Istiodactylidae

Systematics and distribution

Remains of taxa that can be confidently assigned to Istiodactylidae have been found in the UK and China, in rocks dating from the Early Cretaceous period (Barremian to Aptian stage). Arbour and Currie (2011) described Canadian Gwawinapterus beardi as a member of Istiodactylidae living in the late Cretaceous (upper Campanian stage); however, Witton (2012) suggested the tooth replacement pattern in this animal does not match that of pterosaurs, suggesting that the species might be non-pterosaurian. The earliest known species might be Archaeoistiodactylus linglongtaensis, from the Middle Jurassic of China; however, it also has been suggested that the holotype specimen of this species might actually be a poorly preserved specimen of Darwinopterus. Hongshanopterus, a supposed istiodactylid from China, has been reclassified as a non-istiodactylid member of Ornithocheiroidea of uncertain phylogenetic placement by Witton (2012).

Istiodactylids were medium-sized pterosaurs with flat, rounded jaws similar to that of a duck. They had small teeth lining their jaws, however, and this can mostly be seen in the more advanced genera such as Istiodactylus.

Classification

Below is a cladogram showing the phylogenetic placement of this group within Pteranodontia from Andres and Myers (2013).

The cladogram below is a topology recovered by Kellner et al. (2019). In the analyses, they recovered Istiodactylidae within the more inclusive group Istiodactyliformes, and assigned both Istiodactylus and Liaoxipterus to a new subfamily called Istiodactylinae, but kept Nurhachius as a basal member.

Paleobiology

Lifestyle

Unlike most ornithocheiroids, istiodactylids bear morphologies suited to a terrestrial life and many of their fossils have been found in freshwater-deposits. Istiodactylids are considered to be pterosaurian equivalents to vultures: acting as the clean-up crew in their habitats. The swimming abilities of Istiodactylids have not been analyzed, in contrast to Ornithocheirids.

References

References

1. Hone, David W. E., Fitch, Adam J., Ma, Feimin, and Xu, Xing. 2020. An unusual new genus of istiodactylid pterosaur from China based on a near complete specimen. ''Palaeontologia Electronica'' 23(1):a09. https://doi.org/10.26879/1015 palaeo-electronica.org/content/2020/2931-a-new-istiodactylid-pterosaur
2. Mark P. Witton. (2012). "New Insights into the Skull of ''Istiodactylus latidens'' (Ornithocheiroidea, Pterodactyloidea)". PLOS ONE.
3. Arbour V.M.. (2011). "An istiodactylid pterosaur from the Upper Cretaceous Nanaimo Group, Hornby Island, British Columbia, Canada". Canadian Journal of Earth Sciences.
4. Vullo R.. (2012). "Reappraisal of ''Gwawinapterus beardi'' from the Late Cretaceous of Canada: a saurodontid fish, not a pterosaur". Journal of Vertebrate Paleontology.
5. Lü J.. (2010). "A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning, China". Global Geology.
6. David M. Martill. (2011). "A new monofenestratan pterosaur from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of Dorset, England". Acta Palaeontologica Polonica.
7. (2012). "New Insights into the Skull of ''Istiodactylus latidens'' (Ornithocheiroidea, Pterodactyloidea)". PLOS ONE.
8. (2013). "Lone Star Pterosaurs". Earth and Environmental Science Transactions of the Royal Society of Edinburgh.
9. (2019). "First complete pterosaur from the Afro-Arabian continent: insight into pterodactyloid diversity". Scientific Reports.