Imagine that you find a fossil skeleton of a Late Devonian vertebrate.Which feature would enable you to conclude that it was fully a tetrapod?
A) a flattened skull with dorsally facing orbits
B) the loss of skeletal support for any gills
C) the loss of dorsal and anal fins
D) well-developed joints between vertebrae, and between vertebrae and the pelvis
E) lungs to enable breathing of atmospheric oxygen

Question

Quizplus · Accepted Answer

Well-developed joints between vertebrae and between vertebrae and the pelvis are a key feature of tetrapods that distinguish them from their fish ancestors. This skeletal structure allowed for the evolution of limbs capable of supporting the animal's body weight on land. The other features listed, such as flattened skull with dorsally facing orbits, loss of skeletal support for gills, and lungs, are also features of tetrapods, but not necessarily unique to them. The loss of dorsal and anal fins is not a definitive feature of tetrapods, as some early tetrapods still retained these structures.

Imagine That You Find a Fossil Skeleton of a Late