The Evolution of Ornithopods: Enhancing Function and Balance

What feature is prominent in enhancing the ornithopod's tail's function as a counterbalance?

1) Narrow hip structure 2) Smaller head and neck 3) Ossified tendons 4) Reduced neural arches on vertebrae

Final answer:

The function of the ornithopod's tail as a counterbalance was enhanced by the presence of ossified tendons.

Explanation: The prominent feature in enhancing the ornithopod's tail's function as a counterbalance to their body mass, especially in bipedal species, is the presence of ossified tendons. These hardened structures would have provided the necessary rigidity to the tail, allowing it to act as an effective counterbalance to the head and neck. The long tails of bipedal ornithopods would help distribute their weight and maintain balance, similar to how the femur alignment and spinal curvature support bipedal locomotion in hominins. The evolution of the axial skeleton also reflects the transition of animals from water to land, requiring a firmer and more ossified vertebral column to support body weight and reduce strain.