extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
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
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
crocodyliform
Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...
found in
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 includes three
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 ...
: ''Shantungosuchus chuhsienensis'' and ''S. brachycephalus'', which were both described by
Yang Zhongjian
Yang Zhongjian, also Yang Chung-chien (; 1 June 1897 – 15 January 1979), courtesy name Keqiang (), also known as C.C. (Chung Chien) Young, was a Chinese paleontologist and zoologist. He was one of China's foremost vertebrate paleontologists. H ...
– usually referred to as "Young" – in 1961 and 1982, and ''S. hangjinensis'', which was described by Xiao-Chun Wu
et al
References
Notes
References
Further reading
*
*
{{Latin phrases
Lists of Latin phrases, E ...
in 1994. ''S. chuhsienensis'' is the type for this genus.
Etymology
The primary part of ''Shantungosuchus name comes from ''Shan-tung'', the Wade-Giles romanization 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 ...
'' (), a
province
A province is almost always an administrative division within a country or sovereign state, state. The term derives from the ancient Roman ''Roman province, provincia'', which was the major territorial and administrative unit of the Roman Empire ...
located on the eastern coast of the
People's Republic 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 ...
, where it was first discovered. The second part, ''suchus'' is an
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
word referring to the Egyptian crocodile deity
Sobek
Sobek (also called Sebek or Sobki, cop, Ⲥⲟⲩⲕ, Souk) was an ancient Egyptian deity with a complex and elastic history and nature. He is associated with the Nile crocodile or the West African crocodile and is represented either in its f ...
that is commonly used as a suffix for
crocodylomorph
Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction.
During Mesozoic and early Cenozoic times, cro ...
genera and crocodile-like animals in general.
Description
''Shantungosuchus chuhsienenis'' was first described from an articulated skeleton that was preserved as an impression of its
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
surface. Its small size, slender body, and triangular skull made it distinct from other atoposaurids.
''Shantungosuchus'' belongs to
Protosuchia
Protosuchia is a group of extinct Mesozoic crocodyliforms. They were small in size (~1 meter in length) and terrestrial. In phylogenetic terms, Protosuchia is considered an informal group because it is a grade of basal crocodyliforms, not a tru ...
, a group of early crocodilian relatives that were all rather small in size, about 1 meter in length, and terrestrial rather than aquatic. They are most easily distinguished from other crocodylians by their short
premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...
and
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
s, a transversely broad shelf on the
jugal bone
The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species.
Anatomy ...
, and a pair of posterolaterally divergent ridges on the
pterygoid Pterygoid, from the Greek for 'winglike', may refer to:
* Pterygoid bone, a bone of the palate of many vertebrates
* Pterygoid processes of the sphenoid bone
** Lateral pterygoid plate
** Medial pterygoid plate
* Lateral pterygoid muscle
* Medial ...
, and two large depressions on the
sphenoid bone
The sphenoid bone is an unpaired bone of the neurocranium. It is situated in the middle of the skull towards the front, in front of the basilar part of occipital bone, basilar part of the occipital bone. The sphenoid bone is one of the seven bones ...
. The angular shape of the rest of the skull is absent from the posterolateral section of the jaw. The dentaries near the
symphysis
A symphysis (, pl. symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint.
# A symphysis is an amphiarthrosis, a slightly movable joint.
# A growing together ...
are superficially asymmetrical. All known forms of Shantungosuchus also have a square-shaped fossa on the jugal, and a leaf-shaped
palatine bone
In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ''pa ...
.
Taxonomy
Two of the species of'' Shantungosuchus'', including the type, were described by Yang Zhongjian (referenced here as C.C. (Chung Chien) Young) in 1961. Since the description of ''S. chuhsienensis'', there has been uncertainty about the placement of the genus. It was suggested to be an
atoposaurid
Atoposauridae is a Family (biology), family of crocodile-line archosaurs belonging to Neosuchia. The majority of the family are known from Late Jurassic to Early Cretaceous marine deposits in France, Portugal, and Bavaria in southern Germany. The ...
by several different authors from the 1960s to the 1980s,.
However, in Xiao-Chun Wu's 1994 description of ''S. hangjinensis'', he noted the bones were more similar to the family
Protosuchidae
Protosuchidae was a family of crocodylomorph reptiles from the Late Triassic, Jurassic, and Cretaceous time periods. They were closely related to the Gobiosuchidae.
Distribution
Triassic protosuchids are known from Lesotho, Argentina, and Arizon ...
rather than Atoposauridae, and proposed to classify it as such.
Protosuchia has recently been considered a
paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
grouping of early crocodyliforms. Protosuchia is now commonly split into two groups: the basal family
Protosuchidae
Protosuchidae was a family of crocodylomorph reptiles from the Late Triassic, Jurassic, and Cretaceous time periods. They were closely related to the Gobiosuchidae.
Distribution
Triassic protosuchids are known from Lesotho, Argentina, and Arizon ...
, which is a true
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
, and a group of basal crocodyliforms more closely related to '' Hsisosuchus'' and
Mesoeucrocodylia
Mesoeucrocodylia is the clade that includes Eusuchia and crocodyliforms formerly placed in the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day.
Diagnosis
It was long known that M ...
. Clark et al. (2004) recovered ''Shantungosuchus'' as closely related to mesoeucrocodylians, and Buscalioni (2017) found the genus to group in a clade with ''Sichuanosuchus'' and
Shartegosuchidae
Shartegosuchidae is an extinct family of Late Jurassic and Early Cretaceous crocodylomorphs. The family is named after the Late Jurassic Shar Teeg Beds in southwestern Mongolia, from which most shartegosuchid remains have been found. Five genera ...
, which was formally named Shartegosuchoidea by Dollman et al. (2018) in their description of a new ''Shartegosuchus'' specimen.
Distribution and habitat
''Shantungosuchus chuhsienensis'' has been found in the Early Cretaceous (
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...
-
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...
)
Mengyin Formation
The Meng-Yin or Mengyin Formation () is a geological formation in Shandong, China, whose strata date back to the Berriasian and Valanginian stages of the Early Cretaceous.Luohandong Formation of
Outer Mongolia
Outer Mongolia was the name of a territory in the Manchu-led Qing dynasty of China from 1691 to 1911. It corresponds to the modern-day independent state of Mongolia and the Russian republic of Tuva. The historical region gained ''de facto' ...
, and ''S. brachycephalus'' may also have been found in the same region.Lü, J. & Wu, X-C. 1996 Restudy of Shantungosuchus brachycephalus Young, 1982. Vert. PalAs. 34, 184-201. The Luohandong formation provides clues to the environment of ''Shantungosuchus''. For instance, ''S. hangjinensis'' likely shared its
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
with fish such as ''
Sinamia
''Sinamia'' is an extinct genus of amiiform fish which existed in China, Japan, and possibly South Korea during the Early Cretaceous period. Like the related bowfin, it has an elongated low-running dorsal fin, though this was likely convergent ...
'', the turtle ''
Ordosemys
''Ordosemys'' is an extinct genus of sea turtle from the Cretaceous period
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 ...
'', and another species of crocodile-like reptile called '' Ikechosaurus'', and several types of
dinosaurs
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 ...
- though none have been identified to the level of genus.