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So after looking into this situation a bit, it's interesting but I think the ICZN made the correct decision.
It has nothing at all to do with Lambeosaurus, as back in the 1920s-1940s cheneosaurs were seen as a valid group of small hadrosaurids with low crests (like aublysodontids vs. tyrannosaurs in the 1980s-1990s). So in 1920,
Procheneosaurus is named by Matthew based on those two sentences and without a species, but that was allowed before 1931, so it would be hypocritical to criticize
Procheneosaurus for this and not a thousand other genera now viewed as valid (and an explicit type specimen and indication the author intended to create a new name weren't needed until 2000, so those are highly irrelevant). In 1931,
Tetragonosaurus preaceps was named by Parks based on what is even now (Evans, 2007) recognized as the same genus along with T. erectofrons. In 1935 Lull was presumably writing what would be the highly influential Lull and Wright (1942) hadrosaurid
monograph and asked the ICZN for a solution (as opposed to now where petitioners always have a stated desired outcome). In 1936, the ICZN voted and decided that
Procheneosaurus was valid, but hadn't dealt with Tetragonosaurus or species yet.
It's now 1942, Lull and Wright's monograph is published, and in it they state the ICZN's conclusion that "Procheneosaurus
is, therefore, a perfectly definable genus and in no sense a nomen nudum." What they do is make
praeceps the type species of Procheneosaurus. The ICZN writes Lull in 1943 and weirdly uses the monograph as evidence
preaceps should be the type species of Procheneosaurus, while also using Article 13.3 ("every new genus-group name published after 1930 ... must, in addition to satisfying the provisions of
Article 13.1, be accompanied by the fixation of a type species in the original publication [Art. 68] or be expressly proposed as a new
replacement name (nomen novum) [Art. 67.8]") to declare
Tetragonosaurus invalid. This is all published by Hemming (1947) in BZN as Opinion 193.
So in a way Lull created the solution to his own problem, but I think it's the correct one for what was thought to be known at the time. Jay's right that the original specimens of
Procheneosaurus and praeceps are different, but they were viewed as conspecific at the time. So if Lull would have given the 1920
Procheneosaurus based on AMNH 5340 a new species name, it would have immediately been sunk into
praeceps and thus been both useless and defying Article 11.5 ("To be available, a name must be used as valid for a taxon when proposed"). This effectively gave
Procheneosaurus a new type specimen, which I'm not a fan of but happens in Dinosauria (e.g.
Stegosaurus, Coelophysis, Majungasaurus, Archaeopteryx). And it is weird that there is no way AFAIK to designate a type species for a genus named after 1930 after the fact (but you can for genera named earlier), so this does invalidate
Tetragonosaurus. How do preaceps and erectofrons survive as valid then? Well, for a species name "the generic name need not be valid or even available" (Article 11.9.3.1). So the decision followed all the rules, didn't produce additional
names, and got to honor both Matthew and Parks.
Of course now based on Evans' 2007 thesis and resulting publications, we assign both original
Procheneosaurus AMNH 5340 and the praeceps type to Lambeosaurus
sp. and the erectofrons type to Corythosaurus sp.. I've been in favor of indeterminate species within a genus, so hypothetically this would lead to
Procheneosaurus praeceps (type, indet.), P. lambei, P. magnicristatus and
P. indet. (AMNH 5340; former type of Procheneosaurus). Dimirjian's petition was to "request to set aside Opinion 193 and remove
Procheneosaurus Official List of Generic Names in Zoology, and Tetragonosaurus from the Official Index of Rejected and Invalid Generic Names in Zoology", which seems unnecessary.
Tetragonosaurus can remain invalid, and all that needs to happen is for
Lambeosaurus to gain priority over Procheneosaurus. The ICZN (2019) stated "Following discussion with the author, the Case is now closed", so I wonder what happened.
Mickey Mortimer
From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of Justin Tweet <thescelosaurus@gmail.com>
Sent: Thursday, September 17, 2020 10:23 AM To: dinosaur-l@usc.edu <dinosaur-l@usc.edu> Subject: Re: [dinosaur] Procheneosaurus Ah, yes, Procheneosaurus, based on two sentences, no type species, a type specimen by implication, and no indication that the author intended to create a new name. If this were 2020 instead of 1920, it would be another name in a museum
exhibition guidebook, another "Xinghesaurus", but it was "named" before 1931, under much laxer rules, so it got by. The fact that the rules for pre-1931 names permitted it to be accepted is not an argument for
Procheneosaurus, but an argument against the rules.-Justin
On Thu, Sep 17, 2020 at 11:24 AM Tyler Greenfield <tgreenfield999@gmail.com> wrote:
-- Justin Tweet
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