Sporeidales

Sporeidales is an extinct order of ray-finned fish that lived during the Late Cretaceous period. These fish are primarily known from fossil remains found in North America, particularly in formations such as the Judith River Formation of Montana and the Dinosaur Park Formation of Alberta. The order is characterized by a series of unique anatomical features, including a distinctive arrangement of fin rays and scales, which differentiate them from other known Cretaceous fish groups.

The exact taxonomic placement of Sporeidales has been a subject of scientific discussion, with various researchers proposing different relationships to modern fish lineages. Some studies suggest a potential link to teleost fish, the largest and most diverse group of ray-finned fishes, while others propose more basal positions within the Actinopterygii. The limited fossil evidence, often consisting of fragmented skeletal material, has contributed to the challenges in fully understanding their evolutionary history and relationships.

Fossils of Sporeidales are typically found in freshwater or brackish water sedimentary deposits, indicating their habitat preferences during the Cretaceous. Their diet and ecological role are not well understood due to the scarcity of detailed fossil evidence. The extinction of Sporeidales, like many other Cretaceous organisms, is presumed to be related to the K-Pg extinction event that marked the end of the Mesozoic Era. Further discoveries and analyses of Sporeidales fossils could provide valuable insights into the diversity and evolution of fish communities during the Late Cretaceous.