Drjevæliformes

Drjevæliformes is an order of extinct ray-finned fish that lived during the Late Cretaceous period, approximately 99.6 to 66 million years ago. The order is named after the type genus Drjevælla, which means "tree trunk" in Old Norse, reflecting the trunk-like shape of some of its fossils. Drjevæliformes is characterized by its elongated, cylindrical body, which is thought to have been used for burrowing or anchoring in the seafloor.

The order is divided into two families: Drjevællidae and Drjevællopsidae. Drjevællidae includes the type genus Drjevælla, as well as the genera Drjevællops and Drjevællopsis. Drjevællopsidae includes the genus Drjevællopsis, which is distinguished by its more elongated and slender body.

Fossils of Drjevæliformes have been found in Europe, North America, and Asia. They are thought to have been bottom-dwelling fish, living in shallow marine environments. The exact ecology and behavior of Drjevæliformes are still not well understood, but their unique body shape suggests that they may have had specialized adaptations for their environment.

Drjevæliformes went extinct at the end of the Cretaceous period, along with the non-avian dinosaurs, likely due to the same catastrophic event that caused the Cretaceous-Paleogene extinction event. Despite their brief existence, Drjevæliformes are an important part of the fossil record, providing insights into the evolution of ray-finned fish and the diversity of life during the Late Cretaceous.