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Galeamopus, new sauropod genus, Brontosaurus, genus revived, Diplodocidae revised

Ben Creisler

A new open access paper:

Emanuel Tschopp, Octávio Mateus & Roger B.J. Benson (2015)
A specimen-level phylogenetic analysis and taxonomic revision of
Diplodocidae (Dinosauria, Sauropoda) .
PeerJ 3:e857
doi: https://dx.doi.org/10.7717/peerj.857

Diplodocidae are among the best known sauropod dinosaurs. Several
species were described in the late 1800s or early 1900s from the
Morrison Formation of North America. Since then, numerous additional
specimens were recovered in the USA, Tanzania, Portugal, and
Argentina, as well as possibly Spain, England, Georgia, Zimbabwe, and
Asia. To date, the clade includes about 12 to 15 nominal species, some
of them with questionable taxonomic status (e.g., ‘Diplodocus’ hayi or
Dyslocosaurus polyonychius), and ranging in age from Late Jurassic to
Early Cretaceous. However, intrageneric relationships of the iconic,
multi-species genera Apatosaurus and Diplodocus are still poorly
known. The way to resolve this issue is a specimen-based phylogenetic
analysis, which has been previously implemented for Apatosaurus, but
is here performed for the first time for the entire clade of

The analysis includes 81 operational taxonomic units, 49 of which
belong to Diplodocidae. The set of OTUs includes all name-bearing type
specimens previously proposed to belong to Diplodocidae, alongside a
set of relatively complete referred specimens, which increase the
amount of anatomically overlapping material. Non-diplodocid outgroups
were selected to test the affinities of potential diplodocid specimens
that have subsequently been suggested to belong outside the clade. The
specimens were scored for 477 morphological characters, representing
one of the most extensive phylogenetic analyses of sauropod dinosaurs.
Character states were figured and tables given in the case of
numerical characters.

The resulting cladogram recovers the classical arrangement of
diplodocid relationships. Two numerical approaches were used to
increase reproducibility in our taxonomic delimitation of species and
genera. This resulted in the proposal that some species previously
included in well-known genera like Apatosaurus and Diplodocus are
generically distinct. Of particular note is that the famous genus
Brontosaurus is considered valid by our quantitative approach.
Furthermore, “Diplodocus” hayi represents a unique genus, which will
herein be called Galeamopus gen. nov. On the other hand, these
numerical approaches imply synonymization of “Dinheirosaurus” from the
Late Jurassic of Portugal with the Morrison Formation genus
Supersaurus. Our use of a specimen-, rather than species-based
approach increases knowledge of intraspecific and intrageneric
variation in diplodocids, and the study demonstrates how
specimen-based phylogenetic analysis is a valuable tool in sauropod
taxonomy, and potentially in paleontology and taxonomy as a whole.


News stories:







Again, my mistake for prematurely posting the name Galeamopus about a
week ago off the Sauriermuseum Aathal website. As a reminder, here's
the link to the press material in German, which was open to all, but
had an embargo on the name itself. I found the name in a web search
for new dinosaur announcements and should have rechecked the source
before posting.