Two Diplomystus Fossil Fish on Plate

Approximately 48 million years old Diplomystus was a herring-like fish that lived in the early Eocene (roughly 48 million years ago) and was prolific in freshwater environments the world round. They are usually found in the Green River Formation (more on that later) and are really impressive fossil specimens. The detailing of the ribs down to the fins is really something to take in. It’s still crazy to us that something that lived so long ago is right in front of us in vivid detail. While it’s a very pretty specimen, Diplomystus was a fierce little fish. Diplomystus is an extinct genus of freshwater, ray-finned predators. It had a distinctive jaw that protruded aggressively outward from the mouth at an angle that allowed it to feed in surface waters and devour such prey as the smaller Knightia fish. The fossils above were small but mighty fish although some fossils show it could reach up to 20 inches long!  These fossil fish provide an interesting look into our earth’s ancient past. These particular Diplomystus were discovered in the Green River formation which is an absolutely mind boggling location. It's one of the most important fossil sites for understanding the Eocene. It’s located in western Colorado, eastern Utah and southwestern Wyoming. During the Eocene, this region was located at much the same latitude it is today, though global temperatures were very different. The fossils, especially plants, found at this site indicate that the climate was moist temperate or sub-tropical, with temperatures ranging from 56-74 degrees fahrenheit. In addition to the plants, another piece of evidence suggesting that the climate was sub-tropical was the presence of fossilized crocodiles. Crocodiles can only survive in areas with a constant, warm temperature. Yeah, Utah had crocodiles at one point. Wild right?  Regardless of if you’re starting your fossil collection or you’ve already got one going, adding one of these is sure to impress all that view it. Plus, if you read all of this, you’ve got a cool story to go along with your new fossil fish friend.