Question

Why is knowledge of the Sarcopterygii lineage so important in understanding the evolution of
terrestrial vertebrates?

Answer 1

 They are important for the study of evolutionary processes involved in the water to land transition of vertebrates. The evolution of a true neck, that is, the complete separation of the pectoral girdle from the cranium, is one of the most intriguing morphological transitions known among vertebrates.

The lobe-finned fishes are the sister group to the ray-finned fishes. They are characterized by their paired, fleshy pectoral, and pelvic fins that are each articulated via a single bone. Ancestral records clearly show us that terrestrial vertebrates evolved from lobe-finned fishes nearly 400 million years ago.