''Eoazhdarcho'' is a

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 ...

azhdarchoid Azhdarchoidea (International Phonetic Alphabet, , meaning "azhdarchid-like forms") is a group of pterosaurs within the suborder Pterodactyloidea. Pterosaurs belonging to this group lived throughout the Early Cretaceous, Early and Late Cretaceous ...

pterodactyloid Pterodactyloidea ( ; derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger") is one of the two traditional suborders of pterosaurs ("wing lizards"), and contai ...

pterosaur Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...

named in

2005 2005 was designated as the International Year for Sport and Physical Education and the International Year of Microcredit. The beginning of 2005 also marked the end of the International Decade of the World's Indigenous Peoples, Internationa ...

by Chinese

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

Lü Junchang Lü Junchang (; 1965 – 9 October 2018) was a Chinese palaeontologist and professor at the Institute of Geology, Chinese Academy of Geological Sciences. An expert on Mesozoic reptiles, he described and named dozens of dinosaur and pterosaur taxa ...

and Ji Qiang. The type and only known species is ''Eoazhdarcho liaoxiensis''. The

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 ...

was found in the

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

-age

Lower Cretaceous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker * Lower (surname) * Lower Township, New Jersey *Lower Receiver (firearms) * Lower Wick Gloucestershire, England See also * Nizhny {{Disambiguation ...

Jiufotang Formation The Jiufotang Formation () is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see Jehol Biota). It is a member of the Jehol group. T ...

of Chaoyang,

Liaoning ) , 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 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 ...

Etymology

The genus name, ''Eoazhdarcho'', combines a Greek ''eos'', "dawn" with the name of the genus ''

Azhdarcho ''Azhdarcho'' is a genus of azhdarchid pterosaur from the late Cretaceous Period (geology), Period of the Bissekty Formation (middle Turonian stage, about 92 million years ago) of Uzbekistan, as well as the Zhirkindek Formation of Kazakhstan a ...

'', with the implication it was an early related form of the latter. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''liaoxiensis'', refers to the ancient region

Liaoxi Liaoxi () was a former province in Northeast China, located in what is now part of Liaoning and Jilin ) , image_skyline = Changbaishan Tianchi from western rim.jpg , image_alt = , image_caption = View of Heaven La ...

Description

''Eoazhdarcho'' is based on

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

GMN-03-11-02, a partial skeleton and lower jaw, and is distinguished from other pterosaurs by the proportions of its bones. The metacarpals are very elongated but the cervical vertebrae and hind limbs are not. It was relatively small by azhdarchoid standards, with a

wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the opposite wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingsp ...

of about 1.6 meters (5.2 feet).

Classification

The describers first assigned ''Eoazhdarcho'' to the

Azhdarchidae Azhdarchidae (from the Persian word , , a dragon-like creature in Persian mythology) is a family of pterosaurs known primarily from the Late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the Early Cre ...

in a basal position, and compared it to ''Azhdarcho''. However, in 2006 they published a

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis, determining that several forms, among them ''Eoazhdarcho'', were united in a natural group, a separate

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

that could be set apart from an Azhdarchidae proper. In 2008 that clade was by Lü, Unwin and colleagues named the Chaoyangopteridae — the sister group of the Azhdarchidae within a much larger

Azhdarchoidea Azhdarchoidea ( , meaning "azhdarchid-like forms") is a group of pterosaurs within the suborder Pterodactyloidea. Pterosaurs belonging to this group lived throughout the Early and Late Cretaceous periods, with one tentative member, '' Tendaguri ...

— with ''Eoazhdarcho'' as one of the members.Lü, J., Unwin, D.M., Xu, L., and Zhang, X. (2008). "A new azhdarchoid pterosaur from the Lower Cretaceous of China and its implications for pterosaur phylogeny and evolution." ''Naturwissenschaften'', 95: 891–897 In 2014, a

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

conducted by Brian Andres and colleagues had recovered ''Eoazhdarcho'' as the

basalmost In phylogenetics, basal is the direction of the ''base'' (or root) of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to th ...

member of the family Chaoyangopteridae, sister taxon to the subfamily Chaoyangopterinae. The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

of their analysis is presented on the left. Later, in 2018, a

conducted by paleontologist Nicholas Longrich and colleagues had recovered ''Eoazhdarcho'' in a different position within the

Neoazhdarchia Azhdarchoidea ( , meaning " azhdarchid-like forms") is a group of pterosaurs within the suborder Pterodactyloidea. Pterosaurs belonging to this group lived throughout the Early and Late Cretaceous periods, with one tentative member, '' Tendagu ...

, as a basal member of the clade Neopterodactyloidea. The cladogram of their analysis is presented on the right: Topology 1: Andres ''et al.'' (2014). Topology 2: Longrich ''et al.'' (2018).

References

External links

''Eoazhdarcho''
in The Pterosauria {{Portal bar, Paleontology, China Early Cretaceous pterosaurs of Asia ? Fossil taxa described in 2005 Taxa named by Lü Junchang