Brachysuchus

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Brachysuchus
Temporal range: Late Triassic, 228–209  Ma
Exhibit Museum of Natural History, Ann Arbor - IMG 9131.JPG
Skull of Brachysuchus megalodon in the University of Michigan Museum of Natural History
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Phytosauria
Family: Parasuchidae
Genus: Brachysuchus
Case, 1929
Type species
Brachysuchus megalodon
Case, 1929

Brachysuchus (meaning "wide crocodile") is an extinct genus of phytosaur known from the late Triassic period (Carnian stage) of Dockum Group in Texas, United States. It is known from the holotype UMMP 10336 [1] is composed of a skull, lower jaws and partial postcranium and from the associated paratype UMMP 14366, nearly complete skull, recovered from the 'Pre-Tecovas Horizon' in the Dockum Group. [2] [3] It was first named by Case in 1929 and the type species is Brachysuchus megalodon. Its closest relative was Angistorhinus . [3] However, its rostral crest was much smaller than that of Angistorhinus, and the rostrum as a whole is shorter and thicker.

Features

The lower jaws of Brachysuchus are expanded at the tip to form a large bulge, holding the creature's largest tusks. The surface of this part of the bone has a wrinkled look, with many blood vessels running through it. In the lower jaw, there are three tusks in each side of this protuberance. Behind this part the jaws have fused together for a little under half their length before diverging after thirty-one of forty-six post-protuberance teeth. While some of the tusks at the tip are missing, most of the rest of the teeth in the jaw are still present. There are new tusks forming in the sockets, indicating that Brachysuchus regrew teeth all its life. There is a large foramen between the dentary, the angular and the prearticular that passes right through the jaw (visible on the picture). [4]

The teeth themselves are asymmetrical in cross-section, with the outer side more convex than the inner side. This asymmetry increases from front to back. They are long and conical, and those from the ninth to twenty-ninth have flutings on the sides. From the thirtieth to the forty-ninth, they have no flutings but are crenulated and broaden antero-posteriorly. This suggests that these teeth were better for slicing prey than the previous tusks and conical teeth, which would have impaled and injured it. In parts of the jaws the fused section in the middle rises so high that the teeth could only grip prey and could probably have done little damage. [4]

The prearticular is fused with the articular. [4]

The skull is around 125 cm long, with a distinctive hooked tip. It is much shorter and broader than that of many phytosaurs such as Leptosuchus or Angistorhinus. The eye sockets are narrow and long, and the fenestrae are smaller and less rounded than Angistorhinus. It has a comparatively small rostral crest. There are several rough surfaces at the posterior end denoting probable muscle attachments, which show that it had very powerful jaw muscles and a strong bite. [4] [5]

Overall Brachysuchus was approximately eight metres long, much bigger than most contemporary phytosaurs. It had extremely heavy jaws and a relatively short fused region, giving it a wider bite. There is also evidence of heavily developed jaw muscles. This, as well as the cutting teeth mentioned earlier, indicates that Brachysuchus preyed on different animals to its thinner-jawed relatives. Instead of using its jaws to catch fish, it was able to attack and feed off the heavily armoured stegocephalians that roamed the surrounding area, and would probably have eaten other phytosaurs if food was scarce. The slightly deformed tip of one specimen's lower jaw suggests that it used a lot of force to break through its prey's armour. [4]

Related Research Articles

Phytosaurs are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. and are sometimes referred to as parasuchians. Phytosauria, Parasuchia, Parasuchidae, and Phytosauridae have often been considered equivalent groupings containing the same species. Some recent studies have offered a more nuanced approach, defining Parasuchidae and Phytosauridae as nested clades within Phytosauria as a whole. Phytosaurs were long-snouted and heavily armoured, bearing a remarkable resemblance to modern crocodilians in size, appearance, and lifestyle, as an example of convergence or parallel evolution. The name "phytosaur" means "plant reptile", as the first fossils of phytosaurs were mistakenly thought to belong to plant eaters.

<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.

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

Venaticosuchus is a genus of pseudosuchian archosaurs from the family Ornithosuchidae. Known from a single species, Venaticosuchus rusconii, this genus is described based on an incomplete skull and jaw collected from the Late Triassic (Carnian) Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina, which was deposited around 230 million years ago. This fossil material has been termed the holotype specimen PVL 2578. Venaticosuchus incorporated a myriad of features present in the other two genera of ornithosuchids, Ornithosuchus and Riojasuchus. However, it also had several unique traits, relating to the lower jaw.

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

Paleorhinus is an extinct genus of widespread basal phytosaur known from the Late Triassic. The genus was named in 1904 based on the type species Paleorhinus bransoni, which is known from Wyoming and Texas in the United States. Another valid species, Paleorhinus angustifrons from Bavaria, Germany, is also commonly referred to the genus. Paleorhinus had a length of about 2.5 meters.

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

Parasuchus is an extinct genus of basal phytosaur known from the Late Triassic of Andhra Pradesh and Madhya Pradesh, India. At its most restricted definition, Parasuchus contains a single species, Parasuchus hislopi. Parasuchus hislopi is one of several species belonging to a basal grade of phytosaurs, typified by the genus Paleorhinus. Historically, Paleorhinus has been known from better-described fossils, and many species have been lumped into that genus. Parasuchus hislopi, despite being described earlier than Paleorhinus, was considered an undiagnostic chimera until new neotype fossils were described in the late 1970s. Parasuchus hislopi and the two unambiguously valid species of Paleorhinus are all closely related; some authors have historically described them all under the species Paleorhinus, while others place the two Paleorhinus species into Parasuchus according to the principle of priority.

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

Rutiodon is an extinct genus of mystriosuchine phytosaurs from the Late Triassic of the eastern United States. The type species of Rutiodon, Rutiodon carolinensis, encompasses a large number of skulls and assorted postcranial fossils discovered in the Cumnock Formation of North Carolina. Fossils referable to the species are also known from Pennsylvania, New Jersey, and Virginia. Rutiodon carolinensis is the most well-described species of phytosaur in eastern North America, though its validity as a natural taxon has been questioned. Some paleontologists also recognize a larger and more robust species, Rutiodon manhattanensis, which is known from teeth and postcranial fossils from New Jersey and Pennsylvania.

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

Desmatosuchus is an extinct genus of archosaur belonging to the Order Aetosauria. It lived during the Late Triassic.

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

Nicrosaurus (/nɪkroʊˈsɔrəs/) is an extinct genus of phytosaur reptile existing during the Late Triassic period. Although it looked like a crocodile, it was not closely related to these creatures, instead being an example of parallel evolution. The main difference between Nicrosaurus and modern crocodiles is the position of the nostrils – Nicrosaurus's nostrils, or external nares, were placed directly in front of the forehead, whereas in crocodiles, the nostrils are positioned on the end of the snout. A 2013 study has also found that ilium of Nicrosaurus is quite distinctive from all other phytosaurs.

Mesosuchus is an extinct genus of basal Rhynchosaur from early Middle Triassic deposits of Eastern Cape, South Africa. It is known from the holotype SAM 5882, a partial skeleton, and from the paratypes SAM 6046, SAM 6536, SAM 7416 and SAM 7701 from the Aliwal North Euparkeria site. Mesosuchus is quite small, spanning around 30 cm in length. Mesosuchus was discovered and named by David Meredith Seares Watson in 1912.

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

Angistorhinus is an extinct genus of phytosaur known from the Late Triassic period of Texas and Wyoming, United States. It was first named by Mehl in 1913 and the type species is Angistorhinus grandis. Other species from Texas and Wyoming, A. alticephalus, A. gracilis and A. maximus, are cospecific with the type species. Angistorhinus is known from the holotype UC 631, partial skull and lower jaws recovered from the Popo Agie Formation, Chugwater Group, Wyoming and from the associated paratype UM 531, a partial skull, TMM 31098-1, skull and lower jaws and ROM 7977, partial skull and lower jaws, recovered from the 'Pre-Tecovas Horizon' in the Dockum Group, Texas. A possible second species, A. talainti is known from the Triassic of Morocco. In 1995, Long and Murry created the new combination, Angistorhinus megalodon by synonymy for Brachysuchus. Hungerbühler and Sues (2001) hypothesised that Angistorhinus is a junior synonym of Rutiodon. However, in 2010 Michelle R. Stocker retained the validity of Brachysuchus and of A. grandis.

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

Smilosuchus is an extinct genus of leptosuchomorph parasuchid from the Late Triassic of North America.

<i>Anaschisma</i> Extinct genus of amphibians

Anaschisma is an extinct genus of large temnospondyl amphibians. These animals were part of the family called Metoposauridae, which filled the crocodile-like predatory niches in the late Triassic. It had large skull about 62 centimetres (24 in) long, and possibly reached 3 metres (9.8 ft) long. It was an ambush hunter, snapping up anything small enough to fit in its huge jaws. It was very common during the Late Triassic in what is now the American Southwest.

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

Leptosuchus is an extinct genus of leptosuchomorph phytosaur with a complex taxonomical history. Fossils have been found from the Dockum Group and lower Chinle Formation outcropping in Texas, New Mexico, and Arizona, USA, and date back to the Carnian stage of the Late Triassic.

Pravusuchus is an extinct genus of leptosuchomorph parasuchid phytosaur known from the Late Triassic of Arizona, United States. It contains a single species, Pravusuchus hortus, which is known from three specimens. These specimens were previously referred to Smilosuchus or to Leptosuchus, but Pravusuchus's autapomorphy, its phylogenetic position as well as a trait shared with mystriosuchins, justified the erection of a new taxon for the material.

<i>Protome</i> (genus) Extinct genus of reptiles

Protome is an extinct genus of parasuchid phytosaur from the Late Triassic of Arizona, represented by a single species, Protome batalaria. It is known from a single holotype incomplete, partially disarticulated skull and left lower jaw called PEFO 34034 from the Upper Lot's Wife beds, Sonsela Member of the Chinle Formation in Petrified Forest National Park. The skull was discovered in 2004 by Michelle Stocker and Bill Parker and was described by them as a specimen of Smilosuchus adamanensis. It was placed in the new genus Protome in 2012. The genus name Protome is the Greek word for an animal's face. The specific name batalaria is the Latin word for battleship, which is a reference to Battleship NW, the locality within Petrified Forest where the skull was found.

<span class="mw-page-title-main">Fish jaw</span>

Most bony fishes have two sets of jaws made mainly of bone. The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx, are used to further process the food and move it from the mouth to the stomach.

The Colorado City Formation is a Late Triassic geologic formation in the Dockum Group of Texas, United States. It has previously been known as the Iatan Member, Colorado City Member or 'Pre-Tecovas Horizon'.

Syntomiprosopus is an extinct genus of archosauriform, possibly a crocodylomorph from the Late Triassic period of Arizona. The type and only known species is S. sucherorum. Syntomiprosopus was unusually short-snouted, comparable to the Late Cretaceous notosuchian Simosuchus, and is regarded as an example of convergent evolution between Triassic stem-archosaurs and Cretaceous archosaurs.

<i>Colossosuchus</i> Genus of reptile

Colossosuchus is an extinct genus or large mystriosuchine phytosaur from the Upper Triassic Tiki Formation of India. It was among the largest known phytosaurs, reaching a length of over 8 m (26 ft). Among its characteristic features are the dome-shaped head and downturned tip of the upper jaw. Colossosuchus was part of an endemic radiation of phytosaurs from India, closely related to two additional forms not yet named. The genus is monotypic, only including the species Colossosuchus techniensis.

<i>Jupijkam</i> Genus of reptile

Jupijkam is an extinct genus of phytosaur from the Late Triassic of Nova Scotia, Canada. The genus is monotypic, including only the species Jupijkam paleofluvialis. It is based on a partial skull and a few other fragments from the White Water Member of the Blomidon Formation. Along with unnamed fossils from the Fleming Fjord Formation of Greenland, these remains represent the northernmost record of phytosaurs. Jupijkam is named after Jipijka'm, the great horned serpent of Mi'kmaq mythology.

References

  1. "UMMP VP 10336". University of Michigan Online Repository of Fossils. University of Michigan Museum of Paleontology. Retrieved 16 July 2020.
  2. Case, E. C. (1929). "Description of the skull of a new form of phytosaur with notes on the characters of described North American phytosaurs". Memoirs of the University of Michigan Museums, Museum of Paleontology. 2: 1–56.
  3. 1 2 Michelle R. Stocker (2010). "A new taxon of phytosaur (Archosauria: Pseudosuchia) from the Late Triassic (Norian) Sonsela Member (Chinle Formation) in Arizona, and a critical reevaluation of Leptosuchus Case, 1922". Palaeontology. 53 (5): 997–1022. doi: 10.1111/j.1475-4983.2010.00983.x . S2CID   83536253.
  4. 1 2 3 4 5 "Google Scholar". scholar.google.com. Retrieved 2018-05-13.
  5. "Palaeos Vertebrates: Archosauria: Phytosauridae". palaeos.com. Retrieved 2018-05-13.