Sunosuchus | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Family: | † Goniopholididae |
Genus: | † Sunosuchus Young, 1948 |
Species | |
Sunosuchus is an extinct genus of goniopholidid mesoeucrocodylian. Fossils are known from China, Kyrgyzstan, and Thailand and are Jurassic in age, although some may be Early Cretaceous. Four species are currently assigned to the genus: the type species S. miaoi and the species S. junggarensis, S. shartegensis, and S. shunanensis. All species are from China. Goniopholis phuwiangensis, also from Thailand, was reassigned to Sunosuchus by Andrade et al. (2011). [1] The material from Kyrgyzstan has not been assigned to any species.
Sunosuchus has a long, narrow snout and a small skull table. Several characters help diagnose Sunosuchus and distinguish it from other taxa. For example, there are wide pits on the back of the frontal bone. The frontal bone also has a distinctive ridge along part of its midline. The lower jaw has a long symphysis where the two halves come together. This symphysis is formed mostly from the mandibles, but also partially by the splenials. Unlike other goniopholidids, the squamosal bone (which is found near the back of the skull) is narrow. [2]
S. junggarensis is the best known species of Sunosuchus. It was first described in 1996 from the Late Jurassic Junggar Basin in Xinjiang, China. Material belonging to Sunosuchus was collected from Kyrgyzstan in the 1980s and was described in 2000. [2] Many teeth were found, as well as a dorsal vertebra and some vertebral centra, some pelvic bones, part of a fibula and tibia, a few metatarsals, and ventral and neck osteoderms. The only parts of the skull uncovered were squamosal bones. The squamosals are similar to those of other species of Sunosuchus but not those of other genera, which indicates that the material belongs to a species of Sunosuchus. While the specimens bear a strong resemblance to the bones of S. junggarensis, they have not been assigned to any species. [2]
A fifth species, S. shunanensis, was described in 2005 from the Middle Jurassic of Zigong in Sichuan, China. Skulls were collected from the Dashanpu Dinosaur Quarry in 1983, having been found in the Lower Shaximiao Formation. S. shunanensis has a longer snout than other species, being around three times the length of the postorbital region, or the portion of the skull behind the eyes. It also has a wider skull table than other species. The skull is widest at the back rather than between the eyes, a feature only seen in S. shunanensis. Near the back of each maxilla there is a distinct depression. There are unique ridges across the surface of the skull, one pair at the front of the eye socket on the lacrimals, and a second along the sides of the bacioccipitals and the undersurfaces of the exoccipitals at the base of the skull. [3]
Sunosuchus thailandicus was described from northeastern Thailand in 1980. [4] It is known only from the mandible, which is very robust. The tip of the jaw is spoon shaped and wider than the portion of the jaw immediately behind it. The mandible was collected from the Phu Kradung Formation near the town of Nong Bua Lamphu. This single specimen is the most well preserved vertebrate fossil that has been found from the formation; other vertebrates, including dinosaurs, are known only from fragmentary remains. [5] The age of the Phu Kradung Formation is uncertain. It was once thought to be Early Jurassic, which would have made S. thailandicus the oldest species of Sunosuchus. However, the formation has more recently been considered to be Late Jurassic to Early Cretaceous in age, potentially making S. thailandicus the youngest species of the genus. [6] However, a newly discovered specimen showed that S. thailandicus is sufficiently distinct from other nominal species of Sunosuchus to be placed in its own genus, Chalawan . [7]
Sunosuchus was initially classified as a pholidosaurid because its jaws were long, making it a longirostrine, or long-snouted, crocodyliform. Most pholidosaurs are longirostrine, while goniopholidids usually have shorter snouts. Despite the similarities with pholidosaurs, Sunosuchus shares several features with goniopholidids that ally it with the group. Among these features are small supratemporal fenestrae and openings at the front of the palate. [5]
The results of a phylogenetic analysis conducted in 2011 focusing on the interrelationships of goniopholidids is shown below. [1]
Neosuchia |
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The material from Kyrgyzstan is the westernmost record of the geographic range of Sunosuchus. The strata from which this material has been found are similar to those of Mongolian and Chinese Middle and Late Jurassic strata. These areas shared a similar fauna that is characterized by crocodyliforms such as Sunosuchus as well as temnospondyl amphibians and xinjiangchelyid turtles, indicating freshwater environments across the region. Marine hybodont sharks and dipnoans are found in the Kyrgyzstan strata, suggesting that the area was estuarine at the time rather than entirely freshwater. [2]
Nong Bua Lamphu is one of Thailand's seventy-six provinces (changwat). It lies in upper northeastern Thailand, a region also known as Isan or Isaan. Neighbouring provinces are Udon Thani, Khon Kaen, and Loei.
Goniopholis is an extinct genus of goniopholidid crocodyliform that lived in Europe during the Late Jurassic and Early Cretaceous. Like other goniopholidids, it resembled living crocodilians, and probably had a similar ecology as semi-aquatic ambush predators.
Siamosaurus is a genus of spinosaurid dinosaur that lived in what is now known as China and Thailand during the Early Cretaceous period and is the first reported spinosaurid from Asia. It is confidently known only from tooth fossils; the first were found in the Sao Khua Formation, with more teeth later recovered from the younger Khok Kruat Formation. The only species Siamosaurus suteethorni, whose name honours Thai palaeontologist Varavudh Suteethorn, was formally described in 1986. In 2009, four teeth from China previously attributed to a pliosaur—under the species "Sinopliosaurus" fusuiensis—were identified as those of a spinosaurid, possibly Siamosaurus. It is yet to be determined if two partial spinosaurid skeletons from Thailand and an isolated tooth from Japan also belong to Siamosaurus.
Phuwiangosaurus 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 Suteethorn in a 1993 press release and was formally named in 1994. The species was named to honor Princess Maha Chakri Sirindhorn of Thailand, who was interested in the geology and palaeontology of Thailand, while the genus was named after the Phu Wiang area, where the fossil was discovered.
Calsoyasuchus is a genus of crocodylomorph that lived in the Early Jurassic. Its fossilized remains were found in the Sinemurian-Pliensbachian-age Kayenta Formation on Navajo Nation land in Coconino County, Arizona, United States. Formally described as C. valliceps, it is known from a single incomplete skull which is unusually derived for such an early crocodile relative. This genus was described in 2002 by Ronald Tykoski and colleagues; the specific name means "valley head" and refers to a deep groove along the midline of the nasal bones and frontal bones. It has often been interpreted as the earliest diverging member of Goniopholididae, but other studies have recovered it in various other positions.
Goniopholididae is an extinct family of moderate-sized semi-aquatic neosuchian crocodyliformes. Their bodyplan and morphology are convergent on living crocodilians. They lived across Laurasia between the Middle Jurassic and the Late Cretaceous.
The Sao Khua Formation is a middle member of the Khorat Group. It consists of an alteration of pale red to yellowish-gray, fine to medium-grained sandstone and grayish-reddish brown siltstone and clay. Rare pale red to light gray conglomerates, containing carbonate pebbles, are also characteristic of this formation. This geological formation in Thailand dates to the Early Cretaceous age, specifically the Valanginian through Hauterivian stages.
Pholidosauridae is an extinct family of aquatic neosuchian mesoeucrocodylian crocodylomorphs. Fossils have been found in Europe, Africa, North America and South America. The pholidosaurids first appeared in the fossil record during the Bathonian stage of the Middle Jurassic. Jouve & Jalil (2020) described postcranial material of a pholidosaurid from the Paleocene (Danian) of Ouled Abdoun Basin (Morocco), representing the most recent record of the family. The authors also reinterpreted putative Maastrichtian dyrosaurid Sabinosuchus as a pholidosaurid, and argued that at least two independent pholidosaurid lineages reached the Maastrichtian, among which one survived the Cretaceous–Paleogene extinction event. Before the publication of this study it was thought that the family became extinct during the Late Turonian stage of the Late Cretaceous.
Eutretauranosuchus is an extinct genus of goniopholidid crocodyliform. E. delfsi is the only known species within the genus.
Siamosuchus is a genus of goniopholidid mesoeucrocodylian. Its fossils have been recovered from the pre-Aptian-age Lower Cretaceous Sao Khua Formation of eastern Thailand. It is known from a partial skull, most of the right half of the postcranial skeleton, and some bony scutes. Siamosuchus was described by Lauprasert and colleagues in 2007. The type species is S. phuphokensis. Siamosuchus may be closely related to the European genus Goniopholis.
Amphicotylus is an extinct genus of goniopholidid mesoeucrocodylian from the Tithonian of Colorado, Wyoming, and Oklahoma. It was described in 1878.
The Early Cretaceous Phu Kradung Formation is the lowest member of the Mesozoic Khorat Group which outcrops on the Khorat Plateau in Isan, Thailand. This geological formation consists of micaceous, brown to reddish-brown siltstone beds with minor brown and grey shale and sandstone beds. Occasional lime-noduled conglomerate occurs.
Anteophthalmosuchus is an extinct genus of goniopholidid mesoeucrocodylian from the Early Cretaceous of southern England, eastern Spain, and western Belgium.
Chalawan is an extinct genus of pholidosaurid mesoeucrocodylian known from the Late Jurassic or Early Cretaceous Phu Kradung Formation of Nong Bua Lamphu Province, northeastern Thailand. It contains a single species, Chalawan thailandicus, with Chalawan shartegensis as a possible second species.
Coelognathosuchia is an extinct clade of neosuchian crocodyliforms that includes all taxa more closely related to the family Pholidosauridae than to Bernissartia fagesii or Eusuchia. Martin et al. (2014) named the clade after finding goniopholidids and pholidosaurids to group together in their phylogenetic analysis of crocodyliform evolutionary relationships. In their analysis, Pholidosauridae was monophyletic and Goniopholididae was paraphyletic, being an assemblage of successively more basal taxa within Coelognathosuchia. Coelognathosuchia itself was positioned near the base of the larger clade Neosuchia as the sister group to a clade containing the Early Cretaceous neosuchian Bernissartia and Eusuchia, the group that includes all modern crocodilians and their closest extinct relatives.
Liaodactylus is a genus of filter-feeding ctenochasmatid pterosaur from the Jurassic of China. The genus contains one species, L. primus, described by Zhou et al. in 2017. As an adaptation to filter-feeding, Liaodactylus had approximately 150 long, comb-like teeth packed closely together. It is both the earliest known ctenochasmatid and the first filter-feeding pterosaur from the Jurassic Tiaojishan Formation. Later and more specialized ctenochasmatids differ from Liaodactylus in having longer snouts, smaller openings in the skull, and more teeth. Within the Ctenochasmatidae, Liaodactylus was most closely related to the European Ctenochasma.
Varavudh Suteethorn, or Warawut Suteethorn is a Thai palaeontologist and geologist. He is the current director of the Palaeontological Research and Education Centre, Mahasarakham University. He is best known for his work on vertebrate paleontology in northeastern Thailand, having contributed to the discovery of many fossil taxa and dig sites in the Khorat Plateau, as a part of a long-standing collaboration between Thai and French scientists.
Indosinosuchus is a genus of teleosaurid neosuchian that lived during the Late Jurassic or Early Cretaceous in what is now Thailand. It contains two species, the type species I. potamosiamensis and I. kalasinensis, both recovered from the lower Phu Kradung Formation. It is unique among teleosauroids as it is the only named genus known from a freshwater environment, while most other members of the group are marine. Indosinosuchus is placed in the family Teleosauridae, but has a relatively robust skull that bears resemblance to members of the Machimosauridae. Biomechanical analysis of its mandible and teeth suggest that it would have had a substantial bite force comparable to animals like Lemmysuchus. The two Indosinosuchus species however differ in the speed at which they could open and close their jaws, impacting their respective ecology and possibly explaining how they coexisted in the same environment. All known specimens of this genus were recovered from a single locality, which has been interpreted as a mass death site, possibly caused by a drought or flash flood. The precise age of Indosinosuchus is unclear, as the vertebrate fossils of the Phu Kradung Formation support a Late Jurassic age, while palynological data suggests an Early Cretaceous (Berriasian) age.
Yakemys is an extinct genus of macrobaenid turtles from the Late Jurassic-Early Cretaceous (Tithonian-Valanginian?) lower Phu Kradung Formation of Thailand. It is monotypic, containing a single species, Yakemys multiporcata.
Minimocursor is a genus of basal neornithischian dinosaur from the Late Jurassic Phu Kradung Formation of Thailand. The type species is Minimocursor phunoiensis.