Sisteridae

Sisteridae is a family of extinct cartilaginous fishes belonging to the order Lamniformes, which also includes modern mackerel sharks and their relatives. The family Sisteridae is characterized by a number of distinct anatomical features, though much of what is known about them comes from fossilized teeth and vertebrae. These fish are believed to have been present in the oceans during the Cretaceous period, with fossil finds indicating their distribution across various marine environments of that era.

The typical dentition of Sisteridae species suggests they were predatory, likely feeding on smaller fish and other marine organisms. The morphology of their teeth, often described as blade-like with serrated edges, is indicative of a diet that required shearing and tearing. While the exact phylogenetic relationships within Sisteridae are still subject to ongoing research, they are generally placed among the lamniform sharks due to shared skeletal and dental characteristics. The fossil record for this family is relatively limited, with discoveries primarily concentrated in specific fossil-rich locations. This scarcity of complete skeletons makes understanding their full biology and ecological role a challenging endeavor for paleontologists. Further research and new fossil discoveries are crucial for a more comprehensive understanding of Sisteridae and their place in ancient marine ecosystems.