Tikisuchus

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Tikisuchus
Temporal range: Late Triassic, 237–228  Ma
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Pseudosuchia
Family: Rauisuchidae
Genus: Tikisuchus
Chatterjee and Majumdar, 1987
Species:
T. romeri
Binomial name
Tikisuchus romeri
Chatterjee and Majumdar, 1987

Tikisuchus is an extinct genus of rauisuchid archosauromorph. It is known from the Late Triassic Tiki Formation in the Shahdol District of central India and was the first rauisuchid to have been found in Asia. The horizon from which remains have been found is Carnian in age. The type species is T. romeri, named in honor of American paleontologist Alfred Romer. Romer was present at the Tiki locality during the excavation of the fossil, but died before the description of the genus in 1987. Tikisuchus is known only from one specimen, called ISI R 305, which consists of the skull and some postcranial elements of a young individual. [1]

Contents

Description

Compared to other rausuchids, the skull of Tikisuchus was very large. The skull's length is around 40% of the length of the presacral area between the head and the sacrum. The skull is deep, being wide at the back with a narrow rostrum. The teeth are large, recurved and serrated. Like other rauisuchids, it has rows of osteoderms, or bony scutes, along its back. There are two rows of osteoderms. Each osteoderm is rectangular in shape and imbricates, or articulates tightly, with the ones around it. In other rauisuchids, the osteoderms are leaf-shaped rather than rectangular. [1]

Paleobiology

Many other tetrapods were found in association with Tikisuchus representing a diverse Carnian paleofauna. Tetrapods from the Tiki site include Paleorhinus , a phytosaur, Metoposaurus , a temnospondyl, and Paradapedon , a rhynchosaur. The Tiki fauna is similar to that of the German Keuper. [1]

Theropod dinosaurs were also present in the Tiki Formation. Both Tikisuchus and the theropods were large terrestrial predators, and, having been found at the same locality, likely came in close contact with one another. The similar lifestyles of the two carnivores may have resulted in competition for the same food sources. Possible prey would have included rhynchosaurs, trilophosaurs, dicynodonts, and aetosaurs. The authors of the original description of Tikisuchus, Sankar Chatterjee and Pranab Majumdar, suggested that competition between Tikisuchus and theropods was low because of abundant food resources and stabilized ecological interactions. Chatterjee and Majumdar thought that there was an "ecological balance" during the Carnian stage on the basis of little change in the paleofauna of the time. [1] They considered the paleoclimate to have been warm with seasonal wet and dry seasons conducive to the growth of tropical forests. At the end of the Carnian, however, the authors claimed that many prey resources became extinct and the forest environment was replaced by a more open environment. The limited resources would have heightened competition between theropods and rauisuchids like Tikisuchus. Chatterjee and Majumdar considered theropods to be agile pursuit predators while rauisuchids were considered slow ambush predators. Therefore, they suggested that theropods, which were more suited to living in an open environment, outcompeted rauisuchids at the end of the Triassic to become the dominant large land carnivores by the beginning of the Jurassic. [1] However, more recent studies suggest that dinosaurs gained dominance only after the Triassic-Jurassic extinction event in a case of opportunism with no other large archosaurs such as rauisuchids to compete with. [2]

Related Research Articles

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Rauisuchia Informal group of Triassic archosaurs with pillar-erect posture

"Rauisuchia" is a paraphyletic group of mostly large Triassic archosaurs. It belongs to a larger clade called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians than to birds and other dinosaurs. "Rauisuchia" is currently considered an evolutionary grade, or even a wastebin taxon. It includes most of the large, carnivorous pseudosuchians that lived during the Triassic Period. Since crocodylomorphs likely originated from an ancestor that would have been a "rauisuchian", Rauisuchia in its traditional sense is considered paraphyletic as it excludes crocodylomorphs. To designate it as an informal group in scientific literature, the name in its traditional sense is often enclosed in quotation marks. The monophyletic equivalent of the group Rauisuchia is the clade Paracrocodylomorpha. Paracrocodylomorpha consists of two branches: Poposauroidea, which includes a variety of strange archosaurs, and Loricata, which includes traditional "rauisuchians" and their crocodylomorph descendants.

<i>Herrerasaurus</i> Extinct genus of dinosaurs

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<i>Postosuchus</i> Genus of reptiles

Postosuchus, meaning "Crocodile from Post", is an extinct genus of rauisuchid reptiles comprising two species, P. kirkpatricki and P. alisonae, that lived in what is now North America during the Late Triassic. Postosuchus is a member of the clade Pseudosuchia, the lineage of archosaurs that includes modern crocodilians. Its name refers to Post Quarry, a place in Texas where many fossils of the type species, P. kirkpatricki, were found. It was one of the apex predators of its area during the Triassic, larger than the small dinosaur predators of its time. It was a hunter which probably preyed on large bulky herbivores like dicynodonts and many other creatures smaller than itself.

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Poposauridae Extinct family of reptiles

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<i>Gracilisuchus</i> Genus of fossil reptiles

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<i>Parasuchus</i> Extinct genus of reptiles

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<i>Saurosuchus</i> Paracrocodylomorph reptile genus from Late Triassic period

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<i>Doswellia</i> Extinct genus of reptiles

Doswellia is an extinct genus of archosauriform from the Late Triassic of North America. It is the most notable member of the family Doswelliidae, related to the proterochampsids. Doswellia was a low and heavily built carnivore which lived during the Carnian stage of the Late Triassic. It possesses many unusual features including a wide, flattened head with narrow jaws and a box-like rib cage surrounded by many rows of bony plates. The type species Doswellia kaltenbachi was named in 1980 from fossils found within the Vinita member of the Doswell Formation in Virginia. The formation, which is found in the Taylorsville Basin, is part of the larger Newark Supergroup. Doswellia is named after Doswell, the town from which much of the taxon's remains have been found. A second species, D. sixmilensis, was described in 2012 from the Bluewater Creek Formation of the Chinle Group in New Mexico; however, this species was subsequently transferred to a separate doswelliid genus, Rugarhynchos. Bonafide Doswellia kaltenbachi fossils are also known from the Chinle Formation of Arizona.

Ischigualasto Formation

The Ischigualasto Formation is a Late Triassic fossiliferous formation and Lagerstätte in the Ischigualasto-Villa Unión Basin of the southwestern La Rioja Province and northeastern San Juan Province in northwestern Argentina. The formation dates to the Carnian age and ranges between 231.7 and 225 Ma, based on ash bed dating.

<i>Luperosuchus</i> Extinct genus of reptiles

Luperosuchus is an extinct genus of loricatan pseudosuchian reptile which contains only a single species, Luperosuchus fractus. It is known from the Chañares Formation of Argentina, within strata belonging to the latest Ladinian stage of the late Middle Triassic, or the earliest Carnian of the Late Triassic. Luperosuchus was one of the largest carnivores of the Chañares Formation, although its remains are fragmentary and primarily represented by a skull with similarities to Prestosuchus and Saurosuchus.

<i>Chanaresuchus</i> Extinct genus of reptiles

Chanaresuchus is an extinct genus of proterochampsian archosauriform. It was of modest size for a proterochampsian, being on average just over a meter in length. Fossils are known from the Middle and Late Triassic of La Rioja Province, Argentina and Rio Grande do Sul, Brazil. The type species and only currently known species is Chanaresuchus bonapartei was named from the Ladinian-age Chañares Formation in 1971. A second species C. ischigualastensis named in 2012 from the late Carnian-age Ischigualasto Formation, was briefly assigned to Chanaresuchus before being moved to its own genus Pseudochampsa in 2014. C. bonapartei has recently been found in the Carnian Santa Maria Formation in Brazil. Chanaresuchus appears to be one of the most common archosauriforms from the Chanares Formation due to the abundance of specimens referred to the genus. Much of the material has been found by the La Plata-Harvard expedition of 1964-65. Chanaresuchus was originally classified in the family Proterochampsidae, although it has been placed in the family Rhadinosuchidae in more recent studies.

The Chañares Formation is a Carnian-age geologic formation of the Ischigualasto-Villa Unión Basin, located in La Rioja Province, Argentina. It is characterized by drab-colored fine-grained volcaniclastic claystones, siltstones, and sandstones which were deposited in a fluvial to lacustrine environment. The formation is most prominently exposed within Talampaya National Park, a UNESCO World Heritage Site within La Rioja Province.

The Tiki Formation is a Late Triassic geologic formation in Madhya Pradesh, northern India. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus. Phytosaur remains attributable to the genus Volcanosuchus have also been found in the Tiki Formation.

<i>Sanjuansaurus</i> Extinct genus of dinosaurs

Sanjuansaurus is a genus of herrerasaurid dinosaur from the Late Triassic (Carnian) Cancha de Bochas and La Peña Members of the Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina.

<i>Smok <span style="font-style:normal;">(archosaur)</span></i> Extinct genus of reptiles

Smok is an extinct genus of large carnivorous archosaur. It lived during the latest Triassic period. Its remains have been found in Lisowice, southern Poland. The type species is Smok wawelski and was named in 2012. It is larger than any other known predatory archosaur from the Late Triassic or Early Jurassic of central Europe. The relation of Smok to other archosaurs has not yet been thoroughly studied; it may be a rauisuchid, prestosuchid, an ornithosuchid pseudosuchian or a theropod dinosaur.

References

  1. 1 2 3 4 5 Chatterjee, S.; Majumdar, P.K. (1987). "Tikisuchus romeri, a new rauisuchid reptile from the Late Triassic of India". Journal of Paleontology. 61 (4): 787–793. doi:10.1017/S0022336000029139.
  2. Brutasse, S.L.; Nesbitt, S.J.; Irmis, R.B.; Butler, R.J.; Benton, M.J.; Norell, M.A. (2010). "The origin and early radiation of dinosaurs" (PDF). Earth-Science Reviews. 101 (1–2): 68–100. Bibcode:2010ESRv..101...68B. doi:10.1016/j.earscirev.2010.04.001.