Dermal tubercles and bucklers of gigantic stingrays (Dasyatidae) from the Pleistocene of South Carolina and the stratigraphic origin of “Ceratoptera unios” Leidy, 1877

Rays (Batoidea) possess some of the absolutely largest dermal elements of any cartilaginous fish. One of the largest known batoid dermal elements is an isolated fossil tubercle originally interpreted as a manta ray caudal stinger and named Ceratoptera unios Leidy, 1877 from an unknown locality near Charleston, South Carolina. Though recently considered to be a stingray (Dasyatidae), the lack of stratigraphic provenience for the specimen has hampered attempts to identify it. A new collection of gigantic dermal tubercles and bucklers from the Lower Pleistocene Waccamaw Formation of South Carolina includes mid-dorsal tubercles similar in morphology to “ Ceratoptera unios ” and dermal bucklers similar in morphology to those of the extant roughtail stingray Bathytoshia centroura (Mitchill, 1815). Mid-dorsal tubercles and bucklers suggest gigantic stingrays in excess of 3 m disc width. These new specimens suggest that C. unios may have originated from upper Pliocene or Pleistocene deposits, and possible synonymy with Bathytoshia centroura , pending careful study of extant dasyatid dermal elements.