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Re: Arctometatarsalia and Alvarezsauria




As I have recommended before, I think the taxon Arctometatarsalia should be abandoned (just as Bullatosauria was). Restricting it just to ornithomimids (and close relatives) leaves us in the position where calling something "arctometatarsalian" is extremely ambiguous. Is the person referring to a member of cladistic Arctometatarsalia or the much wider group of coelurosaurs that share the "arctometatarsalian" foot (which is now known to be convergent)?
As for the Alvarezsauria mess, I recommended on February 7th that mononykiforms be divided into three separate families: Patagonykidae, Parvicursoridae, and Mononykidae (the latter containing Shuvuuia and Mononykus). This is clear cut, and if you want to combine Parvicursoridae and Mononykidae into one family, you will then have to face the muddled taxonomic history of those forms (which has been periodically debated on DML for several years). I personally would rather have an oversplit classification that is clearcut, rather than forcing ourselves into an unnecessary and endless debate that continually resurfaces.
As for Alvarezsaurus, I support Bonaparte's assignment of it (and it alone) to Family Alvarezsauridae, at least until more material settles the debate over its proposed relationship with the mononykiforms. I prefer to refer to it as Alvarezsaurus (plesion or genus) since the name Alvarezsauridae has so often been used to include the mononykiforms. After all, the purpose of nomenclature is clarity of communication.
I am just trying to make the best of a bad situation. Please be mindful that my "predictions" are an attempt to proactively avoid more such situations in the future (and I fear the Sinovenator assignment is another such situation in the making).
------- Ken Kinman



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