New papers in Geobios (and nomenclatoral gripe)

[gerarus@westnet.com.au]

Two new papers today in Geobios:

Candeiro, C. R. A., A. R. Santos, T. H. Rich, T. S. Marinho & E. C.
Oliveira. 2006. Vertebrate fossils from the Adamantina Formation
(Late Cretaceous), Prata paleontological district, Minas Gerais
State, Brazil. Geobios 39 (3): 319-327.

"In this contribution is given a preliminary up-to-date annotated
list of all fossil vertebrates from the Turonian?Santonian Adamantina
Formation, Bauru Group where it occurs in the Prata paleontological
district which is located 45 km to the west of Prata in Minas Gerais
State, Brazil. The Adamantina Formation is a reddish sandstone in the
Triângulo Mineiro region. These fluviolacustrine sediments were
deposited in a semiarid environment. Three fossil vertebrate sites
occur in the Prata paleontological district. The diversity of
vertebrates in the Adamantina Formation is modest, and its components
comprise a mixture of typical austral Gondwana taxa (such as
abelisaurids, Aeolosaurus) and boreal Gondwana taxa (such as
Carcharodontosauridae). The absence of Laurasian taxa in the upper
part of the Bauru Group is noteworthy. Excepting some turtles,
crocodylians, and one titanosaurid, most of the specimens discovered
in this Group are based on fragmentary and isolated remains, which
make it difficult to correctly identify the fossils. For this reason,
many of the taxa have only been identified in a preliminary manner.
Despite this drawback, the dinosaurs are typical Gondwana forms with
no evidence of Laurasian affinities. This is concordant with the idea
that the Laurasian dinosaurs entered South America at the end of the
Late Cretaceous; i.e. after the Turonian?Santonian, the age of the
Adamantina Formation."

And:

Sachs, S., & J. J. Hornung. 2006. Juvenile ornithopod (Dinosauria:
Rhabdodontidae) remains from the Upper Cretaceous (Lower Campanian,
Gosau Group) of Muthmannsdorf (Lower Austria). Geobios 39 (3):
415-425.

"The fragmentary remains of a juvenile rhabdodontid ornithopod from
the Coal-bearing Complex of the Gosau Group (Lower Campanian,
Grünbach syncline) at Muthmannsdorf near Wiener Neustadt, Lower
Austria are revised. The material, probably belonging to a single
individual, includes a right dentary (lectotype of Iguanodon suessi
Bunzel, 1871, designated herein), teeth, a fragmentary parietal,
fragments of scapula, ?radius, femur, tibia, two vertebrae (lost) and
a manual ungual.
    The lectotype dentary does not provide clear autapomorphies or
sufficient diagnostic features to determine its position within the
Rhabdodontidae at generic level. By this ?Iguanodon suessi? Bunzel,
1871 and the genus ?Mochlodon? Seeley, 1881, to which it was latter
referred as type species, cannot be characterized sufficiently by
differential diagnosis and these are best considered nomina dubia.
Based upon combined character comparisons (mainly postcranial
features) the Muthmannsdorf ornithopod is referred herein to Zalmoxes
Weishampel, Jianu, Csiki and Norman, 2003, a genus so far known from
the late Maastrichtian of Romania. It probably but not evidently
represents a yet unnamed species, most closely related to Zalmoxes
shqiperorum Weishampel, Jianu, Csiki and Norman, 2003. At the present
state of knowledge the Austrian material is not further diagnostic at
the species level and kept in open nomenclature as Zalmoxes sp."

    Unfortunately, this paper follows the not-uncommon, but invalid,
practice of thinking that a _nomen dubium_ doesn't compete
nomenclatorially - it does. If the type material for _Mochlodon_
falls within what is currently called _Zalmoxes_, the genus should be
called _Mochlodon_, not _Zalmoxes_ - even if we can't put the type
material in a reliable position as regards species. The authors seem
to feel that _Mochlodon_ is unusable because the specific specimen
designated as lectotype doesn't exhibit characters distinguishing it
from _Rhabdodon_ rather than _Zalmoxes_, but the hypodigm as a whole
(which they think is probably from a single individual) does show
distinguishing characters at the generic level.
    A couple of other nomenclatorial issues are worth mentioning in
relation to the taxonomic history on p. 417. _Mochlodon robustum_ was
originally published as a synonym of _M. suessi_ (if I interpret the
article correctly), and is only available if it was used a valid name
prior to 1961 (ICZN Article 11.6.1). In relation to _Camptosaurus
inkeyi_ having page priority over the name it is usually regarded as
a synonym of, I should remind you that 'page priority', while a long
tradition, doesn't have any official standing, and relative priority
of two names published at the sae time is determined by the choice of
the first reviewer to regard them as synonymous.

    Cheers,

        Christopher Taylor