Sustain Our Nation's Forests and Grasslands

Fish fossil discovered on Comanche National Grassland

In February, a series of large fossil fish vertebrae were discovered in a drainage area on Comanche National Grassland.

Paleontologist Bruce Schumacher and seasonal employee Kevin Lindahl unearthed and collected the specimen in a plaster jacket. The fossil specimen will be on public display at the Comanche Grassland office in La Junta, Colorado. Ultimately the fossil will go to permanent research collections at the Denver Museum of Nature and Science. The tail structure is remarkably tuna-like and strongly suggests high speed swimming as a pursuit predator. The tail fin measures 85 cm in greatest dimension, and the complete skeleton would have been roughly 2.3 meters (7 feet) in total length. In life, the fish would have weighed around 500 pounds.

The vertebrae were found on a steep slope, eroding from within geologic chalk layers of the Greenhorn Limestone. The Greenhouse Limestones are a series of marine beds that formed in a shallow seaway that covered the mid-continent of North America about 94 million years ago during the Cretaceous Period.