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''Abrosaurus'' (; 'delicate lizard' from the 
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
' meaning 'delicate' or 'dainty' and meaning 'lizard') is a genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of macronaria
Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...
n sauropod dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
from the Middle Jurassic Period
Period may refer to:
Common uses
* Era, a length or span of time
* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
of what is now Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
, one of many dinosaurs found at the Dashanpu Quarry in the Sichuan Province
Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...
of China. Like most sauropods, ''Abrosaurus'' was a quadruped
Quadrupedalism is a form of locomotion where four limbs are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four limbs is said to be a quadruped (from Latin ''quattuor' ...
al herbivore but it was rather small for a sauropod, not much more than 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
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
, with large openings separated by thin bony struts. The only named species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
is ''A. dongpoi'', is named after eleventh-century Chinese poet
A poet is a person who studies and creates poetry. Poets may describe themselves as such or be described as such by others. A poet may simply be the creator ( thinker, songwriter, writer, or author) who creates (composes) poems ( oral or wri ...
Su Shi
Su Shi (; 8 January 1037 – 24 August 1101), courtesy name Zizhan (), art name Dongpo (), was a Chinese calligrapher, essayist, gastronomer, pharmacologist, poet, politician, and travel writer during the Song dynasty. A major personality of ...
, also known as Su Dongpo, who was born in Sichuan.
Discovery and naming
The naming of ''Abrosaurus'' has been a long and convoluted process. ''Abrosaurus'' was discovered in 1984 and was first described in the 1986Ph.D.
A Doctor of Philosophy (PhD, Ph.D., or DPhil; Latin: or ') is the most common degree at the highest academic level awarded following a course of study. PhDs are awarded for programs across the whole breadth of academic fields. Because it is ...
thesis of Chinese paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Ouyang Hui
Ouyang () is a Chinese surname. It is the most common two-character Chinese compound surname, being the only two-character name of the 400 most common Chinese surnames, according to a 2013 study, and is one of the few two-character surnames that h ...
, with the specific name "A. gigantorhinus." However, the publication does not meet ICZN standards so "Abrosaurus gigantorhinus" is considered a '' nomen nudum'' although it has been used incorrectly in at least one paper. Ouyang formally described this species in 1989 under the specific epithet ''A. dongpoensis.'' However, in biological nomenclature
Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species ...
, the Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
suffix ''-ensis'' is used only to honor localities and the name has since been revised to include the more correct ''-i'' suffix, used to honor male individuals. ''Abrosaurus dongpoi'' is now the accepted name for this taxon.
The holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...
, or original specimen, of ''Abrosaurus'', ZDM 5038, is a fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
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. All of the material comes from the famous Dashanpu Quarry near Zigong
Zigong (, ), formed by the merger of the two former towns of Ziliujing (Tzuliuching, literally "self-flow well") and Gongjing (Kungching, literally "offering well"), is a prefecture-level city in Sichuan, southwestern China.
Demographics
Accord ...
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
The Shaximiao Formation () is a Middle Jurassic, Middle to Late Jurassic aged geological formation in Sichuan, China, most notable for the wealth of dinosaurs fossils that have been excavated from its strata. The Shaximiao Formation is exposed in ...
(also called ''Xiashaximiao'') at Dashanpu. These sediments are dated from the Bathonian
In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age.
Str ...
to Callovian
In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...
stages of the Middle Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
Period, or about 168 to 161 million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...
.
Classification
''Abrosaurus'' was originally described as acamarasaurid
Camarasauridae is a family of sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thic ...
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.
References