Bradysaurus baini
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Bradysaurus Temporal range: Capitanian, 265–260 Ma |
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| B. baini skeleton in the Museum für Naturkunde, Berlin | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Procolophonomorpha |
| Family: | †Pareiasauridae |
| Subfamily: |
†Bradysaurinae von Huene, 1948 |
| Genus: |
†Bradysaurus Watson, 1914 |
| Type species | |
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†Bradysaurus baini Seeley, 1892 |
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| Species | |
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| Synonyms | |
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Bradysaurus was a large, early and common pareiasaur, the fossils of which are known from the Tapinocephalus Assemblage Zone (Capitanian age) of the South African Karoo. Along with the similarly large dinocephalia, the bradysaurs constituted the herbivorous megafauna of the late Middle Permian Period. In life they were probably slow, clumsy and inoffensive animals, that had evolved a covering of armoured scutes to protect them against their predators, the gorgonopsians.
Bradysaurus was 2.5 meters 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.
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, were no larger. The advantage of large size was to provide defense against predators and to maintain a stable body temperature (gigantothermy).
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.
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