Understanding the origin and diversification of organisms requires a good phylogenetic estimate of their age and diversification rates. This estimate can be difficult to obtain when samples are limited and fossil records are disputed, as in Dictyoptera. To choose among competing hypotheses of origin for dictyopteran suborders, we root a phylogenetic analysis (~800 taxa, 10 kbp) within a large s...

Phylogenetic hypotheses, biogeographic dispersal models, and evolutionary scenarios are difficult to form but easy to reject: a single fossil may be sufficient. Previously neglected or inaccessible regions bear high potential for the discovery of such fossils, because they shed light on new faunas with unorthodox combinations of taxa, and sometimes reveal representatives of clades that were not...

Actinopterygians (ray-finned fishes) successfully passed through four of the big five mass extinction events of the Phanerozoic, but the effects of these crises on the group are poorly understood. Many researchers have assumed that the Permo-Triassic mass extinction (PTME) and end-Triassic extinction (ETE) had little impact on actinopterygians, despite devastating many other groups. Here, two m...

Ornithischian dinosaur body fossils are extremely rare in Triassic rocks worldwide, and to date the majority of such fossils consist of isolated teeth. Revueltosaurus is the most common Upper Triassic ornithischian dinosaur and is known from Chinle Group strata in New Mexico and Arizona. Historically, all large (>1 cm tall) and many small ornithischian dinosaur teeth from the Chinle have been r...

The origin of the limbless caecilians remains a lasting question in vertebrate evolution. Molecular phylogenies and morphology support that caecilians are the sister taxon of batrachians (frogs and salamanders), from which they diverged no later than the early Permian. Although recent efforts have discovered new, early members of the batrachian lineage, the record of pre-Cretaceous caecilians i...

The end-Permian mass extinction is now robustly dated at 252.6 ± 0.2 Ma (U–Pb) and the Permian–Triassic (P–T) GSSP level is dated by interpolation at 252.5 Ma. An isotopic geochronological timescale for the Late Permian–Early Triassic, based on recent accurate high-precision U–Pb single zircon dating of volcanic ashes, together with calibrated conodont zonation schemes, is presented. The durati...

We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian-Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy) provide evidence for a diversity not yet sampled by body fossils. The integ...

The upper Triassic deposits of the Selous Basin in south Tanzania have not been prospected for fossil tetrapods since the middle of last century, when Gordon M. Stockley collected two rhynchosaur bone fragments from the so called "Tunduru beds". Here we present the results of a field trip conducted in July 2015 to the vicinities of Tunduru and Msamara, Ruvuma Region, Tanzania, in search for sim...

early triassic carbonate ramp sediments of the lower part of the elika formation are known as vermicular limestone. in the moro mountain, northwest iran, the vermicular limestone includes bioturbated dolomitic mudstone, bioclastic packstone and grainstone, algal calcirudite and intraclastic grainstone. these sediments accumulated in their lower part in open marine subtidal and shoal environment...

Contrary to the fast radiation of most metazoans after the end-Permian mass extinction, it is believed that early marine reptiles evolved slowly during the same time interval. However, emerging discoveries of Early Triassic marine reptiles are questioning this traditional view. Here we present an aberrant basal ichthyosauriform with a hitherto unknown body design that suggests a fast radiation ...