A study published this week on the first detailed examination of a large ancient dolphin provides new insights into how dolphins evolved differently than their relatives, the modern great whales.
The study, published Thursday in the scientific journal Current Biology, is the first in-depth analysis of a full skeleton of Ankylorhiza tiedemani, a large dolphin ancestor that had protruding, tusk-like teeth and lived 23 million years ago near what is now the southeastern coast of the United States.
The skeleton was discovered during a construction project in the 1990s. Previous researchers had only a partial snout of the creature.
The lead author of the study, College of Charleston paleontologist Robert Boessenecker, said researchers have long believed these modern toothed whales — or odontoceti, such as dolphins, orcas and belugas — and the larger baleen whales — or cetaceans, such as humpbacks and right whales — look somewhat similar today because they had a common ancestor.
But Boessencker said this ancient dolphin already had many traits similar to those of modern toothed whales, indicating the odontoceti and cetaceans evolved more separately than earlier hypothesized.
The researchers speculate the Ankylorhiza, though smaller than a modern-day orca, was probably a top predator in its time, because it was roughly twice the size of other dolphins of its era. With its large teeth and strong jaw muscles, it likely fed on smaller dolphins, large fish, sea turtles and seabirds, and possibly larger cetaceans as well.