Historically transposed flipper pairs in a mounted plesiosaurian skeleton

Abstract

AbstractPlesiosaurians evolved four wing-like flippers that are morphologically similar to each other and were most likely used in underwater flight. Plesiosaurians have been the subject of a long research history as well as a long history of misidentifications and misinterpretations, especially transposition of parts of or entire fore- and hind flippers. We identified the transposed fore- and hind flippers in a mounted Cryptoclidus eurymerus specimen (GPIT-PV-30092) on display in the Paleontological Collection of Tübingen University. It is likely that the fore- and hind flippers were accidentally transposed when the skeleton was mounted, although, amongst plesiosaurians, the fore- and hind flippers of Cryptoclidus eurymerus are some of the least similar-looking ones. This occurred either during a remounting of the skeleton from a free-standing armature on the ground to a freely “flying” skeleton hanging from the ceiling, or after a research project conducted on the specimen in the 1970s. We summarize osteological characteristics that can be used to correctly identify fore- and hind flippers of this species, and for better future assessment of the plesiosaurian locomotory system.