With the close of the Rio Pterosaur Symposium (which I did not attend), here is the poster and abstract I created for the event. Click image to enlarge and download PDF file (1.2Mb). This poster illustrates the series of taxa leading up to pterosaurs, according to the results of the completely resolved large reptile tree, along with a gradual accumulation of pterosaurian traits, something you’ll never find in archosaurs.
Lepidosaurs have been rejected as pterosaur ancestors (Bennett 1996), but ironically this is exactly where you find them. No wonder their origins have remained mysterious to traditional paleontologists like Nesbitt (2011), Hone and Benton (2007, 2008) and others.
Of course the large reptile tree permits one to continue back in time and phylogeny to see the pterosaur ancestors all the way back to basal tetrapods, but Paliguana (Fig. 1) is a good place to start as it is the first taxon in this lineage to have upper temporal fenestrae. The present list (Fig. 1) includes terrestrial and arboreal taxa, all small and tending toward long-legged and bipedal with an increasing number of extradermal membranes.
This symposium abstract (Fig. 1) follows an earlier one (Peters 2007) that described interrelations within the Pterosauria. I thank the conveners, especially Alex Kellner and Juliana Sayao, for including it.
You can see the Rio Ptero 2013 program here. Several of the headline topics look to expand or support reports first aired here and at www.reptileevolution.com. One appears to be arising from a very unlikely source. Other abstracts are clinging to traditional hypotheses that have been falsified. We’ll look at the most interesting of those individually in future posts.
Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zool J Linn Soc. 118:261–309.
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 292 pp.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.