Joffrichthys triangulpterus
Paleocene
Sentinel Butte Formation
North Dakota

Despite what it looks like, this is NOT a Green River Fish from Wyoming. A small outcrop of the Paleocene-age Sentinel Butte Formation contains a similar, but older fish fauna that has been poorly studied. The deposit contains a high amount of diatomite hence the bright white color. It’s the only fish from this site we have ever seen and didn’t even know the site existed until we came across this specimen from an old collection and did a little research. Very unusual American specimen.

See: A new species of Joffrichthys (Teleostei: Osteoglossidae) from the Sentinel Butte Formation, (Paleocene) of North Dakota, USA, April 2000, Journal of Vertebrate Paleontology 20(1):12-20