Some heterostrophic gastropods from Triassic St. Cassian Formation with a discussion on the classification of the Allogastropoda

Fifteen species of Heterostropha are described, 12 of them for the first time. All are newly interpreted with regard to their taxonomic relation to fossil and living gastropods. The Streptacidoidea with long Paleozoic history are represented in the Late Triassic St. Cassian Formation by several genera that can be differentiated into four families. The Ebalidae are represented byEbala, with smooth protoconch, Cassianebalidae byCassianebala andLoxebala with axially ornamented protoconch. The Donaldinidae of St. Cassian are represented by one species ofDonaldina and two ofNeodonaldina that stand in the continuation of Paleozoic species ofDonaldina. Architectonicoidea with shells coiled in a plane and Valvatoidea appear in the St. Cassian fauna without known Paleozoic relation. In the former superfamily the Architectonicidae can be recognized in the genusRinaldoconchus with two species. Cassianaxidae withCassianaxis, Amphitomariidae withAmphitomaria, Stuoraxidae withStuoraxis andAmpezzogyra have a sinistral protoconch and planispirally coiled dextral teleconchs. They all resemble different modern species that have similarly small shells. Modern Hyalogyrinidae have withAlexogyra a new representative from the Triassic. The Valvatoidea are represented with the generaCarboninia andBandellina of the Cornirostridae in the Triassic representatives. The relation of described species in the system of the Heterostropha is discussed.     

Biological response to experimental damage of the phragmocone and siphuncle in Nautilus pompilius Linnaeus

Tsujino, Y & Shigeta, Y. 2012: Biological response to experimental damage of the phragmocone and siphuncle in Nautilus pompilius Linnaeus. Lethaia, Vol. 45, pp. 443–449. Three adult specimens of Nautilus pomplilius Linnaeus from the Philippines were experimented on to estimate the biological response to damage of the phragmocone and siphuncle in this cephalopod mollusc. In addition, the data obtained from the experiments were used for discussion of shell damage in ammonoids and in other extinct cephalopods. Specimen’s phragmocone and siphuncle were perforated and severed artificially, followed by observations in the laboratory tank during periods of 75 and 132 days. For at least 2 or 3 months, all individuals survived after damage to the phragmocone and siphuncle despite loss of neutral buoyancy. Based on our observations after completion of the experiments, the severed adoral remaining part of siphuncle healed by the siphunclar epithelium. In addition, perforation of the phragmocone was partly repaired by shell secretion from the dorsally extending mantle due to subsequent volution of shell growth. Our experiments revealed that damage to the phragmocone and siphuncle in Nautilus was not necessarily a lethal injury. It may be possible that such biological response also applies to extinct ammonoids and nautiloids. In a similar case of extinct ammonoids and nautiloids, damage to their phragmocone and siphuncle may also not have been a lethal injury as with Nautilus. However, some factors leading to death are likely to be dependent on the degree of damage to the phragmocone and siphuncle and influence of hydraulic pressure. □Ammonoids, injury, nautiloids, Nautilus, phragmocone, repair, siphuncle.     

New finds ofOmphalosaurus and a review of Triassic ichthyosaur paleobiogeography

Triassic ichthyosaurs are very widespread and diverse but most taxa are poorly known. New discoveries, such as described in this paper, underscore the first statement but only slowy invalidate the second. The first associated skeleton of the unusual durophagous ichthyosaurOmphalosaurus (O. wolfi) is reported from the Middle Triassic (earliest Ladinian) of the northern Alps. The vertebrae are of the ichthyosaurian type, firmly establishing the ichthyosaurian affinities of the genus. A round bone from the Muschelkalk of Franconia, Germany, is identified and described as a left humerus ofOmphalosaurus sp. These finds greatly extend the paleogeographic and temporal range ofOmphalosaurus which previously was only known from the western cratonic margin of North America and from Spitsbergen. The new records ofOmphalosaurus allow a revised differential diagnosis of the genus and a revision of its species. Valid species ofOmphalosaurus areO. nettarhynchus, O. nevadanus, andO. wolfi. In conjunction with such new insights into Triassic ichthyosaur distribution, it is necessary to address the validity of the poorly known genera such as the Middle TriassicPessosaurus. This taxon must be considered invalid because it lacks diagnostic characters. In assessing progress in research on Triassic ichthyosaurs and their paleobiogeography, it becomes apparent that supra-specific diversity appears largely known, at least for the pre-Norian record of North America, Europe, and East Asia.     

On the anatomy and relationships ofEfraasia diagnostica (Huene) n. gen., a prosauropod dinosaur (Reptilia: Saurischia) from the Upper Triassic of Germany

Palaeosaurus (?) diagnosticus Huene from the Stubensandstone (Upper Triassic, Norian) of Nordwürttemberg, Germany is made the type species of a new genus of prosauropod dinosaurEfraasia, which is referred to the family Anchisauridae. The anatomy ofEfraasia diagnostica is conservative and it was an ideal ancestor for the later and more specializedAnchisaurus polyzelus of North America. The slenderness of the manus and pes ofEfraasia andAnchisaurus is matched amongst prosauropods only by the feet ofGyposaurus capensis andThecodontosaurus antiquus. Staurikosaurus pricei Colbert from the Upper Triassic of Brazil is probably a very primitive theropod dinosaur.     

Wirbeltierreste aus dem mittleren muschelkalk (trias) von göttingen,west-deutschland

A rich vertebrate fauna is described from the Middle Muschelkalk (Anis, Triassic) north of Gottingen, West-Germany. Completely preserved juvenile fishes ofEosemionotus vogeli Fritsch 1906 occur besides teeth of selachians, scales and some bones of actinopterygians and actinistians and bones of nothosaurs. Genus and species ofEosemionotus vogeli is described and redefined. These findings and search in the literature demonstrate that a rich vertebrate fauna existed in the sea of the Middle Muschelkalk; the contrary is accepted generally.     

Are Spondylosoma and Staurikosaurus (Santa Maria Formation, Middle-Upper Triassic, Brazil) the oldest saurischian dinosaurs?

Spondylosoma absconditum (Ladinian, Middle Triassic) lacks certain Dinosauriformes-Dinosauria characters (sigmoid curve and epipophyses in neck, distally placed deltopectoral crest on humerus) and those present (accessary hyposphene-hypantra vertebral articulations, three sacral vertebrae, elongate pubis) also occur in the Rauisuchia (Crurotarsi, Suchia, Rauisuchiformes).Spondylosoma is tentatively referred to the Rauisuchidae because, as indicated by the ventrolaterally directed sacral ribs, the ilium was held obliquely (and not vertically as in the Poposauridae).Staurikosaurus pricei (Carnian, Upper Triassic), one of the oldest dinosaurs, possesses autapomorphies of Dinosauriformes, Dinosauria, Saurischia, and Herrerasauridae, but it retains certain plesiomorphic characters (subcircular distal end to tibia, ?proximally placed deltopectoral crest, axially unshortened neural spine to sacral 1, ?scapular spine unreduced distally) not present inHerrerasaurus (Carnian, Ischigualasto Formation, Argentina). However, the femur is more derived in the loss of the trochanteric shelf and reduction of the lesser trochanter (as also occurs in some prosauropods). The two vertebrae sacrum ofStaurikosaurus is a plesiomorphic character for Dinosauria (also in other herrerasaurids, German Upper Triassic prosauropodSellosaurus gracilis — ?males), to which was added either a caudosacral (e.g. Santa Maria prosauropodSaturnalia, Sellosaurus gracilis — ?females) or a dorsosacral (e.g. Ischigualasto theropodEoraptor and prosauropodRiojasaurus). Agrosaurus (Upper Triassic, Durdham Down, England — not Australia) is not a herrerasaurid; it is referred to the prosauropod dinosaurThecodontosaurus antiquus (Upper Triassic, Durdham Down).     

The status ofAnarosaurus multidentatus von Huene (Reptilia,Sauropterygia), from the lower anisian of the lechtaler alps (Arlberg,Austria)

The holotype ofAnarosaurus multidentatus von Huene (1958) from the lowermost Anisian of the Austrian Alps is redescribed and referred to the genusCymatosaurus. Eusauropterygian characters shared byA. multidentatus are the elongated and broadened Symphysis, and the contours of the lower jaw suggesting the presence of a constricted snout. Morphological details of the lower jaw Symphysis showA. multidentatus to be close toCymatosaurus among stem-group sauropterygians.Cymatosaurus multidentatus is the only representative of its genus known so far from the Alpine Triassic, and it represents the earliest known sauropterygian from the Alpine Triassic.     

Gradients of strain and strain rate in the hollow muscular organs of soft-bodied animals

The cylindrical shape of soft-bodied invertebrates is well suited to functions in skeletal support and locomotion, but may result in a previously unrecognized cost—large non-uniformities in muscle strain and strain rate among the circular muscle fibres of the body wall. We investigated such gradients of strain and strain rate in the mantle of eight long-finned squid Doryteuthis pealeii and two oval squid Sepioteuthis lessoniana. Transmural gradients of circumferential strain were present during all jets (n = 312); i.e. for a given change in the circumference of the outer surface of the mantle, the inner surface experienced a greater proportional change. The magnitude of the difference increased with the amplitude of the mantle movement, with circular muscle fibres at the inner surface of the mantle experiencing a total range of strains up to 1.45 times greater than fibres at the outer surface during vigorous jets. Differences in strain rate between the circular fibres near the inner versus the outer surface of the mantle were also present in all jets, with the greatest differences occurring during vigorous jetting. The transmural gradients of circumferential strain and strain rate we describe probably apply not only to squids and other coleoid cephalopods, but also to diverse soft-bodied invertebrates with hollow cylindrical or conical bodies and muscular organs.     

A Carapace-Like Bony ‘Body Tube’ in an Early Triassic Marine Reptile and the Onset of Marine Tetrapod Predation

Parahupehsuchus longus is a new species of marine reptile from the Lower Triassic of Yuan’an County, Hubei Province, China. It is unique among vertebrates for having a body wall that is completely surrounded by a bony tube, about 50 cm long and 6.5 cm deep, comprising overlapping ribs and gastralia. This tube and bony ossicles on the back are best interpreted as anti-predatory features, suggesting that there was predation pressure upon marine tetrapods in the Early Triassic. There is at least one sauropterygian that is sufficiently large to feed on Parahupehsuchus in the Nanzhang-Yuan’an fauna, together with six more species of potential prey marine reptiles with various degrees of body protection. Modern predators of marine tetrapods belong to the highest trophic levels in the marine ecosystem but such predators did not always exist through geologic time. The indication of marine-tetrapod feeding in the Nanzhang-Yuan’an fauna suggests that such a trophic level emerged for the first time in the Early Triassic. The recovery from the end-Permian extinction probably proceeded faster than traditionally thought for marine predators. Parahupehsuchus has superficially turtle-like features, namely expanded ribs without intercostal space, very short transverse processes, and a dorsal outgrowth from the neural spine. However, these features are structurally different from their turtle counterparts. Phylogeny suggests that they are convergent with the condition in turtles, which has a fundamentally different body plan that involves the folding of the body wall. Expanded ribs without intercostal space evolved at least twice and probably even more among reptiles.     

<Emphasis Type="Italic">Bevocastria magna</Emphasis> n. sp., eine neue Cyanobakterie aus den obertriassischen Riffkalken des Taurus-Gebirges (Türkei)

Bevocastria magna n. sp., an extremely large nodular species of the genusBevocastria, is described from Upper Triassic (Norian) reef limestones of a locality south of the town of Dereköy (SW Antalya, Turkey). The nodule ofB. magna looks like skeletons of chaetetid sponges which occur commonly at the same locality.B. magna is the first report of the genus from the Triassic deposits of Turkey.     

The original composition of the pro‐ostracum of an early Sinemurian belemnite from Belgium deduced from mode of fossilization and ultrastructure

Abstract: The pro‐ostracum of the early Sinemurian belemnite Nannobelus from the Belgian Province of Luxembourg is preserved as a thin, irregularly mineralized (phosphatized and pyritized), finely laminated structure, which is situated dorsally between the calcified rostrum and phragmocone. It has a median field with a criss‐cross pattern of bluntly pointed, curved growth lines and fine longitudinal ridges, as well as two lateral fields characterized by a fine ornament of closely spaced, longitudinal striae, each lateral field showing a narrow anterior belt‐like portion, the width of which equals about one‐third of that of the median field. Their posterior portion is remarkably asymmetrical, because its free margin (which does not about the median field) curves ventrally and the interspace between striae gradually increases here. The striation of the lateral field is formed by the longitudinally exposed narrow portions of succeeding, overlapping sublayers of the pro‐ostracum. Additionally, an internal sublayer with a silicified, honeycomb‐like structure is demonstrated in the pro‐ostracum. Based on microlamination that is comparable to that of the chitinous gladius in extant squids and on the irregular mineralization (unlike the rest of the shell), the pro‐ostracum is considered to have been originally mainly organic, containing an intermediate cartilaginous sublayer with a typical honeycomb‐like structure. The cartilaginous sublayer supposedly provided protection of the pro‐ostracum against fractures which might have resulted from regular contractions together with the muscular mantle during jet‐propulsion. Ultrastructural and chemical data on Nannobelus favour the interpretation of the pro‐ostracum as a novelty of the skeleton in coleoids rather than as a dorsal projection of the phragmocone wall.     

Analyse microstructurale ďunAulacoceras (Mollusca — Coleoidea) juvénile du Trias de Turquie

Morphology and microstructure of a juvenileAulacoceras, with protoconch, phragmocone and rostrum, are described. External morphology is not very characteristic, so systematical attribution is supported by microstructural data. Moreover rostral growth becomes clear by comparison with adult specimens.     

Rib fabrication in Ostreoidea and Plicatuloidea (Bivalvia,Pteriomorphia) and its evolutionary significance

Ribs of Ostreoidea and Plicatuloidea are defined as antimarginal, that is, perpendicular to the margin throughout growth. Morphogenetically, these ribs are unique, since, unlike radial ribs, they are secreted by a homogeneous mantle margin. Based also on the reconstructed shell secretion cycle in Bivalvia, we propose that ribs of Ostreoidea and Plicatuloidea are formed by a mantle margin which, upon extension from the shell margin, stretches and folds by taking the preformed ribs as templates. In extending perpendicular to the margin (as in all Bivalvia growing isometrically), such a mantle extends the rib pattern antimarginally. Ribs of this kind are purely mechanical structures, as their arrangement depends on the mechanical properties of the mantle and on the environmental conditions. This explains the high irregularity of such ribbing patterns. The presence of antimarginal ribs in both the Ostreoidea and Plicatuloidea sheds light on their origin. The first known oyster, Actinostreon cristadifformis, probably derived from an antimarginally ribbed Prospondylidae gen. indet. in the Late Permian or Early Triassic. Antimarginally ribbed Triassic species formerly included in Placunopsis originated both the Dimyidae Atreta in the Late Triassic and Enantiostreon in the Mid Triassic, which was transitional to Plicatulidae. Therefore, Dimyidae and Plicatulidae are closely connected and grouped under Plicatuloidea, to which Ostreoidea is phylogenetically unrelated.     

Adaptive homoeomorphy in the brachiopods Tetractinella Bittner and Cheirothyris Rollier

The Middle Triassic athyraceanTetractinella and the Upper Jurassic terebratellaceanCheirothyris show a close homoeomorphic resemblance in their external shell form. The homoeomorphy is here interpreted as the result of the parallel evolution of an identical adaptive device. Structurally, the homoeomorphy is due to the development of two pairs of long, narrow radial deflections of the commissure, and consequently of two pairs of marginal projections and radial costae on the shell. Functionally, these projections are interpreted as sensory “antennae”, which carried the sensitive mantle edges outwards beyond the rest of the shell, and hence provided the brachiopods with early warning of the approach of potentially harmful agents in the environment.     

OnStaurikosaums pricei,an early saurischian dinosaur from the Triassic of Brazil,with notes on the Herrerasauridae and Poposauridae

The anatomy of the saurischian dinosaurStaurikosaums pricei Colbert from the Santa Maria Formation (Middle or Upper Triassic) of Rio do Sul, Brazil is redescribed.Staurikosaurus has 9 (or possibly 10) short cervicals, 15 dorsals and 2 sacral vertebrae, a modified brachyiliac pelvic girdle and an elongate hindlimb with the tibia longer than the femur. The new family Staurikosauridae is erected, the Herrerasauridae is redefined, and both families are considered to be Saurischia incertae sedis. The distal part of the “femur” ofPoposaurus gracilis Mehl (Upper Triassic, North America) is the ventral part of the pubes with a footed distal end but, because some members of the Poposauridae have an imperforate acetabulum, this family is transferred from the Saurischia (Theropoda, Carnosauria) to the Thecodontia (Pseudosuchia).     

Taxonomic and biochronological significance of specimens of the Triassic dicynodontDinodontosaurus Romer 1943 in the Tübingen collection

Two species of the dicynodontDinodontosaurus from the Middle Triassic interval of the Santa Maria Formation in Rio Grande do Sul, southern Brazil,D. tener (von Huene 1935) andD. turpior (von Huene 1935), are based on undiagnostic lectotypes and thus arenomina dubia. The oldest valid, available name for a species ofDinodontosaurus isD. oliveirai Romer 1943, the type species of the genus. (The unused senior subjective synonymDiodontosaurus pedroanum Caldas, 1936 has been suppressed by the International Commission on Zoological Nomenclature).Chanaria platyceps Cox 1968 andDinodontosaurus brevirostris Cox 1968 are junior subjective synonyms ofD. oliveirai Romer 1943.Dinodontosaurus thus is a monospecific genus known from the Santa Maria Formation and the Ischichuca (= Chañares) Formation of northwestern Argentina. This dicynodont and associated tetrapods characterize the Chanarian land-vertebrate faunachron, which is of Middle Triassic age, probably Ladinian.     

Structural features of mycorrhizal associations in two members of the Monotropoideae, Monotropa uniflora and Pterospora andromedea

Species in the subfamily Monotropoideae (family Ericaceae) are achlorophyllous and myco-heterotrophic. They have become highly specialized in that each plant species is associated with a limited number of fungal species which in turn are linked to autotrophic plants. This study provides an updated and comprehensive examination of the anatomical features of two species that have recently received attention with respect to their host-fungal specificity. Root systems of Monotropa uniflora and Pterospora andromedea collected from the field were characterized by light microscopy and scanning electron microscopy. All roots of both species were associated with fungi, each root having a well-developed mantle, paraepidermal Hartig net, and intracellular fungal pegs within epidermal cells. The mantle of M. uniflora was multi-layered and numerous outer mantle hyphae developed into cystidia of two distinct morphologies. Large calcium oxalate crystals were present, primarily on the mantle surface. The outer mantle of P. andromedea was more loosely organized, lacked cystidia, and had smaller plate-like as well as cylindrical crystals on the surface and between outer mantle hyphae. Fungal pegs in M. uniflora originated from inner mantle hyphae that penetrated the outer tangential wall of epidermal cells; in P. andromedea, these structures were initiated either from inner mantle hyphae or Hartig net hyphae and penetrated radial walls of epidermal cells. With respect to function, fungal pegs occurred frequently in both host species and, although presumed to be the sites of active nutrient exchange, no direct evidence exists to support this. Differences between these two monotropoid hosts, resulting from the mycorrhizal fungi with which each associates, are discussed.     

The status of the sauropterygian reptilePartanosaurus zitteli Skuphos from the Middle Triassic of the Austrian Alps,with comments onMicroleptosaurus schlössen Skuphos

Partanosaurus zitteli Skuphos 1893 from the Ladinian (Partnachschichten) of the northern Alps (Vorarlberg, Austria) is identified as a junior synonym ofSimosaurus gaillardoti Meyer 1832. Its occurrence in the Germanic Basin (Upper Muschelkalk) predates its appearance in the Alpine Triassic, and suggests faunal interchange between these two faunal provinces during Middle and Upper Ladinian times.Microleptosaurus schlossen Skuphos 1893 is represented by very incomplete material only and must be treated as a nomen dubium.