In Depth
Rhamphorhynchus is one of the classic pterosaurs that have been known to science since the early days of palaeontology. It had what appears to have been a sizeable distribution and aside from the above locations, Rhamphorhynchus specimens have also been attributed to other European countries like the United Kingdom. Unfortunately however, these specimens are sometimes no more than fossilised teeth.
The best preserved and most numerous examples hail from Germany where Rhamphorhynchus was first discovered. Not only do these remains include complete specimens, but also impressions of the wings, revealing their placement and texture. Specimens also display potential dimorphism between males and females.
The jaws of Rhamphorhynchus are filled with sharp needle like teeth, twenty in the top, fourteen in the bottom. When the jaws closed the teeth would intermesh, maximising grip on prey. These jaws have led to the perception that Rhamphorhynchus used them to snatch up fish as it skimmed over the top of the water, although it’s not out of the question that it could also have caught larger insects.
Rhamphorhynchus has been subject to a lot of study to try and find out more about its life. One area has focused upon possible sexual dimorphism between males and females. This is indicated by how long the skull is to the humerus, with different specimens falling into two distinct groups of larger and smaller heads. This is not conclusive proof of dimorphism, but does reinforce the possibility.
Study of the scleral rings has also indicated a nocturnal lifestyle. It is difficult to say with certainty if pterosaurs were warm or cold blooded, but a nocturnal heat source if required could be rocks. Because rocks have a high thermal capacity, they take a long time to warm up in the heat of the sun. However, because they take a long time to warm up they also take a long time to cool down, staying warm to the touch for several hours after night fall. If cold blooded, a nocturnal pterosaur could warm up by ‘hugging’ a rock with its wings to absorb more heat. If Rhamphorhynchus was nocturnal, it would have avoided direct competition with other pterosaurs that were diurnal. CAT scans of Rhamphorhynchus skulls have also allowed for reconstruction of the the inner ear. This has revealed that unlike some other pterosaurs, Rhamphorhynchus typically flew with its head horizontally level (parallel) to the ground.
A huge number of species once existed for Rhamphorhynchus, however many of these came about from the use of Pterodactylus as a wastebasket taxon. It was not until notable differences began to be pointed out that Rhamphorhynchus became separate. Still a large number of differing species existed, or so it was thought until a 1995 study by Chris Bennet revealed that a great many of these specimens actually represented different life stages of the same species. With the revelation that these remains were just juveniles, sub-adults and adults of the same creature, the species list was shortened to just a handful of names. Of these only R. muensteri is generally considered to be true to the genus. The other remaining species which include R. jessoni, R. intermedius, are considered subjective synonyms, while R. tendagurensis thought to be a nomen dubium. Although these species are sometimes referred to, their future validity is uncertain.
Because it is now accepted that the many various specimens represent the same species, it has also revealed valuable insights of changing morphology with age. The jaws of Rhamphorhynchus juveniles are short and blunter than they were in adult specimens. Adults also had shorter and more robust teeth to facilitate larger prey capture that may have broken weaker teeth. Rhamphorhynchus also had a vane on the end of its tail and in juveniles was lancet shaped (like a double edged scalpel). As the individual grew, the vane would become diamond shaped before becoming a triangle when full grown.
Further Reading
– Pterodactylus (Rhamphorhynchus) gemmingi aus dem Kalkschiefer von Solenhofen. – Palaeontographica 1: 1–20. – H. von Meyer – 1846. – Ein Exemplar von Rhamphorhynchus mit Resten von Schwimmhaut. – Sitzungs-Berichte der bayerischen Akademie der Wissenschaften mathematisch naturwissenschaftlichen Abteilung 1927: 29–48. – F. Broili – 1927. – Odontorhynchus aculeatus novo. gen. novo. sp., Ein neuer Rhamphorhynchide von Solnhofen. – Neues Jahrbuch f�r Mineralogie, Geololgie, und Pal�ontologie Beilage-Band 75:543-564. – E. Stolley – 1936. – Untersuchungen �ber die Gattung Rhamphorhynchus. – Neues Jahrbuch f�r Mineralogie, Geologie und Palaeontologie, Beilage-Band 77: 455–506. – Koh – 1937. – Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke S�ddeutschlands. – Palaeontographica, A 148: 1-33, 148: 132-186, 149: 1-30. – P. Wellnhofer – 1975. – A statistical study of Rhamphorhynchus from the Solnhofen Limestone of Germany: Year-classes of a single large species. – Journal of Paleontology 69: 569–580. – S. C. Bennett – 1995. – Life history of Rhamphorhynchus inferred from bone histology and the diversity of pterosaurian growth strategies. – In Soares, Daphne. PLoS ONE 7 (2): e31392. – E. Prondvai, K. Stein, O. Ősi, M. P. Sander – 2012. – The Late Jurassic pterosaur Rhamphorhynchus, a frequent victim of the ganoid fish Aspidorhynchus?. – PLoS ONE 7 (3): e31945. – E. Frey, & H. Tischlinger – 2012. – Evidence for the presence of Rhamphorhynchus (Pterosauria: Rhamphorhynchinae) in the Kimmeridge Clay of the UK. – Proceedings of the Geologist’s Association 126(3):390-401. – M. O’Sullivan & D. M. Martill – 2015.
