''Chiappeavis'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

enantiornithean The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

from Early Cretaceous of northeastern China. The only

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

is ''Chiappeavis magnapremaxillo''. ''Chiappeavis'' is classified within the

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 ...

Pengornithidae Pengornithidae is a group of early enantiornithines from the early Cretaceous Period of China, with the putative member '' Falcatakely'' possibly extending this clade's range into the Late Cretaceous of Madagascar, and several putative pengornit ...

. It is known from a single, almost complete skeleton including feather impressions discovered in 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 ...

of the Jehol Group. Long feathers formed a fan-shaped tail that was probably employed in flight. The genus name honors Luis Chiappe for his extensive research on

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

birds. The specific name ''magnapremaxillo'' ("large

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

") alludes to the unusually large size of the premaxillary bone, the frontmost bone of the upper jaw. The only specimen (

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 sever ...

, STM29-11), of a subadult individual, was discovered on a single slab in

Jianchang County Jianchang () is a county of Huludao City in the southwest of Liaoning province, China. It is the largest division of Huludao, with an area of , and population of 600,000, located in mountainous terrain west of that city, serviced by China Nationa ...

, Liaoning. Is housed in the Shandong Tianyu Museum of Nature in

Pingyi County Pingyi County () is a county in the south of Shandong Province, China. It is the westernmost county-level division of the prefecture-level city of Linyi. It has a land area of and a population of in 2001. Its special local products are honeysuck ...

, Shandong.

Description

''Chiappeavis'' was large for a pengornithid. The skull was triangular in side view with a blunt snout tip. The tip of the lower jaw is slightly upturned due to the convex underside of the premaxilla. Teeth were either absent in the genus or are not preserved in the only known fossil. However, the absence of teeth in the related ''

Gobipteryx ''Gobipteryx'' (from Gobi eferring to the Gobi Desert where it was first discovered and Greek pteryx “wing”) is a genus of prehistoric bird from the Campanian Age (geology), Age of the Late Cretaceous Period (geology), Period.Elżanowski, ...

'' makes it likely that ''Chiappeavis'' was

edentulous Toothlessness, or edentulism, is the condition of having no teeth. In organisms that naturally have teeth, it is the result of tooth loss. Organisms that never possessed teeth can also be described as edentulous. Examples are the members of the ...

(toothless). The holotype fossil preserves impressions of the wing and tail feathers. Approximately ten

rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...

(long tail feathers) were present; the middle two were the longest (ca. 74 mm), and the outermost the shortest (ca. 56 mm). The rectrices were anchored in a fused mass of tail vertebrae, the

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 ...

, which was wide and short, as typical for pengornithids. The much broader reminges of the wings were up to 140 mm in length. The genus can be differentiated from related genera by a number of unique features, including the convex lower margin of the premaxilla; the long nasal process of the premaxilla (rearwards extension of the premaxilla) that almost reaches the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...

s behind; a sacrum consisting of eight vertebrae; the concave outer margin of the inner trabeculae; and the inclined upper end of the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

References

{{Taxonbar, from=Q41340323 Enantiornitheans Early Cretaceous birds of Asia Jiufotang fauna Cretaceous China Fossil taxa described in 2016