Abrosaurus
Encyclopedia
Abrosaurus is a genus
of macronaria
n sauropod dinosaur
from the Middle Jurassic
Period of what is now Asia
, one of many dinosaurs found at the Dashanpu Quarry
in the Sichuan Province of China
. Like most sauropods, Abrosaurus was a quadruped
al herbivore
but it was rather small for a sauropod, not much more than 30 feet (9 m) long. Its head was boxy and topped with a tall bony arch containing the nostrils.
The generic name meaning 'delicate lizard', refers to the nature of the skull
, with large openings separated by thin bony struts. The only named species
is now known as A. dongpoi, and is named after eleventh century Chinese poet
Su Shi
, also known as Su Dongpo, who was born in Sichuan.
The naming of Abrosaurus has been a long and convuluted process. Abrosaurus was discovered in 1984 and was first described in the 1986 Ph.D.
thesis of Chinese paleontologist Ouyang Hui, with the specific name "A. gigantorhinus". However, this does not meet ICZN
standards of publication, so the species "Abrosaurus gigantorhinus" counts only as a nomen nudum
, although it has been used incorrectly in at least one paper (Zhang & Chen, 1996). Ouyang formally described this species in 1989 under the specific epithet A. dongpoensis, but in biological nomenclature
, the Latin
suffix -ensis is correctly used only to honor localities and the name has since been revised to include the more correct -i suffix, which is used to honor male individuals (Peng & Shu, 1999). Abrosaurus dongpoi is now the accepted name for this taxon.
Abrosaurus was originally described as a camarasaurid sauropod, and while it may not turn out to be a member of that particular family, further research has indicated that it is a basal
member of Macronaria, much like Camarasaurus
itself. However, the remains of Abrosaurus have not been fully described, making its exact placement in the sauropod family tree difficult to determine (Upchurch et al., 2004).
The holotype
, or original specimen, of Abrosaurus is a fossil
skull which is nearly complete and very well-preserved. A fragmentary skull and a skeleton have also been referred to this taxon but published description is lacking (Zhang & Chen, 1996). All of the material comes from the famous Dashanpu Quarry near Zigong
in China, and is housed in the dinosaur museum there. Abrosaurus and at least 4 other species of sauropod are known from the Lower Shaximiao Formation (also called Xiashaximiao) at Dashanpu. These sediments are dated from the Bathonian
to Callovian
stages of the Middle Jurassic
Period, or about 168 to 161 million years ago.
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 macronaria
Macronaria
Macronaria is a clade of sauropod dinosaurs from the Middle Jurassic to Late Cretaceous Periods of what are now North America, South America, Europe, Asia and Africa. The name means 'large nostrils' , in reference to the large nasal openings high on the head that probably supported fleshy...
n sauropod 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....
Period of what is now Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, one of many dinosaurs found at the Dashanpu Quarry
Dashanpu Formation
The Dashanpu Formation is a Mid to Late Jurassic rock formation in China, most notable for the wealth of dinosaurs that have been excavated from the area...
in the Sichuan Province of 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...
. Like most sauropods, Abrosaurus was a quadruped
Quadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al herbivore
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...
but it was rather small for a sauropod, not much more than 30 feet (9 m) long. Its head was boxy and topped with a tall bony arch containing the nostrils.
The generic name meaning 'delicate lizard', refers to the nature of the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, with large openings separated by thin bony struts. The only named species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
is now known as A. dongpoi, and is named after eleventh century Chinese poet
Poet
A poet is a person who writes poetry. A poet's work can be literal, meaning that his work is derived from a specific event, or metaphorical, meaning that his work can take on many meanings and forms. Poets have existed since antiquity, in nearly all languages, and have produced works that vary...
Su Shi
Su Shi
Su Shi , was a writer, poet, artist, calligrapher, pharmacologist, gastronome, and statesman of the Song Dynasty, and one of the major poets of the Song era. His courtesy name was Zizhan and his pseudonym was Dongpo Jushi , and he is often referred to as Su Dongpo...
, also known as Su Dongpo, who was born in Sichuan.
The naming of Abrosaurus has been a long and convuluted process. Abrosaurus was discovered in 1984 and was first described in the 1986 Ph.D.
Ph.D.
A Ph.D. is a Doctor of Philosophy, an academic degree.Ph.D. may also refer to:* Ph.D. , a 1980s British group*Piled Higher and Deeper, a web comic strip*PhD: Phantasy Degree, a Korean comic series* PhD Docbook renderer, an XML renderer...
thesis of Chinese paleontologist Ouyang Hui, with the specific name "A. gigantorhinus". However, this does not meet ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
standards of publication, so the species "Abrosaurus gigantorhinus" counts only as a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
, although it has been used incorrectly in at least one paper (Zhang & Chen, 1996). Ouyang formally described this species in 1989 under the specific epithet A. dongpoensis, but in biological nomenclature
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
, the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
suffix -ensis is correctly used only to honor localities and the name has since been revised to include the more correct -i suffix, which is used to honor male individuals (Peng & Shu, 1999). Abrosaurus dongpoi is now the accepted name for this taxon.
Abrosaurus was originally described as a camarasaurid sauropod, and while it may not turn out to be a member of that particular family, further research has indicated that it is a 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:...
member of Macronaria, much like Camarasaurus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...
itself. However, the remains of Abrosaurus have not been fully described, making its exact placement in the sauropod family tree difficult to determine (Upchurch et al., 2004).
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...
, or original specimen, of Abrosaurus is a fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
skull which is nearly complete and very well-preserved. A fragmentary skull and a skeleton have also been referred to this taxon but published description is lacking (Zhang & Chen, 1996). All of the material comes from the famous Dashanpu Quarry near 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:...
in China, and is housed in the dinosaur museum there. Abrosaurus and at least 4 other species of sauropod are known from the Lower Shaximiao Formation (also called Xiashaximiao) at Dashanpu. These sediments are dated from the Bathonian
Bathonian
In the geologic timescale the Bathonian is an age or stage of the Middle Jurassic. It lasted from approximately 167.7 Ma to around 164.7 Ma...
to Callovian
Callovian
In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
stages of the Middle 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...
Period, or about 168 to 161 million years ago.