Tatisaurus
Encyclopedia
Tatisaurus is a genus
of ornithischian dinosaur
from the Early Jurassic
from the Lower Lufeng Formation in Yunnan
Province in China
. Little is known as the remains are fragmentary.
at Beijing
, excavated fossils near the village of Da Di in Yunnan. Among them was a jaw bone of a herbivorous dinosaur. In 1965 David Jay Simmons named and described it as the type species
Tatisaurus oehleri. The generic name is derived from Da Di, then more usually spelled as "Ta Ti". The specific name honours Oehler. The holotype
, FMNH CUP 2088, was found in the Zhangjiawa Beds of the Lufeng Formation, dating from the Sinemurian
. It consists of a partial left mandible with teeth. The lower jaw bone fragment is, lacking the tip, six centimetres long. The teeth are eroded. It is the only specimen known of the species.
Simmons assigned Tatisaurus to the Hypsilophodontidae, though this group was seen by him as an evolutionary grade
of "primitive" Ornithopoda, ancestral to several ornithischian groups; he felt that Tatisaurus 's affinities were with Scelidosaurus
or the Ankylosauria
. Later, in 1990, the specimen was reviewed by Dong Zhiming
who noted it had similarities with Huayangosaurus
and placed it in the same subfamily, the Huayangosaurinae, hence making it a stegosauria
n.
Later still, in 1996, Spencer Lucas reclassified Tatisaurus as a member of the genus Scelidosaurus, thus as a S. oehleri, in order to use it for a biochron
. This has in 2007 been regarded by David B. Norman
and colleagues as unfounded. They instead consider Tatisaurus to be a dubious
basal
thyreophora
n, showing the thyreophorean synapomorphy
of a ventrally deflected mesial end of the dentary. It would then be one of the oldest known Thyreophora.
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 ornithischian 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 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...
from the Lower Lufeng Formation in Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
Province 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...
. Little is known as the remains are fragmentary.
Discovery and species
In 1948 and 1949 Father Edgar Oehler, a catholic priest working for the Fu Jen Catholic UniversityFu Jen Catholic University
Fu Jen Catholic University is a co-educational Catholic university located in Xinzhuang District, New Taipei City, Republic of China...
at 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...
, excavated fossils near the village of Da Di in Yunnan. Among them was a jaw bone of a herbivorous dinosaur. In 1965 David Jay Simmons named and described it as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Tatisaurus oehleri. The generic name is derived from Da Di, then more usually spelled as "Ta Ti". The specific name honours Oehler. 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...
, FMNH CUP 2088, was found in the Zhangjiawa Beds of the Lufeng Formation, dating from the Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
. It consists of a partial left mandible with teeth. The lower jaw bone fragment is, lacking the tip, six centimetres long. The teeth are eroded. It is the only specimen known of the species.
Simmons assigned Tatisaurus to the Hypsilophodontidae, though this group was seen by him as an evolutionary grade
Evolutionary grade
In alpha taxonomy, a grade refers to a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit.-Definition:...
of "primitive" Ornithopoda, ancestral to several ornithischian groups; he felt that Tatisaurus 's affinities were with Scelidosaurus
Scelidosaurus
Scelidosaurus is a genus of quadrupedal, lightly plated, herbivorous dinosaur about long. It lived during the Early Jurassic Period, during the Hettangian to Sinemurian stages around 199.6 to 194 million years ago. Its fossils have been found in both England and in Arizona, in the United...
or the Ankylosauria
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
. Later, in 1990, the specimen was reviewed by Dong Zhiming
Dong Zhiming
Dong Zhiming , from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, is one of China's leading paleontologists. He began working at the IVPP in 1962, learning from Yang Zhongjian who was director at the time...
who noted it had similarities with Huayangosaurus
Huayangosaurus
Huayangosaurus is a genus of stegosaurian dinosaur from the Middle Jurassic of China. The name derives from "Huayang", an alternate name for Sichuan , and "saurus", meaning "lizard"...
and placed it in the same subfamily, the Huayangosaurinae, hence making it a stegosauria
Stegosauria
Known colloquially as stegosaurs, the Stegosauria are a group of herbivorous dinosaurs of the Jurassic and Early Cretaceous Periods, being found mostly in the Northern Hemisphere, predominantly in what is now North America and China....
n.
Later still, in 1996, Spencer Lucas reclassified Tatisaurus as a member of the genus Scelidosaurus, thus as a S. oehleri, in order to use it for a biochron
Biochron
A Biochron is the length of time represented by a biostratigraphic zone. Biochrons are named after characteristic fossil organisms or taxa that characterise that interval in time.-References:...
. This has in 2007 been regarded by David B. Norman
David B. Norman
David Bruce Norman is a British paleontologist, currently Director of the Sedgwick Museum, Cambridge University. He is a fellow at Christ's College, Cambridge where he teaches geology in the Natural Sciences tripos. He is a member of the Palaeontological Association. He has studied Iguanodon...
and colleagues as unfounded. They instead consider Tatisaurus to be a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
thyreophora
Thyreophora
The Thyreophora were a subgroup of the ornithischian dinosaurs...
n, showing the thyreophorean synapomorphy
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
of a ventrally deflected mesial end of the dentary. It would then be one of the oldest known Thyreophora.
External links
- Tatisaurus at Thescelosaurus! (scroll to Thyreophora i.s.)