Keep in mind, if that were the standard, Titanosauridae would be a nomen dubium but e.g. Deinodontidae wouldn't (unless you elevated Tyrannosaurinae and Albertosaurinae to "family" rank). The situation with Deinodontidae is a nearly exact parallel to Troodontidae. It would be hard to think of a single standard that would uphold one while rejecting the other, except using priority of definition/only recognizing taxa defined as clades.
On Aug 11, 2017, at 1:15 PM, David Marjanovic <email@example.com> wrote:
>> Actually, arguably not. Within Titanosauria there are several proposed and employed "families" (Saltasauridae, Nemegtosauridae, Aeolosauridae, potentially others). It is not at all certain which of these the Titanosaurus indicus material would belong to. If we agreed to put all of these in one family, that would be Titanosauridae. But if we regard them as distinct taxa, and cannot affirm where Titanosaurus goes, we can continue to not use "Titanosauridae".
> Oops, that's true; if Titanosauridae is indistinguishable from two (or more) families that can be distinguished from each other, it is a nomen dubium. I hadn't been paying enough attention to titanosaur nomenclature over the last few years.
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