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Oviraptorosaur Collage: Oviraptorosauria, including all species known from reasonably well-preserved cranial
material, with some indeterminate species or undescribed but well-represented species, including a basal caenagnathid
(left, crested), a species of Conchoraptor (at right), a species of Caudipteryx (top, center).

Oviraptorosauria:
Birdy Dinosaurs with a Penchant for Beaks

Oviraptorosaurs generally encompass a group of theropods known for their large beaks, and crests. Most of these are oviraptorids, however, leaving the diversity of non-oviraptorid or caenagnathid oviraptorosaurs to be a collection of less-well known or more bird-like theropods with feathers and, surprisingly, teeth. It is the purpose of this page to attempt to resolve and describe these from the literature, and to bring a perhaps better light on some fairly unknown or poorly known taxa.

Introduction:

here

Review & History:

Oviraptorosauria was named in 1976 by Barsbold in order to separate the previously named Oviraptoridae from the Ornithomimosauria, similarly named in the same paper. Oviraptorosauria was coined to include the then diversity of oviraptorids that were being recovered in Mongolia during the joint Soviet-Mongolian paleontological expeditions in the 1940's, and once each in the 1970's and 1980's (Coy, 1997). Prior to the naming of Oviraptoridae, however, extensive work in the 1920's and 1930's in the badlands of Alberta, Canada, provided the discovery of several fossils of a variety of theropods or "birds" that would give the most extensive collection of incomplete remains of any group of oviraptorosaurs known to this date. These would later be grouped into various taxa, such as Macrophalangia, Caenagnathus, Chirostenotes, and by the 1970's, in four named species, all but two of which were synonyms. The plentiful but fragmentary nature of these fossils would provide an extensive list of taxa from which all eventually, by the early to mid-1980's and later 1990's, would be compounded into one genus and two species, Chirostenotes (based on some hands) pergracilis and C. sternbergi (the later based on a jaw fragment). Similarly, an ornithomimid-like animal, originally named as a species of Ornithomimus would become a new species of the Mongolian genus Elmisaurus as E. elegans. More extensive work in Mongolia in the 1970's and 1980's by the joint Polish-Mongolian paleontological expeditions would produce ever further material of oviraptorids, and expand our knowledge of Oviraptorosauria overall. But there were more oviraptorosaurs from around the world, including the Cloverly Microvenator, the Turonian Caenagnathasia, and the Barremian Caudipteryx.

All oviraptorosaurs are Cretaceous in Age, spreading out over the Early and Late Cretaceous fairly unevenly. All caenagnathoids (oviraptorids and caenagnathids) are Late Cretaceous in age, and most non-caenagnathoids are Early Cretaceous. Exceptions include the Late Cretaceous Nomingia and the Turonian Caenagnathasia, but otherwise this pattern holds true. Nomingia was the first dinosaur taxon described which would entail a non-avian dinosaur with a pygostyle, in this case formed of at least four fused vertebrae, and would be both a basal oviraptorosaur as well as a caenagnathid; Caenagnathasia became the smallest oviraptorosaur, with an estimated skull length of only three inches (or a little over seven and one-half cm). Microvenator would enjoy status as both a basal coelurid, and even lately a possible relative of Caudipteryx, whereas the latter has been described as a peculiarly flightless bird, and the first truly definitive evidence of feathers in dinosaurs and the nature of dinosaurs as the origin of bird, even though it itself was not on the lineage towards birds but rather at the base of an off-shoot. Chirostenotes would be considered both a coelurid and a dromaeosaurid before it was recognized as a relative of Elmisaurus.

Various Oviraptorosaurs:

Basal Oviraptorosaurs Collage: Basal oviraptorosaurs, non-
Oviraptoridae and non-Caenagnathidae.

Incisivosaurus gauthieri (Xu, Cheng, Wang & Chang, 2002):

Just recently described, this is likely the oldest known oviraptorosaur, known with a full complement of teeth in each jaw bone (maxilla, premaxilla, and dentary), and a short face that is oddly reminiscent of Caudipteryx. The snout was massive, and the teeth are shaped like wedges and appear to have served a chopping function with their lower counterparts on the lateral jaws much as in a pair of shears, with large rodent-like premaxillary teeth that have brought the term "rabbit-like" to the mind of some observers.

Caudipteryx spp. (Ji, Norell, Currie & Ji, 1998):

Now known through several specimens, this small animal has been controversial as a basal oviraptorosaur or primitive bird, or a non-oviraptorosaurian non-bird, but clearly defines a morphology in its short, fully feathered wings, long legs, and a short tail with a broad fan of feathers. The skull is enhanced by teeth only in the premaxilla and long needle-like crown, large eyes, and a delicate down-turned jaw; the beak was probably serrated. The two named species are joined by a possible new species, named "C. sp." which is represented by the only complete specimens of Caudipteryx known, and possesses a unique skull from that of the type species; the second species lacks a skull.

Avimimus portentosus (Kurzanov, 1981):

Though originally described as a strange bird, Avimimus has many features seen in both segnosaurs and oviraptorosaurs, not the least of which includes the structure of its cervical and dorsal vertebrae, and the shape of its ankle which is similar if not nearly identical to that of the younger Elmisaurus. The beds in which Avimimus is known have been variously dated between the Campanian and Maastrichtian (either equivalent to the Djadokhta, Barun Goyot, or Nemegt Formations), but it is not presently clear which formation or age this animal comes from.

Kakuru kujani (Molnar & Pledge, 1980):

Based on a long, slender, opalized tibia, Kakuru is the first and so far only named oviraptorosaur or oviraptorosaur-like animal known from Australia. It shares features of its distal tibia with only Avimimus and Ingenia, leading one to conclude a general relationship with Oviraptorosauria. Its long, slender form has been used to compare to Avimimus in a passive manner.

Kakuru kujani can be accessed through here.

Nomingia gobiensis (Barsbold, Osm�lska, Watabe, Currie & Tsogtbaatar, 2000):

Known from the Late Cretaceous of Mongolia, this oddly birdlike but primitive oviraptorosaur has been questionably linked with Caenagnathidae in recent analyses, but its primitive pelvic structure and shortened tail are at odds with this, and the support has been almost purely vertebral, and I would therefore suggest it is plesiomorphic; this seems especially true given certain similarities in the pelvic structure to Caudipteryx and in the limb structure to both Avimimus, Caudipteryx, and Microvenator. A late-surviving large oviraptorosaur in the Mongolian desert is unusual, but suggests a unique ghost-lineage.

Caenagnathasia martinsoni (Currie, Godfrey & Nessov, 1994 [not 1993]):

This tiny animal, hailing from the Turonian of Qakaqstan, is perhaps the smallest known oviraptorosaur named to date, though Kurzanov suggests that there were jaws recovered of a similar animal even smaller, they are undescribed; the jaws of Caenagnathasia are short and deep, with crenellated beak margins and uniquely still retain vestiges of tooth sockets, reduced to vertical ridges and a medial shelf [go here to see more of a description of oviraptorosaur cranial anatomy, as well as here to see how Caenagnathasia changes the topology of Oviraptorosauria] in Chirostenotes and Oviraptoridae.

Microvenator celer (Ostrom, 1970):

Known from the latest Early Cretaceous of Montana, USA, Microvenator was discovered by the eminent Barnum Brown and originally was going to be named as "Megadontosaurus" by him, when he abandoned this; the name would allude to abundant very large teeth found that would later be referred to Deinonychus when Ostrom (in 1970) would name both animals. A bone from the jaw has been variously referred about the skeleton to the rear of the jaw, to the pelvis, and finally to the front of the jaw; this last interpretation required a quantum leap on the part of Makovicky and Sues in 1998. Many specializations and plesiomorphies in the anatomy of Microvenator have related this animal to the most primitive sister-group of the Oviraptorosauria or as the most basal oviraptorosaur, prior to the discovery of Caudipteryx, and this data should now be reviewed in light of the discovery of both Caudipteryx and Incisivosaurus.

Caenagnathidae & Oviraptoridae:
These two groups are extensive enough in their content to warrant their own pages, totaling 7 named genera (with one unnamed genus) and 10 named species (with at least 6 additional unnamed species and further undescribed species totaling about 3 which have not been well-described or are currently in private collections), which can be linked through below:

Caenagnathidae
Oviraptoridae

Systematics:

A more detailed analysis will be presented on a different page (here) but this here is used to familiarize one's self with the basic topography of the Oviraptorosauria before many of the discussions of each taxon in relation to one another are involved. Similarly, I will discuss here the higher-level taxonomy of the Oviraptorosauria as more detailed than that seen in the Review & History section above.

At first, the name Oviraptorosauria represents a complex in which Barsbold attempted to draw in a cohesive "clade" of all dinosaurs like Oviraptor and his new discovery of Ingenia. The name literally means "[all the] Oviraptor lizards" and in Barsbold's flavor was meant ( 1976b, 1983) to be an exclusive stem from Ornithomimosauria and other similarly named dinosaur groups coined by him, such as Deinocheirosauria (for Deinocheirus [an ornithomimosaur] and Therizinosaurus [a segnosaur], in reference to the huge size, long arms and large claws in both taxa), and later along with Perle, Segnosauria (1980). Barsbold would be the first to taxonomically group Oviraptoridae and Caenagnathidae after grouping them into a single taxonomy, despite the 1960's which brought others to compare the two favorably -- this would not be until 1983, however; the importance of the "stem" term above will become important as it shows a reflection of taxonomic thinking little expressed before the mid-1980's. Prior to the naming of Oviraptorosauria, the taxonomy on the group (as being referred to retroactively) involved a multitude of works on the nature of the Steveville "birds," including Caenagnathus, and Oviraptor was considered to be an unusual type of ornithomimid. Gauthier (1986) regarded Ingenia as an ornithomimosaur as well, but regarded the relationship between Caenagnathus and Oviraptor as closer to birds than were ornithomimosaurs.

Indeed, any reasonable taxonomy of the group would have to include some intent on its content. Since the description of Oviraptorosauria, Barsbold coined the taxa Ingeniinae and Oviraptorinae within the Oviraptorosauria, to include relatively Ingenia and Oviraptor (1981 ), and would later add Conchoraptor to the former (1986 ), and a new species of Oviraptor (1986, as well). This would then be the staple to Oviraptoridae for more than a decade, whereas that of Caenagnathidae would conflate many concepts on taxonomy that will be covered in more detail on the Caenagnathidae page, above. But an issue of content is important. Some systematics believe a name to apply strictly to any implied content; for instance, a Tyrannosaurinae with Alioramus is not Tyrannosaurinae, and in fact cannot ever be. In 1986 , Jacques Gauthier would use the name Oviraptorosauria as a reference to a group of theropods that were all closer in relationship to Oviraptor than they were to Ornithomimosauria, a stem usage that remained in effect for a decade, until the formulation of Sereno in 1998 and 1999 where it would be an application of birds rather than Ornithomimosauria that would be the appropriate "anchor". This is called a stem-based definition (see below, under the Glossary). It should be neccessary to provide a system of stems and nodes within each other, forming a node-stem triplet, that is universal in any clade system.

The following is a cladogram based on the reasoning I provide on the Phylogeny page, though this has not yet received strict attention, and for this purpose only the bases of the major groups are shown resolved to any degree.


--Oviraptorosauria
    |--Avimimus portentosus
    |--Caenagnathasia martinsoni
    |--Caudipteryx
    |    |--C. dongi
    |    |--C. zoui
    |    `--C. sp. (new species? BMP 0001 and IVPP V12430)
    |--Kakuru kujani
    |--Microvenator celer
    |--Nomingia gobiensis
    `--Caenagnathoidea
        |--Caenagnathidae
        |   |--Chirostenotes
        |   |   |--C. pergracilis
        |   |   `--C. sternbergi
        |   `--Elmisaurus
        |       |--E. elegans
        |       `--E. rarus
        `--Oviraptoridae
            |--Citipati
            |   |--C. osmolskae
            |   `--C. sp. (GI 100/42)
            |--Conchoraptor
            |   |--C. gracilis
            |   `--C. sp.
            |--Khaan mckennai
            |--Heyuannia huangi
            |--Ingenia yanshini
            |--Oviraptor philoceratops
            `--"Oviraptor" mongoliensis

The preceeding cladogram is compiled from data on the systematics of oviraptorosaurs that is largely mine in origin, but also benefits from the work of Makovicky and Sues (1998 ), Sues ( 1997), Xu et al. (2002a), Clark et al. (2001, 2002), and Currie and Russell (1988).

There are a total of thirteen characters which may be used as synapomorphies for the stem-defined taxon including Oviraptor, but not Ornithomimus, Segnosaurus, Dromaeosaurus, Troodon (or Saurornithoides), and Passer (or Vultur , as used by de Quieroz and Gauthier, 2001); this clade currently may be described as Oviraptorosauria, though other definitions in current use employ the possibility of segnosaurs as oviraptorosaurs, as they use only either birds or ornithomimosaurs to oppose oviraptorosaurs in the definition:

the supratemporal fenestrae are elongated craniocaudally, longer than wide by 200% or so;

the premaxillary tomial edge is crenellate;

the paroccipital processes are pendant in lateral and posterior view, depending to about half the distance between the base and the ventral edge of the quadrate/articular;

the Meckelian groove is shallow, rather than deeply incised into the dentary;

the surangular bears a short triangular process that invades the external mandibular fenestra from the top and rear;

the external mandibular fenestra length is more than 30% of the total mandible length;

the external mandibular fenestra height is more than 30% of the total mandible height;

the dorsal margin of the external naris is dorsal to the dorsal margin of the antorbital fenestra;

the caudal margin of the external naris is caudal to the rostral margin of the antorbital fenestra;

the dorsoposterior surangular process is as long as high, or longer;

the parietals are longer than the frontals;

the fourth trochanter is absent, replaced by either a notch or a fossa;

the lateral aspect of the ischium is broadly C-shaped, with the obturator process at about half its length.

Within Oviraptorosauria, the Caenagnathidae and Oviraptoridae form a clade that has been named Caenagnathoidea (Sereno, 1999), to the exclusion of forms such as Caudipteryx or Microvenator; other definitions of Oviraptorosauria also utilize the definition proposed for Caenagnathoidea, and it seems prudent to include both lists of synapomorphies. There are twenty characters that are diagnostic for the Caenagnathoidea and these are:

the maxilla is edentulous;

the premaxilla is completely edentulous;

the post-symphyseal dentary is edentulous;

the dorsal surface of the articular glenoid is convex;

the medial facet of the articular glenoid is wider than the lateral facet;

the lateral facet of articular glenoid overhangs the surangular/angular, and a ventral channel at the contact with the surangular defines the passage of a tendon;

the retroarticular process is elongated, longer than high, and the distal facet is oriented perpendicular to the shaft;

the coronoid process is inflected medially;

the articular dorsal crest is oriented sagittally, parallel to the jaw axis;

the splenial is strap-like and shallow, lacking the dorsal lamina;

the dentary symphysis is fused;

the reduction or loss of the dentary medial dentigerous wall;

the splenial progresses rostrally to the symphysis, nearly contacting the symphysis;

the prearticular overlaps the splenial, surpassing the splenial in length;

the medial (palatal) process of the maxillae contact at the midline, above or around the vomer;

the medial lamina of the maxilla with ventral prong-like extension;

the dentary, maxilla, and premaxilla lack a regular pattern of foramina;

the caudal centra are wider than tall;

the caudal centra grade from oblate or kidney-shaped to pentagonal in aspect;

the anterior (or lesser) trochanter is small, finger-like in shape, closely appressed or near to the greater trochanteric crest, without a slot between it and the greater trochanter.

References:

Barsbold R. 1976a. O novom pozdnyemyelovom syemyeystvye myelkikh tyeropod (Oviraptoridae fam. n.) Mongolii. [On a new Late Cretaceous family of small theropods (Oviraptoridae fam. n.) of Mongolia ]. Doklady Akadyemii nauk, SSSR 226: 685-688. [In Russian]

Barsbold R. 1976b. O evolyutsii i sistyematichyeskii dinozavri pyeryednye myezozoichyeskii. [On the evolution and systematics of the late Mesozoic carnivorous dinosaurs]. Trudy -- Sovmyestnaya Sovyetsko-Mongol'skoy Palyeontologichyeskiya Ekspyeditsiya 3: 68-75. [In Russian]

Barsbold R. & Perle A. 1980. Segnosauria -- a new infraorder of carnivorous dinosaurs. Acta Palaeontologica Polonica 25 (1): 185-195.

Barsbold R.; Osm�lska, H.; Watabe M., Currie, P.J.; & Tsogtbaatar K. 2000. A new oviraptorosaur (Dinosauria, Theropoda) from Mongolia: The first dinosaur with a pygostyle. Acta Paleontologica Polonica 45 (2): 97-106.

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.

Clark, J.M.; Norell, M.A.; & Rowe, T. 2002. Cranial anatomy of Citipati osmolskae (Theropoda, Oviraptorosauria), and a reinterpretation of the holotype of Oviraptor philoceratops. American Museum Novitates 3364: 24pp.

Coy, C. 1997. Soviet--Mongolian Paleontological Expeditions. pg. 691-692 in Currie and Padian (eds.) Encyclopedia of Dinosaurs [Academic Press (San Diego & London)].

Currie, P.J.; Godfrey, S.J.; & Nessov, L.A. 1994. New caenagnathid (Dinosauria: Theropoda) specimens from the Upper Cretaceous of North America and Asia. Canadian Journal of Earth Sciences 30 (10): 2255-2272.

Currie, P.J. & Russell, D.A. 1988. Osteology and relationships of Chirostenotes pergracilis (Saurischia, Theropoda) from the Judith River (Oldman) Formation of Alberta. Canadian Journal of Earth Sciences -- Revue de Canadienne des Sciences de la Terre 25: 972-986.

Ji Q.; Norell, M.A.; Currie, P.J.; & Ji S.-a. 1998. Two new feathered dinosaurs from northeastern China. Nature 393: 753-761. [w/ supplementary info.]

Kurzanov, S.M. 1981. [On an unusual theropod from the Upper Cretaceous of Mongolia]. Trudy -- Sovmyestnaya Sovyetsko-Mongol'skoy Palyeontologichyeskiya Ekspyeditsiya 15: 39-50. [In Russian with English summary]

Makovicky, P.J. & Sues, H.D. 1998. Anatomy and phylogenetic relationships of the theropod dinosaur Microvenator celer from the Lower Cretaceous of Montana. American Museum Novitates 3240 : 27pp.

Molnar, R.E. & Pledge, N.S. 1980. A new theropod dinosaur from South Australia. Alcheringa 4: 281-287.

Ostrom, J.H. 1970. Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Yale Peabody Museum Natural History Bulletin 35: 234pp.

Sues, H.-D. 1997. On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from western North America. Journal of Vertebrate Paleontology 17 (3): 698-716.

Xu X.; Cheng Y.-n.; Wang X.-l.; & Chang C.-h. 2002. An oviraptorosaurian dinosaur from China. Nature 419: 291-293. [w/ supplementary info.]

Xu X.; Norell, M.A.; Wang X.-l.; Makovicky, P.J.; & Wu X.-c. 2002. A basal troodontid from the Early Cretaceous of China. Nature 415: 780-784. [w/ supplementary info.]

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