Taphonomy and Palaeoenvironments a new early Permian Tetrapod fauna from Brazil

The Early Permian Pedra de Fogo Formation of Brazil accumulated in a large intracontinentalsag-basin (Parnaíba Basin) located in sub-tropical Gondwana around 20oS(palaeolatitude). With progressive climatic drying, palaeoenvironments changed from a large,shallow lake to expansive exposed mudflats surrounding a shrinking lacustrine wetland,culminating in isolated playas fed by ephemeral streams which finally became an aeoliandune field.Our team has collected over 500 fossils from this formation in northeastern Brazil. Theyinclude actinopterygians, dipnoans and chondrichthyans, together with two fully-articulatedcoelacanths, at least four temnospondyl taxa (the archegosaurid Prionosuchus, thetrimerorhachid Procuhy, the dvinosaur Timonya, and a rhinesuchid), small-to-mid-sizedcaptorhinid reptiles (cf. Captorhinus/Captorhinikos), and a small parareptile, as well asabundant fish-scale bearing spiral coprolites.Three gradationally superimposed sedimentary facies associations are recognized in the Pedrade Fogo Formation: offshore lacustrine, shoreline/carbonate mudflats and finally anephemeral stream/dune complex. The taphonomic style of vertebrate fossils varies withdepositional facies reflecting different modes of post mortem burial.Offshore facies comprise thick beds of massive siltstone and finely-laminatedsiltstone/mudstone couplets showing algal crenulations but no infaunal burrowing, indicativeof an anoxic lake bed. Scattered actinopterygian fish skeletons with scales are rare, but somefine sandstone turbidite/inundate interbeds contain more fully-articulated aquatic tetrapods,some with soft tissue preservation, indicative of death and burial caused by storm induceddensity underflows.The carbonate mudflats facies association contains silicified algal-laminated limestonesdisplaying stromatolite mounds, tepee and desiccation structures typical of alkaline lakeshorelines. Clusters of coprolites and fish-hash lenses comprising masses of isolated teeth andscales are suggestive of heavy predation within drying ponds and channels.The ephemeral stream/dunite facies contains most of the plant material, mainly tree trunksand in places at the top of the formation rare 3-D petrifications of leaves and fructifications.We are revealing a previously unknown diversity of early Permian (+/-280 Mya) tetrapods inGondwana. While some aspects of the fauna (e.g., caporhinids, trimerorhcachids) are similarto those known from the classic Permian redbeds of the southwestern United States, thepresence of taxa such as rhinesuchids suggest that the Gondwanan tropics were an importantcradle of later Permo-Triassic biodiversity. Dvinosaurian temnospondyls were a majorcomponent of these Gondwanan tetrapod communities that originated, and diversified in andaround tropical saline to brackish water lakes and wetlands.Fil: Smith, Roger. University of the Witwatersrand; SudáfricaFil: Cisneros, Juan. Universidade Federal do Piaui; BrasilFil: Angielczyk, Ken. Field Museum of National History; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Kammerer, Christian. North Carolina Museum of Natural Sciences; Estados UnidosFil: Frobisch, Jorg. Humboldt-Universität zu Berlin; Alemania20th Palaeontological Society of Southern Africa Biennial MeetingBloemfonteinSudáfricaThe National Museum, Bloemfontei

Deep-scaled fish (Osteichthyes: Actinopterygii) from the lower Permian (Cisuralian) lacustrine deposits of the Parnaíba Basin, NE Brazil

The richly fossiliferous deposits of the Brazilian Pedra de Fogo Formation originated in an extensive aquatic system in tropical Pangaea, and grade from marginal lacustrine into marine deposits at the depocenter in the western part of the Parnaíba Basin. In addition to the well-known tetrapod and macrofloral records from these deposits, the Pedra de Fogo Formation yields extensive fish fossils indicating a diverse and abundant ichthyofauna. Among the actinopterygians, deep-bodied morphotypes are represented by whole fish as well as disarticulated dermal scales found at various localities in the states of Maranhão and Piauí. The gross morphology, ornamentation, and histology of some of these scales is highly distinctive, indicating the presence of a novel taxon (Piratata rogersmithii gen. et sp. nov.). The external surface of a Piratata scale is covered in multiple round-to-slightly elongated tubercles. The scale lacks a ganoin cover and is made up of cellular bone and odontocomplexes of orthodentine composing the tuberculated scale surface. The scale morphology and ornamentation most closely resemble that of Cleithrolepis granulatus from the Triassic of Australia and Cleithrolepis extoni from the Triassic Stormberg Beds of South Africa, but the new taxon differs from previously described species in several diagnostic morphological features. The use of scale characters in the taxonomy of ray-finned fishes and the palaeogeographic, palaeoenvironmental, and geochronological implications of the new taxon are discussed.Fil: Richter, Martha. British Museum (Natural History); Reino UnidoFil: Cisneros, Juan C.. Universidade Federal do Piaui; BrasilFil: Kammerer, Christian. North Carolina Museum Of Natural Sciences; Estados UnidosFil: Pardo, Jason. Field Museum of National History; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Frobisch, Jorg. Staatliches Museum fur Naturkunde Stuttgart; AlemaniaFil: Angielczyk, Ken. Field Museum of National History; Estados Unido