Arktocara ("Platanista gangetica") which inhabits the tropics, making it its closest living relative. Allodelphinidae also included the genera "Allodelphis", "Goedertius", "Ninjadelphis", and "Zarhinocetus". Its discovery further reinforces the theory that the Platanistoidea river dolphins originated in the oceans. Of the characteristics it shared with other platanistoids was a cylindrical projection of the periotic bone in the ear, deeply grooved rostral sutures on the beak, the widening of the cranium, a depression on the roof of the orbit in the eye socket, a smaller exposed palatine bone in the roof of the mouth, an elongated and convex spine in the tympanic bulla
Endangered Species Act of 1973 birds, 6 reptiles and amphibians and 22 fish. This first list is referred to as the "Class of '67" in "The Endangered Species Act at Thirty", Volume 1, which concludes that habitat destruction, the biggest threat to those 78 species, is still the same threat to the currently listed species. It included only vertebrates because the Department of Interior's definition of "fish and wildlife" was limited to vertebrates. However, with time, researchers noticed that the animals on the endangered species list still were not getting enough protection, thus further threatening their extinction. The endangered species program was expanded by the