Misplaced Pages

Tikisuchus Temporal range: Late Triassic, 237–228 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
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.

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.

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.

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. 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. 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.

References

1. ^ 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.

v t e Pseudosuchia
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Clade: Archosauria Sauropsida see Sauropsida Archosauromorpha see Archosauromorpha Pseudosuchia see below↓
Pseudosuchia Pseudosuchia †Dasygnathoides †Nundasuchus †Phytosauria? †Ornithosuchidae Aenigmaspina? Dynamosuchus Ornithosuchus Riojasuchus Venaticosuchus Suchia †Heteropelta? †Koilamasuchus? †Mandasuchus †Nundasuchus? †Ticinosuchus †Erpetosuchidae Archeopelta? Dyoplax? Erpetosuchus Pagosvenator Parringtonia Tarjadia †Aetosauriformes Acaenasuchus Euscolosuchus Revueltosaurus Aetosauria see Aetosauria †Gracilisuchidae Gracilisuchus Maehary? Parvosuchus Turfanosuchus Yonghesuchus Paracrocodylomorpha see below↓
Paracrocodylomorpha Paracrocodylomorpha †Mambawakale †Poposauroidea Benggwigwishingasuchus Lotosaurus Schultzsuchus? Qianosuchus Ctenosauriscidae Arizonasaurus Bromsgroveia Bystrowisuchus Ctenosauriscus Hypselorhachis Tsylmosuchus? Xilousuchus Poposauridae Dolichobrachium Poposaurus Shuvosauridae Effigia Shuvosaurus Sillosuchus Loricata †Apatosuchus †Arganasuchus †Batrachotomus †Dagasuchus †Decuriasuchus †Etjosuchus †Fasolasuchus †Heptasuchus †Heteropelta? †Incertovenator? †Luperosuchus †Mandasuchus? †Prestosuchus †Procerosuchus †Saurosuchus †Stagonosuchus †Youngosuchus †Rauisuchidae Arganasuchus? Energosuchus? Jushatyria? Polonosuchus Postosuchus Procerosuchus? Rauisuchus Scolotosuchus Scythosuchus? Teratosaurus Tikisuchus? Vivaron Vjushkovisaurus? Vytshegdosuchus? Crocodylomorpha see below↓
Crocodylomorpha Crocodylomorpha †Carnufex †Dibothrosuchus †Dromicosuchus †Hesperosuchus †Heteropelta? †Junggarsuchus †Kayentasuchus †Parrishia †Phyllodontosuchus †Pseudhesperosuchus †Redondavenator †Sphenosuchus †Syntomiprosopus? †Trialestes †Saltoposuchidae Litargosuchus Saltoposuchus Terrestrisuchus †Hallopodidae Almadasuchus Hallopus Macelognathus †Thalattosuchia see Thalattosuchia Crocodyliformes †Entradasuchus †Eopneumatosuchus †Kemkemia †Microchampsa †Platyognathus †Stegomosuchus †Tagarosuchus †Protosuchidae Coloradisuchus Dianosuchus Edentosuchus Erythrochampsa Hemiprotosuchus Hoplosuchus Orthosuchus? Pedeticosaurus? Protosuchus †Notochampsidae Notochampsa Orthosuchus? †Gobiosuchidae Cassissuchus Gobiosuchus Lisboasaurus? Zaraasuchus Mesoeucrocodylia †Dianchungosaurus †Hsisosuchus †Induszalim †Lusitanisuchus †Neuquensuchus †Pachycheilosuchus? †Titanochampsa †Thalattosuchia? †Shartegosuchoidea Hadongsuchus Shantungosuchus Sichuanosuchus Zosuchus Shartegosuchidae Adzhosuchus Fruitachampsa Kyasuchus Nominosuchus Shartegosuchus Metasuchia †Ziphosuchia see Ziphosuchia includes notosuchians Neosuchia see Neosuchia includes crocodilians
See also: Rauisuchia Prestosuchidae Bathyotica Sphenosuchia Protosuchia Mesosuchia Category

• Rauisuchids
• Prehistoric reptiles of Asia
• Fossil taxa described in 1987
• Prehistoric pseudosuchian genera