Monday 21 October 2013

Thoughts on a head crest

 The skull of Tapejara wellnhoferi has bony extensions to the upper and lower mandible and a long spinous bone extending back over the top of the skull.  There is no evidence of soft tissue crests in this species, but since the other tapejarids; Tupandactylus navigens and  Tupandactylus imperator have soft tissue crests it is probable that T. wellnhoferi also had a soft tissue crest.
We can speculate that without the bony spine above the mandible, the crest would need to be small, or flexible.  Perhaps it was inflatable using blood or air sacs.  This would be an interesting notion!
As soft tissue is seldom preserved and in the case of pterosaurs, occasionally seen as just a residue with no structural detail preserved, any speculation could be valid.
Many illustrators see colour preserved in these crests.  I am not sure of this and it seems more likely that the difference in colour seen in some fossils may actually be an artifact of the preservation.  The impression of colour is more likely to be due to differences in tissue density, tissue type or the chemistry of fossilisation.  Give a thought to the scientists who have to interpret this evidence.  It is easy to see things that are not there, just to make sense of the evidence that is there.  Anyway, I like the thought of pterosaurs being able to fold and display soft tissue crests, even if the evidence is not present in the fossil record - or is it?

Friday 11 October 2013

Royal Mail Dinosaur Stamps

 The Royal Mail have issued their dinosaur stamps.  Fist day covers were only available at Post Offices on 10 Oct 2013, but the stamp sets are still available where stocks last.
 The art work on these stamps is by John Sibbick.  His work is found in many pterosaur publications.  Text on the cover card is by Angela Milner from the NHM London.  There are two pterosaur stamps in the set of 10 fist class stamps.  It is interesting that all of the stamps have an area of printed image that extends beyond the normal edge of the stamp, requiring a special perforation cut for the sheets.
 Ornithocheirus represents the pterodactyloid pterosaurs. This species was first described by Harry Govier Seeley in 1869, though the fossils had been known of since 1827.
Dimorphodon represents the older rhamphorhynchoid pterosaurs and was described by William Clift and William John Broderip in 1835.  This description was based on a fossil that was discovered by Mary Anning in 1828.

These stamps are available over the counter at all UK post offices whilst stocks last.

Royal Mail Collectible stamps