Eonessa
Encyclopedia
Eonessa is an enigmatic genus of bird possibly belonging to bird order Gruiformes
and which consists of the single species Eonessa anaticula.
It was first described by Alexander Wetmore
in the Journal of Paleontology
in May 1938. In his paper, Wetmore erected the Anatidae
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
(Oxyura jamaicensis), although Wetmore did not explain his taxonomic placement in the describing paper.
Restudy of the holotype
specimen in 1978 by Storrs Olson and Alan Feduccia
resulted in the removal of Eonessa from Anatidae. Olson and Feduccia placed the genus as Aves incertae sedis
noting it was possibly a member of the polymorphic
order
Gruiformes
. The holotype was collected on August 26, 1936 from the Myton Pocket, Duchesne County, Utah
, USA. The quarry is on the Myton Member of the Uinta Formation and dates to the Middle Eocene, around 46-42 million years ago.
Now in the Princeton University
paleontology collections as specimen number 14399, the holotype and only known specimen is a 13 cm (5 in) long partial wing, consisting of metacarpals down to the partial humerus
. Though found articulated
, the bones were badly crushed during fossil
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.
Gruiformes
The Gruiformes are an order containing a considerable number of living and extinct bird families, with a widespread geographical diversity. Gruiform means "crane-like"....
and which consists of the single species Eonessa anaticula.
It was first described by Alexander Wetmore
Alexander Wetmore
Frank Alexander Wetmore was an American ornithologist and avian paleontologist.-Life:Wetmore studied at the University of Kansas...
in the Journal of Paleontology
Journal of Paleontology
The Journal of Paleontology is a peer-reviewed scientific journal covering the field of paleontology, published by The Paleontological Society.-Indexing:The Journal of Paleontogy is indexed in:*BIOSIS Previews*Science Citation Index...
in May 1938. In his paper, Wetmore erected the Anatidae
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...
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
Ruddy Duck
The Ruddy Duck is a small stiff-tailed duck.Their breeding habitat is marshy lakes and ponds throughout much of North America, and in South America in the Andes. They nest in dense marsh vegetation near water. The female builds her nest out of grass, locating it in tall vegetation to hide it from...
(Oxyura jamaicensis), although Wetmore did not explain his taxonomic placement in the describing paper.
Restudy of the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen in 1978 by Storrs Olson and Alan Feduccia
Alan Feduccia
Alan Feduccia is a paleornithologist, specializing in the origins and phylogeny of birds. He is now Professor Emeritus at the University of North Carolina. Feduccia's principal authored works include two books, The Age of Birds and The Origin and Evolution of Birds, and numerous papers in various...
resulted in the removal of Eonessa from Anatidae. Olson and Feduccia placed the genus as Aves incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
noting it was possibly a member of the polymorphic
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Gruiformes
Gruiformes
The Gruiformes are an order containing a considerable number of living and extinct bird families, with a widespread geographical diversity. Gruiform means "crane-like"....
. The holotype was collected on August 26, 1936 from the Myton Pocket, Duchesne County, Utah
Duchesne County, Utah
Duchesne County is a county located in the U.S. state of Utah. As of 2010 the population was 18,607, a 29.5% increase over the 2000 figure of 14,371. Its county seat is Duchesne and the largest city is Roosevelt.-Geography:...
, USA. The quarry is on the Myton Member of the Uinta Formation and dates to the Middle Eocene, around 46-42 million years ago.
Now in the Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
paleontology collections as specimen number 14399, the holotype and only known specimen is a 13 cm (5 in) long partial wing, consisting of metacarpals down to the partial humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. Though found articulated
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
, the bones were badly crushed during fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
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.