Epidexipteryx
Encyclopedia
Epidexipteryx is a genus
of small avialan
dinosaur, known from one fossil specimen in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology
in Beijing
. Epidexipteryx represents the earliest known example of ornamental feathers in the fossil record. The type specimen
is catalog number IVPP V 15471. It has been reported to be a maniraptora
n dinosaur
from the Middle Jurassic
or Upper Jurassic age Daohugou Beds
of Inner Mongolia
, China
(about 152 to 168 mya).
The specific name, Epidexipteryx hui ("Hu's display feather"), and its Chinese name Hushi Yaolong ("Hu Yaoming's dragon") were coined in memory of paleomammologist Hu Yaoming.
It is known from a well preserved partial skeleton that includes four long feathers on the tail, composed of a central rachis
and vanes. However, unlike in modern-style rectrices (tail feathers), the vanes were not branched into individual filaments but made up of a single ribbon-like sheet. Epidexipteryx also preserved a covering of simpler body feathers, composed of parallel barbs as in more primitive feathered dinosaurs. However, the body feathers of Epidexipteryx are unique in that some appear to arise from a "membranous structure" at the base of each feather. It has been suggested that this may represent a stage in the evolution of the feather.
In all, the skeleton of Epidexipteryx hui measures 25 centimeters (10 inches) in length (44.5 cm or 17.5 in including the incomplete tail feathers), and the authors estimated a weight of 164 grams, smaller than most other basal avialans.
The skull of Epidexipteryx is also unique in a number of features, and bears an overall similarity to the skull of Sapeornis
, oviraptorosaurs and, to a lesser extent, therizinosaur
oids. It had teeth only in the front of the jaws, with unusually long front teeth angled forward, a feature only seen in Masiakasaurus
among other theropods. The rest of the skeleton bore an overall similarity to the closely related Scansoriopteryx
, including a hip configuration unusual among other dinosaurs: the pubis
was shorter than the ischium, and the ischium itself was expanded towards the tip. However, the tail of Epidexipteryx differed significantly from Scansoriopteryx. In Scansoriopteryx, the tail was long, about 300% of total trunk length, while the short tail of Epidexipteryx was only 70% of its trunk length. The tail of Epidexipteryx also bore unusual vertebrae towards the tip which resembled the feather-anchoring pygostyle
of modern birds and some oviraptorosaurs.
Despite its close relationship to avialan birds, Epidexipteryx appears to have lacked remiges (wing feathers), and it likely could not fly. Zhang et al. suggest that unless Epidexipteryx evolved from flying ancestors and subsequently lost its wings, this may indicate that advanced display feathers on the tail may have predated flying or gliding flight.
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 small avialan
Avialae
Avialae is a clade of dinosaurs containing their only living representatives, birds , and the most immediate extinct relatives of birds.-Competing definitions:...
dinosaur, known from one fossil specimen in the collection of the Institute of Vertebrate Paleontology and Paleoanthropology
Institute of Vertebrate Paleontology and Paleoanthropology
The Institute of Vertebrate Paleontology and Paleoanthropology of China is a prominent research institution and collections repository for fossils, including many dinosaur and pterosaurand cat poo specimens...
in Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...
. Epidexipteryx represents the earliest known example of ornamental feathers in the fossil record. The type specimen
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
is catalog number IVPP V 15471. It has been reported to be a maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
or Upper Jurassic age Daohugou Beds
Daohugou Beds
The Daohugou Beds are a series of fossil-bearing rock deposits located in northeastern China, with the type locality around Daohugou village of Ningcheng County south of Chifeng, Inner Mongolia, but extending into southwest Liaoning. The rocks are grey, finely bedded, lacustrine, sandy mudstones...
of 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
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
(about 152 to 168 mya).
The specific name, Epidexipteryx hui ("Hu's display feather"), and its Chinese name Hushi Yaolong ("Hu Yaoming's dragon") were coined in memory of paleomammologist Hu Yaoming.
It is known from a well preserved partial skeleton that includes four long feathers on the tail, composed of a central rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
and vanes. However, unlike in modern-style rectrices (tail feathers), the vanes were not branched into individual filaments but made up of a single ribbon-like sheet. Epidexipteryx also preserved a covering of simpler body feathers, composed of parallel barbs as in more primitive feathered dinosaurs. However, the body feathers of Epidexipteryx are unique in that some appear to arise from a "membranous structure" at the base of each feather. It has been suggested that this may represent a stage in the evolution of the feather.
In all, the skeleton of Epidexipteryx hui measures 25 centimeters (10 inches) in length (44.5 cm or 17.5 in including the incomplete tail feathers), and the authors estimated a weight of 164 grams, smaller than most other basal avialans.
The skull of Epidexipteryx is also unique in a number of features, and bears an overall similarity to the skull of Sapeornis
Sapeornis
Sapeornis is a genus of primitive bird which lived during the Early Cretaceous . The genus contains only the species Sapeornis chaoyangensis which is known from fossils found in Jiufotang Formation rocks near Chaoyang, PRC...
, oviraptorosaurs and, to a lesser extent, therizinosaur
Therizinosaur
Therizinosaurs are theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's Republic of China and Western North America...
oids. It had teeth only in the front of the jaws, with unusually long front teeth angled forward, a feature only seen in Masiakasaurus
Masiakasaurus
Masiakasaurus was a small predatory theropod dinosaur from the Late Cretaceous of Madagascar. It was named in 2001 by Scott D. Sampson, Matthew Carrano, and Catherine A. Forster. Unlike most theropods, the front teeth of Masiakasaurus projected forward instead of straight down...
among other theropods. The rest of the skeleton bore an overall similarity to the closely related Scansoriopteryx
Scansoriopteryx
Scansoriopteryx is a genus of avialan dinosaur. Described from only a single juvenile fossil specimen found in Liaoning, China, Scansoriopteryx is a sparrow-sized animal that shows adaptations in the foot indicating an arboreal lifestyle. It possessed an unusual, elongated third finger...
, including a hip configuration unusual among other dinosaurs: the pubis
Pubis
Pubis may refer to:* Pubis * Mons pubis, a padding of fat that protects the pubis bone...
was shorter than the ischium, and the ischium itself was expanded towards the tip. However, the tail of Epidexipteryx differed significantly from Scansoriopteryx. In Scansoriopteryx, the tail was long, about 300% of total trunk length, while the short tail of Epidexipteryx was only 70% of its trunk length. The tail of Epidexipteryx also bore unusual vertebrae towards the tip which resembled the feather-anchoring 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....
of modern birds and some oviraptorosaurs.
Despite its close relationship to avialan birds, Epidexipteryx appears to have lacked remiges (wing feathers), and it likely could not fly. Zhang et al. suggest that unless Epidexipteryx evolved from flying ancestors and subsequently lost its wings, this may indicate that advanced display feathers on the tail may have predated flying or gliding flight.
History of publication
Due to a pre-publication error, a manuscript of the Epidexipteryx hui description first appeared on a preprint Web portal in late September, 2008. The paper was officially published in the October 23rd, 2008, issue of the journal Nature.External links
- New feathered dinosaur discovered, BBC NewsBBC NewsBBC News is the department of the British Broadcasting Corporation responsible for the gathering and broadcasting of news and current affairs. The department is the world's largest broadcast news organisation and generates about 120 hours of radio and television output each day, as well as online...