Maryland Darter (Ethiostoma sellare), USNM no. 212147 (specimen from the Smithsonian Museum collection, on loan to the FMNH). Field Museum of Natural History, Chicago. Conservation status: extinct. This species had a tiny distribution in tributaries of the lower Susquehanna River, Harford County, Maryland, USA. It was last observed in 1988, its range by then confined to a single riffle in Deer Creek, Maryland. The IUCN has declared the species extinct but the U.S. Fish and Wildlife Service has not and keeps it on the Endangered Species List. Habitat destruction is the most likely cause of its disappearance. ..As biologists describe new species and add to our understanding of the interrelated nature of life on Earth, a species becomes extinct every 20 minutes (100 to 1000 times the background extinction rate as seen in the fossil record). Collections in natural history museums play important roles in conservation, education and research. Most of that work and the associated specimens are not on public display in museums? typically, less than five percent of specimens are exhibited.