Fabrosauridae
Encyclopedia
The Fabrosauridae was originally proposed by Galton (1972
), as a group of basal ornithischia
n dinosaur
s from the Early
to Middle
Jurassic
. However, recent studies indicate the Fabrosaurs are not a natural grouping of dinosaurs, and instead consist of unrelated genera
.
The proposed "Fabrosaurs" descended from a Lesothosaurus
-like animal. Proposed fabrosaurids were 1–2 meters long, and were lightly built and biped
al. Their skulls were triangular and had very large eye sockets. They were herbivorous
and would have used agility to escape predators.
Fabrosaurids are known from southern Africa
in the Upper Triassic and Lower Jurassic, as well as in China
from the Middle and Upper Jurassic
periods. Fabrosaurids bear a semblance to many other members of Ornithischia, and have attracted much interest in phylogenetic studies. However, most genera that were previously referred to as Fabrosauridae are only known from fragmented and partial remains
, with most based on no more than isolated teeth, and their place in Fabrosauridae is questionable. For example, in 1990
, specimens of Agilisaurus found in the Middle Jurassic of Zigong, Sichuan, China, provided further evidence that led to paleontologists resolving systematic problems of the group Fabrosauridae.
Galton (1972), originally proposed the creation of Fabrosauridae based on the finding of cheek teeth. The recent discovery of a Middle Jurassic primitive ornithischian, Agilisaurus louderbacki
, found in the Xiashaximiao Formation of Zigong
, Sichuan Basin
, China
, has led to paleontologists learning more about the phylogeny of fabrosaurids.
Fabrosaurids have many characters that are unique to their physiology, particularly unique tooth morphology and structure, and short forelimb lengths compared to hindlimbs. Unlike many other primitive Ornithischians, such as heterodontosaurids and hypsilophodontids, the teeth of fabrosaurids are very thinly and uniformly enameled. Compared to Agilisaurus, Fabrosaurus is much more primitive in that it has six premaxillary teeth, and a stout prepubis. Agilisaurus differs from Fabrosaurus in that it appears to be larger and more well developed in structure.
The Upper Jurassic ornithischian dinosaur, Gongubusaurus, from China, is thought to be more closely related to fabrosaurids than hypsilophodontids. The type species, G. shiyii, is from the Shangshaximiao Formation in the Rongxian County in Sichuan Basin, has been classified from only a few scattered teeth.
1972 in paleontology
-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-Non-mammalian:...
), as a group of basal 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 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...
s from the Early
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
to Middle
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....
Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
. However, recent studies indicate the Fabrosaurs are not a natural grouping of dinosaurs, and instead consist of unrelated genera
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...
.
The proposed "Fabrosaurs" descended from a Lesothosaurus
Lesothosaurus
Lesothosaurus is an herbivorous ornithischian dinosaur. It was named by paleontologist Peter Galton in 1978, the name meaning "lizard from Lesotho". The genus is monotypic, having only one valid species, Lesothosaurus diagnosticus, within the genus....
-like animal. Proposed fabrosaurids were 1–2 meters long, and were lightly built and biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al. Their skulls were triangular and had very large eye sockets. They were herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
and would have used agility to escape predators.
Fabrosaurids are known from southern Africa
Southern Africa
Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...
in the Upper Triassic and Lower Jurassic, as well as in 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...
from the Middle and Upper Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
periods. Fabrosaurids bear a semblance to many other members of Ornithischia, and have attracted much interest in phylogenetic studies. However, most genera that were previously referred to as Fabrosauridae are only known from fragmented and partial remains
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
, with most based on no more than isolated teeth, and their place in Fabrosauridae is questionable. For example, in 1990
1990 in paleontology
-newly named:-Newly named taxa:-Dinosaurs:* All Anatosaurus species except A. copei were moved to the previously existing genus Edmontosaurus by Brett-Surman* "Seismosaurus" gastroliths documented.-Newly named dinosaurs:...
, specimens of Agilisaurus found in the Middle Jurassic of Zigong, Sichuan, China, provided further evidence that led to paleontologists resolving systematic problems of the group Fabrosauridae.
Galton (1972), originally proposed the creation of Fabrosauridae based on the finding of cheek teeth. The recent discovery of a Middle Jurassic primitive ornithischian, Agilisaurus louderbacki
Agilisaurus
Agilisaurus is a genus of ornithischian dinosaur from the Middle Jurassic Period of what is now eastern Asia. The name is derived from the Latin agilis meaning 'agile' and the Greek sauros meaning 'lizard', and refers to the agility suggested by its lightweight skeleton and long legs...
, found in the Xiashaximiao Formation of Zigong
Zigong
Zigong , ancient name Ziliujing and Gongjing, is a prefecture-level city and the third largest city in Sichuan Province, in southwest China.-Geography:...
, Sichuan Basin
Sichuan basin
The Sichuan Basin is a lowland region in southwestern China. Despite its historical name, it is not only synonymous to Sichuan province, comprising its central and eastern portions as well as part of Chongqing Municipality...
, 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...
, has led to paleontologists learning more about the phylogeny of fabrosaurids.
Fabrosaurids have many characters that are unique to their physiology, particularly unique tooth morphology and structure, and short forelimb lengths compared to hindlimbs. Unlike many other primitive Ornithischians, such as heterodontosaurids and hypsilophodontids, the teeth of fabrosaurids are very thinly and uniformly enameled. Compared to Agilisaurus, Fabrosaurus is much more primitive in that it has six premaxillary teeth, and a stout prepubis. Agilisaurus differs from Fabrosaurus in that it appears to be larger and more well developed in structure.
The Upper Jurassic ornithischian dinosaur, Gongubusaurus, from China, is thought to be more closely related to fabrosaurids than hypsilophodontids. The type species, G. shiyii, is from the Shangshaximiao Formation in the Rongxian County in Sichuan Basin, has been classified from only a few scattered teeth.