Shanxia (named after the
Shanxi Province
Shanxi (; ; Chinese postal romanization, formerly romanised as Shansi) is a landlocked Provinces of China, province of the China, People's Republic of China and is part of the North China region. The capital and largest city of the province is ...
) is a monospecific
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
ankylosaurid
Ankylosauridae () is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known Ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Pal ...
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 Shanxi Province that lived during the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
(
Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...
-
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...
, ~99-71 Ma) in what is now the
Huiquanpu Formation
The Huiquanpu Formation () is a geological formation in Shanxi and Hebei provinces, China, whose strata date back to the Late Cretaceous period. It predominantly consists of purple-red mudstone, with subordinate grey-white sandy conglomerates.
D ...
.
''Shanxia'' may possibly represent a
junior synonym
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
* In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...
of ''
Tianzhenosaurus
''Tianzhenosaurus'' (meaning “Tianzhen lizard”) is a monospecific genus of ankylosaurid dinosaur from the Shanxi Province that lived during the Late Cretaceous (Cenomanian-Campanian, ~99-71 Ma) in what is now the Huiquanpu Formation. ''Tianzh ...
'', an
ankylosaurine also known from the Huiquanpu Formation of
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
.
Discovery and naming
In 1993, Messrs. Lu and Li of the Hebei Geological Survey discovered a partial ankylosaurid skeleton at a locality in the
Shanxi Province
Shanxi (; ; Chinese postal romanization, formerly romanised as Shansi) is a landlocked Provinces of China, province of the China, People's Republic of China and is part of the North China region. The capital and largest city of the province is ...
and notified staff of the
Institute of Vertebrate Paleontology and Paleoanthropology The Institute of Vertebrate Paleontology and Paleoanthropology (IVPP; ) of China is a research institution and collections repository for fossils, including many dinosaur and pterosaur specimens (many from the Yixian Formation). As its name suggest ...
, who collected the material later that year.
[ 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 several ...
specimen, IVPP V11276, consists of a braincase, occiput, skull roof, ?quadratojugal, axis vertebra, cervical vertebrae, dorsal vertebrae, caudal vertebrae, humerus, fragment of ?ilium, femora and an osteoderm.[ The holotype skull is partially reconstructed with plaster to stabilise parts of the skull roof and to attach the skull roof to the braincase.][ Upchurch & Barrett, 2000 noted that the skull had not been artificially widened or lengthened by excess plaster.] The specimen was specifically obtained from the Huiquanpu Formation
The Huiquanpu Formation () is a geological formation in Shanxi and Hebei provinces, China, whose strata date back to the Late Cretaceous period. It predominantly consists of purple-red mudstone, with subordinate grey-white sandy conglomerates.
D ...
and is currently housed at the Institute of Vertebrate Paleontology and Paleoanthropology, Beijing
}
Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
.[
The generic name, ''Shanxia'', refers to the Shanxi Province which is where the holotype was recovered from.][ The specific name, ''tianzhenensis'', refers to the Tian Zhen County.][
In 1999, Sullivans considered ''Shanxia'' as a ]nomen dubium
In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application.
Zoology
In case of a ''nomen dubium'' it may be impossible to determine whether a s ...
and as a possible junior syonynm of ''Tianzhenosaurus''. Sullivan noted that the only diagnosable characteristic, the unique shape of the squamosal horn, of ''Shanxia'' is known to be variable within a single taxon such as ''Euoplocephalus
''Euoplocephalus'' ( ) is a genus of very large, herbivorous ankylosaurid dinosaurs, living during the Late Cretaceous of Canada. It has only one named species, ''Euoplocephalus tutus''.
The first fossil of ''Euoplocephalus'' was found in 1897 i ...
''. Sullivan also noted that due to the presence of two ankylosaurids in the Huiquanpu Formation, they were likely to represent the same taxon. However, Upchurch & Barrett, 2000 considered ''Shanxia'' as a valid taxon based on at least on autapomorphy
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...
or diagnostic trait.[ Thompson et al., 2012 also recovered ''Shanxia'' as a valid taxon based on the caudal projection of the squamosal horns, form of cranial armour and haemal arch attachment.][ Arbour & Currie, 2015 considered that there are no unique characteristics that distinguish ''Shanxia'' from ''Tianzhenosaurus'', and ''Tianzhenosaurus'' from '']Saichania
''Saichania'' (Mongolian meaning "beautiful one") is a genus of herbivorous ankylosaurid dinosaur from the Late Cretaceous period of Mongolia and China.
The first fossils of ''Saichania'' were found in the early 1970s in Mongolia. In 1977 the ...
'', an ankylosaurid from the Barun Goyot
The Barun Goyot Formation (also known as Baruungoyot Formation or West Goyot Formation) is a geological formation dating to the Late Cretaceous Period. It is located within and is widely represented in the Gobi Desert Basin, in the Ömnögovi Pro ...
and Nemegt Formation
The Nemegt Formation (also known as Nemegtskaya Svita) is a geological formation in the Gobi Desert of Mongolia, dating to the Late Cretaceous. The formation consists of river channel sediments and contains fossils of fish, turtles, crocodilian ...
.
Description
Due to the fragmentary nature of the holotype specimen, not much information is known about the exact size and appearance of ''Shanxia''.[
Barrett et al., 1998 distinguished ''Shanxia'' from all other ankylosaurids based on the morphology of the squamosal horns.][ It was noted that the squamosal horns were slender and elongate, inclined at an angle, having a narrow junction with the skull roof in occipital view, and shaped like isosceles triangles in dorsal view.][ An isolated quadratojugal was tentatively assigned to ''Shanxia'' and shares similar features to '']Euoplocephalus
''Euoplocephalus'' ( ) is a genus of very large, herbivorous ankylosaurid dinosaurs, living during the Late Cretaceous of Canada. It has only one named species, ''Euoplocephalus tutus''.
The first fossil of ''Euoplocephalus'' was found in 1897 i ...
''.[ The quadratojugal was described as sub-triangular in shape and generally similar to the quadratojugal horns of other ankylosaurids.][ Upchurch and Barrett, 2000 established two more additional distinguishing characteristics of ''Shanxia'' that differentiate it from other ankylosaurids, including ''Saichania'', which include the absence of a large processus medialis humeri and a pair of large domed sub-rectangular osteoderms on the skull.][ However, similar ossifications are present in ''Tianzhenosaurus''.][ The holotype specimen only preserves one osteoderm, which has been described as oval in outline, sub-triangular in cross-section, excavated ventrally and has a prominent dorsal keel.][
Barrett et al., 1998 noted that the holotype specimen preserves a possible ]synapomorphy
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...
with nodosaurids
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia.
Description
Nodosaurids, like their close relatives the ankylosaurids, were ...
, the hemispherical occipital condyle is oval to subcircular in posterior view and offset from the braincase by a distinct 'neck'.[ However, they did state that some caution is needed in the interpretation of the synapomorphy as the shape of the occipital condyle is not entirely clear and may be primitive for ]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, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. ...
as the feature is also present in ''Tarchia
''Tarchia'' (meaning "brainy one") is a genus of herbivorous ankylosaurid dinosaur from the late Cretaceous of Mongolia.
Discovery and naming
In 1970, a Polish-Mongolian expedition discovered an ankylosaurian skull near Khulsan. In 1977, Ter ...
'', ''Talarurus
''Talarurus'' ( ; meaning "basket tail" or "wicker tail") is a genus of ankylosaurid dinosaur that lived in Asia during the Late Cretaceous period, about 96 million to 89 million years ago. The first remains of ''Talarurus'' were discovered in 19 ...
'', and ''Maleevus
''Maleevus'' (named in honour of Evgeny Maleev) is an extinct genus of herbivorous ankylosaurid dinosaur from the late Cretaceous, around 90 million years ago (possibly 98-83 Ma), of Mongolia.
Discovery and naming
Between 1946 and 1949, Soviet-M ...
''.[
]
Classification
Barrett et al. (1998) originally considered ''Shanxia'' as an ankylosaurid with unknown affiliations, but Sullivan (1999) considered ''Shanxia'' as a nomen dubium, and possibly synonymous with the ankylosaurid ''Tianzhenosaurus'', arguing that the unique shape of the squamosal horns could be a product of individual variation. However, Upchurch and Barrett (2000) reaffirmed the validity of ''Shanxia'' and recognised two new distinguishing characteristics.[ Thompson et al. (2012) recovered ''Shanxia'' as an ankylosaurine, sister taxon to “Crichtonsaurus” benxiensis and more basal than '']Tianzhenosaurus
''Tianzhenosaurus'' (meaning “Tianzhen lizard”) is a monospecific genus of ankylosaurid dinosaur from the Shanxi Province that lived during the Late Cretaceous (Cenomanian-Campanian, ~99-71 Ma) in what is now the Huiquanpu Formation. ''Tianzh ...
'', while Arbour and Currie (2015) recovered ''Shanxia'' as a junior synonym of ''Tianzhenosaurus''. A 2018 study by Wiersma and Irmis considered ''Shanxia'' as a valid taxon, and sister taxon to ''Tarchia kielanae
''Tarchia'' (meaning "brainy one") is a genus of herbivorous ankylosaurid dinosaur from the late Cretaceous of Mongolia.
Discovery and naming
In 1970, a Polish-Mongolian expedition discovered an ankylosaurian skull near Khulsan. In 1977, Teres ...
'' and ''Minotaurasaurus ramachandrani
''Minotaurasaurus'' (meaning “Minos'-bull reptile”) is a monospecific genus of ankylosaurid dinosaur that lived in Mongolia during the Late Cretaceous (late Campanian stage, ~75-71 Ma) in what is now the Djadochta Formation. The type and only ...
''.
A phylogenetic analysis conducted by Thompson et al., 2012 is reproduced below.[
]
Paleoenvironment
The holotype specimen of ''Shanxia'' was recovered from the Huiquanpu Formation, which possibly dates to the Cenomanian
The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...
or Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...
stage of the Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
.[ Due to the absence of index fossils, a precise dating is problematic. The proposed Cretaceous date is based in part on the discovery of ]pliosaur
Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive toot ...
fossils.[ The formation represents a fluvial environment, with the upper part of the formation being extensively reworked by a number of early Tertiary volcanic intrusions.][ ''Shanxia'' would have coexisted with the ]sauropod
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...
''Huabeisaurus
''Huabeisaurus'' (, meaning " North China lizard") was a genus of dinosaur from the Late Cretaceous ( Cenomanian to Maastrichtian stages, around 99.7–70.6 million years ago). It was a sauropod which lived in what is present-day northern Chin ...
'', the ornithopod
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous wo ...
''Datonglong
''Datonglong tianzhenensis'' is an herbivorous ornithischian dinosaur belonging to the Hadrosauroidea, which lived in the Late Cretaceous period in present-day China. It is the type species of the genus ''Datonglong''.
Discovery and naming
In ...
'', the tyrannosauroid
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...
''Jinbeisaurus
''Jinbeisaurus'' (meaning "northern Shanxi Province lizard" after Shanxi Province in China) is a genus of tyrannosauroid dinosaur from the Upper Cretaceous Huiquanpu Formation from Shanxi Province in China. The type and only species is ''Jinbe ...
'' and the ankylosaurid ''Tianzhenosaurus''.
See also
* Timeline of ankylosaur research
This timeline of ankylosaur research is a chronological listing of events in the history of paleontology focused on the ankylosaurs, quadrupedal herbivorous dinosaurs who were protected by a covering bony plates and spikes and sometimes by a club ...
References
External links
{{Taxonbar, from=Q974338
Ankylosaurids
Late Cretaceous dinosaurs of Asia
Fossil taxa described in 1998
Ornithischian genera