Bristol, UK. A new study shows the unusual evolutionary development of the pterosaurs (flying reptiles), becoming more and more specialized throughout their 160 million years on Earth.

Palaeontologists routinely speculate about the rise and departure of species through time, but the new study provides a set of objective measurements of the relative success and breadth of adaptation of pterosaurs through their time on the Earth.


New work by Katy Prentice, who performed the research as part of her undergraduate degree (MSci in Palaeontology and Evolution) at the University of Bristol, significantly advances population studies in paleontology, but the application of rigor to her studies can have broad implications across a variety of other fields. "We're delighted to see a student mastering some tough mathematical techniques, and coming up with such a clear-cut result," said Professor Michael Benton at Bristol.



Extremes in Pterosaur Morphology

The giant and possibly flightless Quetzalcoatlus from the Late Cretaceous of Texas was as tall as a giraffe. The small insectivorous Anurognathus from the Late Jurassic of Germany is seen flying above the artist's head.

The drawings are courtesy of Mark Witton. You can see more of the artist's work on his his web sites: Mark Witton's photostream on flickr, and Pterosaurs: dragons of the air

Click Pic for DetailsUsually, when a new group of animals or plants evolves, they quickly try out all the options. "When we did this study, we thought pterosaurs would be the same", said Prentice. Pterosaurs were the first flying animals — they appeared on Earth 50 million years before Archaeopteryx, the first bird — and they were very successful. "But the amazing thing is that they didn't really begin to evolve until after the birds had appeared."

Katy Prentice did the study in conjunction with her supervisors, Dr Marcello Ruta and Professor Michael Benton. The findings appear in the Journal of Systematic Palaeontology.

They looked at 50 different pterosaurs that ranged in size from a blackbird to the largest of all, Quetzalcoatlus, with a wingspan of 12 metres, four times the size of the largest flying bird today, the albatross.

• They tracked how all the pterosaur groups came and went through their history and recorded in detail their body shapes and adaptations.
  
  
• The new work shows that pterosaurs remained conservative for 70 million years, and then started to experiment with all kinds of new modes of life.
  
  
• After birds emerged and became successful, the pterosaurs were not pushed to extinction, as had been suggested.
  
  
• It seems they responded to the new flyers by becoming larger and trying out new lifestyles.
  
  
• Many of the new lifestyle adaptations were seen in the pterosaurs skulls, as they adapted to feed on different food sources; some were seed-eaters, many ate fish, and later ones even lost their teeth.
  
  
• The rest of the body also showed a surprising amount of variation between the different groups, especially when it is considered that the body forms have to retain many the features necessary to allow flight.

"Pterosaurs were at the height of their success about 125 million years ago, just as the birds became really diverse too," said Dr Marcello Ruta. "Our new numerical studies of all their physical features show they became three times as diverse in adaptations in the Early Cretaceous than they had been in the Jurassic, before Archaeopteryx and the birds appeared."

Pterosaurs dwindled and disappeared 65 million years during the mass extinction that killed the dinosaurs. In their day they had been a fair match for the birds, and the two groups divided up aerial ecospace between them, so avoiding conflict.