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Information about Eurhinodelphis bossi, the long-snouted dolphin.
By Jayson Kowinsky
A rendition of Eurhinodelphis bossi, based on a cast of a skeleton on display at the CMM, the recently discovered specimen, and images of modern dolphins occupying similar ecological niches as the Eurhinodelphis
Eurhinodelphis, the long-snouted dolphin, was a common sight in the ancient mid to late Miocene seas. In fact, Eurhinodelphis bossi, which reaches 6 to 7 feet in length, may possibly be the most common cetacean found in the Miocene Calvert formation. Eurhinodelphis fossils have been found along both the east and west sides of the Miocene Atlantic Ocean, from Maryland and Virginia to France and Belgium
Like all porpoises and dolphins, Eurhinodelphis belong to the Odontocete Order, the toothed whales. Specifically, Eurhinodelphis belongs to a Family of primitive dolphins called Rhabdosteidae, which was traditionally called Eurhinodelphinidae. Members from this Family can be found in Miocene deposits throughout the world including North and South America, Australia, and Europe, as they appeared to be very successful in the Miocene. This primitive dolphin family, ranging in size of 6 to 9 feet in length, is characterized by their incredibly long snouts.
Although Eurhinodelphis was one of the most common dolphins in the Miocene, it is still a primitive dolphin quite unlike any living dolphin today. For starters, this dolphin had complex teeth, which means the teeth are shaped differently depending on their tooth position in the dentition (similar to land mammals). For example, we have molars in the rear of our mouths, and canines and incisors toward the front. The long-snouted dolphins' complex teeth is a vestige left over from their land origins before they returned to the sea long ago in the Paleocene.
Paul holding some of the Eurhinodelphis teeth found during the excavation.
Today's toothed dolphins and whales have evolved simple teeth, they are all peg like and look identical, regardless of their position in the dolphins mouth. Although Eurhinodelphis teeth are complex, they are still tiny and peg shaped, as in the picture above. This means Eurhinodelphis' diet was similar to that of today's dolphins, mainly crustaceans and small fish.
Also, due to Eurhinodelphis' extremely long snout, it looks quite unlike any of today's common dolphins. Although the long snout may superficially appear similar to today's River dolphins, Eurhinodelphis are not related. There is also a major difference in the long snouts: Eurhinodelphis has no teeth toward the front of the snout. It may have used the long toothless end of the snout to dig and sift through the sand, stirring up its hiding prey (a behavior that can be seen in dolphins today). Perhaps it may have used it's long snout to bat at schooling fish to stun them. Determining the use of this long snout lies in the realm of speculation, but it is interesting to ponder.
At any rate, by the end of the Miocene, these strange looking Rhabdosteidae dolphins, which were as common as the dolphins one sees at a beach today, were becoming extinct. They were being replaced by the evolution of the modern dolphins, which are still with us today.
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