Incisivosaurus
Encyclopedia
Incisivosaurus is a genus
of small, probably herbivorous theropod dinosaur
from the early Cretaceous Period of what is now the People's Republic of China
. The first specimen to be described (by Xu et al. in 2002), IVPP V13326, is a skull that was collected from the lowermost levels (the fluvial
Lujiatun beds) of the Yixian Formation
(dating to the Barremian
stage about 125 million years ago) in the Sihetun area, near Beipiao City
, in western Liaoning
Province. The most significant, and highly unusual, characteristic of this dinosaur is its apparent adaptation to an herbivorous or omnivorous lifestyle. It was named for its prominent, rodent
-like front teeth, which show wear patterns commonly found in plant-eating dinosaurs. The specific name gauthieri honors Dr. Jacques Gauthier
, a pioneer of the phylogenetic method of classification.
n. Their cladistic analysis indicated that Incisivosaurus lies at the base of the oviraptorosaurian group, making it more primitive than Caudipteryx
and the oviraptorids
. A subsequent study by Osmolska et al. in 2004 described the distinguishing skeletal features of Incisivosaurus, including a long snout that made up about half the total length of the skull, a slender lower jaw with a long fenestra (opening), and its distinctive, large, flattened front teeth. In addition to these unique features, Incisivosaurus shared many traits with more typical oviraptorosaurs, allowing its classification with that group. Several features, including its numerous teeth (most advanced oviraptorids were toothless), show that it was a primitive member of the group, and several features of the skull even support a relationship with the therizinosaur
s, another theropod group that was probably herbivorous.
In 2009 the holotype
skull was scanned and analyzed in three dimensions. The results indicated that Incisivosaurus had less bird - like air spaces in the skull bones than later oviraptorosaurs did. It also found that Incisivosaurus had reduced olfactory lobes and expanded optic lobes similar to ornithomimosaurs. It suggested that the most birdlike features of oviraptorosaurs may have been convergent with birds.
Incisivosaurus is assumed to have been feather
ed like most other maniraptora
n theropods. Its total body length has been estimated at just under 1 meter (3 ft.). It is possible that Incisivosaurus is the same species as Protarchaeopteryx
, though more fossil specimens are needed before the two can be directly compared.
series Prehistoric Park
, which theorized that Incisivosaurus used its "wing" feathers for displaying and that it or a similar form was ancestral to gliding and flying forms.
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, probably herbivorous theropod 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 early Cretaceous Period of what is now the People's Republic of 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...
. The first specimen to be described (by Xu et al. in 2002), IVPP V13326, is a skull that was collected from the lowermost levels (the fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
Lujiatun beds) 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...
(dating to the Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
stage about 125 million years ago) in the Sihetun area, near Beipiao City
Beipiao
Beipiao is a city in Chaoyang prefecture, Liaoning province, in Northeast China. It has a population of 202,807. The main industry in the area is coal mining. With vertical shafts of almost 1000m, these are some of the deepest coal mines in China. The coal produced is used for coking...
, in western Liaoning
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...
Province. The most significant, and highly unusual, characteristic of this dinosaur is its apparent adaptation to an herbivorous or omnivorous lifestyle. It was named for its prominent, rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
-like front teeth, which show wear patterns commonly found in plant-eating dinosaurs. The specific name gauthieri honors Dr. Jacques Gauthier
Jacques Gauthier
Jacques Armand Gauthier is a vertebrate paleontologist, comparative morphologist, and systematist, and one of the founders of the use of cladistics in biology....
, a pioneer of the phylogenetic method of classification.
Description
The initial description of Incisivosaurus by Xu et al. showed that the skull, which measures approximately 10 cm in length (4 inches), preserves the most complete dentition known for any oviraptorosauriaOviraptorosauria
Oviraptorosaurs are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot - like skulls, with or without bony crests atop the head...
n. Their cladistic analysis indicated that Incisivosaurus lies at the base of the oviraptorosaurian group, making it more primitive than Caudipteryx
Caudipteryx
Caudipteryx is a genus of peacock-sized theropod dinosaurs that lived in the Aptian age of the early Cretaceous Period . They were feathered and remarkably birdlike in their overall appearance....
and the oviraptorids
Oviraptoridae
Oviraptoridae is a group of bird-like, herbivorous and omnivorous maniraptoran dinosaurs. Oviraptorids are characterized by their toothless, parrot-like beaks and, in some cases, elaborate crests. They were generally small, measuring between one and two metres long in most cases, though some...
. A subsequent study by Osmolska et al. in 2004 described the distinguishing skeletal features of Incisivosaurus, including a long snout that made up about half the total length of the skull, a slender lower jaw with a long fenestra (opening), and its distinctive, large, flattened front teeth. In addition to these unique features, Incisivosaurus shared many traits with more typical oviraptorosaurs, allowing its classification with that group. Several features, including its numerous teeth (most advanced oviraptorids were toothless), show that it was a primitive member of the group, and several features of the skull even support a relationship with the 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...
s, another theropod group that was probably herbivorous.
In 2009 the holotype
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...
skull was scanned and analyzed in three dimensions. The results indicated that Incisivosaurus had less bird - like air spaces in the skull bones than later oviraptorosaurs did. It also found that Incisivosaurus had reduced olfactory lobes and expanded optic lobes similar to ornithomimosaurs. It suggested that the most birdlike features of oviraptorosaurs may have been convergent with birds.
Incisivosaurus is assumed to have been feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
ed like most other 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 theropods. Its total body length has been estimated at just under 1 meter (3 ft.). It is possible that Incisivosaurus is the same species as Protarchaeopteryx
Protarchaeopteryx
Protarchaeopteryx is a genus of turkey-sized feathered theropod dinosaur from China. Known from the Jianshangou bed of the Yixian Formation, it lived during the early Aptian age of the Early Cretaceous, approximately 124.6 million years ago...
, though more fossil specimens are needed before the two can be directly compared.
In popular culture
Incisivosaurus was featured in the third episode of the ITVITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
series Prehistoric Park
Prehistoric Park
Prehistoric Park is a six-episode mockumentary television mini-series that premiered on ITV on 22 July 2006 and on Animal Planet on 29 October 2006. The program was produced by Impossible Pictures, who also created Walking with Dinosaurs. In 2007, ITV cancelled Prehistoric Park, but introduced the...
, which theorized that Incisivosaurus used its "wing" feathers for displaying and that it or a similar form was ancestral to gliding and flying forms.
External links
- Incisivosaurus at DinoData
- sinopix.com (photo of skull, with skull of juvenile Liaoceratops below)
- Incisivosaurus gauthieri at DigiMorphDigiMorphDigital Morphology , part of the National Science Foundation Digital Libraries Initiative, creates and shares 2D and 3D visualizations of the internal and external structure of living and extinct vertebrates, and a growing number of 'invertebrates.'...