Earlier this year, in the journal Gondwana Research, paleontologists Gerald Grellet-Tinner and Vlad Codrea announced an unexpected pterosaur. Consisting solely of a triangular hunk of bone found in the 70 million year old rock of Romania, the fossil was presented as a snout piece of Thalassodromeus sebesensis, a new species of a previously-named genus. This was very strange.
The original Thalassodromeus species – T. sethi – lived 42 million years earlier in Early Cretaceous Brazil. If this new animal really belonged to the same genus, as Grellet-Tinner and Codrea proposed, then paleontologists were missing an extended period of this pterosaur’s history. Grellet-Tinner and Codrea tentatively filled in the gap with hypotheses about dispersal routes, the co-evolution of Thalassodromeus with flowering plants, and the odd “island effect” that alters species bound to geographic dots in the ocean, but there is a much simpler explanation for the out-of-place pterosaur. This “pterosaur” was really a turtle.
In a comment to the same journal, Gareth Dyke and 19 other paleontologists affirm that the peculiar Thalassodromeus bone from Romania is actually a piece of a turtle’s belly shell. The single piece of bone lacks any characteristic that conclusively identifies it as belonging to a pterosaur. “[I]t is not a pterosaur head crest, or a pterosaur bone of any kind,” the researchers write. Rather, the bone is a perfect fit for part of the bottom shell of a Cretaceous turtle named Kallokibotion that has been known from the same area for about 90 years. Sadly, Dyke and co-critics write, “the misidentification of one fragmentary fossil [led] to a cascade of elaborate ideas with increasingly far-reaching implications.”
Grellet-Tinner and Codrea had entertained the turtle possibility in the supplementary information of their study, but rejected it in favor of a pterosaur interpretation. And they still uphold their original conclusion.
In their own reply, Codrea and Grellet-Tinner say their critics’ comments are “most welcome” but then pile on personal jabs and conclude with a cryptic line that the “conspicuous persistence, hastiness, and zeal of [the critical comment], may indeed reflect of deeper, perhaps irritating, issues in Transylvania.” Just as strange, Codrea and Grellet-Tinner complain that their critics have not studied the fossil in person, yet principally defend their own position by citing figures from other studies.
Codrea and Grellet-Tinner promise that planned 3D scans of the fossil “will concomitantly eliminate any doubt regarding [the specimen], if there were any.” I’m betting the results come up turtle. The shape and anatomy of the bone are a much better fit for a familiar chelonian than a pterosaur unstuck in time. Such is the nature of paleontology. The true identity of puzzle pieces isn’t always what we first expect them to be.
The pterosaur-turtle mix-up isn’t the only case of mistaken identity, though. A different team of researchers has just revised the identity of another European pterosaur.
In 1990 paleontologists found a pair of weird bones in England’s Cromhall Quarry. They seemed to be hand bones – metacarpals – from a pterosaur, and this was especially interesting because the site was Late Triassic in age. If the identification was correct, then the bones would be from the early days of these leathery-winged reptiles and the only evidence of pterosaurs in Triassic England.
But upon re-examination, paleontologists Fabio Marco Dalla Vecchia and Andrea Cau found that the bones more closely match the fingers of weird “monkey lizards” called drepanosaurs. Other bones from these weird, clasp-footed reptiles have been found in the same quarry, but were not known in 1990, and so it was easy to mistake the unusual fossils for pterosaur hand bones. The upshot, Dalla Vecchia and Cau write, is “there is no unequivocal evidence of pterosaurs in the Triassic of the UK.” Sometimes that’s the way the pterosaur crumbles.
[For more on the Thalassodromeus debacle, read Mark Witton's post breaking down the details.]
Codrea, V., Grellet-Tinner, G. 2014. Reply to comment by Dyke et al. on “Thalassodromeus sebesensis, an out of place and out of time Gondwanan tapejarid pterosaur” by Grellet-Tinner and Codrea. Gondwana Research. doi: 10.1016/j.gr.2014.08.003
Dalla Vecchia, F., Cau, A. 2014. Re-examination of the purported pterosaur wing metacarpals from the Upper Triassic of England. Historical Biology. doi: 10.1080/08912963.2014.933826
Dyke, G., Vremir, M., Brusatte, S., Bever, G., Buffetaut, E., Chapman, S., Csiki-Sava, Z., Kellner, A., Martin, E., Naish, D., Norell, M., Ősi, A., Pinheiro, F., Prondavi, E., Rabi, M., Rodrigues, T., Steel, L., Tong, H., Vila Nova, B., Witton, M. 2014. Thalassodromeus sebesensis – a new name for an old turtle. Comment on “Thalassodromeus sebesensis, an out of place and out of time Gondwanan tapejarid pterosaur,” Grellet-Tinner and Codrea. Gondwana Research. doi: 10.1016/j.gr.2014.08.004
Grellet-Tinner, G., Codrea, V. 2014. Thalassodromeus sebesensis, an out of place and out of time Gondwanan tapejarid pterosaur. Gondwana Research. http://dx.doi.org/10.1016/j.gr.2014.06.002