''Alexornis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

enantiornithine The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

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 ...

s from the Bocana Roja Formation of

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

.Tykoski, R. S., & Fiorillo, A. R. (2010). An enantiornithine bird from the lower middle Cenomanian of Texas. ''Journal of Vertebrate Paleontology'', 30(1), 288-292. This geological formation has been dated to the late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

period, and more specifically to the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

age, about 73 mya. The type and only known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

is ''Alexornis antecedens''. Its name means "Alex's ancestral bird"; ''Alexornis'' from the given name of

ornithologist Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and th ...

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 ...

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''ornis'', "bird", and ''antecedens'',

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for "going before" or "ancestral". ''A. antecedens'' is known only from a single fragmentary skeleton including shoulder, wing, and leg bones, but lacking a skull. It was about the size of a sparrow. The specimen was discovered in 1971 and described and named in 1976 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 ...

. Brodkorb considered the species to be similar to some modern birds, and at the time, recognized it as one of the few known Cretaceous "land birds" after ''

Gobipteryx minuta ''Gobipteryx'' (from Gobi eferring to the Gobi Desert where it was first discovered and Greek pteryx “wing”) is a genus of prehistoric bird from the Campanian Age of the Late Cretaceous Period.Elżanowski, A. (1974): Preliminary note on th ...

'' (most other Cretaceous birds at the time were thought to be aquatic or semi-aquatic).

Classification

''Alexornis'' was originally described as an early member of the modern bird group and, more specifically, as a possible ancestor of the

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 ...

Coraciiformes The Coraciiformes are a group of usually colourful birds including the kingfishers, the bee-eaters, the rollers, the motmots, and the todies. They generally have syndactyly, with three forward-pointing toes (and toes 3 & 4 fused at their base) ...

(

kingfishers Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...

and relatives) and

Piciformes Nine families of largely arboreal birds make up the order Piciformes , the best-known of them being the Picidae, which includes the woodpeckers and close relatives. The Piciformes contain about 71 living genera with a little over 450 species, of ...

(

woodpecker Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions. ...

s and relatives). However, when the first recognized enantiornithine fossils were discovered, it soon became clear that ''Alexornis'' was an additional member of this group.Walker, C. A., Buffetaut, E., & Dyke, G. J. (2007). Large euenantiornithine birds from the Cretaceous of southern France, North America and Argentina. ''Geological Magazine, London'', 144(6), 977. Enantiornithes are characterized by a reversed articulation of the ''scapula'' and ''coracoid'' bones in the shoulder, and in 1983 Larry Martin showed that Brodkorb has accidentally switched these two bones in his original description, confused by their reversed anatomy.Martin, L. 1983. The origin and early radiation of birds. In Perspectives in Ornithology, Essays Presented for the Centennial of the American Ornithologists’ Union, pp. 291-338. In the past, ''Alexornis'' has been allied with the similarly sized

Central Asia Central Asia, also known as Middle Asia, is a subregion, region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes t ...

n genus ''

Kizylkumavis ''Kizylkumavis'' this is a genus of enantiornithine birds which lived during the Late Cretaceous and is known from fossils found in the Bissekty Formation of the Kyzyl Kum, Uzbekistan Uzbekistan (, ; uz, Ozbekiston, italic=yes / , ; russian ...

'', based on characteristics which are known to unite them with other Cretaceous birds in the group Enantornithes.

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 ...

argued in 1996 that ''Alexornis'' formed a natural group, the Alexornithidae, with ''Kizylkumavis'' and a second type of central Asian bird, ''

Sazavis ''Sazavis'' was an enantiornithine bird from the Late Cretaceous. It might have been related to '' Nanantius'' and lived in what is now the Kyzyl Kum of Uzbekistan. There is a single species known to date, ''Sazavis prisca''. Etymology Gen ...

''. Among the enantiornithes, ''Alexornis'' shares many similarities of its skeletal anatomy with South American birds from about the same time period, including ''

Martinavis ''Martinavis'' is a genus of enantiornithine birds which existed in what is now southern France, North America and Salta Province, Argentina during the late Cretaceous period. It was named by Cyril A. Walker, Eric Buffetaut and Gareth J. Dyke ...

'' and ''

Elbretornis ''Elbretornis'' is an extinct genus of enantiornithine which existed in what is now Salta Province, Argentina during the late Cretaceous period. Etymology It was named by Cyril A. Walker and Gareth J. Dyke in 2009, and the type and so far ...

'', and is united with them in the group

Euenantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

.Walker, C. A., & Dyke, G. J. (2009). Euenantiornithine birds from the late Cretaceous of El Brete (Argentina). ''Irish Journal of Earth Sciences'', 27(1), 15-62.

References

{{Taxonbar, from=Q4254960 Euenantiornitheans Bird genera Late Cretaceous birds of North America Fossil taxa described in 1976 Taxa named by Pierce Brodkorb