Mystriosuchus

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Mystriosuchus
Temporal range: Upper Triassic
Mystriosuchus planirostris skull.JPG
Skull of M. planirostris
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Phytosauria
Family: Phytosauridae
Subfamily: Pseudopalatinae
Genus: Mystriosuchus
Fraas, 1896
Species
  • M. planirostris (von Meyer, 1863 [originally Belodon planirostris]) (type)
  • M. westphali Hungerbuhler, 2000

Mystriosuchus (meaning "spoon-crocodile")[1] is an extinct genus of phytosaur that lived in the Late Triassic (middle Norian) in Europe. It was first named by Eberhard Fraas in 1896, and includes two species: M. westphali and the type species, M. planirostris.[2]

Description[edit]

1914 life restoration

Mystriosuchus planirostris measured about 4 m (13 ft), according to a complete skeleton which was found in 1995.[3] The postcranial anatomy of the skeleton suggests that Mystriosuchus was more adapted to aquatic life than other known phytosaurs, possessing shorter and more paddle-like limbs.[3] Cranial morphology is suggestive of a primarily fish eating diet, having long jaws like those of the modern gharials.[2]

M. planirostris, as the name implies, has a rather "plain" snout, without osseous ornamentation or crests. M. westphali, on the other hand, has multiple bony crests along the upper jaw, most prominently at the base and tip of the snout. As keratinous crests are known in phytosaurs,[4] it is possible that M. planirostris had soft tissue ornamentation.

Vertebrae[edit]

Mystriosuchus possesses many vertebrae, with 25 in the neck and torso, two in the pelvis, and 74 in the tail. The vertebral column is complete and nearly all articulated, although a portion of the tail can only be seen from top view. The vertebrae behind the axis vertebra are platycoelous(one surface flat and one concave), and are approximately rectangular in shape. Because of incomplete preservation, it can't be distinguished where the neck meets the torso, although at least 17 of the 25 vertebrae come from the latter. The trunk vertebrae are lower and wider than the neck vertebrae, but are still lightly built. The pelvic vertebrae have wide ribs which attach to the ilium (largest pelvis bone). The tail is longer than the rest of the body, being 51% of the total length of the taxon. The first 17 vertebrae of the tail are similar to those of the neck and trunk, being platycoelous and subrectangular. Chevrons are present after the fourth vertebra, but are only loosely attached for the beginning of the tail. At the end of the tail the vertebrae become more slanted, and the chevrons form an inverted 'T' shape, which is not seen in other phytosaurs but in sauropterygians or some crocodilians.[3] A complete specimen also has adapted tail bones which may show the presence of an expansion of the flesh to form a "fin".[5]

Classification[edit]

M. westphali skull

Mystriosuchus used to be placed in its own subfamily, Mystriosuchidae,[6][7] but subsequent cladistic analysis grouped it with other members of Pseudopalatinae, despite having several physical differences from most of the genera in this group.[2] Originally considered to be a freshwater genus, a recent specimen from Northern Italy has shown that some Mystriosuchus specimens lived a completely marine life.[8] In their paper on Parasuchus, Christian Kammerer and colleagues noted that Mystriosuchini has priority over Pseudopalatinae, so synonymized Pseudopalatinae with Mystriosuchini.[9]

Below is a cladogram from Stocker (2012):[10]

Phytosauria 

Wannia scurriensis

Paleorhinus bransoni

"Paleorhinus" sawini

Phytosauridae

Brachysuchus megalodon

Angistorhinus

Rutiodon carolinensis

"Machaeroprosopus" zunii

Protome batalaria

Leptosuchomorpha

"Phytosaurus" doughtyi

TMM 31173-120

Leptosuchus crosbiensis

Leptosuchus studeri

Smilosuchus lithodendrorum

Smilosuchus adamanensis

Smilosuchus gregorii

Pravusuchus hortus

Pseudopalatinae

Machaeroprosopus mccauleyi

Mystriosuchus westphali

Machaeroprosopus pristinus

References[edit]

  1. ^ dipbsf.uninsubria.it Mystriosuchus planirostris description Retrieved on May 25th, 2008.
  2. ^ a b c Hungerbühler, A. 2002. The Late Triassic phylosaur Mystriosuchus westphali, with a revision of the genus. Palaeontology 45(2): 377-418.
  3. ^ a b c Gozzi, E.; Renesto, S.A. (2003). "Complete specimen of Mystriosuchus (Reptilia, Phytosauria) from the Norian (Late Triassic) of Lombardy (Northern Italy)". Rivista Italiana Di Paleontologia e Stratigrafia. 109 (3): 475–498.
  4. ^ Stocker, M. R. & Butler, R. J. 2013. Phytosauria. Geological Society, London, Special Publications 379, 91-117.
  5. ^ Renesto, S.A.; Lombardo, C. (1999). "Structure of the tail of a phytosaur (Reptilia, Archosauria) from the Norian (Late Triassic) of Lombardy (Northern Italy)". Nota Breve, Rivista Italiana di Paleontologia e Stratigrafia. 105 (1): 135–144.
  6. ^ von Huene, F. 1915. On reptiles of the New Mexican Trias in the Cope Collection. Bulletin of the American Museum of Natural History 34: 485-507.
  7. ^ Long, R.A. & Murry, P.A. 1995. Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. Bulletin of the New Mexico Museum of Natural History and Science 4 ‡254 pp.
  8. ^ Gozzi, E. & Renesto, S.A. 2003. Complete specimen of Mystriosuchus (Reptilia, Phytosauria) from the Norian (Late Triassic) of Lombardy (Northern Italy). Rivista Italiana Di Paleontologia e Stratigrafia 109(3): 475-498.
  9. ^ Kammerer, C. F., Butler, R. J., Bandyopadhyay, S., Stocker, M. R. (2016), Relationships of the Indian phytosaur Parasuchus hislopi Lydekker, 1885. Papers in Palaeontology, 2: 1–23. doi: 10.1002/spp2.1022 http://onlinelibrary.wiley.com/doi/10.1002/spp2.1022/abstract
  10. ^ Stocker, M. R. (2012). "A new phytosaur (Archosauriformes, Phytosauria) from the Lot's Wife beds (Sonsela Member) within the Chinle Formation (Upper Triassic) of Petrified Forest National Park, Arizona". Journal of Vertebrate Paleontology. 32 (3): 573–586. doi:10.1080/02724634.2012.649815.

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