''Eonessa'' is an enigmatic genus of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

possibly belonging to

order

Gruiformes The Gruiformes are an order (biology), order containing a considerable number of living and extinct bird family (biology), families, with a widespread geographical diversity. Gruiform means "crane-like". Traditionally, a number of wading and t ...

and which consists of the single species ''Eonessa anaticula''. It was first described 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 ...

in the ''

Journal of Paleontology The ''Journal of Paleontology'' is a peer-reviewed scientific journal covering the field of paleontology. It is published by the Paleontological Society. Indexing The ''Journal of Paleontology'' is indexed in: *BIOSIS Previews *Science Citatio ...

'' in May 1938. In his paper, Wetmore erected the

Anatidae The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating ...

subfamily Eonessinae, and placed ''Eonessa'' as the oldest Anatidae genus in the fossil record. This placement was possibly due to a resemblance to the modern

ruddy duck The ruddy duck (''Oxyura jamaicensis'') is a duck from North America and one of the stiff-tailed ducks. The genus name is derived from Ancient Greek ''oxus'', "sharp", and ''oura'', "tail", and ''jamaicensis'' is "from Jamaica". Taxonomy The ru ...

(''Oxyura jamaicensis''), although Wetmore did not explain his taxonomic placement in the describing paper. Restudy of the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen in 1978 by

Storrs Olson Storrs Lovejoy Olson (April 3, 1944 – January 20, 2021) was an American biologist and ornithologist who spent his career at the Smithsonian Institution, retiring in 2008. One of the world's foremost avian paleontologists, he was best known ...

and

Alan Feduccia John Alan Feduccia (born 25 April 1943) is a paleornithologist specializing in the origins and phylogeny of birds. He is S. K. Heninger Distinguished Professor Emeritus at the University of North Carolina. Feduccia's authored works include thre ...

resulted in the removal of ''Eonessa'' from Anatidae. Olson and Feduccia placed the genus as Aves

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

noting it was possibly a member of the polymorphic

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

. The holotype was collected on August 26, 1936 from the Myton Pocket,

Duchesne County, Utah Duchesne County ( ) is a county in the northeast part of the U.S. state of Utah. As of the 2010 United States Census, the population was 18,607. Its county seat is Duchesne, and the largest city is Roosevelt. History Much of Duchesne County was ...

,The Paleobiology Database ''Eonessa anaticula'' page
/ref> USA. The quarry is on the Myton Member of the

Uinta Formation The Uinta Formation is a Formation (geology), geologic formation in northeastern Utah. The name appears on a geologic map accompanying the Clarence King Fortieth Parallel report for 1876 but not defined until 1878 as the Uinta Group. As defined, ...

and dates to the

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

, around 46-42 million years ago. Now in the

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

paleontology collections as specimen number 14399, the holotype and only known specimen is a 13 cm (5 in) long partial wing, consisting of

metacarpal In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ...

s down to the partial

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

. Though found

articulated An articulated vehicle is a vehicle which has a permanent or semi-permanent pivot joint in its construction, allowing it to turn more sharply. There are many kinds, from heavy equipment to buses, trams and trains. Steam locomotives were someti ...

, the bones were badly crushed during

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

ization. The bones, after further matrix removal in the 1970s, are very slender and with little diagnostic detail and little to no similarity to modern Anatidae members. The general proportions are closer to Gruiformes birds that have been found in the same rock formations; however, the lack of detail does not allow firm placement into the order.

References

{{Taxonbar, from=Q21359341 Paleogene birds of North America Prehistoric bird genera Fossil taxa described in 1938 Bird enigmatic taxa Taxa named by Alexander Wetmore