Carcharocles And Megaselachus

[Al Dente]

I was wondering what reason Cappetta had for changing the genus Carcharocles to Megaselachus for megalodon. In his 1987 Handbook of Paleoichthyology he used Carcharocles because it had precedence over the other names. In his 2006 publication-- Elasmobranchii post-triadici he uses Megaselachus. I'll probably not get a chance to read the later publication and I was wondering if anyone here has read it and found a reason for the change.

[siteseer]

Al Dente,

I have not seen this explained either. As you said, it was Cappetta who resurrected Carcharocles because he found that Jordan and Hannibal (1923) had erected the genus to account for "Squalus" auriculatus teeth. Any species that would be seen to belong to the same genus as auriculatus would therefore also belong within Carcharocles. Squalus had been a catch-all for many species before it was sorted out and finally reserved only for certain dogfish species.

When you look at the description for Carcharocles, you see that it is rather incomplete by modern standards and that the teeth chosen to represent it are a mix of Carcharocles (megalodon and chubutensis - or just early megalodon) and Carcharodon carcharias teeth.

The only thing that I can think of is that since 1987, Cappetta found something in Glickman (1964) that made him rethink his previous assessment - perhaps a more complete description exists there. However, Casier (1960) made the distinction between Carcharodon and shark we have been calling Carcharocles too and proposed Procarcharodon for the non-Carcharodon teeth. Someone would have to explain why we should not be using Procarcharodon in that case.

I have not seen Glikman (1964) but Purdy et al. (2001) stated that Glickman proposed Megaselachus solely for megalodon, reassigning angustidens and auriculatus to Otodus. I do not see how megalodon, angustidens, and auriculatus could belong to separate genera.

Of course, even with the sloppy description, Carcharocles could still be deemed the oldest, sufficiently-supported genus for megalodon by the ICZN (International Code of Zoological Nomenclature), which is like the "Supreme Court" for settling disputes over the validity of scientific names for animals. Whatever the ICZN decides the name should be would become the final official name (I think there is an appeal process too) if this situation ever "goes to trial."

I think it was David Ward who said that Carcharocles should be retained as the genus for megalodon if only out of common sense (putting a stop to this periodic name-changing), basically saying, "Let's pick a name and go with it."

Jess

Casier, E. 1960.

Note sur la collection des poissons paleocenes et eocenes de l'Enclave de Cabinda (Congo). Annales du Musee Royal du Congo Belge, serie A, 3(1)2. 48 p.

Glickman, L.S. 1964. (in Russian)

Paleogene Sharks and their Stratigraphic Significance. Academy of Science of the USSR. Moscow/Leningrad. 228 p.

*I have seen the last name spelled as "Gluckman," "Gluckman" with an umlaut over the "u," and "Glueckman" as well.

Jordan, D.S. and H. Hannibal. 1923.

Fossil Sharks and Rays of the Pacific Slope of North America. Bull. So. Cal. Acad. Sci. Vol. 22: 27-68.

Purdy, R.W., V.P. Schneider, S.P. Appelgate, J.H. McLellan, R.L. Meyer, and B.H. Slaughter. 2001.

The Neogene Sharks, Rays, and Bony Fishes from Lee Creek Mine, Aurora, North Carolina. In: Geology and Paleontology of the Lee Creek Mine, North Carolina, III. C. E. Ray and D. J. Bohaska (eds.). Smithsonian Contributions to Paleobiology. 90. Smithsonian Institution Press, Washington D.C. pp. 71-202.

I was wondering what reason Cappetta had for changing the genus Carcharocles to Megaselachus for megalodon. In his 1987 Handbook of Paleoichthyology he used Carcharocles because it had precedence over the other names. In his 2006 publication-- Elasmobranchii post-triadici he uses Megaselachus. I'll probably not get a chance to read the later publication and I was wondering if anyone here has read it and found a reason for the change.

[Al Dente]

Al Dente,

I have not seen this explained either. As you said, it was Cappetta who resurrected Carcharocles because he found that Jordan and Hannibal (1923) had erected the genus to account for "Squalus" auriculatus teeth. Any species that would be seen to belong to the same genus as auriculatus would therefore also belong within Carcharocles. Squalus had been a catch-all for many species before it was sorted out and finally reserved only for certain dogfish species.

When you look at the description for Carcharocles, you see that it is rather incomplete by modern standards and that the teeth chosen to represent it are a mix of Carcharocles (megalodon and chubutensis - or just early megalodon) and Carcharodon carcharias teeth.

The only thing that I can think of is that since 1987, Cappetta found something in Glickman (1964) that made him rethink his previous assessment - perhaps a more complete description exists there. However, Casier (1960) made the distinction between Carcharodon and shark we have been calling Carcharocles too and proposed Procarcharodon for the non-Carcharodon teeth. Someone would have to explain why we should not be using Procarcharodon in that case.

I have not seen Glikman (1964) but Purdy et al. (2001) stated that Glickman proposed Megaselachus solely for megalodon, reassigning angustidens and auriculatus to Otodus. I do not see how megalodon, angustidens, and auriculatus could belong to separate genera.

Of course, even with the sloppy description, Carcharocles could still be deemed the oldest, sufficiently-supported genus for megalodon by the ICZN (International Code of Zoological Nomenclature), which is like the "Supreme Court" for settling disputes over the validity of scientific names for animals. Whatever the ICZN decides the name should be would become the final official name (I think there is an appeal process too) if this situation ever "goes to trial."

I think it was David Ward who said that Carcharocles should be retained as the genus for megalodon if only out of common sense (putting a stop to this periodic name-changing), basically saying, "Let's pick a name and go with it."

Jess

Siteseer

Thanks for taking the time to reply. It will be interesting to see what collectors will be calling these teeth years from now. It seems like a lot of change in the last several years to extinct shark names.