Today, researchers are using the fossils of the Olympicetus thalassodon an early toothed whale which existed around 26.5 and 30.5 million years ago, to better understand the early history and diversification of modern dolphins, porpoises and other toothed whales. 

According to paleontologist Jorge Velez-Juarbe of the Natural History Museum of Los Angeles County, some of their characteristics, like multi-cusped teeth, symmetric skulls and forward position of the nostrils, made them appear to be more like an intermediate between archaic whales and present-day dolphins.

Its fossils, along with those of two other closely related odontocetes were found in the Pysht Formation, a geologic unit along the coast of the Olympic Peninsula in Washington State and dated to between 26.5 and 30.5 million years.

The researchers discovered that the Olympicetus and their close kin belong to a family called Simocetidae, which was one of the earliest diverging groups of toothed whales, and was known to have existed in the North Pacific.

Velez-Juarbe said the Olympicetus' teeth as "truly weird," as they were heterodont (meaning the teeth had different shapes along the toothrow). "This stands out against the teeth of more advanced odontocetes whose teeth are simpler and tend to look nearly the same.”

In addition, there were also difference in body size and other feeding-related structures, suggesting that the simocetids used different methods to catch their prey and were likely to prefer other types of prey animals.