''Ordosipterus'' is a pterosaur belonging to the suborder

Pterodactyloidea Pterodactyloidea (derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger" meaning "winged finger", "wing-finger" or "finger-wing") is one of the two traditional ...

. Its

holotype 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 ...

specimen was discovered in

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, and dated back to the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

period (

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

stage). Further analysis conclude that it was a genus of

dsungaripterid Dsungaripteridae is a group of pterosaurs within the suborder Pterodactyloidea. They were robust pterosaurs with good terrestrial abilities and flight honed for inland settings. Classification In 1964 Young created a family to place the recentl ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is 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 to ...

Discovery and naming

In the early 21st century, Chinese paleontologist Ji Shuan found a jaw of a pterosaur near the village of Xinzhao, which is north of Otog Qi,

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

. The find was reported in the scientific literature in 2017.Ji SA, Lu LW, Zhang LF, Yuan CX, Jiang S, Chen XY, Hou YD, 2017, "Recent progress in the study of the Early Cretaceous dinosaur fauna from the Ordos region, Inner Mongolia". ''Geology in China'', 44 (1): 196–197 In 2020, the type and only species ''Ordosipterus planignathus'' was named and described by Ji. The generic name combines a reference to the Ordos basin with a Latinized Greek ''pteron'' (meaning "wing"). The specific name is a combination of the Latin ''planus'' (meaning "flat"), and the ancient Greek ''gnathos'' (meaning "jaw"). The holotype, IG V13-011, has been found in a layer of

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

, belonging to the lower Luohandong Formation, and may be dated back to the

stage of the Early Cretaceous. The holotype consists only of a set of deformed paired lower jaws forming the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

Description

Size

The left dentarium of ''Ordosipterus'' has been stated to be around long, while the right dentarium is only measured to be . It is very difficult to determine a size estimate for this pterosaur, but the holotype cannot have been from a large individual, judging by its size. Ji stated that the closely related ''

Dsungaripterus ''Dsungaripterus'' is a genus of dsungaripterid pterosaur with an average wingspan of . ''Dsungaripterus'' lived during the Early Cretaceous in what is now China, and its first fossil was found in the Junggar Basin. Description ''Dsungaripter ...

'' was clearly much larger than ''Ordosipterus''.

Distinguishing traits

Ji identified some distinguishing traits that are unique in the Dsungaripteridae. This includes the dentarium of the lower jaw being as wide as the

symphysis A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint. # A symphysis is an amphiarthrosis, a slightly movable joint. # A growing together ...

, and the middle part of the symphysis showing a weak ridge on the bottom. The top of the dentarium also forms a shelf bounded by a clear lateral ridge, which is parallel to the curved exterior. Along the jaw edge of the dentarium, there are low tooth sockets that are widely spaced, the space increasing to the rear. The distance between two adjacent tooth sockets varied from one and a half to three times their diameter.

Skeleton

The dentarium bears at least eight teeth, five of which along the symphysis in a straight line, the rear three in a slightly inward curving row. Most of the tooth sockets are elevated, but much lower than in other dsungaripterids such as ''Dsungaripterus'', and are found to be oval, with the long axis directed along the jaw, and the tooth sockets somewhat bulge upwards, though not extremely. Only the sixth left tooth is preserved in the fossil, and it appears to be short and blunt in comparison to other dsungaripterids. The middle four of the left teeth sockets are larger than the rear two. More precisely, the gap increases to the rear, ranging from 1.54 to 3.13 times the diameter of the anterior tooth. With a length of , the symphisis forms a broad scoop-shaped plate with strongly curved side edges. At the back of the symphysis a short groove forms a notch with a V-shaped cross section. The side gradually merges into the bottom. The ridge on the bottom of the symphysis ends in front of the trailing edge. The branches of the dentaria are low in side view; their top edge and bottom edge are parallel. The dentarium bends slightly upwards from the sixth tooth.

Classification

''Ordosipterus'' was placed in the

Dsungaripteridae Dsungaripteridae is a group of pterosaurs within the suborder Pterodactyloidea. They were robust pterosaurs with good terrestrial abilities and flight honed for inland settings. Classification In 1964 Young created a family to place the recentl ...

, although not on the basis of an exact

cladistic Cladistics (; ) 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 typically shared derived char ...

analysis. The exact place in the evolutionary tree is therefore uncertain, but this genus was thus placed as a dsungaripterid due to the typical swollen tooth sockets seen in many members of that group.

Paleobiology

Many dsungaripterids have often been seen as

durophagous Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil tu ...

species that cracked shellfish with their convex teeth. ''Ordosipterus'' shows a moderate bulge in its teeth, but not the extreme outgrowth that would have been useful for cracking. The broad lower jaws suggest a different way of eating, though Ji does not consider this issue.

References

{{Portal bar, Paleontology, Cretaceous, China Dsungaripterids Taxa described in 2020 Fossil taxa described in 2020 Aptian genus first appearances Early Cretaceous pterosaurs of Asia