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Complexity of the Oviraptoridae
This is meant as a short-form discussion of the two recent
theropod dinosaurs assigned to the oviraptorids, *Khaan
mckennai* and *Ciripati osmolskae.* In addition to these taxa,
there are still several other specimens out there of some
questionable identity, but are distinct nonetheless. These are
not the last of the oviraptorids you?ll hear from.
Oviraptorids seem to be restricted to the Mongolian Gobi, and
only spread in time from the late Cenomanian to the early
Maastrichtian, given recent estimates of time for The Djadokhta,
Barun Goyot, and directly over the latter, the Nemegt
Formations. These are not datable formations by conventional
means, but at least the last formation can be compared faunally
to the North American Judith River, which can be dated, and is
essentially late-Campanian to early Maastrichtian; thus, the
Barun Goyot Formation is between the middle and late Campanian
in age. The Djadokhta has rough or absent contacts, though the
fauna is quite similar to the Barun Goyot, suggestive of being
contemporaneous strata. However, there are forms known only in
the Djadokhta and Barun Goyot, but these forms will be absent in
the Nemegt; similarly, there are forms known only in the Barun
Goyot and the Nemegt, likewise unknown in the Djadokhta,
suggesting that there is a series present. It is possible
portions of the Barun Goyot and Djadokhta were laid down at the
same time, in nearby areas, but what speaks against this is that
the lithostratigraphy and geology are different: the Djadokhta
is primarily aeolian sandstones with fresh-water course and
pools; the Barun Goyot preserves more siltstones and is more
cross-bedded with stream-sediments and small lakes; the Nemegt
resembled the Judith River, in being very watery, southern
Louisiana-like.
All in all, the Oviraptoridae is a very definable group of
animals, diagnosed primarily by features of the skull, including
the shortening of the snout and lower jaw, enlargement of the
orbit, form of the palate, expansion and pneumatic form of the
cranial roofing bones, loss of the tomial edge of the maxilla,
the sigmoid lower jaw margin and dorsal margin, an external
mandibular fenestra that extends more than 50% into the
posterior of the dentary, loss of the medial dentigerous wall,
and a few other interesting innovations. In the postcranium,
they are also diagnostic: the pubes lack any ventral curvature
of the shaft, unlike *Nomingia* or *Chirostenotes,* or
*Caudipteryx,* but like *Microvenator*; and except for
*Oviraptor mongoliensis* the ilium is low and about as equally
high in front of the acetabulum as above it.
Known and named oviraptorids (by species) are quite plentiful,
now:
*Oviraptor philoceratops* Osborn, 1924b (= ?Fenestrosaurus?
Osborn, 1924a; n.n.) / Djadokhta ? late Cenomanian, early
Campanian or middle Campanian? Size: skull 6?7 inches,
probably about 6?7 feet or 1.8?2.4m total length.
*Oviraptor mongoliensis* Barsbold, 1988 (= ?Rinchenia? Barsbold,
1997; n.n.) / Nemegt ? late Campanian or early Maastrichtian?
Size: skull 6 inches, probably only about 6 feet or 1.8m total
length.
*Ingenia yanshini* Barsbold, 1981 (= *Oviraptor yanshini*
(Barsbold, 1981) Paul, 1988) / Djadokhta and Barun Goyot ?
late Cenomanian to middle or late Campanian? Size: skull 5?6
inches, 5?6 feet or 1.5?1.8m in total length.
*Conchoraptor gracilis* Barsbold, 1986 / Barun Goyot ? middle or
late Campanian? Size: skull ~5.5?6 inches, around 6 feet or
1.7m in total length.
*Khaan mckennai* Clark, Norell, & Barsbold, 2001 / Djadokhta ?
late Cenomanian to early or middle Campanian? Size: skull ~4.3
inches, less than 5 feet or 1.2m total length.
*Citipati osmolskae* Clark, Norell, & Barsbold, 2001 (*Oviraptor
philoceratops* sensu Webster, 1996) / Djadokhta ? late
Cenomanian to early or middle Campanian? Size: skull 5.5
inches, probably around 5?6 feet or 1.2?1.8m total length
[postcrania not completely prepared, not including many dorsal
or sacral vertebrae].
It should be noted that there is an almost near perfect
correlation between the length of the skull and the total
postcrania + cranial length in oviraptorids, on the order of
close to 1:12. This should be kept in mind when restoring the
postcrania of an incomplete skeleton with a skull, or putting
the skull on a postcranial skeleton.
And there are a few more specimens that are not described as
yet that qualify as diagnostic species. This includes the
elongated skull referred to as *Ingenia* by Webster, 1996;
Novacek, 1996; Dashzeveg et al., 1993; a skull of a
*Conchoraptor*-like animal in the travelling Great Russian
Dinosaur Exhibit, the very large oviraptorid that, as Mickey and
I have said recently, is not *Oviraptor philoceratops* in spite
of Barsbold, 1981, 1983, this being based on extensive
comparison to the type skull, which resembles *O. mongoliensis*
more and has a caudally extensive cranial crest [and apomorphy
of the genus]. Norell et al., 2001, suggest the animal may be a
species of *Citipati* but it is likely they held off describing
the animal pending further study: unlike all other oviraptorids,
Citipati osmolskae has a much longer neck, derived forehead and
skull features, and the humerus of the nesting specimen is quite
distinct (pers. obs.). The large specimen, GI (SPS) 100/42 [or
IGM 100/42, if you prefer] may be the sister group to *C.
osmolskae,* but is not that species. Until further analysis is
performed on both type specimens, it would be wise to refrain
from referring GI 100/42 to *Citipati* (as Norell et al., 2001,
suggest).
There is a some overlap in the diversity at one spot for many
oviraptorids, though only one oviraptorid is known from the
Nemegt (elmisaurids are present, but only three or four
specimens are known, all belonging Elmisaurus rarus and of
limited material, appendicular only). *Oviraptor* and *Ingenia*
are both known together, as are *Conchoraptor* and *Ingenia,*
and *Khaan* and *Citipati* both occur at the same sublocality
within Ukhaa Tolgod, Ankylosaur Flats, known for its
*Pinacosaurus* material (Novacek, 1996). Several of the newer
skulls undescribed refer to material from the Djadokhta and
Barun Goyot Formations, and would if totaled count up to 4 or so
new species based on what I?ve seen.
Within the Oviraptoridae, there is a distinct set of
morphologies, easily described by the three principle taxa:
ingeniine, for those with very short hands, arms;
conchoraptorine for those with intermediately elongate hands,
but a third finger shorter than the second and closer to the
pollex in size, and a moderately pneumatic skull, as well as a
premaxilla with very large denticles; oviraptorine, for those
with very elongated hands and a cranial crest that extends
caudally to the rear of the skull (sagittal crest). Using this
criteria, *Khaan* is a conchoraptorine for the most part, as
suggested by Norell et al., 2001, and *Ciripati* is closer to
oviraptorines, but still appears to be conchoraptorine, as is GI
100/42.
Key features:
*Khaan mckennai*:
Generally, *Khaan* possesses an elongate neck of 13 cervicals,
and a skull with a high, dorsally rounded margin, short second
and third digits with a robust pollex, and a metatarsus more
than 50% the femoral length and a pes nearly equal the length of
the tibia, and considerably longer than that of other
oviraptorids for which this material is known. Norell, et al.,
2001, diagnose *Khaan* based on the following features:
metacarpal II does not contact distal carpals, unexpanded
mediolaterally (internal/externally). Furthermore, there is no
parietal crest or a median parietal ridge (as in *Oviraptor* and
GI 100/42 respectively), a narrow metacarpal I, the long axis of
the external nares oriented subhorizontally (as in Ingenia),
fused nasals, premaxilla inclined dorsocaudally, relatively
shallow nasals caudally, caudal ramus of the jugal longer than
the rostral ramus, dentary underlies the angular instead of
forming a lateral flange (as in *Ciripati*). A postacetabular
ala longer than the preacetabular ala, pedal digit III longer
than metatarsal III, and a short, high exoccipital process, are
diagnostic to the species as well.
*Ciripati osmolskae*:
The majority of features are a suite of characters relating to
the dorsal half of the skull being rostrally displaced relative
to the ventral half; the lower jaw is not affected. These are:
occiput oriented dorsocaudally if the jugal was level, rostral
margin of the premaxilla vertical, jugal ascending ramus
perpendicular to the ventral bar formed byt the caudal and
rostral rami, narrow V-shaped angle between jugal and squamosal
rami of the quadratojugal, extreme lateral expression of the
palate ventral to the jugal/maxilla margin (hypertrophy of the
oviraptorid synapomorphy). Furthermore, the cervical vertebrae
are very elongate with centra twice as long as wide (centra are
nearly twice as wide as tall, as in *Microvenator,*
*Chirostenotes,* *Ciripati,* *Khaan,* *Ingenia,* *O.
philoceratops,* and GI 100/42), and sternal lateral processes
sharply triangular and elongated, with parietals elongated
rostrally nearly to the level of the anterior margin of the
orbits.
Relationships:
*Khaan* resembles *Ingenia* is having a relatively short arm,
a nearly strait ischium along the caudal/dorsal surface, a
robust metatarsus, and short second and third manal digits. It
resembles *Conchoraptor* in the degree of pneumatization of the
skull, the dorsally expanded nasals, the general form of the
lower jaw including a short triangular instead of prong-shaped
invading process of the surangular into the external mandibular
fenestra. It is generally a primitive oviraptorid, though more
derived and similar to *Oviraptor* than to *Ingenia.* Generally,
this animal, based on the hand, form of the cranium and degree
of pneumatization, resembles *Conchoraptor,* and this may
indicate a monophyletic group. *Ciripati,* *Oviraptor,* *Khaan,*
GI 100/42, and *Conchoraptor* all share extensively pneumatized
cranial bones, whereas *Ciripati* shares with *Oviraptor* and GI
100/42 the dorsally expanded nasal pneumatic chambers, extensive
premaxillary pneumatization, a premaxillary sagittal crest, and
also share a tear-shaped external nares, narrowest caudally, but
the short axis is much larger than in other oviraptorids.
*Ciripati* and *O. mongoliensis* have similar humeri, with the
proximal margin of the deltopectoral crest arising to the level
of the humeral head, but similar to GI 100/42 in the general
form of the shaft, which bears a mediocaudally inflected head
and cranial inflected distal condyles, but a generally strait
shaft. *Ciripati* seems to be closer to *Oviraptor* than to
*Conchoraptor* or *Ingenia,* and is thus an oviraptorine
Barsbold, 1986, and Barsbold et al., 1990/1992 argued that the
prescence of a small nasal ?pocket? or ?bulla? next to the nasal
tract in the nasals of *Conchoraptor,* *Oviraptor,* GI 100/42,
kept these taxa together to the exclusion of the skull of
*Ingenia.* However, the type skull of *Ingenia* does in fact
possesses a nasal bulla, and this feature may thus be used to
diagnose Oviraptoridae. The absence of this feature in a skull
referred to *Ingenia* by Paul, 1988, Zpal MgD-I/95 (see
Osmólska, 1976) and the general primitive features of the skull
may be ontogenetic, as the skull appears to be subadult or
juvenile. For one thing, few closed sutures exists, and many
margins between the braincase bones are present.
So, the following phylogeny may be in evidence:
--Caenagnathoidea
|--Caenagnathidae
`--Oviraptoridae
`--+--Ingenia yanshini
|--ZPAL MgD-I/95
`--+--?Conchoraptorinae?
| |--Conchoraptor gracilis
| `--Khaan mckennai
`--Oviraptorinae
|--+--Ciripati osmolskae
| `--GI (SPS) 100/42
`--Oviraptor
|--O. philoceratops
`--O. mongoliensis
A test for the phylogeny is currently underway by several
researchers, including Osmólska, Barsbold, and The team at the
AMNH (Norell, Clark,, Chiappe, Makovicky).
References:
Barsbold R. 1981. Bezzubyye dinozavra Mongolii [The toothless
dinosaurs of Mongolia]. Trudy ? Sovmyestnaya
Sovyetsko?Mongol?skaya Palyeontologichyeskaya Ekspyeditsiya 15:
28-39.
Barsbold R. 1983. Khishchnikh dinozavry myela Mongolii [The
carnivorous dinosaurs of Mongolia]. Trudy ? Sovmyestnaya
Sovyetsko?Mongol?skaya Palyeontologichyeskaya Ekspyeditsiya 19:
1-120.
Barsbold R. 1986. Raubdinosaurier oviraptoren [Theiving
dinosaurs, the oviraptors] pp. 210-223 in Vorobyeva (ed.)
Herpetologische Untersuchungen in der Mongolischen Volkrepublik.
Akadyemiya nauk S.S.S.R. Institut Evolyutsionnoy Morfologii i
Ekologii Zhivotnykh im. A.M. Syevyertsova [Moscva {Moscow}].
Barsbold R. 1988. O kostnom gryebnye i shlyemye na chyeryepye
u khishchnykh dinozavrov ? oviraptorov [On the crest and helmet
of the skull in the carnivorous dinosaurs, the oviraptors].
Trudy ? Sovmyestnaya Sovyetsko?Mongol?skaya
Palyeontologichyeskaya Ekspyeditsiya 34: 77-80.
Barsbold R.; Maryanska, T.; and Osmólska, H. 1990.
Oviraptorosauria. pp. 249-258 in Weishampel, Dodson, & Osmólska
(eds.) The Dinosauria (California Academy of Sciences Press
[Berkeley, California]). [second printing, paperback, 1992]
Barsbold R. 1997. Oviraptorosauria. pp. 505-509 in Currie and
Padian (eds.) Encyclopedia of Dinosaurs (Academic Press [New
York, New York]).
Clark, J.M.; Norell, M.A.; & Barsbold R. 2001. Two new
oviraptorids (Theropoda: Oviraptorosauria), Upper Cretaceous
Djadokhta Formation, Ukhaa Tolgod, Mongolia. Journal of
Vertebrate Paleontology 21(2): 209-213.
Dashzeveg D.; Novacek, M.J.; Norell, M.A.; Clark, J.M;
Chiappe, L.M.; Davidson, A.R.; McKenna, C.; Dingus, L.; Swisher,
C.C., III; Perle A. 1995. Unusual preservation in a new
vertebrate assemblage from the Late Cretaceous of Mongolia.
Nature 374: 446-449.
Osborn, H.F. 1924b. Three new Theropoda, Protoceratops zone,
Central Mongolia. American Museum Novitates 144: 1-12.
Osmólska, H. 1976. New light on the skull anatomy and
systematic position of Oviraptor. Nature 262: 683-684.
Paul, G.S. 1988. Predatory Dinosaurs of the World: A Complete
Illustrated Guide. (New York Academy of Science [New York, New
York]) 464pp.
=====
Jaime A. Headden
Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
Where the Wind Comes Sweeping Down the Pampas!!!!
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