[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Glishades ericksoni, a new hadrosauroid from Montana



Dear DMLers,
Albert Prieto-Márquez described a new ornithopod, Glishades ericksoni,
from Glacier County of Montana (Two Medicine Formation). G. ericksoni
was published in today's Zootaxa.

To be honest, I'm not particularly satisfied with Prieto-Márquez's
hadrosauroid nomenclature. His Hadrosauridae (node-based name)
consists of Hadrosaurus foulkii (and possibly also Tethyshadros
insularis; see Fig. 2. and 3. of the paper) and Saurolophidae
(labelled on the cladogram as it was a branch-based name but defined
as "the last common ancestor of Saurolophus osborni, Lambeosaurus
lambei, and all its descendants", which is a node-based definition).
Saurolophidae contains Saurolophinae and Lambeosaurinae. I can
understand that the position of H. foulkii may require some
nomenclatural acts (it was found outside of Lambeosaurinae +
"Hadrosaurinae", so a new potentially self-destructive node-based name
[i.e., a name that would be used only if H. foulkii is found outside
the "Saurolophus osborni + Lambeosaurus lambei" clade] can be
introduced) but is it really necessary to introduce a new name with
"-idae" within another "-idae" (there is Weishampel et al.'s [1993]
Euhadrosauria; see also Horner et al's [2004] paper in the second
edition of The Dinosauria)?

Other data should be published in "Prieto-Márquez, A. (In press).
Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using
parsimony and Bayesian methods. Zoological Journal of the Linnean
Society."

Here is the abstract of the new paper:

Prieto-Márquez, A. 2010. Glishades ericksoni, a new hadrosauroid
(Dinosauria: Ornithopoda) from the Late Cretaceous of North America.
Zootaxa 2452: 1–17.

A new genus and species of hadrosauroid dinosaur, Glishades ericksoni,
is described based on paired partial premaxillae collected from the
Upper Cretaceous Two Medicine Formation of Montana, in the Western
Interior of the United States of America. This taxon is diagnosed on
the basis of a unique combination of characters: absence of everted
oral margin, arcuate oral margin with wide and straight, obliquely
oriented, and undeflected anterolateral corner, grooved transversal
thickening on ventral surface of premaxilla posterior to denticulate
oral margin, and foramina on anteromedial surface above oral edge and
adjacent to proximal end of narial bar. Maximum parsimony analysis
positioned G. ericksoni as a derived hadrosauroid. Exclusion of G.
ericksoni from Hadrosauridae was unambiguously supported by the lack
in AMNH 27414 of a dorsomedially reflected premaxillary oral margin.
Furthermore, the maximum agreement subtree positioned G. ericksoni as
the sister taxon to Bactrosaurus johnsoni. This position was
unambiguously supported by posteroventral thickening on the ventral
surface of the premaxilla (independently derived in saurolophid
hadrosaurids and Ouranosaurus nigeriensis) and having foramina on each
premaxilla on the anterior surface, adjacent to the parasagittal plane
of the rostrum (reconstructed as independently derived in
Brachylophosaurus canadensis, Maiasaura peeblesorum, and Edmontosaurus
annectens).

Best,
-- 
Daniel Madzia
web: www.wildprehistory.org
mail: daniel.madzia@gmail.com
skype: danielmadzia