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The crux of our disagreement might be based on your answer to this. Take these two statements which you support-
"from a phylogenetic taxonomy standpoint, it's a really BAD idea for a taxonomically valid genus to have a nomen dubium as a type species."
"Because _D. longus_ is the type species of the genus Diplodocus, but is itself not diagnosable, a retention of _D. longus_ as type species would create insecurities and confusion concerning the use of _Diplodocus_ as a genus."
My question is- What bad outcome could occur because a species undiagnosable within its genus is the type species?
Mickey Mortimer
From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of Tim Williams <tijawi@gmail.com>
Sent: Thursday, October 15, 2020 7:06 PM To: dinosaur-l@usc.edu <dinosaur-l@usc.edu> Subject: Re: [dinosaur] Diplodocus status Mickey Mortimer <mickey_mortimer111@msn.com> wrote:
> There isn't even agreement that Diplodocus longus IS undiagnostic. True, but beside the point. The assessment that a particular taxon is a nomen dubium is always subjective. > - Even IF Diplodocus longus was undiagnostic, undiagnostic species CAN be the type species of diagnostic genera. There's nothing in the ICZN arguing against that. Just because it's not proscribed by the ICZN, doesn't necessarily mean it's a good idea. In fact, from a phylogenetic taxonomy standpoint, it's a really BAD idea for a taxonomically valid genus to have a nomen dubium as a type species. A nomen dubium is a valid name (nomenclature), but not a valid species (taxonomy). Scientifically, there's no point pretending that a nomen dubium is a valid species simply for the purpose of nomenclature. > - The argument about future-proofing for nomenclatural stability has zero urgency because all parties involved agree Diplodocus longus is definitely the same genus as D. carnegii, even the authors who > petitioned the ICZN in the first place. Tim et al. would be arguing for an official nomenclatural change based on a case that nobody thinks is true or even likely. See response immediately above. > - If we continue with this philosophy of designating the most complete species as the type species or the most complete specimen the neotype [*snip* Mickey's voluminous list of taxa] It's a bad > philosophy. I didn't say (or even imply) that we needed the most complete specimen as the type species, or the most complete specimen as the neotype. But when we have a scientifically well-known genus with a dodgy holotype (as in the case of _Diplodocus longus_), it would be helpful to have a species based on an unambiguously diagnostic specimen as the new type species. I thought Tschopp and Mateus (2016) presented a strong case in their petition, especially this statement: "Because _D. longus_ is the type species of the genus Diplodocus, but is itself not diagnosable, a retention of _D. longus_ as type species would create insecurities and confusion concerning the use of _Diplodocus_ as a genus." Thus, the petition aimed to resolve the "insecurities and confusion" of _Diplodocus_. Rebutting the petition by scouring the _D. longus_ holotype for perceived diagnostic characters does nothing to prevent _Diplodocus_ from one day becoming a dubious genus. |