Hadoneinidae

Hadoneinidae is a family of extinct cartilaginous fishes belonging to the order Euselachii. These ancient sharks lived during the Mesozoic Era, with fossils primarily found in deposits dating back to the Jurassic and Cretaceous periods. The family is characterized by distinct dental morphology, with numerous small, flattened teeth that were likely adapted for crushing or grinding. Unlike many modern sharks that possess large, serrated teeth for tearing flesh, hadoneinid teeth suggest a diet that may have included hard-shelled invertebrates or other benthic organisms.

The fossil record of Hadoneinidae is relatively sparse, with most discoveries consisting of isolated teeth. However, these teeth have been found in various locations worldwide, indicating a relatively widespread distribution during their existence. The taxonomic classification of Hadoneinidae has been subject to revision as new fossil evidence emerges and analytical techniques improve. While their exact phylogenetic position within the larger shark lineages is still debated, they are generally understood to represent a specialized branch of early sharks that did not survive into the Cenozoic. Their extinction likely coincided with broader faunal turnover events at the end of the Cretaceous period.