Plesiosaur refs: Tatenectes and Pantosaurus

[bh480@scn.org]

Plesiosaur refs: Tatenectes and Pantosaurus
Ben Creisler bh480@scn.org
In case these items have not been mentioned here:

O'Keefe, F. R. & W. Wahl, Jr., 2003. Preliminary report on 
the osteology and relationships of a new aberrant 
cryptocleidoid plesiosaur from the Sundance Formation, 
Wyoming. Paludicola. 4(2): 48-68.
AB: The cryptocleidoid plesiosaur Tatenectes laramiensis, 
new genus, is described from the Redwater Shale Member of 
the Sundance Formation, Natrona County, Wyoming. The 
holotype of this species was a partial skeleton that has 
since been lost. A neotype is designated that preserves 
the same elements present in the holotype. A second 
specimen is referred to the taxon, and this specimen 
includes cranial material. The preserved cranial elements 
are the left squamosal, a partial right frontal, several 
isolated teeth, the parasphenoid, and large portions of 
the left and right pterygoids. The skull shares many 
traits with that of Kimmerosaurus, a cryptocleidoid 
plesiosaur from the Kimmeridge Clay of England. However, 
the palate is derived, and resembles those of the poorly-
understood cimoliasaurid plesiosaurs of the Cretaceous of 
the southern hemisphere. This similarity is established 
via comparison with the skull of an undescribed taxon from 
late Jurassic of Cuba. The cryptocleidoid plesiosaurs 
underwent an extensive radiation in the Late Jurassic, and 
more research attention is needed, beginning with 
additional preparation and collection of Tatenectes.

O'Keefe, F. R. & W. Wahl, Jr., 2003. Current taxonomic 
status of the plesiosaur Pantosaurus striatus from the 
Upper Jurassic Sundance Formation Wyoming. Paludicola. 4
(2): 37-46.
AB: Plesiosaur material has been known from the Redwater 
Shale member of the Sundance Formation (Jurassic: 
Oxfordian) of Wyoming for over 100 years, but has received 
little research attention. Here we report on the taxonomic 
status of a long-necked cryptocleidoid plesiosaur from the 
Redwater Shale, the correct identity of which is 
Pantosaurus striatus Marsh 1893. The taxon Muraenosaurus 
reedii Mehl 1912 is shown to be a junior synonym of 
Pantosaurus striatus. Pantosaurus is described on the 
basis of the holotype and referred specimens, and found to 
be a cryptocleidoid plesiosaur possessing between 35 and 
40 cervical vertebrae. These vertebrae are very similar in 
proportion and anatomical detail to those of Muraenosaurus 
leedsii from the Oxford Clay of England. However, the 
forelimb of Pantosaurus is diagnostic and differs from 
that of Muraenosaurus in several particulars, the most 
important being the relatively large size of the radius 
and its corresponding humeral articulation. Although no 
cranial material is available at this time, we believe 
that Pantosaurus striatus is a valid taxon.