A fishy mosasaur: the axial skeleton of Plotosaurus (Reptilia, Squamata) reassessed

Summary, in English

The concept of convergence, that is, how unrelated animals independently evolve similar morphological traits, is a fundamental aspect of evolution. Hitherto, the Mesozoic ichthyosaurs were regarded as the sole obligate marine reptiles that achieved a fully streamlined body and a semilunate tail fluke. However, analyses of vertebral centrum morphometrics and process orientation have revealed that a subsequent clade of secondarily aquatic reptiles, the mosasaurs (here exemplified by the advanced, mid-Maastrichtian mosasaurine Plotosaurus), had developed a deep, fusiform body and a probable pursuit-predatory behaviour by the time of their sudden extinction at the Cretaceous-Paleogene boundary. Stringent physical constraints and selection pressures, imposed by the surrounding water, probably were responsible for this spectacular example of large-scale evolutionary convergence.

• Author: Johan Lindgren; John W. M. Jagt; Michael W. Caldwell
• Department/s: Lithosphere and Biosphere Science
• Publishing year: 2007
• Language: English
• Pages: 153-160
• Publication/Series: Lethaia
• Volume: 40
• Issue: 2
• Links: http://dx.doi.org/10.1111/j.1502-3931.2007.00009.x
• Document type: Journal article
• Publisher: Taylor & Francis
• Topic: Geology
• Keywords: tail stock; tail fin; surface; propulsive; Plotosaurus; Mosasauridae; displacement unit; hypocercal
• Status: Published
• ISBN/ISSN/Other: ISSN: 0024-1164