial hypothesis, which suggests flight evolved from ground-dwelling running ancestors.
4. Fossil evidence, such as that of Archaeopteryx, supports the idea that early birds had traits conducive to tree climbing and gliding.
5. The arboreal hypothesis helps explain the evolution of feathers initially for insulation or display before being co-opted for flight.

Review Questions

Related terms

Archaeopteryx:

An early bird-like dinosaur with both avian and reptilian features that provide evidence for evolutionary theories such as the arboreal hypothesis.

Cursorial Hypothesis: A competing theory suggesting that avian flight evolved from fast-running terrestrial ancestors rather than tree-dwellers.

Feathers: Complex structures initially evolved for purposes other than flight, like insulation or display, later adapted for aerial locomotion.