''Longicrusavis'' (meaning "long shin bird" in
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 ...
) 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 n ...
of
basal
Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''.
Science
* Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure
* Basal (medicine), a minimal level that is nec ...
ornithuromorph
Euornithes (from Greek ' meaning "true birds") is a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to ''Sinornis''.
Description
Clarke ''et al''. (2006) found that the most primitive k ...
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 ...
found only at
Dawangzhangzi village in
Liaoning Province,
China. ''Longicrusavis'' was a ground dwelling carnivore, a
wader
245px, A flock of Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots
Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflats in order to foraging, ...
, and part of
biological family
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of fa ...
Hongshanornithidae, considered to have been a dominant species in the
Jehol Biota
The Jehol Biota includes all the living organisms – the ecosystem – of northeastern China between 133 and 120 million years ago. This is the Lower Cretaceous ecosystem which left fossils in the Yixian Formation and Jiufotang Formation. These ...
, the prehistoric Chinese ecosystem which supported them.
The name Hongshanornithidae represents one of China's oldest recorded cultures in the region, the
Hongshan culture
The Hongshan culture () was a Neolithic culture in the West Liao river basin in northeast China. Hongshan sites have been found in an area stretching from Inner Mongolia to Liaoning, and dated from about 4700 to 2900 BC.
The culture is named af ...
.
Description
''Longicrusavis'' is a ground dwelling carnivore 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 seve ...
specimen PKUP V1069, found from the
Lower Cretaceous
Lower may refer to:
*Lower (surname)
*Lower Township, New Jersey
*Lower Receiver (firearms)
*Lower Wick Gloucestershire, England
See also
*Nizhny
Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...
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 ...
in Liaoning Province, China.,
which consists of
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especia ...
slab and
counter slab
A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason f ...
. The skeleton is nearly complete and belongs to an adult individual, with
carbonized feathers preserved in full plumage with visible colouration around the head and forelimbs.
Like the closely related genus ''
Hongshanornis'', ''Longicrusavis'' has hindlimbs that are very long relative to the forelimbs. ''Longicrusavis'' has a
rostrum that is more robust than that of ''Hongshanornis''. The skull, though broken in the individual specimen, would be roughly triangular in shape with large eye socket
orbits
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a ...
. In lateral view, the dorsal margin of the skull is slightly concave, but not as much as the dorsal margin of the skull of ''Hongshanornis'', where there is an abrupt constriction at the rostrum.
Although no teeth are preserved, they were likely present in the upper jaw owing to the presence of alveoli, or tooth sockets, in 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. The ...
. Otherwise, Longicrusavis is one of the closest examples to a toothless bird with an evolving beak. ''
Hongshanornis'' also appears to have alveoli, despite being described as toothless when it was first named.
No alveoli are found in the mandible, indicating that it was likely
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 ...
. ''Longicrusavis'' exhibits an obvious long, thin, pointed
beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for fo ...
.
Comparison of the tail feathers to another similar discovery, both possessing a long fan shaped tail improving flight, suggests these to be the oldest form of bird with this type of tail.
Implications
''Longicrusavis'' is important because detailed evidence of transitioning dinosaurs to birds are rare. Specimen PKUP V1069 also gives us, in conjunction with another palaeontological discovery five years before, evidence a range of small specialised birds from the early Cretaceous, 120-130 million years ago.
The holotype evidencing the discovery is held at the 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 ...
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 ...
(IVPP) as part of a collection.
Jehol Biota
The ''Longicrusavis'' fossil was part the Jehol Biota from which is unearthed a whole range of palaeontological finds including dinosaurs, mammals, birds, fishes and invertebrates. "The Jehol Biota never fails to stop giving, and the research to be done on these fossils is virtually endless!" said O'Connor who has determined at least three evolutionary stages to divide history based on the Dabeigou (130ma), Yixian (125ma), and Jiufotang (120ma) Formation periods issuing the Longicrusavis are the earlier Yixian and Jiufotang.
References
{{Taxonbar, from=Q6673917
Early Cretaceous birds of Asia
Yixian fauna
Fossil taxa described in 2010
Hongshanornithids