Replacement of Rostral Teeth in Sawfishes and Sawsharks

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. American Society of Ichthyologists and Herpetologists (ASIH)is collaborating with JSTOR to digitize, preserve and extend access to Copeia.In recent sawfishes, Pristis (order Batoidei), rostral teeth that are lost are not replaced and those not severely damaged in use increase in size throughout life. Presumably similar conditions pertain to fossil sawfish genera having socket-like attachments for rostral teeth. In recent sawsharks, Pristiophorus and Pliotrema (order Selachii), rostral teeth are replaced if lost and do not increase in size after reaching a functional position. Similarities in tooth development and the process of replacement were observed in recent sawsharks (Selachii) and in the Cretaceous sawfish genus Sclerorhynchus (Batoidei). Also, the pattern of varying length of rostral teeth in adults of recent sawsharks (Selachii), which is explained by the appearance of both new and replacement teeth at intervals during growth, offers a possible explanation for the presence of rostral teeth of various lengths in the Cretaceous ganopristid sawfish Onchopristis numidus (Batoidei).

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…They also reported damage from incidental capture in other types of fishing gear ranges from broken rostral teeth to broken rostrums. The loss of rostral teeth could be especially detrimental because, unlike other elasmobranchs, smalltooth sawfish do not replace lost teeth (Slaughter and Springer 1968). Since the smalltooth sawfish's rostrum is its primary means for acquiring food, the loss of rostral teeth may impact an animal's ability to forage and hunt effectively.…”

The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae)

“…Their rostral teeth are attached to the rostrum via connective tissue and, when lost, they are replaced in a conveyor-belt fashion like elasmobranch oral dentition (Schaeffer 1963;Slaughter and Springer 1968;Cappetta 1987). The peduncle of the rostral teeth is expanded (Cappetta 1987).…”

“…Pristid sawfish possess rostral teeth that grow continuously from the base and are attached to the rostrum via alveoli (Slaughter and Springer 1968;Compagno and Last 1999). The peduncle is not expanded and the dentine cap is easily worn off (Slaughter and Springer 1968).…”

Records of the northern hemisphere Cretaceous Sawfish genusOnchopristis(order batoidea) from New Zealand

“…As noted above, the numbers of barbs present appear somewhat proportional to length, which would suggest that barb numbers increased with tooth maturity. Another point to be considered is the occurrence of replacement teeth at intervals during growth, which has been noted in sawfish (Slaughter & Springer 1968). This would not only account for teeth of various lengths, as Slaughter and Springer (1968) noted for O. numidus, but would also explain variation in barb numbers between teeth on the same rostrum.…”

“…Another point to be considered is the occurrence of replacement teeth at intervals during growth, which has been noted in sawfish (Slaughter & Springer 1968). This would not only account for teeth of various lengths, as Slaughter and Springer (1968) noted for O. numidus, but would also explain variation in barb numbers between teeth on the same rostrum. Schaeffer (1963) considered that heterochronic eruption may be a marked feature of ganopristine tooth growth.…”