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Preliminary Report On The Osteology And Relationships Of A New Aberrant Cryptocleidoid Plesiosaur From The Sundance Formation, Wyoming, F. Robin O’Keefe, William Wahl Jr.
Preliminary Report On The Osteology And Relationships Of A New Aberrant Cryptocleidoid Plesiosaur From The Sundance Formation, Wyoming, F. Robin O’Keefe, William Wahl Jr.
F. Robin O’Keefe
The cryptocleidoid plesiosaur Tatenectes laramiensis, new genus, is described from the Redwater Shale Member of the Sundance Formation, Narrona 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 …
Morphologic And Ontogenetic Patterns In Elasmosaur Neck Length, With Comments On The Taxonomic Utility Of Neck Length Variables, F. Robin O’Keefe, Norton Hiller
Morphologic And Ontogenetic Patterns In Elasmosaur Neck Length, With Comments On The Taxonomic Utility Of Neck Length Variables, F. Robin O’Keefe, Norton Hiller
F. Robin O’Keefe
Elasmosaur cervical vertebrae are common fossils, but their taxonomic utility is limited due to a lack of understanding concerning their shape within and among taxa. In this paper, we analyze data from complete elasmosaur necks in an attempt to quantify and understand the variation in centrum dimensions. In accord with previous studies, variation in cervical centrum shape is found to stem from at least three sources: ontogeny, intracolumn variation, and intercolumn or taxonomic variation. Ontogenetic variability seems reminiscent of that seen in Cryptoclidus, with an overall positive allometry in the length of all centra that is accentuated in the mid-cervical …