Hongshanornis
Encyclopedia
Hongshanornis is a genus
of ornithurine
bird known from the early Cretaceous
lake deposits of the Yixian Formation
, Inner Mongolia
, China
. The only known specimen (an adult with fully preserved plumage) was recovered in 2005. It was likely a strong flier and due to its long legs, Hongshanornis appears to have been a wader, feeding in the shallows of lakes. The holotype specimen is currently held by the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
The describers of Hongshanornis noted a unique bone in the end of the lower jaw which they equated with the beak-bearing predentary
bone in ornithischia
n dinosaurs. Such bones have also been found in more advanced birds like Hesperornis
. The authors said, "the preservation of a predentary bone confirms that this structure is not unique to ornithischian dinosaurs, but was common in early ornithurine birds." However, other scientists later cast doubt on this interpretation, arguing that there is no evidence linking the structure in ornithurines with the one in ornithischians. They also pointed out that the supposed predentary of Hongshanornis lacks the characteristic pits and grooves associated with the beak in true early beaked birds, and that the presence of any beak is doubtful.
The describers of Hongshanornis noted the apparent presence of a large feathered crest on the head, though the feather traces are extremely poor quality and it may be an artifact of preservation.
ns). However, the validity of the clade
uniting the short-tailed bird groups Enantiornithes
, Ornithurae, and more basal birds such as Confuciusornis
is increasingly viewed as suspect, with half of the few supposedly unique pygostylian traits — including the pygostyle
itself — now known or strongly suspected to be homoplasies.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of ornithurine
Ornithurae
Ornithurae is the name of a natural group which includes all modern birds as well as their extinct relatives with plough-shaped pygostyles, a bone at the end of the tail which allows the tail feathers to fan and retract....
bird known from the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
lake deposits of the Yixian Formation
Yixian Formation
The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans 11 million years during the early Cretaceous period...
, Inner Mongolia
Inner Mongolia
Inner Mongolia is an autonomous region of the People's Republic of China, located in the northern region of the country. Inner Mongolia shares an international border with the countries of Mongolia and the Russian Federation...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. The only known specimen (an adult with fully preserved plumage) was recovered in 2005. It was likely a strong flier and due to its long legs, Hongshanornis appears to have been a wader, feeding in the shallows of lakes. The holotype specimen is currently held by the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
Description
The teeth are very reduced and were not preserved in the only known specimen. At first, this led scientists to conclude that the teeth were absent in both the upper and lower jaws, probably replaced with a beak, which would represent the earliest known beaked ornithurine bird. However, later study of the specimen showed that tooth sockets were present in the preserved parts of the jaw, and comparison with related forms showed that it did have teeth and probably lacked a beak.The describers of Hongshanornis noted a unique bone in the end of the lower jaw which they equated with the beak-bearing predentary
Predentary
The predentary is an 'extra' bone in the front of the lower jaw, which extended the dentary . It is found in the fossilised remains of ornithischian dinosaurs, which were herbivorous. The predentary coincided with the premaxilla in the upper jaw. Together they formed a beak-like apparatus used to...
bone in ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n dinosaurs. Such bones have also been found in more advanced birds like Hesperornis
Hesperornis
Hesperornis is a genus of flightless aquatic birds that spanned the first half of the Campanian age of the Late Cretaceous period . One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an important early find in the history of avian...
. The authors said, "the preservation of a predentary bone confirms that this structure is not unique to ornithischian dinosaurs, but was common in early ornithurine birds." However, other scientists later cast doubt on this interpretation, arguing that there is no evidence linking the structure in ornithurines with the one in ornithischians. They also pointed out that the supposed predentary of Hongshanornis lacks the characteristic pits and grooves associated with the beak in true early beaked birds, and that the presence of any beak is doubtful.
The describers of Hongshanornis noted the apparent presence of a large feathered crest on the head, though the feather traces are extremely poor quality and it may be an artifact of preservation.
Classification
Hongshanornis is normally classified as an ornithurine or ornithuromorph, a fairly advanced lineage of short-tailed birds. Howeve,r some features are so primitive that some researchers have suggested it belongs to a more primitive lineage of short-tailed birds (pygostyliaPygostylia
Pygostylia is a group of birds which includes Confuciusornis and all of the more derived birds; the Ornithothoraces. Chiappe defined the Pygostylia as "the common ancestor of the Confuciusornithidae and Neornithes plus all its descendants". This is a node-based definition.Chiappe united the...
ns). However, the validity of the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
uniting the short-tailed bird groups Enantiornithes
Enantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
, Ornithurae, and more basal birds such as Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...
is increasingly viewed as suspect, with half of the few supposedly unique pygostylian traits — including the pygostyle
Pygostyle
Pygostyle refers to a number of the final few caudal vertebrae fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these....
itself — now known or strongly suspected to be homoplasies.
