Egertonia
Egertonia is an extinct genus of prehistoric marine and estuarine ray-finned fish known from the Late Cretaceous to the middle Eocene. It contains one known species, E. isodonta, although indeterminate remains potentially referable to other species are also known. It was a member of the Phyllodontidae, an extinct family of elopomorph fish with crushing tooth plates, which are the primary remains found of the genus.
Excluding dubious records from the Campanian and Maastrichtian of eastern North America, the earliest confirmed occurrences of the genus in the fossil record are from the Maastrichtian of Madagascar and Tamil Nadu, India. These formations are suggestive of a fluvial-estuarine environment with frequent marine intrusions. Notably, despite Egertonia expanding its range to the Northern Hemisphere during the Cenozoic, both of these early localities are Gondwanan in origin. These fossil tooth plates are reminiscent of E. isodonta.
As with several other members of its family, Egertonia survived the Cretaceous-Paleogene extinction event and it became more widespread during the Cenozoic, when the type species E. isodonta appears. The earliest remains of E. isodonta are from the Late Paleocene of South Carolina. It becomes much more common during the Eocene, when remains are known from the Ypresian to Bartonian of the eastern United States, Ypresian of England, and the Lutetian of Barbados. Indeterminate Egertonia fossils are known from the Lutetian of England, Ypresian of Belgium, and the Ypresian of India. It went extinct at some point during the mid-late Eocene.