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

Polcyn, Michael J.; Lindgren, Johan LU ; Bardet, Nathalie; Cornelissen, Dirk; Verding, Louis and Schulp, Anne S. (2012) In Bulletin de la Société Géologique de France 183(2). p.123-136
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Halisaurus arambourgi, Morocco, Cretaceous, Halisaurinae
in
Bulletin de la Société Géologique de France
volume
183
issue
2
pages
123 - 136
publisher
Geological Society of France
external identifiers
  • wos:000304508900007
ISSN
0037-9409
DOI
10.2113/​gssgfbull.183.2.123
language
English
LU publication?
yes
id
fb337047-6d27-44a6-a3ad-9e17e537eb52 (old id 2911732)
date added to LUP
2012-07-23 14:05:08
date last changed
2016-04-15 20:57:43
@article{fb337047-6d27-44a6-a3ad-9e17e537eb52,
  abstract     = {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.},
  author       = {Polcyn, Michael J. and Lindgren, Johan and Bardet, Nathalie and Cornelissen, Dirk and Verding, Louis and Schulp, Anne S.},
  issn         = {0037-9409},
  keyword      = {Halisaurus arambourgi,Morocco,Cretaceous,Halisaurinae},
  language     = {eng},
  number       = {2},
  pages        = {123--136},
  publisher    = {Geological Society of France},
  series       = {Bulletin de la Société Géologique de France},
  title        = {Description of new specimens of Halisaurus arambourgi BARDET & PEREDA SUBERBIOLA, 2005 and the relationships of Halisaurinae},
  url          = {http://dx.doi.org/10.2113/​gssgfbull.183.2.123},
  volume       = {183},
  year         = {2012},
}