Stagonosuchus

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Stagonosuchus
Temporal range: Anisian
~247–242  Ma
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Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Family: Prestosuchidae
Genus: Stagonosuchus
von Huene, 1939
Species:
S. nyassicus
Binomial name
Stagonosuchus nyassicus
von Huene, 1939
Synonyms
  • Prestosuchus nyassicus? von Huene, 1939

Stagonosuchus is an extinct genus of loricatan, or possibly a species of Prestosuchus . Fossils have been found from the Late Triassic Manda Formation in Tanzania that are Anisian in age.

Description

Unlike other rauisuchians, which have a prominent ridge on the ilium called the supra-acetabular buttress that overlies the femur, Stagonosuchus possesses only a slight thickening on the surface of the bone. [1] [2] In Stagonosuchus, the pubis is broad and plate like, while in other genera it is narrower and may have a prominent "foot" like that of some theropod dinosaurs. [3]

The centra of the vertebrae are constricted to some extent, though not as much as in other rauisuchians such as Saurosuchus . In the vertebrae, the neural canals (through which the spinal cord would pass) extend into the centra, forming deep concavities. [4] A wide articulation between the hyposphene and hypantrum in successive vertebrae prevented any lateral movement of the spine. A small accessory neural spine projects near the larger main spine, possibly as an extra attachment for bracing ligaments. Stagonosuchus also has many laminae, or ridges of bone on the vertebrae. [5]

Classification

Friedrich von Huene, who named the genus in 1938, first classified Stagonosuchus as a rauisuchid. [6] In 1967, Alfred Romer placed Stagonosuchus in the newly erected family Prestosuchidae. [7] However, this was likely due to the close similarities shared between the two families which made classification difficult. Stagonosuchus has since been considered a rauisuchid. A 2010 study on archosaurian phylogeny found Stagonosuchus to be outside both Rauisuchidae and Prestosuchidae in a more basal position within Rauisuchia. The study erected the name Rauisuchoidea to include it and other basal taxa that were closely related to rauisuchids and prestosuchids, including Ticinosuchus (traditionally thought to be a prestosuchid) and Arganasuchus and Fasolasuchus (previously considered rauisuchids). [8] A 2011 study found Ticinosuchus to be the closest relative of Stagonosuchus despite a conspicuous difference in size between the two forms (Ticinosuchus is much more gracile than the larger Stagonosuchus). [5] A 2020 study argued that Stagonosuchus was a second species of Prestosuchus , Prestosuchus nyassicus. [9]

Related Research Articles

<span class="mw-page-title-main">Rauisuchia</span> Informal group of Triassic archosaurs with pillar-erect posture

"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians than to birds and other dinosaurs. First named in the 1940s, Rauisuchia was a name exclusive to Triassic archosaurs which were generally large, carnivorous, and quadrupedal with a pillar-erect hip posture, though exceptions exist for all of these traits. Rauisuchians, as a traditional taxonomic group, were considered distinct from other Triassic archosaur groups such as early dinosaurs, phytosaurs, aetosaurs, and crocodylomorphs.

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

Teratosaurus is a genus of rauisuchians known from the Triassic Stubensandstein of Germany. It is estimated to be 6.2 meters (20.35 ft) long.

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

Gracilisuchus is an extinct genus of tiny pseudosuchian from the Late Triassic of Argentina. It contains a single species, G. stipanicicorum, which is placed in the clade Suchia, close to the ancestry of crocodylomorphs. Both the genus and the species were first described by Alfred Romer in 1972.

<span class="mw-page-title-main">Rauisuchidae</span> Extinct family of reptiles

Rauisuchidae is a group of large predatory Triassic archosaurs. Some disagreement exists over which genera should be included in the Rauisuchidae and which should be in the related Prestosuchidae and Poposauridae, and indeed whether these should even be thought of as separate valid families. Rauisuchids occurred throughout much of the Triassic, and may have first occurred in the Early Triassic if some archosaurian taxa such as Scythosuchus and Tsylmosuchus are considered to be within the family.

<span class="mw-page-title-main">Prestosuchidae</span> Extinct family of reptiles

Prestosuchidae is a polyphyletic grouping of carnivorous archosaurs that lived during the Triassic. They were large active terrestrial apex predators, ranging from around 2.5 to 7 metres in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time. While resembling erythrosuchids in size and some features of the skull and skeleton, they were more advanced in their erect posture and crocodile-like ankle, indicating more efficient gait. "Prestosuchids" flourished throughout the whole of the middle, and the early part of the late Triassic, and fossils are so far known from Europe, India, Africa (Tanzania), Argentina, and Paleorrota in Brazil. However, for a long time experts disagree regarding the phylogenetic relationships of the group, what genera should be included, and whether indeed the "Prestosuchidae" constitute a distinct family.

<i>Ticinosuchus</i> Extinct species of reptile

Ticinosuchus is an extinct genus of suchian archosaur from the Middle Triassic of Switzerland and Italy.

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

Saurosuchus is an extinct genus of large loricatan pseudosuchian archosaurs that lived in South America during the Late Triassic period. It was a heavy, ground-dwelling, quadrupedal carnivore, likely being the apex predator in the Ischigualasto Formation.

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

Prestosuchus is an extinct genus of pseudosuchian in the group Loricata, which also includes Saurosuchus and Postosuchus. It has historically been referred to as a "rauisuchian", and was the defining member of the family Prestosuchidae, though the validity of both of these groups is questionable: Rauisuchia is now considered paraphyletic and Prestosuchidae is polyphyletic in its widest form.

<i>Batrachotomus</i> Genus of reptiles

Batrachotomus is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. Batrachotomus was described by palaeontologist David J. Gower 22 years after its discovery.

<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.

Yarasuchus is an extinct genus of avemetatarsalian archosaur that lived during the Anisian stage of the Middle Triassic of India. The genus was named and described in 2005 from a collection of disarticulated but fairly complete fossil material found from the Middle Triassic Yerrapalli Formation. The material is thought to be from two individuals, possibly three, with one being much more complete and articulated than the other. The type and only species is Y. deccanensis. Yarasuchus was a quadruped roughly 2–2.5 metres (6.6–8.2 ft) long, with an elongated neck and tall spines on its vertebrae. Unlike other quadrupedal Triassic reptiles, the limbs and shoulders of Yarasuchus were slender, and more like those of ornithodirans.

Arganasuchus is an extinct genus of "rauisuchian" (loricatan) archosaur. It is known from a single species, Arganasuchus dutuiti. Fossils of this genus have been found in Upper Triassic rocks of the Argana Basin, Morocco. Though its remains were initially referred to Ticinosuchus when discovered during the 1970s, in 2007 it was identified as a distinct genus with unique features of the pubis and maxilla. Arganasuchus also had several anatomical details in common with Batrachotomus, Fasolasuchus, and Postosuchus, though its relations with other loricatans remains unresolved. Arganasuchus is considered a carnivore due to its large, knife-shaped teeth.

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

Fasolasuchus is an extinct genus of loricatan. Fossils have been found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina that date back to the Norian stage of the Late Triassic, making it one of the last "rauisuchians" to have existed before the order became extinct at the end of the Triassic.

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

Heptasuchus is an extinct genus of loricatan pseudosuchian known from the Middle or Late Triassic upper Chugwater Group of Wyoming, United States. It contains a single species, Heptasuchus clarki, the first formally recognized "rauisuchian" or loricatan pseudosuchian from North America.

Rauisuchus is a genus of extinct archosaurs which lived in what is now the Geopark of Paleorrota, Brazil, during the Late Triassic period. It contains one species, R. tiradentes.

Procerosuchus is an extinct genus of loricatan archosaur. Fossils have been collected from the Late Triassic Santa Maria Formation in Geopark of Paleorrota, Rio Grande do Sul, Brazil, which is Carnian in age. The genus was first described by the German paleontologist Friedrich von Huene in 1942.

<span class="mw-page-title-main">Loricata</span> Extinct clade of reptiles

Loricata is a clade of archosaur reptiles that includes crocodilians and some of their Triassic relatives, such as Postosuchus and Prestosuchus. More specifically, Loricata includes Crocodylomorpha and most "rauisuchians", a paraphyletic grade of large terrestrial pseudosuchians which were alive in the Triassic period and ancestral to crocodylomorphs.

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

Youngosuchus is an extinct genus of archosaur from the Middle Triassic of China. The type species is Y. sinensis. Y. sinensis was first described in 1973 as a new species of the erythrosuchid Vjushkovia. In 1985, it was reassigned as its own genus of rauisuchid. A 1992 study supported the original classification of Youngosuchus sinensis as an erythrosuchid, but more recent studies classify it as a "rauisuchian"-grade loricatan archosaur completely unrelated to Vjushkovia, which is most likely a synonym of Garjainia.

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

Decuriasuchus is an extinct genus of loricatan from the Middle Triassic period. It is a carnivorous archosaur that lived in what is now southern Brazil, in Paleorrota. It was first named by Marco Aurélio G. França, Jorge Ferigolo and Max C. Langer in 2011 and the type species is Decuriasuchus quartacolonia. The generic name means "unit of ten crocodiles" in Latin and Greek in reference to the ten known specimens and the animal's possible group behavior. The specific name refers to the Quarta Colonia region where the fossils were collected.

Schultzsuchus is an extinct genus of pseudosuchian from the Triassic Santa Maria Formation of Brazil. Initially described as a species of Prestosuchus, a 2024 study found the taxon to differ in multiple aspects of its anatomy, enough to warrant it being placed in a distinct genus. Unlike Prestosuchus, which is a more derived member of Loricata, Schultzsuchus appears to have been a basal member of the clade Poposauroidea.

References

  1. Gower, D. J. (2000). "Rauisuchian archosaurs (Reptilia:Diapsida): An overview" (PDF). Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 218 (3): 447–488. doi:10.1127/njgpa/218/2000/447.
  2. Sulej, T (2005). "A new rauisuchian reptile (Diapsida: Archosauria) from the Late Triassic of Poland". Journal of Vertebrate Paleontology. 25 (1): 78–86. doi:10.1671/0272-4634(2005)025[0078:ANRRDA]2.0.CO;2. S2CID   86284626.
  3. Bonaparte, J. F. (1984). "Locomotion in rauisuchid thecodonts". Journal of Vertebrate Paleontology. 3 (4): 210–218. doi:10.1080/02724634.1984.10011976.
  4. Dawley, R. M.; Zawiskie, J. M.; Cosgriff, J. W. (1979). "A rauisuchid thecodont from the Upper Triassic Popo Agie Formation of Wyoming". Journal of Paleontology. 53 (6): 1428–1431.
  5. 1 2 Lautenschlager, Stephan; Julia Brenda Desojo (2011). "Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus ferox and Stagonosuchus nyassicus". Paläontologische Zeitschrift. 85 (4): 357–381. doi:10.1007/s12542-011-0105-1. hdl: 11336/68929 . S2CID   86671911.
  6. Huene, F.v. (1936). "Übersicht über Zusammensetzung und Bedeutung der Thecodontia". Zentralblatt für Mineralogie, Geologie und Paläontologie. 1936: 162–168.
  7. Romer, A. S. (1967). Vertebrate Paleontology. Chicago: University of Chicago Press. p. 468.
  8. Brusatte, S.L.; Benton, M.J.; Desojo, J.B.; Langer, M.C. (2010). "The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida)" (PDF). Journal of Systematic Palaeontology. 8 (1): 3–47. doi:10.1080/14772010903537732. hdl: 20.500.11820/24322ff3-e80e-45f2-8d53-d35fd104195c . S2CID   59148006.
  9. Desojo, Julia Brenda; Baczko, María Belén von; Rauhut, Oliver W. M. (2020-02-18). "Anatomy, taxonomy and phylogenetic relationships of Prestosuchus chiniquensis (Archosauria: Pseudosuchia) from the original collection of von Huene, Middle-Late Triassic of southern Brazil". Palaeontologia Electronica. 23 (1): 1–55. doi: 10.26879/1026 . hdl: 11336/127498 . ISSN   1094-8074.