Coelacanthus ("Hollow Spine") is a genus of extinct coelacanths that first appearing during the Permian period. In fact, this was the first genus of coelacanths ever described, as the order Coelacanthiformes is named after it.
They bear a superficial similarity to the living Latimeria, though they were smaller, and had more elongated heads. Individuals grew up to 3 feet in length, and had small lobed fins, suggesting that Coelacanthus were open-water predators.
Coelacanthus was a long-lived genus with a worldwide distribution. They survived the Permian–Triassic extinction event, and eventually died out during the Upper Jurassic, around 145 million years ago.