The Tangled Taxonomic History
of the Sandtiger Shark
The Sandtiger Shark has undergone several name changes since its discovery. In many older (pre-1970) technical and popular books on sharks, the scientific name of this species was almost always given as Carcharias taurus. The species was so named by the great 19th century Turkish naturalist Constantine Samuel Rafinesque in 1810, based on a specimen caught off the coast of Sicily. In 1837, German biologists Müller and Henle introduced the genus Triglochis for this species. In 1838, as part of his monumental five-volume work on fossil fishes, the eminent Swiss-American naturalist Jean Louis Rodolphe Agassiz described Odontaspis cuspidata, based on fossil teeth. This name was used for 120 years.
In 1961, three eminent paleontologists and ichthyologists — E.I. White, W. Tucker, and N.B. Marshall — submitted a proposal to repeal ICZN Opinion 47, which gave priority to the genus Carcharias for the species taurus. White and his co-authors argued that the genus Odontaspis should be conserved in favor of Carcharias on two main grounds. Firstly, Odontaspis Agassiz 1838 was used far more frequently in the scientific literature than Carcharias Rafinesque 1810, especially with regard to fossil species. Secondly, Odontaspis appeared to be congeneric (that is, a member of the same genus) with Carcharias. In 1965, based on this argument, the ICZN rejected Carcharias (voting 20 to 2), placing it on their Official Index of Rejected and Invalid Generic names in Zoology (Opinion 723.5a, name no. 1746). As such, Odontaspis won by default and this genus was used for taurus.
In a 1977 paper on the phyletic relationships of living sharks and rays Leonard J.V. Compagno of the South African Museum — without stating his reasons — removed taurus from Odontaspis and placed it into a relatively unknown genus, Eugomphodus Gill 1862. In his 1984 FAO Species Catalogue, Sharks of the World, Compagno finally revealed his reasons for doing so. According to Compagno, based on cranial, vertebral, dental, and external morphological characters, Carcharias is NOT congeneric with Odontaspis. He cites a few, rather vague examples of these characters, including:
Odontaspis: snout long and conical; two rows of large upper anterior teeth on each side of symphysis (center of the jaw); first dorsal fin noticeably larger than second, closer to pectoral fin bases than pelvic bases
taurus: snout short and flattened; three rows of large upper anterior teeth on each side of symphysis; first dorsal fin about as large or slightly larger than second, closer to pelvic bases than pectoral bases.
Compagno therefore proposed Eugomphodus, the next oldest valid genus after Carcharias, be used for taurus. Compagno is arguably the world's foremost authority on the anatomy, classification, and evolutionary interrelationships of sharks and their relatives the batoids and chimaeras. In an earnest desire to keep up-to-date, just about everyone followed Compagno's example. But unbeknownst to most of them, Compagno had been crusading for the reinstatement of Carcharias for many years. In 1987, the ICZN published Opinion 1459, conserving Carcharias. Compagno had finally won his case.
But it wasn't until 1990 that Compagno published a list of the features he uses to separate Carcharias from Odontaspis.:
Odontaspis: snout bulbous; teeth reduced in size; trunk elongate relative to head and precaudal tail; vertical fenestra (opening) in rostrum (snout cartilages) enlarged
Carcharias: first dorsal fin shifted posteriorly; air gulping as buoyancy mechanism; basal plate (undersurface) of cranium arched below anterior part of suborbital shelves (ridges under the eyes)
Compagno follows most of these characters with question marks, suggesting that he is not certain about their validity as taxonomic indicators. Some taxonomists — notably Guido Dingerkus of the Museum National D'Histoire and John Morrissey of Hofstra University — remain unconvinced that the characters Compagno proposes are sufficient to warrant placing taurus is a genus separate from Odontaspis. Paleoichthyologist Henri Cappetta, of the Laboratoire de Paleontologie, prefers to use the genus Synodontaspis for the living species taurus. Time will tell which view will prevail. But, for the time being, the correct binomial to be used for the Sandtiger Shark is once again Carcharias taurus.