Some of the answers lie at my Lyme Regis gallery. Along with the paintings you'll find 'Palaeoart Case Studies', short explanations outlining the path from fossil to reconstruction. In each case, relevant fossil material is also provided to demonstrate how much - or little - artists have to work with. There's six of these in total, and I'll be sharing most or all of them here over the next few weeks. First up are the crowd-pleasing giant azhdarchid pterosaurs, animals which are so commonly reconstructed that we must know buttloads about their anatomy and proportions. Or do we? Read on to find out how confident, or not, pterosaur palaeoartists really are about reconstructions of giants like Arambourgiania philadelphiae, below.
Giant azhdarchid pterosaurs: iconic, famous, mysterious
|Reconstruction of the giraffe-sized monster pterosaur Arambourgiania philadelphiae. The dirty secret is that 95% of what you see here is extrapolated from other animals.|
|Arambourgiania philadelphiae holotype vertebra, UJA VF1. From Martill et al. 1998. Scale bar represents 100 mm.|
When attempting to restore the appearance of a poorly known fossil species, the first port of call is the anatomy of more completely known, close relatives - the closer the better. The best known azhdarchid species have 3 and 5 m wingspans, so were only a fraction of the size of their bigger cousins. With such a size difference, it is not sensible to assume that the larger animals were perfectly scaled-up versions of these smaller ones. Organisms rarely evolve different sizes without changing proportion somewhere. Bones of larger animals are often more robustly built than those of smaller ones, for instance, because bigger animals have greater masses to support. This is certainly true for giant azhdarchids, as is an disproportionate increase their neck lengths which correlates with size. Paying attention to seemingly trivial scaling details like this can make a tremendous difference to the accuracy of a reconstruction, especially when a lot of extrapolation is involved.
However, this is only half of the story about restoring giant azhdarchids, because deciding which animals are closely related among this group can be difficult. Not all azhdarchids were alike, and the interrelationships between them is unclear. In these muddy taxonomic waters, palaeoartists have to make some educated guesses. Whereas palaeontologists can admit that their data has limitations or that the relevant studies have not been done, palaeoartists have to stretch current data to finish their work. Artists restoring animals with poorly determined taxonomy like giant azhdarchids have to decide which other animals serve as the best models for their reconstructions, and this often involves some degree of intuition and opinion. Such palaeoartworks are especially vulnerable to being proved inaccurate when new data becomes available. Until then, the best reconstructions of these animals are simply those which use the most careful extrapolations and guesswork, and this should be borne in mind when looking at any reconstruction of a giant azhdarchid or other, poorly known fossil species.
Come back soon for the next case study!
- Martill, D. M., Frey, E., Sadaqah, R. M., & Khoury, H. N. (1998). Discovery of the holotype of the giant pterosaur Titanopteryx philadelphiae ARAMBOURG 1959, and the status of Arambourgiania and Quetzalcoatlas. Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen, 207, 57-76.