A scuba diver has found the skull of an extinct dolphin that lived between 28 and 30 million years ago in the Wando River, near Charleston, South Carolina. It is a new species of cetacean that was only one meter long and lacking teeth.
The group of scientists who have studied the fossil remains has named the species as Inermorostrum Xenopus. The description of this new specimen from the Oligocene period has been published in the scientific journal Proceedings of the Royal Society.
Robert W. Boessenecker, a professor of geology at the University of Charleston and lead author of the study, points out that this dwarf dolphin had a short snout, with large lips and possibly mustaches.
The lack of teeth indicates that they will probably feed by sucking their prey from the bottom of the sea, instead of biting them or tearing them to chew them. This surprises the researchers since this primitive animal is placed in the evolutionary branch that soon originated the toothed whales, Odontoceti. The discovery also adds a new variety in the form of ingestion and nutrition in a prehistoric period in which these eating habits diversified.
Danielle Fraser, a paleontologist at the Canadian Museum of Nature and co-author of the study, says that Inermorostrum Xenopus opens new questions about the evolution of early marine mammals. The fact that it was fed by suction at such an early stage of evolution may indicate an increase in ocean productivity, according to the researcher.
For its part, Boessenecher believes that the dolphin caught squids and other soft invertebrates living on the seabed, sucking them in a way somewhat similar to the way today’s walruses do.
Scientists also stress the fact that this ancient cetacean was smaller than its closest relatives and significantly smaller than the current bottlenose dolphins, which are two to three and a half meters long. It is believed that this fossil dwarf fossil, which has only been found a skull, was the size of a modern porpoise and weighed about 55 kilos.