''Bradysaurus'' is a genus of large, primitive and widespread

pareiasaur Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with osteoderms which covered large areas of the body. They first appeared in southern Pangea during the Middle Per ...

. They possessed a covering of armoured

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...

s, likely serving as defense against their main predators, the

gorgonopsia Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of Saber-toothed predator, sabre-toothed therapsids from the Middle Permian, Middle to the Upper Permian, roughly between 270 and 252 million years ago. ...

ns. Fossils of ''Bradysaurus'' are known from the ''

Tapinocephalus ''Tapinocephalus'' ("low, depressed head") is an extinct genus of large herbivorous dinocephalians that lived during the Middle Permian Period in what is now South Africa. Only the type species, ''Tapinocephalus atherstonei'' is now considered v ...

Assemblage Zone In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties ...

(

Capitanian In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between and million years ago. It was preceded by t ...

age) of the South African

Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe Khoemana (also known as !Orakobab or Korana) word is a semidesert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is ...

. Along with the similarly large

dinocephalia Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. ...

, the bradysaurs constituted the

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

megafauna In zoology, megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and Neo-Latin ''fauna'' "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately , this lower en ...

of the late

Middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...

Period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

Description

''Bradysaurus'' was in length and half a tonne to a tonne in weight. The skull was large (about 42 to 48 centimeters long), broad and rounded at the front. It was coarsely sculptured and knobby, with the sutures between the bones not clearly visible. The marginal teeth were high-crowned, with only a few cusps, which is a primitive characteristic. The feet were short and broad, the phalangeal count being 2,3,3,3,2 on the fore-foot and 2,3,3,4,3 on the hind. The whole body is protected by dermal scutes, although these are not as thick or heavy as in more advanced forms.

Classification and species

''Bradysaurus'' is the only member of the subfamily Bradysaurinae. It is the most primitive known pareiasaur and can be considered a good ancestral type from which the others developed. Its large dimensions show that, even very early in their evolutionary history, these strange animals had already attained an optimal size. Even later, more advanced forms, like ''

Scutosaurus ''Scutosaurus'' ("shield lizard") is an extinct genus of pareiasaur parareptiles. Its genus name refers to large plates of armor scattered across its body. It was a large anapsid reptile that, unlike most reptiles, held its legs underneath its b ...

'', were no larger. The advantage of large size was to provide defense against predators and to maintain a stable body temperature (

gigantothermy Gigantothermy (sometimes called ectothermic homeothermy or inertial homeothermy) is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high bo ...

). Kuhn 1969 lists no fewer than nine species for this genus, but this is certainly an excessive number. Boonstra 1969 distinguishes only four species on the basis of tooth structure, two of which Kuhn places in the genus ''Embrithosaurus''. The genera ''Brachypareia'', ''Bradysuchus'', ''Koalemasaurus'', and ''Platyoropha'' are synonyms of ''Bradysaurus''. ''B. baini'' (Seeley, 1892) is from the ''Tapinocephalus'' zone, Lower Beaufort Beds, Karoo basin, South Africa. This is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

for the genus. The quadra-jugal region (cheek-bones) were only moderately developed. The snout was broad and rounded and there were 15 or 16 pairs of overlapping teeth in each jaw. This animal could be considered a generic early pareiasaur. According to Lee, 1997, the available material of ''B. baini'' lacks distinguishing

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...

or characteristics. ''B. seeleyi'' (Haughton and Boonstra, 1929) is from the ''Tapinocephalus'' zone, Lower Beaufort Beds, Karoo basin, South Africa. This is a less common form. Boonstra, 1969, considered this a valid species of ''Bradysaurus'' and Lee, 1997, considers this animal a sister group to more advanced pareiasaurs. ''B. seelyi'' seems to be closely related to ''Nochelesaurus'' and ''

Embrithosaurus ''Embrithosaurus'' was a pareiasaur from the Permian of South Africa. Description ''Embrithosaurus'' was in length and in weight. The skull is relatively deep and narrow. The body is lightly armoured with thin, smooth dermal scutes. Species * ...

''. In contrast to the more numerous but similarly sized ''B. baini'', the cheekbones were heavy and greatly enlarged. There were 19 or 20 pairs of strongly overlapping teeth on each jaw.

References

* Boonstra, L. D. 1969, "The Fauna of the Tapinoephalus Zone (Beaufort Beds of the Karoo)," Ann. S. Afr. Mus. 56 (1) 1-73, pp. 29–32 * Edwin H. Colbert, 1965, The Age of Reptiles, The World Naturalist, Weidenfeld and Nicolson, London, pp. 52–3 * Barry Cox, R.J.G.Savage, Brian Gardiner,

Dougal Dixon Dougal Dixon (born 1 March 1947) is a Scottish geologist, palaeontologist, educator and author. Dixon has written well over a hundred books on geology and palaeontology, many of them for children, which have been credited with attracting many to ...

, 1988 ''Illustrated Encyclopaedia of Dinosaurs and Prehistoric Animals'' *

Carroll Lane Fenton Carroll Lane Fenton (February 12, 1900, Butler County, Iowa – November 16, 1969, New Brunswick, New Jersey) was a geologist, paleontologist, neoichnologist, and historian of science. Biography Fenton was the author and illustrator of num ...

and

Mildred Adams Fenton Mildred Adams Fenton (November 14, 1899 – December 7, 1995) trained in paleontology and geology at the University of Iowa. She coauthored dozens of general science books with her husband, Carroll Lane Fenton, including ''Records of Evolution' ...

, 1958, ''The Fossil Book'', Doubleday & Co., Garden City, New York, p. 306 * Kuhn, O, 1969, Cotylosauria, part 6 of ''Handbuch der Palaoherpetologie'' (Encyclopedia of Palaeoherpetology), Gustav Fischer Verlag, Stuttgart & Portland, * Lee, MSY (1997), Pareiasaur phylogeny and the origin of turtles. ''Zool. J. Linnean Soc.'', 120: 197-280

External links

Bradysaurs
at Palaeos {{Taxonbar, from=Q137709 Pareiasauria Guadalupian reptiles of Africa Fossil taxa described in 1914 Capitanian genus first appearances Capitanian genus extinctions Prehistoric reptile genera