''Zhuchengtitan'' (meaning "
Zhucheng
Zhucheng () is a county-level city in the southeast of Shandong province, People's Republic of China. It is under the administration of Weifang city and had at the 2010 census a population of 1,086,222 even though its built-up (''or metro'') area ...
titan") is a genus of
titanosaur
Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...
ian
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 ...
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 Late
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
of
Shandong
Shandong ( , ; ; alternately romanized as Shantung) is a coastal province of the People's Republic of China and is part of the East China region.
Shandong has played a major role in Chinese history since the beginning of Chinese civilizati ...
,
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 ...
. It contains a single species, ''Z. zangjiazhuangensis'', named by Mo Jinyou and colleagues in 2017 from a single
humerus
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...
. ''Zhuchengtitan'' can be identified by the extreme width of the top end of its humerus, as well as the expansion of the deltopectoral crest on its humerus; both of these characteristics indicate that it was likely closely related to ''
Opisthocoelicaudia
''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the head and neck wa ...
''. However, it differs from the latter by the flatter bottom articulating surface of its humerus. ''Zhuchengtitan'' lived in a
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
environment alongside ''
Shantungosaurus
''Shantungosaurus'' (meaning "''Shandong Lizard''") is a genus of very large saurolophine hadrosaurid dinosaur found in the Late Cretaceous Wangshi Group of the Shandong Peninsula in China, containing a single species, ''Shantungosaurus giganteu ...
'', ''
Zhuchengtyrannus
''Zhuchengtyrannus'' (meaning "Zhucheng tyrant") is a genus of tyrannosaurid theropod dinosaur known from the Campanian stage of the Late Cretaceous of Shandong Province, China. It belongs to the subfamily Tyrannosaurinae, and contains a single ...
'', and ''
Sinoceratops
''Sinoceratops'' is an extinct genus of ceratopsian dinosaur that lived approximately 73 million years ago during the latter part of the Cretaceous Period in what is now Shandong province in China. It was named in 2010 by Xu Xing ''et al.'' f ...
''.
Discovery and naming
''Zhuchengtitan'' is known from a single
humerus
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...
that was discovered in the
Wangshi Group
The Wangshi Group () is a geological Group in Shandong, China whose strata date back to the Coniacian to Campanian stages of the Late Cretaceous.[Zhucheng
Zhucheng () is a county-level city in the southeast of Shandong province, People's Republic of China. It is under the administration of Weifang city and had at the 2010 census a population of 1,086,222 even though its built-up (''or metro'') area ...]
,
Shandong
Shandong ( , ; ; alternately romanized as Shantung) is a coastal province of the People's Republic of China and is part of the East China region.
Shandong has played a major role in Chinese history since the beginning of Chinese civilizati ...
,
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 ...
. The primary fossil localities within this region are the Longgujian, Kugou, and Zangjiazhuang Quarries. In 2008, researchers from the Zhucheng Dinosaur Culture Research Center uncovered the humerus and some other
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 ...
bones at the Zangjiazhuang Quarry; the humerus was catalogued as ZJZ-57 at the center. While the humerus is mostly complete, the outer edge of the top end, all edges of the bottom end save for the rear edge, and the deltopectoral crest have all been partially lost to damage. Additionally, the preserved portions are twisted.
Locally, the Wangshi Group is further divided into two smaller units, the Xingezhuang and Hongtuya Formations. Deposits in the Xingezhuang Formation consist of multi-colored
clastic rock
Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus,Essentials of Geology, 3rd Ed, Stephen Marshak, p. G-3 chunks, and smaller grains of rock broken off other rocks ...
s formed from
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
,
sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.
Most sandstone is composed of quartz or feldspar (both silicates) ...
, and grey-colored
clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4).
Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
, while deposits in the Hongtuya Formation consist of red interfingering layers of sandstone and
conglomerate, capped at the top by a
basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
layer. The boundary between the two is formed by sandy conglomerate and sandstone deposits;
ZJZ-57 originates from this boundary.
In 2017, ZJZ-57 was described by Mo Jinyou, Wang Kebai, Chen Shuqing, Wang Peiye, and
Xu Xing in a
research paper published in the ''Geological Bulletin of China''. They named it as a new genus and species of
titanosaur
Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...
ian sauropod ''Zhuchengtitan zangjiazhuangensis''; the genus name ''Zhuchengtitan'' combines Zhucheng with 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 ...
suffix ''titan'' ("
titan", for "titanosaur"), while ''zangjiazhuangensis'' refers to its origin from the Zangjiazhuang Quarry.
Description
![Opisthocoelicaudia](https://upload.wikimedia.org/wikipedia/commons/f/fe/Opisthocoelicaudia.jpg)
The humerus ZJZ-57 (when viewed from the front) measures long, wide at the top, wide at midshaft, and wide at the bottom. It can be identified by the extreme width of its top end compared to other titanosaurs, which is 0.55 times its whole length. This figure is closest to the 0.49 of ''
Saltasaurus
''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...
''
and the 0.56 of ''
Opisthocoelicaudia
''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the head and neck wa ...
''.
Consequently, the robustness index (RI) (the ratio between the average of the three width measurements and the length) is also quite high, at 0.39; ''Saltasaurus'' has an RI of 0.35, while ''Opisthocoelicaudia'' has an RI of 0.38. The width arises from the inner edge of the bone, which is angled more sharply inwards at the top end of the bone than the bottom end.
Further below, the shaft of the bone is cylindrical in cross-section, with the long axis oriented sideways. The deltopectoral crest, which is located on the front surface near the top end of the bone, is very prominent, and bears a hook-like process about of the way down its length. It extends downwards to the midshaft of the bone, and sideways so that it occupies the outer of the bone's width. In ''Opisthocoelicaudia'', the crest is wider, occupying of the bone's width. The humerus forms a wide depression on the portion of the shaft further inward than the crest.
Near the top end on the back of the bone, there are two depressions bordering a central ridge, which extends upwards to support the rounded
humeral head
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a round ...
. On the bottom of the bone, the two
condyles
A condyle (;Entry "condyle"
in
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
and
ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
are separated by a broad but shallow intercondylar groove, and there is a low but robust ridge on either side of the groove. These structures are more prominent in ''Saltasaurus'' and ''Opisthocoelicaudia''. The condyles are expanded towards the front of the bone; viewed from the bottom, the surface of the condyles is very roughened.
Classification
On account of the inward and downward expansion of the deltopectoral crest, the localized swelling of the bone surrounding the crest, and the presence of a projecting process of the way down the length of the crest, Mo and colleagues assigned ''Zhuchengtitan'' to the
Saltasauridae
Saltasauridae (named after the Salta region of Argentina where they were first found) is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Asia, North America, and Europe. Th ...
, given the status of these traits as defining characteristics of the group.
Despite differences in the condyles, they recognized that the form and proportions of the humerus, including the RI, were most similar to ''Opisthocoelicaudia''. Thus, they hypothesized that ''Opisthocoelicaudia'' and ''Zhuchengtitan'' may be closely related, but noted that this conclusion would need to be confirmed by the discovery of additional material. As for other
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 area ...
n titanosaurs, ''Zhuchengtitan'' can be distinguished from ''
Qingxiusaurus'', ''
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 ...
'', ''
Borealosaurus
''Borealosaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of northern China. The type species is ''Borealosaurus wimani'', which was named in 2004.
Description
The type and only species is ''Borealosaurus wimani ...
'', and ''
Phuwiangosaurus
''Phuwiangosaurus'' (meaning "Phu Wiang lizard") is a genus of titanosaur dinosaur from the Early Cretaceous (Valanginian-Hauterivian) Sao Khua Formation of Thailand. The type species, ''P. sirindhornae'', was described by Martin, Buffetaut, and ...
'' by the greater width of the top end of its humerus as well as its better-developed deltopectoral crest. It cannot be compared with other genera that lack preserved humeri.
Paleoecology
![Shantungosaurus life](https://upload.wikimedia.org/wikipedia/commons/5/5f/Shantungosaurus_life.png)
The deposits from which ''Zhuchengtitan'' originated are characteristic of
alluvial fan
An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...
s,
braided river
A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''.
Braided streams tend to occur in rivers with high sediment l ...
s, and
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
s. Based on
argon-argon dating of the basalt layer at its top end, the Hongtuya Member at Zangjiazhuang has been estimated at 73.5 Ma in age, which places it during the
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 ...
epoch of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
period.
Other dinosaurs found at Zangjiazhuang include the
hadrosaurid
Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which inclu ...
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 ...
''
Shantungosaurus giganteus'' (referred to by Mo and colleagues as "''Huaxiasaurus maximus''"),
the
tyrannosaurid
Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...
theropod
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...
''
Zhuchengtyrannus magnus'',
and the
ceratopsid ''
Sinoceratops zhuchengensis''.
Dinosaur fossils at Zangjiazhuang generally only consist of a few specimens except for the thousands of ''Shantungosaurus'' specimens that are known, which likely represent the victims of a sudden mass mortality event.
See also
*
2017 in archosaur paleontology
The year 2017 in archosaur paleontology was eventful. Archosaurs include the only living dinosaur group — birds — and the reptile crocodilians, plus all extinct dinosaurs, extinct crocodilian relatives, and pterosaurs. Archosaur palaeontology ...
References
{{Taxonbar, from=Q42864717
Saltasaurids
Campanian life
Late Cretaceous dinosaurs of Asia
Cretaceous China
Fossils of China
Paleontology in Shandong
Fossil taxa described in 2017