''Parabohaiornis'' is an extinct

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 ...

of bohaiornithid

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 ...

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 ...

known from the Early Cretaceous of Liaoning Province, northeastern China. It contains a single species, ''Parabohaiornis martini''.

Discovery

''Parabohaiornis'' was first described and named by Min Wang, Zhong-He Zhou, Jingmai K. O'Connor and Nikita V. Zelenkov in

2014 File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...

and the

type species In 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 species that contains the biological type specime ...

is ''Parabohaiornis martini''. The generic name combines 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 of the ...

prefix ''para'', meaning "close to", with the generic name of '' Bohaiornis'', the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...

of the

Bohaiornithidae Bohaiornithidae is a group of early predatory enantiornitheans from the early Cretaceous Period of China. All known specimens come from the Jiufotang Formation and Yixian Formation, dating to the early Aptian age, 125–120 million years ago. B ...

family, in reference to the morphological similarity between ''Parabohaiornis'' and other bohaiornithids. The specific name, ''martini'', honors the late

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Prof. Larry Dean Martin, for his contributions to the study of the evolution of birds. ''Parabohaiornis'' is known from the

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 ...

IVPP V 18691, a nearly complete and partially articulated skeleton and

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, and from the referred specimen IVPP V 18690, an articulated partial skeleton missing only the skull,

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 ...

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 ...

and hands. Both specimens are preserved in single slabs and are currently housed at the

Institute of Vertebrate Paleontology and Paleoanthropology The Institute of Vertebrate Paleontology and Paleoanthropology (IVPP; ) of China is a research institution and collections repository for fossils, including many dinosaur and pterosaur specimens (many from the Yixian Formation). As its name sugges ...

Beijing } Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...

. The specimens were collected at deposits near the Lamadong Town,

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 ...

of the Liaoning Province, 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 ...

, dating to the Aptian stage of the Early Cretaceous, approximately 120.3

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

Description

''Parabohaiornis'' differs from all other known bohaiornithid Enantiornithes by possessing a combination of traits. It has three and four teeth on the

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 ...

and

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

, respectively. Unlike '' Longusunguis'', ''

Zhouornis ''Zhouornis'' is an extinct genus of enantiornithine bird known from the Early Cretaceous Jehol Group (Aptian stage) of western Liaoning Province, northeastern China. ''Zhouornis'' was first named by Zihui Zhang, Luis M. Chiappe, Gang Han and A ...

'' and ''

Sulcavis ''Sulcavis'' is a genus of enantiornithean birds. One species is named, ''Sulcavis geeorum''. The fossil was found in Early Cretaceous (121-125 million years ago) rocks in Liaoning Province, China. ''Sulcavis'' is the first discovery of a bird ...

'', its nasal bone lacks a maxillary process. Unlike ''Sulcavis'' and '' Bohaiornis'', it lacks an intercondylar incisure on the

tibiotarsus The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These s ...

. In ''Parabohaiornis'', the

acromion In human anatomy, the acromion (from Greek: ''akros'', "highest", ''ōmos'', "shoulder", plural: acromia) is a bony process on the scapula (shoulder blade). Together with the coracoid process it extends laterally over the shoulder joint. The ac ...

process is straight, and is parallel to the scapular shaft, whereas in ''Longusunguis'' and ''Sulcavis'' this process is deflected dorsally. ''Parabohaiornis'' has a distinctive length ratio of 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 ...

to the third

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...

of 0.92–0.99, in comparison to 1.06 in ''Longusunguis'', 0.79 in ''Sulcavis'', 0.66 in ''Zhouornis'' and an estimated ratio of 0.82 in ''Bohaiornis''. Finally, while in other bohaiornthids the proximal

phalanx The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particularly ...

is more than 80% the length of the penultimate phalanx of the fourth digit, in ''Parabohaiornis'' it is much shorter (less than 70%). The referred specimen of ''Parabohaiornis'' is indistinguishable from the holotype in morphology, possessing all

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l traits that distinguish this genus from other bohaiornithids. Both specimen came from subadult individuals, the referred being more mature than the holotype, as evident by the absence or degree of fusion in some compound bones, such as the

carpometacarpus The carpometacarpus is a bone found in the hands of birds. It results from the fusion of the carpal and metacarpal bone, and is essentially a single fused bone between the wrist and the knuckles. It is a smallish bone in most birds, generally flat ...

and tarsometatarsus.

Phylogeny

The

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 ...

position of ''Parabohaiornis'' was explored by Wang ''et al.'' (2014) using a data matrix that includes 56

avialae 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 ...

n taxa, scored based on 262 morphological traits. ''Parabohaiornis'' was recovered as an advanced bohaiornithid, closely related to '' Bohaiornis'' whose specimens were collected at a nearby locality, also near the Lamadong Town. 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 shows the phylogenetic position of ''Parabohaiornis'' among the Enantiornithes following this analysis.

References

{{Taxonbar, from=Q15644504 Euenantiornitheans Bird genera Early Cretaceous birds of Asia Fossil taxa described in 2014 Paleontology in Liaoning