By Aodhán Ó Gogáin, Inventory Assistant, National Museum of Ireland
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Pterosaurs are a group of flying reptiles that lived during the Mesozoic Era, which lasted between 252 Ma (millions of years ago) to 65 Ma and includes the Jurassic Period, a time when dinosaurs roamed the Earth. One pterosaur, Rhamphorhynchus (“Ram – foh – rin – kus”), is found in Jurassic sediments at Solnhofen, Germany (Fig. 1). Rhamphorhynchus, like all pterosaurs, had modified forelimbs that formed its wings. However, unlike the wings of bats and birds, pterosaur wings are mostly formed from having an elongated 4th finger (Fig. 2) from which a skin membrane extended from the tip in towards the body. This skin membrane in Rhamphorhynchus was bare, whereas the main body of the animal was covered in proto-feathers that acted as insulation (Fig. 3). By pterosaur standards, Rhamphorhynchus was relatively small: some members of this group could grow to the size of a two-seater airplane, far larger than any bird that ever lived.
Predatory adaptations
During the Jurassic, Germany was covered by a shallow tropical sea that had several island archipelagos on which Rhamphorhynchus would have lived. The beak of Rhamphorhynchus is elongated and packed full of large slender conical teeth (Fig. 4). These teeth point towards the front of the beak, and Rhamphorhynchus probably used these forward-pointing teeth to spear fish and cephalopods (octopus, squid and cuttlefish) as it skimmed over the surfaces of the sea. Fossil cephalopods from Solnhofen have been found with Rhamphorhynchus teeth embedded in them.
The diversity of Mesozoic life
The rocks in which Rhamphorhynchus is preserved were deposited in a salty lagoon. Other fossil finds from these rocks show that the seas in which Rhamphorhynchus hunted were teeming with ichthyosaurs and plesiosaurs (two groups of large marine reptiles), plus fish, shrimp, and squids. In the skies flew a host of insects, as well as Archaeopteryx, one of the first birds to have evolved. Towards the end of the Mesozoic Era, pterosaurs started to decline and birds started filling their ecological niches. They were finally brought to extinction, at the end of the Cretaceous Period, by the same meteorite impact that wiped out the dinosaurs.
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Acknowledgements
Thank you to Dr Patrick Roycroft (National Museum of Ireland's Curator of Geology) for allowing access to the specimen.
