Tuesday, 27 June 2017

A New Name For Germanodactylus rhamphastinus

The Jurassic flying reptile, "Germanodactylus rhamphastinus", formerly "Diopecephalus rhamphastinus", formerly "Pterodactylus rhamphastinus", formerly Ornithocephalus ramphastinus Wagner, 1851 (not a typo), has a long and complicated taxonomic history. A taxonomic history that has hopefully come to an agreeable conclusion with it placed in its own monotypic genus Altmuehlopterus.

See full size version © Dyn0saur Steven Vidovic

Altmuehlopterus rhamphastinus (Wagner 1851) has been named in honour of Naturpark Altmühltal, through which the Altmühl river flows in Bavaria, Germany. "Germanodactylus rhamphastinus" has been considered a member of a genus distinct from Germanodactylus by several researchers conducting studies into Jurassic pterosaurs. In the past, the geographically significant name Daitingopterus was proposed, but due to the rules of naming species and genera, the name could not be used. The result of a study recently published in a special volume focusing on pterosaur palaeobiology was the proposal of an equally geographically significant name.

The academic paper "The taxonomy and phylogeny of Diopecephalus kochi (Wagner, 1837) and ‘Germanodactylus rhamphastinus’ (Wagner, 1851)" used the most comprehensive cladistic analysis (a method of discovering evolutionary trees) of pterosaurs to date, tests of morphospace, and detailed comparative anatomy studies to test hypotheses of inter-species relationships amongst fossils known from the Solnhofen region of Bavaria, Germany.

Altmuehlopterus would have flown over 'Solnhofen', Bavaria approximately 152 million years ago. At that time, Bavaria was a chain of islands located in a warm shallow sea, dominated by reefs. This ecosystem produced a unique environment in which animals were able to die, sink, be buried and entombed in fine-grained, finely laminated limestone without decomposing or being scavenged excessive amounts. This limestone, often referred to as plattenkalk or lithographic limestone – due to its use in the early publishing industry – can preserve soft-tissues, such as feathers and skin impressions. The famous feathered Archaeopteryx is from this rock formation, in addition to some notable dinosaurs and pterosaurs. In the case of Altmuehlopterus, we know it had a soft-tissue striated head-crest. And we know from closely related species, also discovered in the same deposits, that it would have had a fur-like covering.

Also in this academic paper, the validity of the genus Diopecephalus was tested. At present, the genus is maintained, but evidence supporting it or contradicting it is not strong. The problem is that Diopecephalus is represented only by juvenile individuals and it is not clear what it might have grown into.

In this study, the 'Solnhofen' monofenestratan pterosaur species are put into geological context. The part of the cladogram comprising those species is made up of a suite of transitional species and groups, between Monofenestrata and Ornithocheiroidea. It seems that the 'Solnhofen' lithographic limestones span a period of time in which the 'pterodactyloid evolutionary experiment' was in its initial stages. The Solnhofen provided a beautiful environment for maritime pterosaurs and coastal pterosaurs. although there is no reason to think Altmuehlopterus ate a diet comprising mainly of fish as it has been inferred in the past. It is entirely possible that Altmuehlopterus hunted small vertebrates on the many small islands in the region, maybe even other pterosaurs and their offspring.

The cladistic analysis is substantial and finds some novel relationships, and so it deserves a blog post of its own. In the meantime, why not read the paper?