boundary. The regional prevalence of MISS is attributable to a decrease in bioturbation and grazing pressure as a result of aridification and temperature increase. The disappearance of MISS later in the Early Triassic has been interpreted as a signal of increased bioturbation and recovery of terrestrial ecosystems. Aquatic biota In the oceans, the most common Early Triassic hard-shelled marine invertebrates were bivalves, gastropods, ammonites, echinoids, and a few articulate brachiopods. Conodonts experienced a revival in diversity following a nadir during the Permian. The first oysters appeared in the Early Triassic. They grew on the shells of living ammonoids as epizoans. Microbial reefs were common, possibly due to lack of competition with metazoan reef builders as a result of the extinction. However, transient metazoan reefs reoccurred during the Olenekian wherever permitted by environmental conditions. Ammonoids show blooms followed by extinctions during the Early Triassic. Aquatic vertebrates diversified after the extinction. Fishes: Typical Triassic ray-finned fishes, such as Australosomus, Birgeria, Bobasatrania, Boreosomus, Pteronisculus, Parasemionotidae and Saurichthys appeared close to the Permian-Triassic boundary, whereas neopterygians diversified later during the Triassic. Many species of fish had a global distribution during the Early Triassic. Coelacanths show a peak in their diversity and new modes of life (Rebellatrix). Chondrichthyes are represented by Hybodontiformes like Palaeobates, Omanoselache, Lissodus, some Neoselachii, as well as last survivors of Eugeneodontida (Caseodus, Fadenia). Amphibians: Relatively large, marine temnospondyl amphibians, such as Aphaneramma or Wantzosaurus, were geographically widespread during the Induan and Olenekian ages. The fossils of these crocodile-shaped amphibians were found in Greenland, Spitsbergen, Pakistan and Madagascar. Reptiles: In the oceans, first marine reptiles appeared during the Early Triassic. Their descendants ruled the oceans during the Mesozoic. Hupehsuchia, Ichthyopterygia and sauropterygians are among the first marine reptiles to enter the scene in the Olenekian (e.g. Cartorhynchus, Chaohusaurus, Utatsusaurus, Hupehsuchus, Grippia, Omphalosaurus, Corosaurus). Other marine reptiles such as Tanystropheus, Helveticosaurus, Atopodentatus, placodonts or the thalattosaurs followed later in the Middle Triassic. The Anisian aged ichthyosaur Thalattoarchon was one of the first marine macropredators capable of eating prey that was similar in size to itself, an ecological role that can be compared to that of modern orcas. Fossil gallery See also Geologic time scale Triassic Mass extinction References Further reading External links GeoWhen Database - Early Triassic Palaeos scotese 01 Geological epochs 01 de:Buntsandstein