Flugsaurier 2018: ‘Young istiodactylid’ nests with tall pterodactylids in the LPT

Flugsaurier 2018 opens today, August 10,
and the abstract booklet is out. So it’s time to take a look at some of the news coming out of that Los Angeles pterosaur symposium. Since the purpose of the symposium is increase understanding of pterosaurs, I hope this small contribution helps.

Hone and Xu at Flugsaurier 2018
describe, “An unusual and nearly complete young istiodactylid from the Yixian Formation, China (Fig. 1). The specimen shows the characteristic istiodactylid cranial features of tooth shape and enlarged nasoantorbital fenestra. However, it has proportionally large hindlimbs and wing proportions that are similar to those of azhdarchids. This has led to suggestion that the specimen may be a composite and that only the cranial material is istiodactylid. Preparation work around some key parts revealed no inconsistencies in the matrix or evidence of glue. The specimen is held in the Erlianhaote Dinosaur Museum, Erlianhote, China.”

Reconstructed as is
(Fig. 2) and added to the large pterosaur tree (LPT, 233 taxa, not yet updated due to no museum number nor genus name) the young ‘istiodactylid’ nests as a large derived pterodactylid. 13 steps separate this taxon from the Istiodactylus clade.

Ornithocheirids,
like Istiodactylus (Figs. 3, 4) and the SMNL PAL 1136 specimen (Fig. 5), share a very large wing finger, a short metacarpus, a warped deltopectoral crest, small free fingers and deeply keeled sternal complex not found in the Erlianhote specimen.

It’s better not to eyeball certain specimens.
Sometimes you have to run them through a phylogenetic analysis to find out what they are. That’s what the LPT is for. It minimizes taxon exclusion and handles convergence.

Pterosaurs are still lepidosaurs.
So they follow lepidosaur fusion patterns, which follow phylogeny. Hone and Xu made the mistake of imagining pterosaurs might have archosaur fusion patterns that follow ontogeny.

Why am I not at Flugsaurier 2018?
In addition to about a dozen reasons that I can list later, or your can guess now, I can be more helpful and timely here.

References
Andres B and Ji Q 2006. A new species of Istiodactylus (Pterosauria, Pterodactyloidea) from the Lower Cretaceous of Liaoning, China. Journal of Vertebrate Paleontology, 26: 70-78.
Bowerbank JS 1846. On a new species of pterodactyl found in the Upper Chalk of Kent P. giganteus). Quarterly Journal of the Geological Society 2: 7–9.
Bowerbank JS 1851. On the pterodactyles of the Chalk Formation. Proceedings of the Zoological Society, London, pp. 14–20 and Annals of the Magazine of Natural History (2) 10: 372–378.
Bowerbank JS 1852. On the pterodactyles of the Chalk Formation. Reports from the British Association for the Advancement of Science (1851): 55.
Hone DWE and Xu 2018. An unusual and nearly complete young istiodactylid from the Yixian Formation, China. Flugsaurier 2018: the 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 53–56.
Hooley RW 1913. On the skeleton of Ornithodesmus latidens. An ornithosaur from the Wealden shales of Atherfield (Isle of Wight)”, Quarterly Journal of the Geological Society, 69: 372-421
Howse SCB, Milner AR and Martill DM 2001. Pterosaurs. Pp. 324-335 in: Martill, D. M. and Naish, D., eds. Dinosaurs of the Isle of Wight, The Palaeontological Association
Wang X, Rodrigues T, Jiang S, Cheng X and Kellner AWA 2014. An Early Cretaceous pterosaur with an unusual mandibular crest from China and a potential novel feeding strategy. Scientific Reports 4 : 6329, pp. 1-9. | DOI: 10.1038/srep06329
Witton MP 2012. New Insights into the Skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea). PLoS ONE 7(3): e33170. doi:10.1371/journal.pone.0033170

wiki/Istiodactylus