Benthosuchus

Abstract: The “capitosaurs” from the Lower Triassic of Madagascar are revised. Benthosuchus madagascariensis Lehman, 1961, and Wetlugasurus milloti Lehman, 1961, are combined in the new combination Watsonisuchus madagascariensis on the basis of the most complete growth series among capitosaurians. A phylogenetic analysis showed that the genus Watsonisuchus is justified, although its species W. madagascariensis is not the most derived within the genus. The skull growth of W. madagascariensis clearly shows an allometric trend, but the fact that adults have more dermo-sensory grooves than juveniles suggests surprisingly that they may have become progressively more aquatic during growth. The ontogeny of W. madagascariensis is compared with that of other temnospondyls. Different longi-rostrine conditions are observed in Permian and Triassic stereospondylomorphs (archegosaurians and capitosaurians, respectively). They are interpreted as convergences rather than are a synapomorphy of the clade.

Abstract: The status of the temnospondyl family Capitosauridae is reviewed. Only by the inclusion of the genera MastodonsaurusEocyclotosaurus can this group be considered monophyletic. This view is based on a range of robust characters which in combination constitute the most parsimonious hypothesis. The traditional view that MastodonsaurusEocyclotosaurus are sister taxa of Benthosuchus is demonstrated to be based on highly variable and/or homoplastic features, whose ancestral condition is moreover uncertain. The Capitosauridae encompasses the following successive sister groups: (1) various species of Parotosuchus (which do not necessarily form a monophylum); (2) the genera EryosuchusMastodonsaurus (which are probably monophyletic); and (3) a range of taxa with semi-closed or entirely closed otic notches, including the genera WellesaurusKupferzelliaEocyclotosaurus, and Cyclotosaurus. The closure of the otic notch, an oft-cited trend among capitosaurs, is most easily explained to have occurred only once, namely within the more advanced capitosaurids; the stratigraphical significance of this feature is, however, very limited. key words: Temospondyli, Stereospondyli, Capitosauridae, phylogeny.

Abstract: The trematosauroid genus Benthosuchus Efremov, 1937 is revised and its diagnosis is emended. This genus includes the previously established B. sushkini, B. korobkovi, and B. bashkiricus, and the new species B. gusevae described here. The new form is archaic relative to congeners and is similar in a number of characters to the archaic capitosaurid Wetlugasaurus samarensis, which confirms direct affinity of the two genera.