Eostrix

Eostrix is an extinct genus of primitive owl the extinct family Protostrigidae from early Eocene of Wyoming and the London Clay of England. It was erected by Pierce Brodkorb in 1971 to place a fossil species known until that time as Protostrix mimica.

Two species are recognised. E. martinellii was described in 1972 from a left tarsometatarsus (lower leg bone) recovered from an escarpment above the southeastern bank of Cottonwood Creek in Fremont County, Wyoming by Jorge Martinelli on a field trip in 1970 under the auspices of the University of Kansas. The strata was a Lysite member of the Wind River Formation. Martinelli was studying paleontology at the University of Barcelona. Paleontologists Larry D. Martin and Craig C. Black from the Museum of Natural History named it in his honour. The smaller of the two species, it was similar in size to the living long-eared owl (Asio otus). Differences in the trochleas (grooves) of the lower end of the tarsometatarsus set it apart from living owls, namely a groove in the trochlea for digit 2, a deeper posterior groove in a relatevely narrow trochlea for digit 3, and an unusually rounded trochlea for digit 4.