''Kryptodrakon'' is an extinct

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 ...

of pterodactyloid

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 ...

from the Middle to

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 ...

with an age of approximately 162.7 million years. It is known from a single

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''Kryptodrakon progenitor''. The age of its fossil remains made ''Kryptodrakon'' the basalmost and oldest pterodactyloid known to date. Krytodrakon NT small

Discovery and naming

In 2001, pterosaur bones were discovered in

Xinjiang Xinjiang,; , SASM/GNC romanization, SASM/GNC: Chinese postal romanization, previously romanized as Sinkiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an Autonomous regions of China, autonomous region of the China, People' ...

by Chris Sloan. The bones were first identified as those of a theropod;

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 ...

James Clark later recognized their pterosaurian nature. In 2014, Brian Andres, Clark and Xu Xing named and described the type species ''Kryptodrakon progenitor''. The generic name means ''hidden dragon'' from Greek κρυπτός, ''kryptos'' (''hidden''), and δράκων, ''drakon'' (''dragon''). The name alludes to the film '' Crouching Tiger, Hidden Dragon,'' which included some scenes filmed near the type locality. The specific name ''progenitor'' means ''ancestor'' or ''founder of a family'' in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

, and refers to the animal's status as the most basal member of the Pterodactyloidea. The

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 ...

, IVPP V18184, was uncovered in a layer of the Shishugou Formation dating from the Callovian– Oxfordian and having a minimum age of 161 million years. It consists of a partial skeleton lacking the skull. It contains fragments of both wings including the right fourth metacarpal, parts of the shoulder girdle and the second sacral vertebra. The bones were not articulated but were discovered in a small area of , at a considerable distance from other fossil remains, and thus likely represent a single individual. The bones were largely preserved three-dimensionally, without strong compression. The holotype probably was an adult individual.

Description

''Kryptodrakon'' has an estimated

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 . Its fourth

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

is relatively slender and elongated, a strong indication that ''Kryptodrakon'' is a pterodactyloid. The fourth metacarpal has a minimum length of , while the

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

has an estimated length of between and . These relative proportions are within the range of pterodactyloids. The radius shows an

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...

: it possesses an extra lump on the front outer lower side. The skeleton shows no signs of pneumatization.

Phylogeny

The main author performed 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, the most extensive ever published about the Pterosauria and providing clade definitions for most pterosaur groups previously undefined. The analysis showed that ''Kryptodrakon'' is the sister species of all other known Pterodactyloidea, together forming the Lophocratia, and thus the basalmost pterodactyloid known, if Pterodactyloidea is defined '' sensu'' Padian 2004 as containing those species possessing a metacarpal with at least 80% of the length of the

, homologous to ''

Pterodactylus ''Pterodactylus'' (from ) is a genus of extinct pterosaurs. It is thought to contain only a single species, ''Pterodactylus antiquus'', which was the first pterosaur to be named and identified as a flying reptile and one of the first prehis ...

''. The species is about five million years older than the oldest pterodactyloids previously discovered. A supposedly older pterodactyloid, a partial jaw referred to the group Ctenochasmatidae, had been described from the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

of the UK.Buffetaut, E. and Jeffrey, P. (2012). "A ctenochasmatid pterosaur from the Stonesfield Slate (Bathonian, Middle Jurassic) of Oxfordshire, England." ''Geological Magazine'', (advance online publication) However, this specimen probably represents a teleosaurid stem-crocodilian instead of a pterosaur. Below is a

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 ...

showing the results of a

phylogenetic 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 dat ...

analysis presented by Longrich, Martill, and Andres, 2018.Longrich, N.R., Martill, D.M., and Andres, B. (2018)
Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary.
''PLoS Biology'', 16(3): e2001663.

Paleobiology

''Kryptodrakon'' lived in a terrestrial or in-land habitat, far from the coast. Andres and colleagues saw this as an indication that the Pterodactyloidea had a terrestrial origin. The relatively short wings of ''Kryptodrakon'' confirm this hypothesis, as long-winged species of modern birds and long-winged

pterosaurs Pterosaurs are an extinct clade of flying reptiles in the Order (biology), 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). Pterosau ...

tend to live at the coast and short-winged species tend to inhabit

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

s, as was shown by a study published as part of the describing article.

References

{{Taxonbar, from=Q16643876 Pterodactyloidea Oxfordian life Late Jurassic pterosaurs of Asia Jurassic China Fossils of China Paleontology in Xinjiang Fossil taxa described in 2014 Taxa named by Xu Xing

Discovery and naming

Description

Phylogeny

Paleobiology

See also

References