Reblogged from http://www.lincoln.ac.uk/news/2017/12/1421.asp
For many years, palaeontologists have been uncovering the mysteries of reptiles, dinosaurs and other animals which roamed the earth more than 150 million years ago.
Now, in a fascinating feature for one of the world’s leading academic journals, Science, Dr Charles Deeming from the University of Lincoln, UK, shines a light on the reproductive biology of the pterosaurs – winged reptiles that flourished throughout the age of dinosaurs.
Dr Deeming, an avian and reptilian reproduction specialist in the School of Life Sciences at the University has studied pterosaur reproduction for 12 years. He has reviewed new research by an international team of research led by Xiaolin Wang which examined a find of more than 200 pterosaur eggs and associated embryos belonging to a pterosaur species known as Hamipterus tianshanensis.
The study by Wang et al, published in the same edition of the journal, also investigated lines of arrested growth in bone sections, enabling the age of the animal to be estimated.
Writing in the Perspectives section of Science today (1st December 2017), Dr Deeming explained: “The fact that these flying reptiles even laid eggs was only recently confirmed in 2004, with the report of two eggs from China, and one from Argentina that contained well-developed pterosaur embryos.
“We now know that pterosaur eggs had soft, parchment like shells comparable to those laid by modern-day lizards. Wang et al’s study supports this interpretation, as does a previous study of a smaller number of eggs from the same site. The fossilised eggs show little evidence of shell calcification, and many show a dimpling of the shell as seen in dead, dehydrated lizard eggs.
“Due to the nature of the shells, scientists believe that pterosaur eggs were buried, precluding any form of contact incubation by the parents. Adults may have attended or defended nests, which would explain the presence of adult skeletons in the specimen reported by Wang et al.
Wang et al suggests that pterosaurs nested in colonies, but Dr Deeming suggests that appropriate nesting sites might have been in short supply. Like modern-day sea turtles, female pterosaurs may have inadvertently dug up existing nests, revealing previously buried eggs, which could result in them drying out.
Dr Deeming added: “It is rare in studies of pterosaurs to find data which can provide such an insight into the development of an extinct species from the earliest stage to maturity, but care is needed when assessing the developmental stage of embryos from what remains a limited data set.
“We now have many questions to address: were the eggs buried in sand or covered in vegetation? Was clutch size limited to two (as suggested by previous fossil finds)? Why are so many of the eggs showing signs of dehydration? Hopefully additional finds of equally spectacular fossils will help us answer such questions for pterosaurs and allow us to paint an increasingly complete picture of reproduction in these extinct species.”
Dr Deeming’s article is available to read in full online here: http://science.sciencemag.org/content/358/6367/1124
To access the research paper by Wang et al visit: