not 2, but 3 new oviraptorids

[GUNTER.VANACKER@ELECTRABEL.COM]

Allow me to make a summary of the Norell et al. paper.

First I would like to say, that I actually like the names that have been
given to the 2 new species. The names Citipati osmolskae (Hasla Osmolska's
lord of the funeral pyre) and Khaan mckennai (Malcolm Mc Kenna's ruler) were
clearly chosen to honour 2 people that have made considerable contributions
to the scientific study of dinosaurs (the species epithet), while the
generic name shows that Norell et al. have much respect for the Mongolian
traditions. It's becoming a real trend, to incorporate native traditions of
the countries where new dinosaur specimens are being discovered (also
Sereno's Niger dinosaurs, several Argentinian species ...), into the
eventual name of these species. While this often means that these names are
difficult to pronounce, we sure end up with original and recognisable names,
while strengthening the relationship with the people of these countries.


Now, back to business;


Citipati osmolskae is based on following material:

(holotype, IGM 100/978) nearly complete skeleton (of which only the skull,
several cervical vertebrae and the shoulder girdle have been prepared at the
moment, but these elements include plenty of diagnostic characters to assign
the specimen to a new species).

(referred, IGM 100/979) partial postcranium overlying a nest with
elongatoolithid eggs (referral to C. osmolskae is based on its large size
and differences from the contemporary genus Khaan, the describers are
probably correct by doing so, but there remains a small possibility that
this specimen belongs to yet another oviraptorid species from Ukhaa Tolgod,
perhaps an additional species within the genus Citipati).

(referred, IGM 100/971) embryonic skeleton within elongatoolithid egg
(confidently referred to C. osmolskae on the basis of the nearly vertical
premaxilla; It's very exciting to finally have an actual dinosaur species
assigned to the ubiquitous elongatoolithid oofamily; you'll probably have
seen the beautiful reconstruction of this famous embryo, which in my opinion
should have displayed downy feathers rather than the scaled skin).

C. osmolskae's main differences from other oviraptorids; has a shorter skull
than Oviraptor philoceratops, differs from "Rinchenia" mongoliensis in
lacking a convex crest on frontals and parietals, has a taller and more
highly pneumatized nasal than Conchoraptor, and differs from all other
oviraptorids in the fact that its dorsal part of the skull is shifted
anteriorly and has more elongate cervical vertebrae. The skull is 50% larger
than known specimens of Khaan, Conchoraptor and Ingenia, which may indicate
that Citipati was a relatively large oviraptorid, up to 3 m (10ft) in
length.


Khaan mckennai, based on;

(holotype, IGM 100/1127) complete skeleton (slightly disarticulated in the
thorax)

(referred, IGM 100/1002) nearly complete skeleton (lacking the distal half
of the tail). This specimen was found in close proximity to the holotype,
this is the "Romeo and Juliet" pair that was prominently shown on a National
Geographic speciel a few years ago.

(referred, IGM 100/973) nearly complete skeleton

K. mckennai is very similar to Conchoraptor (also lacks the specializations
and dorsal crest of O. philoceratops) It differs from Conchoraptor in
several features of the narial region. The proximal reduction of its third
metacarpal is a distinctive autapomorphy of K. mckennai, otherwise the
postcranium is unspecialized. Free uncinate processes are present interlaced
with ribs. Differs from Ingenia in that metacarpal I is not extremely broad.
This taxon was previously tentatively identified as Ingenia, but preparation
of the postcranium revealed that it represents a new genus (mainly based on
distinctive characters of the manus). The size of this species is similar to
Conchoraptor and Ingenia, estimated at an average of 2 m (6-7 ft).


Citipati sp. based on;

(IGM 100/42) skull with several associated cervical vertebrae

This material was previously referred to O. philoceratops. Norell et al.
state that it may represent a second species of Citipati (pending further
study). The premaxilla, circumnarial pneumatization and an accessory opening
anterior to the nares are similar to C. osmolskae. However, IGM 100/42
differs from C. osmolskae in several other features (unfused vomers,
anterior edge of premaxilla is concave in lateral view, and the cervical
vertebrae are not elongate).
So, all listmembers that have a database with dinosaur species on the
Internet (DinosaurIcon, DINODATA ...), should include a Citipati sp. into
their Citipati entry.



Some additional comments on the Norell et al. paper;

The describers suggest that the Djadochta Formation (to which Ukhaa Tolgod
belongs) may be contemporary with the Barun Goyot Formation; no
superpositional relations between these to formations are known, and an
increasing number of taxa is shared between the two formations. I'd say that
Ukhaa Tolgod (and the two new oviraptorids) is probably earliest to mid
Campanian (83 to 76 MYA).

While Norell et al. do mention the other nesting oviraptorid that was
discovered by Currie & Dong (Djadochta Fmt, Bayan Mandahu, Inner Mongolia,
China, 1996), they apparently did not unclude it into their research. While
it is contemporary with the Ukhaa Tolgod specimens, and may thus belong to
one of the newly named species, there still remains the possibility that it
belongs to a separate genus. I think that this specimen should remain an
"unnamed oviraptorid" until (and if) synonymy with an already named species
can established, or receives an entirely new species name.

Norell et al. are not convinced of the close relationship that is often
suggested for Therizinosaurs and Oviraptorosaurs, they also doubt that
Caudipteryx (and Microvenator) is closely related to oviraptorids, and
Norell states that he has a paper in press to prove all this.

With the assignment of IGM 100/42 to Citipati sp., Norell et al. have
started the much needed review of all specimens that have been referred to
the existing oviraptorid genera. However, they do state that each of the
holotypes of the existing species can be distinguished by at least one
autapomorphy. So, a complete review of all oviraptorid specimens can only
result in more new species. A thorough phylogenetic analysis of the family
Oviraptoridae is also needed to determine the exact relationship between all
these species.

This paper again demonstrates the unusual amount of theropod taxa present at
Ukhaa Tolgod, which may have important implications for dinosaur
predator-prey ratios. The only common herbivorous dinosaurs at Ukhaa Tolgod,
were ankylosaurids; I wouldn't consider this to be attractive prey for all
those deinonychosaurs, troodontids and oviraptorids that were present. It's
likely that most theropods were feeding on lower vertebrates (lizards etc.),
invertebrates and particularly the relatively abundant small mammals. Also,
since The AMNH-Mongolian expeditions were focusing on theropods, there
probably remain several types of herbivores to be discovered (multiple
ankylosaurid taxa, but also "protoceratopids", pachycephalosaurs ...).



Regards,
Gunter Van Acker

quote of the day; (Donald Gennaro) "We are going to make a fortune with this
place"