Llanocetidae

The Llanocetidae family consists of one extinct genus, Llanocetus denticrenatus, which lived during the Late Eocene Epoch, approximately 37.8 to 33.9 million years ago. This ancient whale is considered one of the earliest known baleen whales.1

Fossil evidence, including a skull measuring about 2 meters (6.5 feet) long, suggests Llanocetus was a large animal. Unlike modern baleen whales that lack teeth as adults, Llanocetus possessed teeth throughout its life. These teeth, with deep grooves separating rounded cusps, were likely used for filter feeding, possibly capturing invertebrates and small fish.1

The analysis of Llanocetus fossils indicates that the evolution of filter feeding in whales may have predated the development of specialized baleen plates. Additionally, evidence suggests Llanocetus had adaptations for deep diving, similar to modern whales, protecting its brain from extreme pressure changes.1