Diplomystus Aspiration w/ additional fish in belly | Green River Formation | Wyoming

Specimen approx. size: 19.5"

Matrix approx. size: 23.25" x 30" x 1.5"

This piece has had minimal restoration.

Known as an aspiration, this fossil captures a Diplomystus that died trying to swallow its prey whole. The prey fish, a Priscacara, was too large for the Diplomystus to swallow. Additionally, fish like the Priscacara are known to deploy their dorsal spines as a defense mechanism. This also made it difficult to swallow, resulting in the Diplomystus choking to death on its prey. Only some of the Priscacara's spines can be seen sticking out of the Diplomystus' mouth. The Diplomystus also has an additional fish inside its stomach that it had already consumed. Gluttonous behavior resulted in this Diplomystus' untimely demise. This immensely rare occurrence provides a glimpse into a unique dynamic ecological event that has been frozen in time for millions of years.

Diplomystus is an extinct genus of freshwater clupeomorph fish distantly related to modern-day extant herrings, alewives, and sardines. The genus was first named and described by Edward Drinker Cope in 1877.

Ray-finned Fish - Diplomystus dentatus

Order Ellimmichthyiformes, Family Paraclupeidae

The last known species of the Ellimmichthyiformes order went extinct sometime in the middle Eocene. D. dentatus is a primitive relative of the modern day herring. The genus Diplomystus is also known from fossil deposits in China.

D. dentatus is the 2nd most common fossil fish found from Fossil Lake. Specimens ranging from embryonic size (about 0.7 inches) to full-grown adults (about 26 inches) are common. Smaller-sized specimens are more commonly found in mid-lake than near-shore deposits. This suggests that D. dentatus spawned in open water.

This species' upturned mouth indicates it fed at the surface of Fossil Lake. D. dentatus specimens are commonly found with other fish stuck in their mouths, including other D. dentatus specimens.