Thalassodromidae

Thalassodrominae or Thalassodromidae (meaning "sea runners", due to previous misconceptions of skimming behavior; they are now thought to be terrestrial predators) is a group of azhdarchoid pterosaurs from the Cretaceous period. Its traditional members come from Brazil, however, other possible members also come from other places, including the United States, Morocco, and Argentina. Thalassodrominae is considered either to be a subfamily within the pterosaur family Tapejaridae, or as a distinct family, Thalassodromidae, within the clade Neoazhdarchia, closely related to dsungaripterids or azhdarchids.

Classification

Thalassodrominae traditionally includes only two genera, '' Thalassodromeus'' and ''Tupuxuara'', and was defined to include them and any other descendants of their most recent common ancestor. The classification of thalassodromines is controversial. Some studies, including one by Lü and colleagues in 2008, have found that the thalassodromines are more closely related to the azhdarchids than to the tapejarids,Lü, J., Unwin, D.M., Xu, L., and Zhang, X. (2008). "A new azhdarchoid pterosaur from the Lower Cretaceous of China and its implications for pterosaur phylogeny and evolution." ''Naturwissenschaften'', and have placed them in their own family (which has sometimes been referred to as Tupuxuaridae,Martill, D.M., Bechly, G., and Heads, S.W. (2007). "Appendix: species list for the Crato Formation." In: Martill, D.M., Bechly, G., and Loveridge, R.F. (eds.), 2007. ''The Crato Fossil Beds of Brazil: Window into an Ancient World.'' Cambridge University Press, Cambridge. Pp. 582–607. though Thalassodrominae was named first). Alternately, they have been considered a family within the clade Neoazhdarchia, as Thalassodromidae.

Below are three alternate cladograms resulting from studies of azhdarchoid relationships. The first, presented by Felipe Pinheiro and colleagues in 2011, found the thalassodromines as a subgroup within the Tapejaridae.Pinheiro, F.L., Fortier, D.C., Schultz, C.L., De Andrade, J.A.F.G. and Bantim, R.A.M. (in press). "New information on ''Tupandactylus imperator'', with comments on the relationships of Tapejaridae (Pterosauria)." ''Acta Palaeontologica Polonica'', in press, available online 03 Jan 2011. The second, presented by Lü and colleagues in 2008, found them to be closer to the Azhdarchidae, though they used the name Tupuxuaridae for the group. The third, presented by Brian Andres, James Clark and Xu Xing in 2014, also found thalassodromines closer to azhdarchids, and as the sister group of the dsungaripterids.

More recently, the Late Cretaceous genera ''Alanqa'' and ''Aerotitan'', typically considered azhdarchids, have been recovered as thalassodromines (the group is defined as Thalassodromidae in the study). However, their remains are fragmentary, so this assignment is only tentative, and a 2021 study further show dissimilarities between them and azhdarchids, with ''Aerotitan'' being a true azhdarchid while ''Alanqa'' was a basal azhdarchoid related to '' Keresdrakon''. Similarly, the Maastrichtian '' Javelinadactylus'' has been proposed to be a thalassodromine, although previous assessments of the material have favored an azhdarchid identity over a thalassodromine one.Mark P. Witton (2013), Pterosaurs: Natural History, Evolution, Anatomy, Princeton University Press, ISBN 978-0-691-15061-1 This same study also recovers ''Argentinadraco'' (already of uncertain affinities) as a thalassodromine as well.

References

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Tapejaromorphs
Albian first appearances
Maastrichtian extinctions