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Eurhinodelphis - A Common Miocene Cetacean - Facts and Information about the Extinct Long-Snouted Dolphin




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Eurhinodelphis Extinct Dolphin Sketch

My rendition of Eurhinodelphis bossi - The Long-Snouted Dolphin - Miocene of the Calvert Cliffs.


Fast Facts about the Extinct Long Snouted Dolphin

Eurhinnodelphis bossi on display at the Calvert Marine Museum, from the Calvert Cliffs - Miocene

Eurhinodelphis bossi on display at the Calvert Marine Museum


Name: Eurhinodelphis - Greek Meaning: Eurhino = Well-Nosed, Delphis = Dolphin. "Well-Nosed Dolphin" or "Great Nosed Dolphin". The name comes from the extremely long snout on this dolphin.

Taxonomy: Eurhinodelphis, like all dolphins, are Mammals.
Class: Mammalia - Order: Cetacea - SubOrder: Odontoceti - Family: Eurhinodelphinidae - Genus: Eurhinodelphis - Species: up to 3 species

Age: Miocene
Eurhinodelphis lived around 23 to 5 million years ago.

Distribution: Global
Fossils of Eurhinodelphis are found throughout the world in Miocene marine sediments, from North America and Europe to Australia.

Physical Appearance: Like a normal Dolphin, but with a very long snout
Eurhinodelphis would have looked like a modern dolphin today... Except for the insanely long snout!

Body Size: 6 to9 feet (2 - 3 meters)
Eurhinodelphis are an average sized dolphin. The long snout would have taken up almost 1/3 of its body size.

Teeth:
Their teeth look similar to todays dolphins, small, conical, and peg-like.

Diet:Fish
Since they have small, peg-like teeth, similar to todays dolphins, they would be well suited for eating small fish and squid, like todays dolphins. The extremely long snout may indicate they were specialized feeders, and may have batted at schools of fish with their snouts.

Fun Facts:
The snout! It's HUGE!!!!





Eurhinodelphis: The Details

A jaw section of Eurhinodelphis bossi, from the Calvert Cliffs - Miocene

Image of a Eurhinodelphis jaw section and rib from a fossil specimen found in the Miocene Calvert Cliffs. The lower jaw is almost completely exposed here. Notice the length of the snout.


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 dolphins, Eurhinodelphis belongs 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 still retained slightly complex teeth, which means the teeth are shaped differently depending on their tooth position in the dentition (similar to land mammals - we have molars, canines, and incisors). Although the teeth in this dolphin were only slightly complex, these teeth were still 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.

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.





References:

Mchedlidze G.A.; Translated by Chakravarthy, R. (1984). General Features of the Paleobiological Evolution of Cetacea. New Delhi: Oxonian Press. Translated for Smithsonian Institution Libraries.



Recommended Book:

The Walking Whales: From Land to Water in Eight Million Years
By: J. G. M. "Hans" Thewissen, 2014
This is a great book for learning about whale evolution. It's the most up to date book (2014), and has all of the recent discoveries over the past decade. Hans Thewissen gives a firsthand account of the fossil discoveries, from their origins as small land dwelling mammals to modern whales. He is also one of the leading researchers in the field of whale paleontology. This is a great book for if you are interested in understanding whale evolution. Check it out.





Eurhinodelphis Fossil Identification:

Unfortunately, Eurhinodelphis fossils look almost identical to the dozens of other small to medium dolphin fossils found in Miocene exposures.
Unless there is a skull found, it is very difficult it not impossible to determine what type of dolphin isolated fossils come from. This includes vertebra and individual teeth.
However, since Eurhinodelphis has an unmistakable long, slender snout, with small teeth spaced close together, jaw fragments can be identified.

Below are fossil identification images for Eurhinodelphis fossils:

Eurhinodelphis bones from the Calvert Cliffs excavation

Image of jaw and skull sections, ribs, and vertebra of a Eurhinodelphis Fossil.




Eurhinodelphis fossil jaw fragment identification guide

This is an image of a few random jaw fragments. Notice the Eurhinodelphis jaw section has small, closely spaced root holes.


For more images of a Eurhinodelphis specimen, go to the Eurhinodelphis Excavation Article.





Kellogg's Eurhinodelphis 1923 Plates

Kellogg described a Eurhinodelphis specimen from the Calvert cliffs in Maryland in 1923. His publication has identification plates for the partial specimen he described. Below are a few plates from his publication:



Kellogg, Remington. (1923). On the occurrence of remains of fossil porpoises of the genus Eurhinodelphis in North America. Proceedings of the United States National Museum 66(26):1-40. No. 2462 PP 1-69. April 24.




From Kellogg 1923 - Eurhinodelphis Fossil skull

Eurhinodelphisbossi skull - Plate 1 and 2 from (Kellog, 1925)

From Kellogg 1923 - Eurhinodelphis
 Fossil Ribs

Eurhinodelphis bossi Fossil Ribs - Plate 14 from (Kellog, 1925)

From Kellogg 1923 - Eurhinodelphis
 Fossil Vertebra

Eurhinodelphis bossi Dorsal Vertebra - Plate 7 from (Kellog, 1925)

From Kellogg 1923 - Eurhinodelphis
 Fossil Skull

Another Eurhinodelphis bossi Skull - Plate 15 from (Kellog, 1925)
This one has the end of the long snout broken off.