Roger Malcolm Harris Smith

Evolutionary Studies Institute · Geological Sciences, University of the Witwatersrand

The latest Permian mass extinction (LPME) was triggered bymagmatism of the Siberian Traps Large Igneous Province (STLIP), which left an extensive record of sedimentary Hg anomalies at Northern Hemisphere and tropical sites. Here, we present Hg records from terrestrial sites in southern Pangea, nearly antipodal to contemporaneous STLIP activity, pro...

The sternum is a stabilizing element in the axial skeleton of most tetrapods, closely linked with the function of the pectoral girdle of the appendicular skeleton. Modern mammals have a distinctive sternum characterized by multiple ossified segments, the origins of which are poorly understood. Although the evolution of the pectoral girdle has been...

The sedimentology and taphonomy of in-situ fossils from earliest Triassic strata (Induan) in the southern Karoo Basin of South Africa is presented as evidence for episodes of drought-induced mass death of the resident tetrapods. Abundant skeletons are preserved in a 2 m-thick tabular silty-sandstone capping a multi-storeyed low-sinuosity channel sa...

Dicynodont therapsids are widely used in Permo-Triassic vertebrate biostratigraphy. However, recent taxonomic revisions have left few valid species with broad enough geographic distributions to use in establishing interbasinal correlations; instead, most currently recognized dicynodont species are basinal endemics. This is particularly true of the...

We describe two partial skulls of juvenile individuals of Moradisaurus grandis, a moradisaurine captorhinid from the upper Permian Moradi Formation of northern Niger. The juvenile skulls are less than half the length of the largest known skull of M. grandis, and differ in featuring a transversely narrow mandible, only five rows of maxillary teeth,...

Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic–Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood. For instance, knowledge on their behaviour is limited, although herding in sauropodomorphs has been well doc...

The Middle Triassic uppermost Omingonde Formation of Namibia records a fossil tetrapod fauna including stahleckeriid dicynodonts and probainognathian and traversodontid cynodonts, similar to other contemporary Gondwanan deposits. GSN F382 is a large predatory ‘rauisuchian’ archosaur from the uppermost Omingonde Formation that was originally identif...

Temnospondyl specimens collected recently in the Middle-?Late Triassic of the Ruhuhu (Tanzania) and Luangwa (Zambia) rift basins are described and figured. They are attributed to cf. Cherninia megarhina (Chernin & Cosgriff, 1975), Mastodonsauroidea indet., Stereospondyli indet., and cf. Stereospondyli, as well as intercentra of small adult individu...

A new burnetiamorph therapsid, Isengops luangwensis, gen. et sp. nov., is described on the basis of a partial skull from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Isengops is diagnosed by reduced palatal dentition, a ridge-like palatine-pterygoid boss, a palatal exposure of the jugal that extends far anter...

Recently collected temnospondyl fossils from the Cisuralian Pedra de Fogo Formation (north-eastern Brazil) indicate a diverse assemblage of aquatic tetrapods, including the dvinosaurs Timonya anneae and Procuhy nazariensis. Here we present revised diagnoses for these species and detailed descriptions of their holotypes. Timonya anneae is distinguis...

Significance Mass extinctions permanently altered life’s evolutionary trajectory five times in Earth’s history, and the end-Permian extinction was the greatest of these biotic crises. South Africa’s unparalleled fossil record provides a window into mass extinction dynamics on land. We analyze a unique dataset comprising hundreds of precisely positi...

Earth’s largest biotic crisis occurred during the Permo–Triassic Transition (PTT). On land, this event witnessed a turnover from synapsid- to archosauromorph-dominated assemblages and a restructuring of terrestrial ecosystems. However, understanding extinction patterns has been limited by a lack of high-precision fossil occurrence data to resolve e...

In the late 1980's the discovery of late Permian helical burrow casts containing articulated skeletons of the small herbivorous therapsid Diictodon feliceps led to conjecture that they may have been used for oviposition/parturition and shelter for infants. Here we present new fossil evidence in support of this interpretation and discuss the possibi...

A new parareptile from the Cisuralian Pedra de Fogo Formation of north-eastern Brazil is described. Karutia fortunata gen. et sp. nov. is the first Gondwanan member of Acleistorhinidae, a clade previously known only from North America but thought to be closely related to the Russian Lanthanosuchidae. A re-examination of parareptile phylogeny indica...

Numerous fossils of the toothed dicynodont Endothiodon have been collected previously from the Permian K5 formation of the Metangula Graben (Niassa, Mozambique). However,no identifiable vertebrate fossils have been reported from other stratigraphic units in the basin. Here we report likely Triassic tetrapod remains from the base of the Fubué Format...

Archosauria (birds, crocodilians and their extinct relatives) form a major part of terrestrial ecosystems today, with over 10 000 living species, and came to dominate the land for most of the Mesozoic (over 150 Myr) after radiating following the Permian-Triassic extinction. The archosaur skull has been essential to this diversification, itself dive...

The late Permian (Lopingian) Cistecephalus Assemblage Zone (CiAZ) of the Karoo Supergroup in South Africa has recently been radiometrically-dated to range from 256 to 255 My. It encompasses approximately one million years of the late Wuchiapingian epoch, at a time when the ancient intra-continental lowlands of southern Gondwana had fully recovered...

The earliest Triassic (Induan) Lystrosaurus Assemblage Zone has long been recognised as a particularly significant biozone in palaeoecological and palaeoenvironmental studies as it contains a community assemblage that records the survival and recovery from the end-Permian mass extinction (EPME). Here renamed the Lystrosaurus declivis Assemblage Zon...

The Endothiodon Assemblage Zone is the third oldest tetrapod biozone of the Beaufort Group (Adelaide Subgroup, Karoo Supergroup). It is situated between the underlying Tapinocephalus and overlying Cistecephalus assemblage zones and in the southwestern part of the basin corresponds to the majority of the Poortjie and Hoedemaker members of the Teeklo...

The Pedra de Fogo Formation in the Parnaíba Basin of northeastern Brazil hosts a recently discovered lacustrine fauna and provides the only known record of the Captorhinidae in South America. Here, new captorhinid remains from this unit are described. Two partial mandibles, including one formerly ascribed to the genus Captorhinus, are here referred...

Our recent comprehensive review of the Permian-Early Triassic tetrapod tracksites from South Africa includes a revision of the ichnotaxonomy and the incorporation of a large quantity of new material. The paper also discusses, in light of the revised ichnotaxonomy and palaeontology of several sites, trackmaker attribution and the biostratigraphy of...

The end-Permian mass extinction (EPME) is widely recognised as the largest mass extinction in Phanerozoic history. In marine strata the main extinction event is well constrained, and has been radiometrically-dated to an interval of some 60 kyr, approximately 251.9 million years ago. However, the age and duration of the EPME in the terrestrial realm...

Dicynodonts were herbivorous non-mammalian synapsids that were relatively abundant on the landmass of Pangea from the Mid Permian to Late Triassic. The dicynodont genus Endothiodon is well known from late Permian strata of the Karoo Basin of South Africa. It is characterised by replacement waves of internal tooth rows on the premaxilla and dentary;...

Over the past decade non-destructive, three-dimensional visualization and analysis of fossils using X-ray tomography has greatly advanced palaeontological studies worldwide. Micro-computed tomography (microCT) is now accepted as best practice in palaeontological studies to augment the anatomical description of newly discovered fossils. Despite adva...

The fossil record of mid to late Permian terrestrial vertebrates in the South African Karoo Basin is regarded as the most abundant and diverse in the world. Despite the extensive research on body fossils, to-date the vertebrate footprint sites have not been subjected to an anatomy-consistent ichnotaxonomic investigation. Here we present a comprehen...

Graphical abstract

Supplemental photos of all the studied material with scale, midline and footprint orientation

Triassic-aged fossil vertebrates have been sporadically collected from the Fremouw Formation, central Transantarctic Mountains, since their initial discovery in the late 1960s, giving paleontologists insight into high-latitude faunas in the wake of the end-Permian mass extinction event. On a recent expedition (2010–2011), a small reptile skeleton w...

Although Permian fossils have been known from the Parnaíba Basin for two centuries, and some faunal and flora elements are well known worldwide, research on the fossil assemblages from this basin has lagged relative to other, more accessible basins. In the last decade, however, there has been a significant increase in the study of fossils from the...

We report new data on the climate, paleoenvironments, and burial history of tetrapod fossils in the Middle Triassic Lifua Member of the Manda Beds (Songea Group) of southern Tanzania. Two bone-bearing intervals have been identified, both hosted by rubified floodplain mudrocks deposited alongside rivers that flowed from the Ruhuhu rift scarps into a...

Stable carbon isotope analysis of coexisting soil calcite and organic matter sampled from modern, California soil profiles representing 18 different U.S. Department of Agriculture (USDA) official soil series yields 51 paired calcite–organic matter δ¹³C values (Δ¹³Ccc-om values). These paired values correspond to atmospheric pCO2 estimates ranging f...

The two vertebrate fossil assemblages from the ?Middle Triassic Ntawere Formation have been known since the 1960s, but little new work has been done since the description of novel taxa in the 1960s and 1970s. Three recent field seasons have increased vertebrate diversity in the upper Ntawere assemblage and expanded biostratigraphic connections betw...

The Permian-Triassic mass extinction (PTME) was one of the transformative events of the Phanerozoic, marked by extinction, post-Permian transformation of surviving ecosystems, and the formation of new communities. The South African Karoo Basin has served as the primary source of data on the terrestrial component of these events, but its global appl...

Burnetiidae is a family of basal therapsids that is known from sequences of late Permian (Lopingian) age from southern and eastern Africa and European Russia. Recent discoveries of related genera within the broader clade Burnetiamorpha have added to our understanding of morphological variation in the group but have eroded the list of characters def...

Two new species of therocephalian therapsids are described from the upper Permian Teekloof Formation of the Karoo Basin, South Africa. They include two specimens of a whaitsiid, Microwhaitsia mendrezi gen. et sp. nov., and a single, small whaitsioid Ophidostoma tatarinovi gen. et sp. nov., which preserves a combination of primitive and apomorphic f...

Major transformations in brain size and proportions, such as the enlargement of the brain during the evolution of birds, are accompanied by profound modifications to the skull roof. However, the hypothesis of concerted evolution of shape between brain and skull roof over major phylogenetic transitions, and in particular of an ontogenetic relationsh...

Late Permian Karoo Basin tectonics in South Africa are reflected as two fining-upward megacycles in the Balfour and upper Teekloof formations. Foreland tectonics are used to explain the cyclic nature and distribution of sedimentation, caused by phases of loading and unloading in the southern source areas adjacent to the basin. New data supports thi...

Stable oxygen isotope compositions of phosphate (δ¹⁸Op) and carbonate (δ¹⁸Oc) of Permo-Triassic tetrapod teeth and bones reported along with their stratigraphic position, estimated age, palaeolatitudes and their carbonate content. Asterisks represent diagenetically altered values. DOI: http://dx.doi.org/10.7554/eLife.28589

The only true living endothermic vertebrates are birds and mammals, which produce and regulate their internal temperature quite independently from their surroundings. For mammal ancestors, anatomical clues suggest that endothermy originated during the Permian or Triassic. Here we investigate the origin of mammalian thermoregulation by analysing apa...

The temnospondyl Rhinesuchidae included more than 20 nominal taxa, many of which were based on poorly preserved and taxonomically indeterminate holotypes. In the present contribution, a comprehensive revision of Rhinesuchidae is presented based on a re-examination of every nominal species. As a result, we recognize eight valid species: Rhinesuchus...

The relationship between dinosaurs and other reptiles is well established, but the sequence of acquisition of dinosaurian features has been obscured by the scarcity of fossils with transitional morphologies. The closest extinct relatives of dinosaurs either have highly derived morphologies or are known from poorly preserved or incomplete material....

A new lithostratigraphic framework is introduced for the Permian Balfour and upper Teekloof formations (lower Beaufort Group) in the main Karoo Basin of South Africa. The Balfour Formation's Barberskrans Member (BM) is identified as the Oudeberg Member at its current type location. Thus the BM requires renaming, and is here defined as the Ripplemea...

Based on specimens previously identified as Tropidostoma , a new taxon of dicynodont ( Bulbasaurus phylloxyron gen. et sp. nov.) from the Karoo Basin of South Africa is described. Bulbasaurus is a medium-sized dicynodont (maximum dorsal skull length 16.0 cm) restricted to the Tropidostoma Assemblage Zone (early Lopingian) of the Beaufort Group. Bul...

Phylogenetic data matrix

Several studies of the marine sedimentary record have documented the evolution of global climate during the Permo-Triassic mass extinction. By contrast, the continental records have been less exploited due to the scarcity of continuous sections from the latest Permian into the Early Triassic. The South African Karoo Basin exposes one of the most co...

Since its discovery, Euparkeria capensis has been a key taxon for understanding the early evolution of archosaurs. The braincase of Euparkeria was described based on a single specimen, but much uncertainty remained. For the first time, all available braincase material of Euparkeria is re-examined using micro-computed tomography scanning. Contrary t...

The turtle shell is a complex structure that currently serves a largely protective function in this iconically slow-moving group. Developmental and fossil data indicate that one of the first steps toward the shelled body plan was broadening of the ribs (approximately 50 my before the completed shell). Broadened ribs alone provide little protection...

CT-rendering of specimen UFPI PV001, holotype of Timonya anneae, cranium and partial postcranium. Rotation around the long axis of the skeleton.

Supplementary Figure 1, Supplementary Table 1, Supplementary Note 1-2, Supplementary Discussion and Supplementary References

Terrestrial vertebrates are first known to colonize high-latitude regions during the middle Permian (Guadalupian) about 270 million years ago, following the Pennsylvanian Gondwanan continental glaciation. However, despite over 150 years of study in these areas, the bio-geographic origins of these rich communities of land-dwelling vertebrates remain...