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DIPLOMYSTUS FOSSIL FISH FOR SALE
More About Diplomystus
Diplomystus is a genus of fossil paraclupeid (herring-like) fish that are distantly related to modern herring and sardines. There are currently seven recognized species that fall within the genus of Diplomystus. Of the seven, Diplomystus dentatus is perhaps the most common; a product of the aggressive mining of the Green River Formation. While herrings and sardines are open-ocean predatory fish, Diplomystus lived by and large in freshwater environments. Diplomystus fossils are found throughout the various depths of Fossil Lake. Certain recurring trends provide a glimpse into the reproductive and feeding strategies of these fish.
An 8 inch long fossil Diplomystus from the Lingren Quarry.
These fish are the second most common fish found in the Green River Formation of Wyoming, occurring primarily alongside the small herring species Knightia, the most prevalent in the formation. Diplomystus fossils have a wide geographic distribution, occurring on almost every continent. The most significant find outside the United States was of Diplomystus shengliensis in a fossilized freshwater lake in China. This species is most closely related to D. dentatus, the poster child species out of the Green River Formation. Linking D. shengliensis and D. dentatus is an important step in understanding the past proximity of the North American and Asian continents.
Along with the other fish occurring in the Green River Formation, these lakebed dwellers are dated at 48 million years old in the Eocene epoch. Paleontologists believe that the Diplomystus was a sort of living fossil itself within the Eocene Green River lake environment, surviving through most of the Ellimmichthyidae order’s existence from the early Cretaceous to Diplomystus’s eventual extinction in the middle Eocene, ending the lineage.
Diplomystus birdi is another notable species coming out of deposits in Hakel and Hjoula, Lebanon. This species has an ovular body shape that contrasts D. dentatus's sleeker, tapered shape. Fossils from this locality are Cretaceous in age and show the temporal depth of the genus and how phenotypical differences can be quite different within a genus.
Fun Fact - Because Diplomystus is so common in the Green River Formation, there are lots of opportunities to find superbly preserved specimens that can be prepared as fine art presentations. In 1960, the American president Dwight Eisenhower presented the Emperor of Japan with a beautiful Diplomystus specimen as a token of friendship with the nation of Japan.
Identifying Features
Many of the fish that come out of the Green River Formation are often easily mistaken for other visually similar species. This happens primarily with Priscacara and Cockerellites, but there can be some confusion between Knightia and Diplomystus. This relationship between Diplomystus, Knightia, and modern herrings is incredibly evident in the shapes of their mouths, relative sizes, and other morphological features. Despite their plethora of shared characteristics, there are a few glaring differences that distinguish these two genera. Aside from the overall trend towards larger sizes than the other clupeomorphs, the most recognizable defining feature among Diplomystus is a long row of bony scutes on the ventral side of the fish between the belly and the tail. There are bony scutes that extend from the back of the head to the dorsal fin as well. Knightia lacks these features and looks like a typical herring or sardine.
What Did Diplomystus Eat And What Ate Them?
The upturned mouth of Diplomystus is suggestive of a fish that feeds between mid-depths and at surface level, with smaller individuals leading a primarily planktivorous diet like their modern descendants. Larger specimens are known to have been piscivorous when the opportunity arose. This is evident in the fossil record, where Diplomystus specimens are observed with Knightia in their stomachs, and sometimes even other members within their species! Priscacara and Cockerilities were apparently a snack of choice for Diplomystus, but they appeared to be a rather tough one to stomach: many Diplomystus have been found dead with a Cockerilities in their mouths. These mid-gulp deaths are often referred to as “aspirations”, which are very popular on the fossil market when they appear. Ingesting Priscacara was done head-first to avoid being punctured by their perch-like spines.
An aspiration fossil of a Diplomystus that died trying to each another Diplomystus.
“There's always a bigger fish” not only applies in the fictional universe of Star Wars, but in aquatic ecosystems through history. Just as Diplomystus fed on Knightia, other larger fish fed on Diplomystus. If they weren’t being snacked on by a Phareodus or gar, then they may have ended up as lunch for any number of birds or aquatic reptiles, such as Trionychid turtles or crocodilians like Borealosuchus.
How Did Diplomystus Reproduce?
The size difference of Diplomystus individuals at different lake depths is a major indicator of how the fish reproduced in its environment. Because the fish found at greater depths are typically significantly smaller and in greater numbers, paleontologists conjecture that the species reproduced in the open waters of the lake and moved closer to the shore as they attained larger size. This phenomenon is contradictory to most other fishes' life cycles, where baby fish live closer to the shore.
References
Grande, Lance, A revision of the fossil genus Diplomystus : with comments on the interrelationships of clupeomorph fishes. American Museum novitates ; no. 2728. 1982. New York, N.Y. : American Museum of Natural History
Grande, Lance, The Lost World of Fossil Lake: Snapshots from Deep Time. 2013. The University of Chicago Press.
Dig Your Own Fossil Fish
Fossil Lake Safari, operated by FossilEra Adventures near Kemmerer, Wyoming, offers a unique, hands-on fossil hunting experience for all ages. Here, visitors can split open rock from the 50-million-year-old Fossil Lake formation—one of the world’s most diverse and fossil-rich sites. Best of all, you get to keep the fossils you uncover!
