''Garjainia'' is an extinct genus of erythrosuchid archosauriform

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

from the

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. It was approximately long. It contained two species, ''Garjainia prima'' from the Yarengian/Yarkenskian Supergorizont of Russia, and ''Garjainia madiba'' from the Burgersdorp Formation ( ''Cynognathus'' Assemblage Zone A) of South Africa. "''Vjuskovia triplicostata''", a name assigned to some erythrosuchid fossils from Russia, has been synonymized with ''Garjainia prima''.

Discovery

''Garjainia prima'' was first discovered in a small village in

by a farmer. The exact date of the discovery is not known but its believed to have been found some time in the early 1950s. A later find is ''G. madiba'', which was found in

in the 1960s. In the same locality another much larger erythrosuchid was also found, called ''

Erythrosuchus africanus ''Erythrosuchus'' (from , 'red' and , 'crocodile') is an extinct genus of archosauriform reptiles from the early Triassic of South Africa. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South ...

'', which was one of the largest terrestrial predators of the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

(250 million years ago)

Description

''Garjainia prima'' is believed to have been between in length, with ''Garjainia madiba'' having a length of . Apart from its much smaller size, it was quite similar to its close relative ''

Erythrosuchus ''Erythrosuchus'' (from , 'red' and , 'crocodile') is an extinct genus of archosauriform reptiles from the early Triassic of South Africa. Remains have been found from the Cynognathus Assemblage Zone of the Beaufort Group in the Karoo of South ...

''. The skull was very large and extremely robust; the strong lower jaw was armed with robust, curved teeth, and the muzzle was high and narrow. The legs were short but sturdy, while the tail was shorter than that of other primitive archosauriforms such as '' Proterosuchus''.The humerus was extremely massive in ''Garjainia'', while the shoulder blade was hourglass-shaped and the dorsal ribs were very elongated, giving the animal a high-profile. Two species belonging to this genus are known: ''Garjainia prima'' from Russia and ''G. madiba'' from South Africa. The African species differs from the Russian one in the presence of large bony protuberances on the lateral surfaces of the jugal and postorbital bones. ''G. madiba'' also has more teeth and a more elongated postacetabular process of the ilium. ''G. madiba'''s bosses are unknown among other erythrosuchids. The reason that these bosses are present is unknown. Possible solutions are that they were signs of maturity or

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

. These bosses are one of the autapomorphies of ''Garjainia''.

Classification

Garjainia was an erythrosuchid archosauriform. It was originally described by Soviet researcher VG Otschev, who classified it in its own family, Garjainidae. However, another Soviet scientist, Tatarinov, considered the genera ''Erythrosuchus'' and ''Garjainia'' to be synonymous. ''Garjainia'' has since been classified as a separate genus, part of the Erythrosuchidae. In addition, attention has been drawn to the existence of many primitive characteristics in this animal, which has led to suggestions that ''Garjainia'' represents a transitional form between the Proterosuchidae (a large, likely

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

lineage) and the family Erythrosuchidae.David Gover. The tarsus of erythrosuchid archosaurs, and implications for early diapsid phylogeny . Zoological Journal of the Linnean Society , 1996, 116: 347–375. PDF online. Below is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

based on the phylogeny of Parrish (1992).

References

Erythrosuchidae Early Triassic reptiles of Africa Early Triassic reptiles of Europe Prehistoric reptile genera {{paleo-reptile-stub