DARREN NAISH - While dinosaurs walked the land and plesiosaurs and ichthyosaurs swam in the seas, pterosaurs – the flying reptile of the Mesozoic Era – flew overhead.
Pterosaurs didn’t just fly: many were capable walkers as well, and we also think that some pterosaurs were good climbers and swimmers, too. In fact pterosaurs of many kinds were an important and constant presence across the Mesozoic world.
Thanks to spectacularly preserved fossils, we know that pterosaurs were furry and probably warm-blooded. Their membranous wings were not simple sheets of skin but complex structures containing stiffening fibres, a looping blood vessel system and an air-filled layer.
Remarkably, pterosaur wings were supported by a single, super-enlarged fourth finger, with the three remaining fingers being small, clawed organs used in walking and probably in climbing and grooming.
The evolutionary origins of pterosaurs are obscure, but primitive members of the group were abundant during the Triassic, about 220 million years ago.
Many of these early pterosaurs had complex teeth, and long tails were a normal feature of the group. About 170 million years ago, during the Jurassic, a new group called Pterodactyloidea evolved.
In contrast to earlier kinds of pterosaur, these were short tailed, and members of several of their sub-groups were entirely toothless. Several pterodactyloid groups evolved to giant sizes with wingspans of over 5 m and even over 10 m being achieved by some species.
Many pterosaur fossils have been discovered in the UK, the various species belonging to lineages that cover the whole span of pterosaur diversity. This week I and colleagues published a new pterosaur species discovered in the Lower Cretaceous rocks of the Isle of Wight.
The animal is currently known only from a well-preserved pelvic girdle just 40 mm long (see diagram below), but that’s enough for us to work out that we’re dealing with a new species, and also what sort of pterosaur this species represents.
We’ve named it Vectidraco daisymorrisae. The generic name Vectidraco means something like ‘dragon from the Isle of Wight’, while the species name honours Daisy Morris, the girl who discovered the specimen and donated it to The Natural History Museum, London. Daisy was just five years old when she made this discovery and one of my co-authors, Martin Simpson, has written a book about Daisy and her pterosaur.
Several features of the Vectidraco pelvis allow us to work out that the species most probably belongs to a group of pterodactyloids called the azhdarchoids. We also included the specimen in several computer-assisted phylogenetic analyses, and these seem to confirm our identification of it as an azhdarchoid too. Vectidraco grouped close to the tapejarids (a group of relatively small, short-snouted azhdarchoids known from Brazil, Spain and China), and was probably tapejarid-like in shape and lifestyle.
Azhdarchoids are, in my opinion, among the most interesting of pterosaurs. All are from the Cretaceous, all are toothless, and many (perhaps all) were especially well adapted for life in terrestrial environments like woodlands, tropical forests and floodplains.
Bony head crests are a typical feature of the group, as are adaptations in the fore- and hindlimbs for quadrupedal walking. As well as tapejarids, the group includes the somewhat larger thalassodromids (famous for their sail-like head crests), and the sometimes gigantic, long-snouted azhdarchids.
By comparing Vectidraco to azhdarchoids known from better remains, we’re able to work out that it probably had a wingspan of about 75 cm, and was about 35 cm from snout to tail. In other words, it was similar in size to a gull or a large crow. It was probably crested, and with limb proportions that allowed it to be a reasonably good walker and runner on the ground and an expert flier when in cluttered habitats like forests.
Giant azhdarchoids like these azhdarchids may well have been predators of such animals as small dinosaurs. Small azhdarchoids like Vectidraco might have eaten smaller animals like frogs, lizards or insects, and perhaps fruits and fungi.
- Dr Darren Naish is based at the Ocean and Earth Science department of the University of Southampton (UK) where he works on dinosaurs, pterosaurs, marine reptiles and other vertebrates. Current areas of special interest include Cretaceous ichthyosaur diversity, early tyrannosaur evolution, and azhdarchoid pterosaurs. He is perhaps best known for his work on his favourite dinosaur, the early tyrannosaur Eotyrannus from the Isle of Wight. His Tetrapod Zoology blog (currently hosted by Scientific American) is regarded as the world's foremost zoology blog.
- Illustration of Vectidraco by Mark Witton