''Ambopteryx'' (meaning "both wing") is a genus of scansoriopterygid

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

from the

Oxfordian stage The Oxfordian is, in the ICS' geologic timescale, the earliest age of the Late Jurassic Epoch, or the lowest stage of the Upper Jurassic Series. It spans the time between 163.5 ± 1.0 Ma and 157.3 ± 1.0 Ma (million years ago). The Oxfordian ...

of the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the ...

of China. It is the second dinosaur to be found with both feathers and bat-like membranous wings. ''Yi'', the first such dinosaur, was described in 2015 and is the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to ''Ambopteryx''. 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 ...

is thought to be a sub-adult or adult. The specimen is estimated to have had a body length of and a weight of . The genus includes one species, ''Ambopteryx longibrachium''.

Etymology

The generic name ''Ambopteryx'' is derived from the

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 ...

word ''ambo'' meaning "both" and

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 p ...

word ''πτέρυξ'' (''pteryx'') meaning "wing", a reference to the animal's membranous wings and bird-like body plan. The specific name ''longibrachium'' is derived from the Latin words ''longus'' meaning "long" and ''brachium'' meaning "upper arm".

Holotype

The holotype specimen, IVPP V24192, is an articulated and nearly complete skeleton with associated soft tissue preserved on a slab and a counter slab. It was recovered in 2017 from the stratigraphic equivalent of the

Haifanggou Formation The Haifanggou Formation (), also known as the Jiulongshan Formation (), is a fossil-bearing rock deposit located near Daohugou () village of Ningcheng County, in Inner Mongolia, northeastern China. The formation consists of coarse conglomerate ...

near Wubaiding Village in the Liaoning Province and belongs to the Yanliao Biota. The wing membrane is preserved as a continuous brownish layer on the matrix surrounding the left hand, right forelimb, and abdomen. The head, neck, and shoulder regions are covered with dense layers of feather.

Description

Like other scansoriopterygids, ''Ambopteryx'' had a short, blunt head and a hyper-elongate third finger. It was previously believed that scansoriopterygids used their third finger to extract grubs from wood, like the

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

aye-aye The aye-aye (''Daubentonia madagascariensis'') is a long-fingered lemur, a strepsirrhine primate native to Madagascar with rodent-like teeth that perpetually grow and a special thin middle finger. It is the world's largest nocturnal primate. ...

. However, Wang et al. think the primary function of the third finger was the attachment of the wing membrane, or patagium, as their fingers were probably surrounded by membranous tissue and had limited mobility. Among scansoriopterygids, ''Ambopteryx'' was most closely related to ''Yi'', with which it shared a "styliform element", an elongate bone that extended from the distal (far) end of the

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

. The styliform element was slightly curved and tapered towards the distal end. It supported the wing membrane, which stretched from the third finger down to the abdomen. Ambopteryx size comparison

The

forelimb A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

s of ''Ambopteryx'' were about 1.3 times longer than the

hindlimb A hindlimb or back limb is one of the paired articulated appendages (limbs) attached on the caudal ( posterior) end of a terrestrial tetrapod vertebrate's torso.http://www.merriam-webster.com/medical/hind%20limb, Merriam Webster Dictionary-Hindl ...

s, with the

being shorter than the

humerus The humerus (; ) 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 and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

and almost twice as wide as the width of the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

. Unlike most other non-avian theropods, it had a short tail that lacked a transitional point and ended in a

pygostyle Pygostyle describes a skeletal condition in which the final few caudal vertebrae are fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these. The pygostyle is the main compo ...

, a set of fused tail vertebrae. The only other non-avian theropod that are known to have had a pygostyle are certain

oviraptorosaurs Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or w ...

and therizinosaurs.

Diet

The

abdominal The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso ...

region of ''Ambopteryx'' contains a small number of

gastrolith A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In oth ...

s and large fragments of what appears to be bone. The bone probably represents stomach contents. Previously, the diet of scansoriopterygids was unknown but their unusual dental morphology and the presence of gastroliths and possible bone fragments in ''Ambopteryx'' suggests they were omnivorous.

References

{{Taxonbar, from=Q63637265 Fossil taxa described in 2019 Prehistoric paravians Gliding animals Feathered dinosaurs Late Jurassic dinosaurs of Asia Fossils of China