Wednesday 11 July 2012

New species of Rhamphorhynchid Pterosaur from the Late Jurassic Solnhofen Limestone.

The Rhamphorhynchids were an early group of Pterosaurs which were typically small in size, lacked crests and had teeth. They form a genuine taxonomic group, as opposed to the 'Rhamphorhynchoids' which is a name applied to all Non-Pterodactyloid Pterosaurs. The Rhamphorhynchids appeared in the Middle Jurassic and persisted till the end of the period.

In a paper published in the journal PLoS One on 5 July 2012, a team of scientists led by David Hone of the Department of Biology and Environmental Sciences at University College Dublin, describe a new species of Rhamphorhynchid Pterosaur from the Late Jurassic Solnhofen Limestone fossil lagerstätte of Southern Germany.

The Solnhofen Limestone, or Solnhofen Plattenkalk, formed towards the end of the Jurassic, as a result of intense global warming that covered most of what is now Southern Germany with a shallow tropical sea. This was populated by abundant reef-forming Sponges and Corals, leading to the formation of numerous lagoons, in which the waters became cut of from the surrounding sea, then became hyper-saline due to evaporation. Hyper-saline environments have excellent potential for fossil preservation, as most scavenging and bioturbating organisms (i.e. animals that eat carcasses and turn over sediments) are excluded by the water chemistry. The Solnhofen Limestone has produced a large number of excellently preserved vertebrate and invertebrate fossils in fine-grained layered limestones, including every known specimen of the Dinosaur-Bird Archaeopteryx.

The new specimen was found in Late Kimmeridgian (slightly over 150 million years old) deposits in the Brunn Quarry in Upper Palatinate, Eastern Bavaria, 25 km northwest of the city of Regensburg. It is named Bellubrunnus rothgaengeri, where Bellubrunnus means 'Beauty of Brunn' and rothgaengeri honours the discoverer of the fossil, Monika Rothgaenger. It is preserved as a complete skeleton, plus the outline of the entire body, though no detail of the soft tissue could be found.

Bellubrunnus rothgaengeri, complete specimen. Scale bar is 1 cm. Hone et al. (2012).

Bellubrunnus rothgaengeri shows forward curving of the fourth wing phalanx, i.e. the final bone in the wing, a feature that is not seen to this extent in any other known Pterosaur. This does not appear to be a preservational feature as it is seen in both wingtips, and no other bones in the animal appear distorted. The exact purpose of this is unclear, though it may have made the animal more maneuverable in flight.

Reconstruction of Bellubrunnus rothgaengeri, by artist Matt Van RooijenHone et al. (2012).

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