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Johan Lindgren

Johan Lindgren

Senior lecturer

Johan Lindgren

Description of new specimens of Halisaurus arambourgi BARDET & PEREDA SUBERBIOLA, 2005 and the relationships of Halisaurinae

Author

  • Michael J. Polcyn
  • Johan Lindgren
  • Nathalie Bardet
  • Dirk Cornelissen
  • Louis Verding
  • Anne S. Schulp

Summary, in English

Halisaurine mosasaurs are poorly known, represented by a small number of specimens from the Santonian-Maastrichtian (similar to 86 Ma - similar to 66 Ma), but enjoyed broad palaeobiogeographic distribution during that time. They are important for understanding mosasaur evolution because certain aspects of their morphology retain the relatively plesiomorphic or minimally modified squamate conditions; however, existing material is limited and certain anatomical details are lacking. We report here two new specimens of Halisaurus arambourgi including a well-preserved, nearly complete skull and posteranial skeleton, and a partial skull that preserves details of the braincase and quadrate. We focus our description on morphology that augments the original description of this species and provides comparisons with other halisaurines. Braincase and temporal arcade characters confirm the plesiomorphic nature of Halisaurus, supporting a relatively basal position of Halisaurinae within Mosasauridae. Comparisons of cranial morphology support reconstruction of relationships within Halisaurinae, indicating that H. arambourgi is most closely related to H. platyspondylus, Phosphomsaurus (= H. ortliebi) is the sister taxon to those taxa, and Eonatator is the most basal described halisaurine. The proportions of the epipodials and the caudal vertebral centrum morphometrics indicate H. arambourgi is more derived than the Santonian to early Campanian Eonatator sternbergii but less derived than a Halisaurus sp. specimen from the mid-Maastrichtian of the Moreno Formation of California, USA. Moreover, vertebral morphometrics reveals that H. arambourgi possessed a downturned tail that likely supported a crescent-like fluke.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2012

Language

English

Pages

123-136

Publication/Series

Bulletin de la Société Géologique de France

Volume

183

Issue

2

Document type

Journal article

Publisher

Geological Society of France

Topic

  • Geology

Keywords

  • Halisaurus arambourgi
  • Morocco
  • Cretaceous
  • Halisaurinae

Status

Published

ISBN/ISSN/Other

  • ISSN: 0037-9409