Search

This paper provides a description and analysis of cranial remains of a rhynchosaur from the Upper Triassic Evangeline Member of the Wolfville Formation of Nova Scotia, Canada. This material, primarily comprising jaw elements, represents the first definitive record of Late Triassic rhynchosaurs from eastern North America. All cranial bones can be assigned to Hyperodapedontinae. The dentition of the Nova Scotian hyperodapedontine differs from those of Hyperodapedon and Isalorhynchus. The maxilla apparently did not have more than two lateral rows and two medial rows of teeth. The teeth of the lateral row closest to the single groove dividing the maxillary tooth plate are more than twice as large as those of the medial row closest to the groove. The lateral and medial tooth-bearing portions of the maxilla become increasingly crest-like during ontogeny. The dentary lacks a lingual row of teeth. Based on this combination of features, the hyperodapedontine material from the Evangeline Member is assigned to a new taxon, Oryctorhynchus bairdi, gen. et sp. nov., which is the sister species to an unnamed hyperodapedontine taxon from Wyoming. This clade was recovered as the sister taxon to Hyperodapedon spp. in the phylogenetic analysis. The late Carnian or earliest Norian tetrapod assemblage from the Evangeline Member represents a mixture of faunal elements from a wide paleolatitudinal range, suggesting a more cosmopolitan distribution for continental tetrapods during the early Late Triassic than previously assumed.

Dicynodont fossils were first collected in the Luangwa Basin, Zambia, in the 1920s, but limited detailed study and taxonomic uncertainty have obscured their biostratigraphic utility and their implications for topics such as dicynodont biogeography and the effects of the end-Permian extinction. Here we present a comprehensive taxonomic revision of the dicynodonts of the Luangwa Basin, taking into account specimens in all major museum collections and new material collected by our team in 2009. We recognize 14 dicynodont species from the Upper Permian Upper Madumabisa Mudstone: Pristerodon mackayi, Endothiodon sp., Diictodon feliceps, Compsodon helmoedi, Emydops sp., Dicynodontoides cf. D. nowacki, a new tusked cistecephalid, cf. Katumbia parringtoni, Kitchinganomodon crassus, Oudenodon bainii, Odontocyclops whaitsi, Dicynodon huenei, Syops vanhoepeni, and a new lystrosaurid. Previous reports of Lystrosaurus in the basin appear to be in error. In addition, we found no significant partitioning of dicynodont taxa in the northern and southern parts of the basin, despite substantial differences in preservation, indicating the presence of a single faunal assemblage in the Upper Permian. The Madumabisa dicynodont assemblage is best correlated with the Cistecephalus Assemblage Zone of South Africa. The shared presence of Dicynodon huenei and possibly Katumbia in the Luangwa Basin and the Ruhuhu Basin of Tanzania suggests that the Tanzanian Usili Formation also can be correlated with the Cistecephalus zone. Interestingly, the Madumabisa assemblage from Zambia is more similar to the coeval assemblage from South Africa, despite its closer geographic proximity to Tanzania. The Karoo and Ruhuhu basins also include more endemic species in the Permian than the Luangwa Basin. The Middle Triassic Ntawere Formation preserves four dicynodont species (Kannemeyeria lophorhinus, “Kannemeyeria” latirostris, Zambiasaurus submersus, Sangusaurus edentatus), which occur at two stratigraphic levels. The lower Ntawere assemblage resembles that of the Omingonde Formation of Namibia in the presence of Kannemeyeria lophorhinus and potentially Dolichuranus (if “K.” latirostris represents this taxon). The upper Ntawere assemblage shares the genus Sangusaurus with that of the Manda beds of Tanzania and includes the endemic Zambiasaurus. Comparisons of these assemblages to the Omingonde and Manda suggest that both are best correlated with the Cynognathus C subzone. When combined with data on other tetrapod taxa, our revised dicynodont assemblages contribute to an emerging picture of broad faunal similarity in southern and eastern Africa during the Late Permian, and increasing differentiation between the South African and other Karoo basins following the end-Permian extinction.

The discovery of a Middle to Late Triassic (∼225 to 230 million years old) terrestrial vertebrate fauna from Madagascar is reported. This fauna documents a temporal interval not well represented by continental vertebrate assemblages elsewhere in the world. It contains two new prosauropod dinosaurs, representing some of the earliest dinosaur occurrences known globally. This assemblage provides information about the poorly understood transition to the dinosaur-dominated faunas of the latest Triassic.