A new gomphodont cynodont (Traversodontidae) from the Middle–Late Triassic Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence,Brazil

The tetrapod faunas from the terrestrial Middle–Late Triassic basins of Africa and South America are among the richest in the world, especially in non‐mammalian cynodonts. Despite the great abundance of cynodont specimens found in these basins, there are few known taxa that exhibit interbasinal distributions. Here we describe a new species of traversodontid cynodont of the genus Scalenodon from the Triassic Dinodontosaurus Assemblage Zone of the Santa Maria Supersequence, from the state of Rio Grande do Sul, Brazil. Scalenodon ribeiroae sp. nov. is based on a partial skull that possesses a combination of features not observed in any other South American traversodontid: ellipsoid upper postcanines with the transverse crest formed by three cusps, lacking a mesiobuccal accessory cusp, and with lingual cusp projected lingually creating a concave lingual surface on the upper postcanines; the paracanine fossa is positioned medially to the upper canine, and jugal lacks a suborbital process. A phylogenetic analysis places the new taxon in a basal position within the Family Traversodontidae, with the African Scalenodon angustifrons as sister‐taxon. The new specimen of Scalenodon represents the first record of this genus outside of the Manda Beds of Tanzania, and reinforces the biostratigraphical and biogeographical connection between Gondwanan Middle–Late Triassic tetrapod faunas. Although recent advances have been made, our current knowledge of these faunas is limited by the lack of absolute dates for most units and by uncertainties in the taxonomy and stratigraphical provenance of key fossils.     

A New Species Of The Late Triassic Rhynchosaur Hyperodapedon From The Santa Maria Formation Of South Brazil

A new rhynchosaur, Hyperodapedon huenei sp. nov., is described from the Upper Triassic Santa Maria Formation of the Paraná Basin, Brazil. The holotype is an almost complete skull and mandible, collected at Inhamandá, in the state of Rio Grande do Sul, Brazil. The diagnosis of the genus Hyperodapedon Huxley is revised to include not only H. huxleyi Lydekker and H. gordoni Huxley (as generally accepted), but also the new species described here, various specimens usually assigned to ' Scaphonyx fischeri ' Woodward, and ' S '. sanjuanensis Sill. H. huenei sp. nov. exhibits a number of plesiomorphic features and appears to be the least derived species of Hyperodapedon , forming a sister taxon to the remaining members of the genus. A preliminary phylogenetic analysis for the more derived rhynchosaurs is presented. ' Scaphonyx ' sulcognathus Azevedo and Schultz represents the sister taxon of Hyperodapedon , while ' Rhynchosaurus ' spenceri Benton is considered to be a more derived Middle Triassic rhynchosaur. key words : Rhynchosauria, Hyperodapedon , Triassic, Brazil.     

Osteology of Rauisuchus tiradentes from the Late Triassic (Carnian) Santa Maria Formation of Brazil,and its implications for rauisuchid anatomy and phylogeny

As the eponymous type species for rauisuchians, Rauisuchus tiradentes von Huene, 1938 represents an important but inadequately known specimen. The revision of the type material from the Upper Triassic (Carnian) Santa Maria Formation of Brazil reveals new anatomical data and previously unrecognised characters, including three new possible autapomorphies: a knob‐like thickening on the base of the posterior process of the premaxilla; short and ventrally keeled cervicals lacking postzygodiapophyseal laminae; and mid‐caudal vertebrae with an accessory neural spine and a postspinal lamina. Several elements are re‐identified, including a postorbital (originally identified as postfrontal) and a pterygoid (originally identified as a prefrontal), and additional material from a secondary fossil site, originally assigned to R. tiradentes, including a left ilium, is excluded. Based on the recovered information and new morphological data, the systematic position of R. tiradentes is tested in a comparison of two phylogenetic reanalyses. Both analyses differ in respect to the phylogenetic position of R. tiradentes, and recover ‘rauisuchians’ as a paraphyletic assemblage of non‐crocodylomoprh archosaurs. © 2014 The Linnean Society of London     

A new traversodontid cynodont from the Santa Maria Formation (Ladinian-Carnian) of southern Brazil, with a phylogenetic analysis of Gondwanan traversodontids

The Traversodontidae is a Triassic family of nonmammalian cynodonts, recorded worldwide, characterized by its bucco-lingually expanded postcanines. A recently discovered fauna in the locality of Santa Cruz do Sul, corresponding to the Santa Maria Formation of the Brazilian Middle/Upper Triassic (Ladinian/Carnian), is made up exclusively of nonmammalian cynodonts with an abundance of traversodontids. A new taxon, Santacruzodon hopsoni gen. et sp. nov . , the most commonly recorded traversodontid cynodont in the fauna, is described here. It is diagnosed by an autapomorphy, a very large posterolabial cusp in the upper postcanine, representing more than half of the labial crest, and a suite of traits present in other traversodontids. Among these features are the descendent flange of the jugal developed as a ball-shaped projection, also known in the Madagascan traversodontid Dadadon isaloi , and the presence of symmetrical incisors with numerous mesial and distal marginal cuspules, feature shared with the North American taxon Arctotraversodon plemmyridon . A phylogenetic analysis of traversodontids from Gondwana, based on a data matrix of 28 characters (mostly dental) and 15 terminals (13 traversodontids, including the new species, plus Diademodon and Trirachodon ) was performed. The new traversodontid appears as the sister taxon of Dadadon . A monophyletic Carnian group composed of Exaeretodon , Menadon and Scalenodontoides , with the Carnian Gomphodontosuchus , and the Ladinian Massetognathus as successive outgroups is also supported. In line with a recent phylogenetic hypothesis, a nonmonophyletic relationship for Scalenodon 'species' from the Anisian Manda beds also results from our analysis. Based on the cladogram obtained, morphological trends of change in the dentition of traversodontids throughout the Triassic are suggested.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 139 , 529−545.     

A new Hyperodapedon (Archosauromorpha,Rhynchosauria) from the Upper Triassic of India: implications for rhynchosaur phylogeny

A new species of the rhynchosaur genus Hyperodapedon, namely H. tikiensis, is described from well‐preserved skeletal elements that were collected from the Upper Triassic Tiki Formation of India. Hyperodapedon tikiensis is diagnosed on the basis of several cranial and postcranial features including longer than wide basipterygoid process, crest‐shaped maxillary cross section lateral to the main longitudinal groove, deeply excavated neural arches of mid‐dorsal vertebrae, long scapular blade, a pronounced deltopectoral crest, proximal humeral end much broader than distal end, iliac length greater than iliac height, equal pre‐ and postacetabular iliac lengths and circular femoral cross section. Two distinct morphotypes of the maxillary tooth plates can be discerned, which are attributed to ontogenetic variations. A maximum‐parsimony analysis was carried out to show that the order Rhynchosauria is characterized by nine cranial and one postcranial character states. The analysis reveals that Otischalkia elderae is invalid and the basal forms, Howesia and Mesosuchus, are closely related. The Mid‐Triassic genus Ammorhynchus is more derived and forms a sister group to the Late Triassic subfamily Hyperodapedontinae. Isalorhynchus and Teyumbaita are basal to the pandemic genus Hyperodapedon. Twenty‐four characters that are not homoplasious document major patterns of skeletal evolution in rhynchosaurs. From laterally oriented scapula and slender propodials, the postcranial skeleton evolved into a more robust form as is evident from nearly vertical scapula and increase in the robustness of the propodials. Shortening of the femur is noted in the derived Late Triassic forms as exemplified in Hyperodapedon gordoni, Hyperodapedon huxleyi and H. tikiensis.     

A new rhynchosaur maxillary tooth plate morphotype expands the disparity of the group in the Ischigualasto Formation (Late Triassic) of Northwestern Argentina

Abstract

Rhynchosaurs are a clade of quadruped, herbivorous stem-archosaur diapsids restricted to the Triassic Period. The group became globally distributed and the numerically dominant tetrapods of several terrestrial ecosystems before their extinction. Derived rhynchosaurs are characterized by a specialized masticatory apparatus, composed of a blade-and-groove occlusion with multiple longitudinal maxillary tooth rows. The morphology of the maxillary tooth plate has shown to be taxonomically and phylogenetically informative. So far, two rhynchosaur maxillary tooth plate morphotypes are known in Argentina, one belonging to an unnamed stenaulorhynchine from the Chañares Formation and the other to the hyperodapedontine Hyperodapedon sanjuanensis, the single rhynchosaur species currently name for the Ischigualasto Formation. Here we describe a new rhynchosaur maxillary tooth plate morphotype based on an indeterminate hyperodapedontine specimen from the Ischigualasto Formation. This maxillary tooth plate (PVL 2728) possesses a single longitudinal groove that divides symmetric lateral and medial tooth-bearing areas with relatively large tooth crowns, which is an uncommon combination of features among hyperodapedontines. These qualitative observations in addition to quantitative analyses show that the morphology of PVL 2728 differs from that of, at least, other sampled South American rhynchosaurs. Therefore, this specimen expands the morphological disparity of rhynchosaurs in northwest Argentina and southwestern Pangaea.     

First 'Rauisuchian' archosaur (Pseudosuchia,Loricata) for the Middle Triassic Santacruzodon Assemblage Zone (Santa Maria Supersequence), Rio Grande do Sul State,Brazil

The ‘Rauisuchia’ are a group of Triassic pseudosuchian archosaurs that displayed a near worldwide distribution. In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes). Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei. Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis.     

A new species of basal rhynchosaur (Diapsida: Archosauromorpha) from the early Middle Triassic of South Africa,and the early evolution of Rhynchosauria

Rhynchosauria was an important clade of herbivorous archosauromorph reptiles during the Triassic, with a worldwide distribution. We describe a new genus and species of early rhynchosaur, E ohyosaurus wolvaardti gen. et sp. nov. , from the early Middle Triassic (early Anisian) Cynognathus Assemblage Zone (Subzone B) of the Karoo Supergroup, South Africa. Eohyosaurus wolvaardti is known from a single skull, and is recovered as the sister taxon of Rhynchosauridae in a new phylogenetic analysis. Cynognathus Subzone B has previously yielded the stratigraphically oldest well‐understood rhynchosaur species, Mesosuchus browni and Howesia browni. Eohyosaurus wolvaardti increases the rhynchosaur diversity within this stratigraphical horizon to three species. Intriguingly, all currently confirmed rhynchosaur occurrences from the Early Triassic to earliest Middle Triassic are from South Africa. This may suggest a relatively restricted palaeogeographical distribution for early rhynchosaurs, followed by a global dispersal of rhynchosaurids during the Middle Triassic. © 2015 The Linnean Society of London     

Neoselachian (Chondrichthyes, Elasmobranchii) diversity across the Cretaceous-Tertiary boundary

Fishes are often thought to have passed through mass extinctions, including the Cretaceous-Tertiary (KT) event, relatively unscathed. We show that neoselachian sharks suffered a major extinction at the K/T boundary. Out of 41 families, 7 became extinct (17±12%). The proportional measure increases at lower taxic levels: 56±10% loss of genera (loss of 60 out of 107) and 84±5% loss of species (loss of 182 out of 216). However, the Maastrichtian and Danian are characterized by a high number of singleton taxa. Excluding singletons we have calculated a 34±11% loss of genera and a 45±9% loss of species. The simple completeness metric (SCM) for genera displays a decrease from the Maastrichtian (94%) to the Danian (85%) indicating a rather complete fossil record of neoselachian genera. The extinctions were heavy among both sharks and batoids (skates and rays), but most severe among batoids, which lost almost all identifiable species. There were equal losses among open marine apex predators (loss of Anacoracidae, Cretoxyrhinidae, and Scapanorhynchidae) and durophagous demersal forms from the continental shelf and shallow seas (Hypsobatidae, Parapaleobatidae, Sclerorhynchidae, Rhombodontidae). Benthopelagic and deep-sea forms were apparently little affected. New families with similar ecological roles (Carcharhinidae, Isuridae, Torpedinidae) replaced these families in the Danian, and full diversity of the different shark and batoid groups had been recovered by the end of the Paleocene or early Eocene. Sharks and rays suffered levels of extinction entirely in line with other groups of organisms at the K/T extinction event.     

A new herrerasaurid (Dinosauria, Saurischia) from the Upper Triassic Ischigualasto Formation of northwestern Argentina

Herrerasauridae comprises a basal clade of dinosaurs best known from the Upper Triassic of Argentina and Brazil, which have yielded remains of Herrerasaurus ischigualastensis and Staurikosaurus pricei, respectively. Systematic opinion regarding the position of Herrerasauridae at the base of Dinosauria has varied. Here we describe a new herrerasaurid, Sanjuansaurus gordilloi gen. n., sp. n., based on a partial skeleton from Carnian-age strata of the the Upper Triassic Ischigualasto Formation of northwestern Argentina. The new taxon is diagnosed by numerous features, including long, band-shaped and posterolaterally oriented transverse process on the posterior cervical vertebrae; neural spines of the sixth to eighth dorsal vertebrae, at least, bearing acute anterior and posterior processes; scapula and coracoid with everted lateral margins of the glenoid; and short pubis (63% of the femoral length). Phylogenetic analysis placed Sanjuansaurus within a monophyletic Herrerasauridae, at the base of Theropoda and including Herrerasaurus and Staurikosaurus. The presence of Sanjuansaurus at the base of the Ischigualasto Formation, along with other dinosaurs such as Herrerasaurus, Eoraptor, Panphagia, and Chromogisaurus suggests that saurischian dinosaurs in southwestern Pangea were already widely diversified by the late Carnian rather than increasing in diversity across the Carnian-Norian boundary.     

A new Brazilian species of Petunia (Solanaceae) from interior Santa Catarina and Rio Grande do Sul,Brazil

Petunia interior, a new species from interior Santa Catarina and Rio Grande do Sul, is described, and its morphological distinction from related species and features of its habitat are discussed.     

Taxonomic diversity and community structure of arbuscular mycorrhizal fungi (Phylum Glomeromycota) in three maritime sand dunes in Santa Catarina state,south Brazil

Community structure and species richness of arbuscular mycorrhizal fungi (Phylum Glomeromycota) were studied in sand dune sites at Itapiruba (southern), Joaquina (intermediate) and Praia Grande (northern) beaches along the coast of the state of Santa Catarina, Brazil. In each site, a 20 × 20 m plot was established and 20 soil samples collected in a regular grid pattern. Fungal spores were extracted from each sample, counted and identified to species level. A total of 25 species were recovered belonging to seven genera and five families in the Glomeromycota. Gigaspora albida and Acaulospora scrobiculata occurred in >50 % of samples at all three sites. Other common species whose sample frequency was >50 % in one or two sites were Scutellospora weresubiae, Scutellospora cerradensis and Racocetra gregaria, while the remaining majority of species were detected in <25 % of samples within a given site. Dune sites could be differentiated based on the higher frequency of occurrence of S. cerradensis and Acaulospora morrowiae in Itapiruba, S. weresubiae in Joaquina, and Scutellospora hawaiiensis in Praia Grande. No differences across sites were observed for species richness and total spore numbers, the latter averaging from 28.8 to 31.8 spores per 100 ml soil. Shannon diversity was significantly higher in Praia Grande compared to the other two sites. Differences in the relative spore abundance of genera among dunes were detected only for Scutellospora, which was significantly more abundant in the Joaquina beach. Community structure, as depicted by species rank/log abundance graphs, was not significantly different between areas according to the Kolmogorov–Smirnov two-sample test. Species accumulation curves demonstrated that 13 samples were enough to detect 90 % of all species. Overall, sand dune systems share similar arbuscular mycorrhizal fungal communities despite being geographically distant (150 km) from each other.     

The chondrichthyan fauna from the Middle-Late Triassic of Guanling (Guizhou province,SW China)

The Recent volutids Cymbiola and Melo burrow in a forward direction. This agrees well with the spiral terrace pattern observed in Eocene Volutidae, thus strengthening the idea that they were forward burrowers as well. The presence of collabral terraces near the aperture in the Cassidae suggests an oblique burrowing direction, by convergence with the Nassariidae. This is confirmed by observations on living cassids. The sutural canals and associated structures of the Olividae and Seraphidae are functional in detecting whether the posterior region of the shell is buried. This confirms the idea that fossil Strombidae possessing similar features were burrowers.

In contrast with these “predictable”; observations, burrowing was observed in a few gastropods the shell morphology of which would seem to exclude such behaviour, such as Architectonica, Cymatium, Volema and Bolinus. Thus, a few morphologic criteria appear to be reliable and of general applicability in inferring burrowing habits in gastropods. At the same time, the broad variety of burrowing mechanisms and life habits of gastropods makes it unlikely that general criteria will ever be found to exclude burrowing habits on the basis of shell morphology.     

A new ammonoid fauna from the Carnian (Upper Triassic) Kasimlar Formation of the Taurus Mountains (Anatolia,Turkey)

We describe a new ammonoid fauna from the Taurus Mountains of southern Turkey. The Carnian ammonoid fauna from A?a?iyaylabel is presented for the first time. Ammonoids were obtained from limestone to marl beds of an approximately 35‐m‐thick section, which presents the rare opportunity to investigate ammonoid faunas across the Lower–Upper Carnian boundary. Intense sampling near the village of A?a?iyaylabel led to the recognition of a new Lower Carnian (Julian 2) to Upper Carnian (Tuvalian 1) ammonoid fauna from the Kasimlar Formation. The genus Kasimlarceltites gen. nov. is reported for the first time from the Taurus Mountains, which represents the main faunal element and occurs as huge mass occurrence (n ? 1 million). Kasimlarceltites krystyni gen. et sp. nov., Klipsteinia disciformis sp. nov. and Anasirenites crassicrenulatus sp. nov. occur within the Lower Carnian Carbonate member (Units A–B) of the Kasimlar Formation from the Taurus Platform Units. Ammonoids described from the marls of the Tuvalian Marlstone member were deposited during a major, Tethyan‐wide climate crisis – the so‐called Carnian crisis – characterized by a demise of carbonate platforms. Based on the biostratigraphic relevance of certain ammonoid taxa described herein, the age of the analysed parts of the Kasimlar Formation is Julian 2 to Tuvalian 1. The discovery of the new ammonoid assemblages from A?a?iyaylabel substantiates the significance of Upper Triassic faunas within the Taurus Mountains and facilitates the correlation with faunal assemblages from other regions in the Tethyan Realm. The ammonoid fauna and facies indicate a general deepening from open‐platform margins, over deeper shelf settings down to an open marine‐influenced basinal environment. The tentative habitat for Kasimlarceltites gen. nov. is a shallow platform environment to upper mid‐ramp.     

A new Vaccinium (Ericaceae) from Guyanan Brazil

Recent collections from Serra do Aracá in northern Brazil include range extensions for several Guayanan Ericaceae and the newVaccinium pipolyi Luteyn which is herein described and illustrated.