Abstract:
Three taxa have independently evolved an elongated rostrum lined with rostral spines, the extant pristiophorids (sawsharks) and pristids (sawfishes) and the sclerorhynchoids (extinct sawfishes). Ischyrhiza mira is a common sclerorhynchoid found in Cretaceous North American deposits. Isolated rostral spines and oral dentition have been recovered from New Jersey, Delaware, Kansas, Arkansas, Georgia, Mississippi, Texas, New Mexico, and Alberta. Rostral spines are thought to have evolved from dermal denticles and serve as a feeding and/or defense adaptation. Very little is known about the microstructure of these structures. We examined the histological composition and organization of Ischyrhiza mira rostral spines using acid etching and scanning electron microscopy. Images show that Ischyrhiza has a tissue architecture that is much more complex than that of dermal denticles located on the body surface.
Team Members
Jack Prothero | Michael Brudy | (Todd Cook) | Penn State Behrend
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