Sarcopterígios

Sarcopterígios, commonly known as lobe-finned fishes, represent a diverse group of bony fishes characterized by their paired fins, which possess a fleshy, lobate structure. This distinct anatomical feature sets them apart from their ray-finned relatives, the actinopterygios. Their skeletal structure within these fins is homologous to the limb bones of tetrapods, suggesting a significant evolutionary link.

The class Sarcopterygii is divided into two subclasses: the Actinistia and the Rhipidistia. The Actinistia, or coelacanths, were once thought to be extinct but have been rediscovered in modern times, living in deep ocean waters. Rhipidistians, on the other hand, are an extinct group that includes the ancestors of amphibians.

Fossil evidence indicates that sarcopterygios first appeared in the Devonian period. They were a dominant group of fishes during this era, occupying various freshwater and marine environments. Their lobate fins are believed to have provided greater maneuverability and support, potentially aiding in their transition from aquatic to terrestrial life. While most sarcopterygios are now extinct, their evolutionary legacy is profound, as they are the direct ancestors of all tetrapod vertebrates, including humans. Modern sarcopterygios are rare and include only a few species of coelacanths.