These bones have not been consolidated or even cleaned thoroughly. There is still phosphate dust in the interseptal spaces on the lamnoid centra.
My reference for the types of vertebrae is Bretton W. Kent, FOSSIL SHARKS OF THE CHESAPEAKE BAY REGION (1994); pp. 9 (with illustrations). Kent refers to Norm Tessman in a 1966 Plaster Jacket article, THE CENOZOIC SHARKS OF FLORIDA.
On page 2 of the 1966 Plaster Jacket article (the very first Plaster Jacket issued), Tessman provides illustrations and simply asserts:
"Two distinct types of vertebrae are readily distinguished. The more primitive shark families have less completely developed vertebrae, referred to as LAMNOID vertebrae, whereas the higher families have a more solid type which are known as SCYLIORHINOID vertebrae."
This suggest to me that Tessman was relying on some earlier work, though such is not cited. (I don't find reference to vertebrae in Tessman's 1969 thesis, THE FOSSIL SHARKS OF FLORIDA.)
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