''Eostrix'' is a genus of extinct primitive

owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

s in the family

Protostrigidae Protostrigidae is a prehistoric family of owls which occurred in North America, Europe, and Asia during the Eocene and early Oligocene periods. Genera include ''Eostrix'', ''Minerva'', '' Oligostrix'', and '' Primoptynx.'Primoptynx poliotauros ...

, along with ''Oligostrix'' and ''Minerva''. These owls date from the early

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, and

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

. They have been described based on fossil remains. The genus was created by

Pierce Brodkorb William Pierce Brodkorb (September 29, 1908, Chicago – July 18, 1992, Gainesville, Florida) was an American ornithologist and paleontologist. Interested in birds since childhood, he was taught to prepare birds at the age of 16. Later, he rec ...

in 1971 to place a fossil species known until that time as ''Protostrix mimica''. The following species are recognised: * ''E. mimica'' described in 1938 by

Alexander Wetmore Frank Alexander Wetmore (June 18, 1886 – December 7, 1978) was an American ornithologist and avian paleontologist. He was the sixth Secretary of the Smithsonian Institution. Early life and education The son of a Country Physician, Frank Al ...

using hindlimb elements in Eocene strata in Wyoming. * ''E. martinellii'' was described in 1972 from a left

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and meta ...

(lower leg bone) recovered from an escarpment above the southeastern bank of Cottonwood Creek in

Fremont County, Wyoming Fremont County is a county in the U.S. state of Wyoming. As of the 2020 United States Census, the population was 39,234, making it the fifth-most populous county in Wyoming. Its county seat is Lander. The county was founded in 1884 and is name ...

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 Call Black Craig Call Black (1932–1998) was an American paleontologist noted for his studies of the vertebrate mammals of the Ice Age. He served as the director of the Museum of Texas Tech University 1972-1975, Carnegie Museum of Natural History 1975-198 ...

from the

University of Kansas Natural History Museum The University of Kansas Natural History Museum is part of the University of Kansas Biodiversity Institute, a KU designated research center dedicated to the study of the life of the planet. The museum's galleries are in Dyche Hall on the unive ...

named it in his honour. The smaller of the two species, it was similar in size to the living

long-eared owl The long-eared owl (''Asio otus''), also known as the northern long-eared owlOlsen, P.D. & Marks, J.S. (2019). ''Northern Long-eared Owl (Asio otus)''. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook o ...

(''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 relatively narrow trochlea for digit 3, and an unusually rounded trochlea for digit 4. * ''E. vincenti'' described in 1980 by Colin Harrison from the early Eocene

London Clay The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from t ...

in England, known from pedal phalanx and proximal

bones. Some scholars think ''E. vincenti'' resembles '' Necrobyas'' more than ''Eostrix''. * ''E. tsaganica'' described in 2011 by

Evgeny Kurochkin Yevgeny Nikolayevich Kurochkin (Евгений Николаевич Курочкин; 12 July 1940 - 13 December 2011) was a Russian paleornithologist at the Paleontological Institute of the Russian Academy of Sciences. He served as President of t ...

and

Gareth J. Dyke Gareth John Dyke is a paleontologist whose work is concerned with the evolutionary history of birds and their dinosaurian relatives. His specific research interests include the phylogenetics of birds, the functional morphology of aves and non-avia ...

, found in Mongolia. In 2016,

Gerald Mayr Gerald Mayr is a German palaeontologist who is Curator of Ornithology at the Senckenberg Research Institute in Frankfurt am Main, Hesse. He has published extensively on fossil birds, especially the Paleogene avifauna of Europe. He is an expert on ...

described ''E. gulottai'' from the early Eocene

Nanjemoy Formation The Nanjemoy Formation is a geologic formation pertaining to both the Wilcox Group and the Pamunkey Group of the eastern United States, stretching across the states of Virginia, Maryland, and District of Columbia. The formation crops out east of ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

. However, in 2022, Mayr, alongside Andrew C. Kitchener, moved '' 'E.' gulottai'' to the genus ''

Ypresiglaux ''Ypresiglaux'' (meaning "Ypresian owl") is an extinct genus of strigiform bird from the Early Eocene London Clay Formation of Essex, United Kingdom and Nanjemoy Formation of Virginia, United States. The genus contains two species: ''Y. michae ...

'' as the new species ''Y. gulottai''.

References

Eocene birds of North America Protostrigidae Eocene birds of Europe Eocene animals of Asia {{Strigiformes-stub