''Eosinopteryx'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s known to the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

epoch of

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. It contains a single

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, ''Eosinopteryx brevipenna''. Some researchers consider it a junior synonym of ''

Anchiornis ''Anchiornis'' is a genus of small, four-winged Paraves, paravian dinosaurs, with only one known species, the type species ''Anchiornis huxleyi'', named for its similarity to modern birds. The Latin name ''Anchiornis'' derives from a Greek word m ...

.''

Discovery and naming

''E. brevipenna'' is known from a single fossil specimen recovered from the

Tiaojishan Formation The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period (Bathonian-Oxfordian (stage), Oxfordian stages). It is known for its Lagerstätte, exceptionally preser ...

of western

Liaoning Province ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

, China, which has been dated to the late Jurassic period ( Oxfordian age), about 160 million years ago. The name ''Eosinopteryx'' is derived from the Greek ''eos'' ("daybreak" or "dawn"), the Latin ''Sinae'' ("Chinese"), and the Greek ''pteryx'' ("feather"). The specific name ''brevipenna'' (from the Latin ''brevis'', "short", and ''penna'', "feather") refers to the reduced plumage preserved in the

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

, YFGP-T5197.

Description

''Eosinopteryx brevipenna'' is known from a single

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 preserve ...

specimen representing the nearly complete skeleton of a subadult or adult individual. The specimen is very small for a non-

avialan Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds, and their closest relatives. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative defi ...

dinosaur, measuring about long. Unlike most troodontids, the snout was very short, shorter than the diameter of the eye socket. The wings were about the same size as those of the related ''

Anchiornis huxleyi ''Anchiornis'' is a genus of small, four-winged paravian dinosaurs, with only one known species, the type species ''Anchiornis huxleyi'', named for its similarity to modern birds. The Latin name ''Anchiornis'' derives from a Greek word meaning " ...

'', with the primary wing feathers being longer than the humerus (upper arm bone). An unusual arrangement of the wing bones would have prevented any flapping motion. The tail was very short compared to most troodontids and dromaeosaurids and also unlike members of those groups, the feet and toes were very slender, lacking highly curved claws for predation or climbing. Unusually, the tail of the only known fossil does not show signs of the presence of complex vaned feathers (

rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the Bird wing, wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those ...

), and the lower tarsals and feet appear to have been featherless, unlike many related species with "hind wings" on the lower legs and feet. A researcher from the

University of Southampton The University of Southampton (abbreviated as ''Soton'' in post-nominal letters) is a public university, public research university in Southampton, England. Southampton is a founding member of the Russell Group of research-intensive universit ...

said in 2013 the discovery of ''Eosinopteryx'' suggests "that the origin of flight was much more complex than previously thought". A 2017 study describing new specimens of ''Anchiornis'' found ''Eosinopteryx'' only distinguishable from ''Anchiornis'' in the length of the tail, but the tail of ''Eosinopteryx'' is incomplete, rendering this distinction invalid. This led some researchers to consider ''Eosinopteryx'' a junior synonym of ''Anchiornis.''

Classification

Though initially classified as a

troodontid Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinos ...

, a more comprehensive analyses of its relationships have found it to be either a primitive paravian or an

. In 2017 re-evaluation of the Harlem ''

Archaeopteryx ''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird'') is a genus of bird-like dinosaurs. The name derives from the ancient Greek (''archaîos''), meaning "ancient", and (''ptéryx''), meaning "feather" ...

'' specimen, ''Eosinopteryx'' is found to be an anchiornithid.

External links

A photograph of the type specimen, published by David Evans' twitter accountA close-up view of the skull, from the same source

References

{{Taxonbar, from=Q3561744 Anchiornithidae Dinosaur genera Oxfordian dinosaurs Tiaojishan Formation Fossil taxa described in 2013 Taxa named by Pascal Godefroit Dinosaurs of China Feathered dinosaurs