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Hainosaurus Dollo, 1885 is Tylosaurus Marsh, 1872



Ben Creisler
bcreisler@gmail.com



A new paper:

Paulina Jimenez-Huidobro & Michael W. Caldwell (2016)
Reassessment and reassignment of the early Maastrichtian mosasaur
Hainosaurus bernardi Dollo, 1885, to Tylosaurus Marsh, 1872.
Journal of Vertebrate Paleontology (advance online publication)
DOI:10.1080/02724634.2016.1096275
http: // www.tandfonline.com/doi/full/10.1080/02724634.2016.1096275


Redescription of Hainosaurus bernardi Dollo, 1885a, from the early
Maastrichtian of the Ciply Phosphatic Chalk of Belgium, results in a
reassignment of the taxon to the genus Tylosaurus Marsh, 1872, because
the genus Hainosaurus cannot be diagnosed independent of Tylosaurus.
The diagnosis of Hainosaurus bernardi by Dollo, 1885a, is reviewed,
and the two incomplete and poorly preserved specimens assigned to the
taxon are compared with recognized species of Tylosaurus. Hainosaurus
was originally diagnosed from characters of the jugal, quadrate,
maxilla, premaxilla, frontal, parietal, and teeth. Here, we show that
most of the characters of these elements are shared with the genus
Tylosaurus, and that those that are not shared, but that are purported
key diagnostic characters for Hainosaurus, are simply not preserved,
or are too poorly preserved to support a differential diagnosis of H.
bernardi at the generic level. The available data support the
conclusion that Hainosaurus is a junior synonym of Tylosaurus because
no anatomical features distinguish the former from the latter. The
genus Tylosaurus occupied a wider geographic and temporal distribution
than has been previously suggested, inhabiting the North Atlantic
Circle Basin from the Turonian to the Maastrichtian. There are
species-level features that support T. bernardi as distinct from other
described species of Tylosaurus.


SUPPLEMENTAL DATA—Supplemental materials are available for this
article for free at www.tandfonline.com/UJVP