Pycnodontiformes

Pycnodontiformes is an extinct order of ray-finned fish that lived from the Triassic to the Eocene epochs. These fish are characterized by their deep, laterally compressed bodies and distinctive, pavement-like teeth, which were arranged in crushing plates. This dental adaptation suggests a diet of hard-shelled invertebrates such as mollusks and crustaceans. The name "pycnodont" itself derives from Greek words meaning "dense tooth."

Fossil evidence indicates that pycnodonts were widespread and inhabited a variety of marine environments, including coral reefs and shallow coastal waters. Their robust teeth were highly effective for processing food, and their body shape likely aided in maneuvering in complex habitats. Many pycnodont species were relatively small, though some reached moderate sizes. The group diversified significantly throughout the Mesozoic Era.

The decline and eventual extinction of Pycnodontiformes occurred towards the end of the Eocene epoch, a period marked by significant environmental changes and mass extinction events. Their specialized feeding apparatus may have made them vulnerable to shifts in prey availability or competition from other fish groups that evolved more generalized feeding strategies. While their exact ecological role is still debated, their prevalence in Mesozoic marine ecosystems suggests they were an important component of ancient food webs.