Vertebrate Fossils from the Marine Triassic of Austria

Krainer, K. Lucas, S. G., and M. Strasser. 2011. Vertebrate fossils from the Northalpine Raibl beds, Western Northern Calcareous Alps, Tyrol (Austria). Austrian Journal of Earth Sciences 104:97-106. [free pdf]

Abstract -

Aus den Nordalpinen Raibler Schichten des Karwendels und der Mieminger Kette in den westlichen Nördlichen Kalkalpen (Tirol,

Österreich) werden Vertebratenreste wie Fischzähne von Actinopetrygiern (

Fischzähne) und laterale Zähne von

beschrieben. Die Vertebratenreste wurden in Onkolithen und Schillagen gefunden, die in dunkle Tonschiefer eingeschaltet

sind. Wir interpretieren diese Lagen als hochenergetische Sedimente (Tempestite), entstanden durch Sturmereignisse in einem

inneren Schelfbereich. Die in dieser Arbeit dokumentierten Vertebratenreste der Raibler Schichten sind ein weiterer Nachweis typischer

Fisch- und Tetrapodentaxa, die in den Meeren der Mittel- und Obertrias in Westeuropa lebten.

Vertebrate fossils such as fish teeth derived from Actinopterygii (Saurichthys morphotype, Colobodus?, indeterminate) and lateral teeth of Paleobates (small sharks) as well as reptile fragments ascribed to Eusauropterygia? and Prolacertiformes are reported from the Northalpine Raibl Beds of the Karwendel and Mieming mountain ranges of the western Northern Calcareous Alps (Tyrol, Austria). The vertebrate fossils occur in oncolite and coquina beds that are intercalated in dark shales. We interpret these intercalated beds as high-energy sediments deposited during storm events (tempestites) in an inner shelf environment. The Raibl vertebrate fossils documented here add another well-established record of characteristic fish and tetrapod taxa that lived in the Middle-LateTriassic seaways that covered Western Europe.Saurichthys Morphotyp, Colobodus?, unbestimmbarePaleobates (kleine Haie) sowie Reptilienfragmente von Eusauropterygiern? und Prolacertiformes

End-Triassic Extinction Reset Evolution of Marine Apex Predators

Thorne, P. M., Ruta, M., and M. J. Benton. 2011. Resetting the evolution of marine reptiles at the Triassic-Jurassic boundary. PNAS Early Online, DOI: 10.1073/pnas.1018959108. [suppl. info]

Abstract - Ichthyosaurs were important marine predators in the Early Jurassic, and an abundant and diverse component of Mesozoic marine ecosystems. Despite their ecological importance, however, the Early Jurassic species represent a reduced remnant of their former significance in the Triassic. Ichthyosaurs passed through an evolutionary bottleneck at, or close to, the Triassic-Jurassic boundary, which reduced their diversity to as few as three or four lineages. Diversity bounced back to some extent in the aftermath of the end-Triassic mass extinction, but disparity remained at less than one-tenth of pre-extinction levels, and never recovered. The group remained at low diversity and disparity for its final 100 Myr. The end-Triassic mass extinction had a previously unsuspected profound effect in resetting the evolution of apex marine predators of the Mesozoic.

New Triassic Paper in PloS ONE

Klein, N. 2010. Long Bone Histology of Sauropterygia from the Lower Muschelkalk of the Germanic Basin Provides Unexpected Implications for Phylogeny. PLoS ONE 5(7): e11613. doi:10.1371/journal.pone.0011613

Abstract

Background

Sauropterygia is an abundant and successful group of Triassic marine reptiles. Phylogenetic relationships of Triassic Sauropterygia have always been unstable and recently questioned. Although specimens occur in high numbers, the main problems are rareness of diagnostic material from the Germanic Basin and uniformity of postcranial morphology of eosauropterygians. In the current paper, morphotypes of humeri along with their corresponding bone histologies for Lower to Middle Muschelkalk sauropterygians are described and interpreted for the first time in a phylogenetic context.

Methodology/Principal Findings

Nothosaurus shows a typical plesiomorphic lamellar-zonal bone type, but varying growth patterns and the occurrence of a new humerus morphotype point to a higher taxonomic diversity than was known. In contrast to the enormous morphological variability of eosauropterygian humeri not assigned to Nothosaurus, their long bone histology is relatively uniform and can be divided into two histotypes. Unexpectedly, both of these histotypes reveal abundant fibrolamellar bone throughout the cortex. This pushes the origin of fibrolamellar bone in Sauropterygia back from the Cretaceous to the early Middle Triassic (early Anisian). Histotype A is assigned to Cymatosaurus, a basal member of the Pistosauroidea, which includes the plesiosaurs as derived members. Histotype B is related to the pachypleurosaur Anarosaurus. Contrary to these new finds, the stratigraphically younger pachypleurosaur Neusticosaurus shows the plesiomorphic lamellar-zonal bone type and an incomplete endochondral ossification, like Nothosaurus.

Conclusions/Significance

Histological results hypothetically discussed in a phylogenetical context have a large impact on the current phylogenetic hypothesis of Sauropterygia, leaving the pachypleurosaurs polyphyletic. On the basis of histological data, Neusticosaurus would be related to Nothosaurus, whereas Anarosaurus would follow the pistosaur clade. Furthermore, the presence of fibrolamellar bone, which is accompanied with increased growth rates and presumably even with increased metabolic rates, already in Anarosaurus and Cymatosaurus can explain the success of the Pistosauroidea, the only sauropterygian group to survive into the Jurassic and give rise to the pelagic plesiosaur radiation.

New Triassic Papers in Rivista Italiana di Palaeontolgia e Stratigrafia.

There are a trio of Triassic papers in the new issue of Rivista Italiana di Paleontologia e Stratigrafia.

Renesto, S. 2010. A new specimen of Nothosaurus from the latest Anisian (Middle Triassic) Besano Formation (Grenzbitumenzone) of Italy. Rivista Italiana di Paleontologia e Stratigrafia 116(2).

Abstract - A nearly complete but disarticulated skeleton of a small sized nothosaur is described. The specimen was collected in 2003 from an outcrop of the Besano Formation (Grenzbitumenzone of Swiss authors) of latest Anisian (Middle Triassic) age, in the Monte San Giorgio Area, northern Italy. The osteology of the postcranial skeleton supports the assignment to the genus Nothosaurus, and also excludes its belonging to Nothosaurus giganteus/Paranothosaurus amsleri already known from coeval localities of the Besano Formation in the Swiss part of the Monte San Giorgio area. Despite the lack of most of the skull, which contains diagnostic characters at the species level for Nothosaurus, the few preserved cranial elements suggest similarities with N. juvenilis which skull, and only known part, is also of comparable size. This specimen is particularly significant because it improves the knowledge of the osteology of N. juvenilis and because the second Nothosaurus species, smaller than N. giganteus/P. amsleri, suggests coexistence of sympatric species characterized by size and, probably, trophic differentiation within the genus Nothosaurus in the Monte San Giorgio area as occurred in the coeval Germanic Basin.

Tintori, A., Sun, Z.-Y., Lombardo, C., Jiang, D.-Y., Sun, Y.-L., and Hao, W.-C., 2010. A new basal neopterygian from the Middle Triassic of Luoping County (South China). Rivista Italiana di Paleontologia e Stratigrafia 116 (2).



Abstract - A new taxon belonging to Neopterygians is described, based on very nicely preserved specimens from the rich vertebrate levels recently discovered in Luoping County, Yunnan Province, South China. This new assemblage dates to Pelsonian (Anisian, Middle Triassic), about the same age of the Panxian Fauna from the nearby Guizhou Province. The Luoping Fauna, yielding this new taxon, is turning out to be one of the most important fish faunas of the whole Middle Triassic and the oldest evidence of the fish radiation of this time span. This new genus of basal neopterygian shows unique derived characters, especially for the almost naked body, with a single row of urodermals covering the body lobe in the tail and a row of very small and thin scales bearing the lateral line canal along the flank. Also in the axial skeleton the new taxon shows peculiar characters such as the neural spines perfectly aligned to each paired neural arches and abdominal ribs well developed. Concerning skull bones, no suborbitals have been detected.
Stockar, R., and Kustatscher, E. 2010. The Ladinian flora from the Cassina Beds (Meride Limestone, Monte San Giorgio, Switzerland): preliminary results. Rivista Italiana di Paleontologia e Stratigrafia 116 (2).


Abstract - A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO WHL, Canton Ticino, Southern Alps) has yielded a small collection of Ladinian plant fossils, together with vertebrate (mostly fish) and invertebrate remains. The flora contains at least five species; conifer remains assignable to the genera Elatocladus, Voltzia and ?Pelourdea are the most common elements. A new species, Elatocladus cassinae n. sp., is formally described. Co-occurring with the conifers are seed ferns (Ptilozamites) and a few putative cycadalean remains (?Taeniopteris). Among the identified genera, only Voltzia has previously been reported from Monte San Giorgio. The fossils presented in this paper indicate that a diversified flora thrived in the region during the Ladinian. Floral composition and preservation patterns are suggestive of a taphonomically-biased record and a relatively far-away source area.