''Cruschedula'' is an enigmatic

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 ...

genus considered to be ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'' which consists of the

single Single may refer to: Arts, entertainment, and media * Single (music), a song release Songs * "Single" (Natasha Bedingfield song), 2004 * "Single" (New Kids on the Block and Ne-Yo song), 2008 * "Single" (William Wei song), 2016 * "Single", by ...

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 ...

''Cruschedula revola''.

Description

The genus was first described by

Florentino Ameghino Florentino Ameghino (born Giovanni Battista Fiorino Giuseppe Ameghino September 19, 1853 – August 6, 1911) was an Argentine naturalist, paleontologist, anthropologist and zoologist, whose fossil discoveries on the Argentine Pampas, especially ...

in his 1899 volume ''Sinopsis geológico-paleontológica. Suplemento. (Adiciones y correcciones.)''. The name was coined by Ameghino from a combination of the ' meaning "shin" and ' meaning "a small sheet of paper". The etymology of the

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

is not clear, but possibly from the '. The genus and species were described from a single partial bone which Ameghino considered to be a

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 ...

section. The bone was found in

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

(

Tinguirirican The Tinguirirican ( es, Tinguiririquense) age is a period of geologic time (36.0–29.0 Ma) within the Late Eocene and Early Oligocene epochs of the Paleogene, used more specifically within the SALMA classification in South America. It follows th ...

Deseadan The Deseadan ( es, Deseadense) age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It fo ...

) beds of the

Deseado Formation Deseado may refer to: Geographic names and features * Deseado (crater), a crater on the planet Mars * Deseado Department, a department in Santa Cruz Province, Argentina * Deseado Massif, a geological formation in Santa Cruz Province, Argentina * D ...

near

San Jorge Gulf The San Jorge Gulf (Golfo San Jorge; Spanish for ''Gulf of St. George'') is a bay in southern Patagonia, Argentina. It is an ocean basin opening to the Atlantic. Its shoreline spans Chubut and Santa Cruz province. The gulf measures approximate ...

in Southern

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

.''Cruschedula''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org Designated the

holotype specimen 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 ...

, it was added to the

Bernardino Rivadavia Natural Sciences Museum The Bernardino Rivadavia Natural Sciences Argentine Museum ( es, Museo Argentino de Ciencias Naturales Bernardino Rivadavia) is a public museum located in the Caballito section of Buenos Aires, Argentina. History and overview The museum owes it ...

along with a large portion of Ameghino's fossil collections.

Taxonomy

In his paper, Ameghino erected the family Cruschedulidae, however in his 1906 paper "Enumeracion de los Impennes Fosiles de Patagonia y de la Isla Seymour" he synonymized the family into Cladornithidae. When described Ameghino envisioned the genus and the family Cladornithidae as a whole to have represented a group of extinct "dry-land"

penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

s. This was because the fossil, having been collected from an outcrop of the

, was thought to be similar to other penguin fossils Ameghino attributed to the same formation. The Deseado Formation preserved a terrestrial environment, and thus the presence of penguins was considered highly unusual. The placement of ''Cruschedula'' as a penguin was not challenged until 1946 by eminent

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

George Gaylord Simpson George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the Modern synthesis (20th century), modern ...

. After examining the holotype, Simpson concluded there were no distinguishable details that defined the bone as from a penguin, but did not have any opinion as to what bird group it may have belonged to. The fossil was again restudied in 1964 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 ...

, who asserted the fossil to not be a

but rather the end of a

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...

. In his ''Catalogue of Fossil Birds'' Brodkorb placed the genus into the diurnal

bird of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...

family

Accipitridae The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-s ...

. This placement was followed by Simpson in his 1972 ''Conspectus of Patagonian fossil penguins'' However, the placement was rejected by Eduardo P. Tonni in his 1980 paper ''The present state of knowledge of the Cenozoic birds of Argentina'' where he considered the bone fragment upon which the genus was erected to be undiagnostic. This assessment was supported by

Storrs L. 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 ...

in 1985, who quoted Tonni's assessment of the ''Cruschedula'' holotype as undiagnostic.

Description

Taxonomy

References

Further reading