Dolphins may look like playful, clever pranksters in the ocean, but it turns out that at least one of their ancestors is more toothed and predatory, with similar characteristics to contemporary whales. A report published Thursday in the journal Current Biology describes how the giant skeleton of an extinct dolphin shows signs of parallel evolution with modern and toothed whales.
The 15-foot skeleton, named Ankylorhiza, was found in South Carolina and lived about 25 million years ago during the Egency. Judging by its skull, teeth, size and nose, it was the top predator of the time. In terms of its skeletal structure, scientists determined that it had a postcranial feature similar to that of modern whales, meaning that their similar aquatic habitats led to some adaptive development.
Some examples include narrowing of the tail stock, an increase in the number of tail vertebrae, and a shorter tibia (upper arm bone) in the fins. This is not evident in the different lines of seals and sea lions, for example, seals and sea lions evolved into different swimming patterns, with very different appearances of their skulls. The skeleton also suggests that Ankylorhiza may have been the first echo whale to become a top predator. According to the researchers, the species “very clearly preys on its massive prey, paving the way for the eventual emergence of killer whales.”