AN UNUSUAL CERVICAL VERTEBRAL COLUMN IN A PLESIOSAUR FROM THE KIOWA SHALE DESCRIBED WITH A NOTE ON TAPHONOMY

The Lower Cretaceous (Albian) Kiowa Formation of Clark County, Kansas, consists of dark gray shale with occasional limestone deposits that represent a near shore environment. Listings of the vertebrate fauna have been produced based on fragmentary materials; however, few individual specimens have been described in the last 100 years. Here an unusual cervical vertebral column of a plesiosaur (KUVP 16375) is described. This specimen consists of 10 articulated cervical vertebrae and a number of disarticulated cervical vertebrae of indeterminate position along the column. The vertebrae are uniquely formed in comparison to known plesiosaurs. Known plesiosaur vertebrae possess narrow width neural spines and ventral rib facets; two rib facets in older formation plesiosaurs and a single facet in younger formation plesiosaurs. Two foramina, called the foramina subcentralia, are present in the ventral surface of known plesiosaur cervicals. The vertebrae described here lack clear rib facets, neural spines, and many of them have an excavated ventral surface and a thin centrum. It is hypothesized that this excavated foramina is the result of taphonomic processes. It is not apparent at this time whether or not this indentation represents a significant diagnostic character. Taphonomy of the column of vertebrae is addressed. Cervical vertebrae of other Kiowa Formation plesiosaurs are compared to the vertebral column (KUVP 16375) described.