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Re: Euhelopodidae and Mamenchisauridae

In a message dated 98-01-26 17:55:27 EST, tkeese1@gl.umbc.edu writes:

<< Someone on the list mentioned these two families as being synonymous a
 little while ago. As I was preparing the latest big update to my dinosaur
 web site the other day, I noticed that _Mamenchisaurus_ was named two
 years before _Euhelopus_. Assuming (perhaps incorrectly?) that the
 families based on these genera were named at the same time that the genera
 themslves were named, shouldn't the proper name of the family be
 Mamenchisauridae? >>

No--for purposes of priority, Euhelopodidae dates from Romer's creation of the
subfamily Euhelopodinae in 1956 (to replace the name Helopodinae Huene, 1932
because the generic name _Helopus_ was preoccupied--and replaced by Romer with
_Euhelopus_). Priority of a family-level name is reckoned from the first time
the name is coined at that level, regardless of whether it is originally
coined as the name of a superfamily, family, subfamily, tribe, or subtribe.

Oskar Kuhn first raised Euhelopodinae to full family level by using the name
Euhelopodidae in 1965. This is still several years before Young & Chao's 1972
creation of Mamenchisauridae.

_Mamenchisaurus_ seems to be part of a lineage/clade that begins with
_Shunosaurus_, passes through _Omeisaurus_, and includes the genus
_Euhelopus_, so there's no clear reason to separate it into its own family or
even subfamily (it would be the only member genus in either). I happen to
think that _Opisthocoelicaudia_ is also part of this lineage/clade and has
nothing to do with titanosaurs, and perhaps also the as-yet-undescribed