Longipterygidae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of early enantiornithean

avialans Avialae ("bird wings") is a clade containing the only living dinosaurs, the birds. It is usually defined as all theropod dinosaurs more closely related to birds (Aves) than to deinonychosaurs, though alternative definitions are occasionally use ...

from the Early Cretaceous epoch of China. All known specimens come from the

Jiufotang Formation The Jiufotang Formation ( Chinese: 九佛堂组, pinyin: ''jiǔfótáng zǔ'') is an Early Cretaceous geological formation in Chaoyang, Liaoning which has yielded fossils of feathered dinosaurs, primitive birds, pterosaurs, and other organisms (see ...

and

Yixian Formation The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its exq ...

, dating to the early Aptian age, 125-120 million years ago.

Description

Longipterygids are characterized by an extremely long,

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...

ed snout (making up over 60% of the total skull length), in which the teeth are restricted to the tips of the jaws. The snouts were straight but slightly concave at a point behind the nostrils, and the bones of the snout tip were solid. Their

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 compone ...

s, the series of fused vertebrae in the tail, were unusually large, and longer than the foot bones. The feet of longipterygids were also specialized relative to other enantiornitheans. Where most enantiornitheans had a long middle toe with a "knuckle" (

trochlea Trochlea (Latin for pulley) is a term in anatomy. It refers to a grooved structure reminiscent of a pulley's wheel. Related to joints Most commonly, trochleae bear the articular surface of saddle and other joints: * Trochlea of humerus (part of ...

) that extended beyond the outer two, the toes of longipterygids were even in length, and attached to the rest of the foot at the same level. This configuration is also seen in some groups of modern birds and is usually considered an adaptation for advanced perching ability. It is likely that longipterygids lived primarily in trees. Because their long jaws tipped with large, often curved teeth are usually considered an adaptation for catching and eating fish, it is likely that they were similar in ecology to modern

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly colored birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species found in the tropical regions of Africa, Asia, and Oceania, ...

s. Other interpretations of their habitus include mud-probing and the probing for insects behind tree bark. A study on Mesozoic avialan diets does recover ''

Longipteryx ''Longipteryx'' is a genus of prehistoric bird which lived during the Early Cretaceous ( Aptian stage, 120.3 million years ago). It contains a single species, ''Longipteryx chaoyangensis''. Its remains have been recovered from the Jiufotang Form ...

'' as a piscivore. A 2022 study however does find them most likely to be generalistic insectivores (sans possibly '' Shengjingornis'' due to its larger size, poorly preserved skull and unusual pedal anatomy), being too small for specialised carnivory and herbivory; the atypical rostrum is tentatively speculated to be unrelated to feeding ecology.

Classification

The Longipterygidae was first coined as a

of enantiornitheans by Zhang and colleagues in 2001. They included only the first known species, ''Longipteryx chaoyangensis'', and placed the family in its own order, Longipterygiformes. While Longipterygiformes has never been formally defined, Longipterygidae was given a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

definition by O'Connor and colleagues in 2009. They defined the clade to include ''Longipteryx'', ''Longisrostravis'', their most recent common ancestor, and all of its descendants. The

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

below was found in the phylogenetic analysis of O'Connor, Gao and Chiappe (2010a). Subsequently, the following cladogram was found in the phylogenetic analysis of Li ''et al.'' (2012):

References

{{Taxonbar, from=Q6673983 Early Cretaceous dinosaurs of Asia Cretaceous China Prehistoric dinosaur families Aptian first appearances Aptian extinctions