Goyocephale
| Goyocephale | ||||||||||||
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Skull of Goyocephale lattimorei |
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| Temporal occurrence | ||||||||||||
| Upper Crayon (middle Campanium ) | ||||||||||||
| 80.6 to 76.4 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Goyocephale | ||||||||||||
| Perle, Maryańska & Osmólska , 1982 |
Goyocephale is a genus of the bird pelvic dinosaur (Ornithischia) from the group of the Pachycephalosauria . With an estimated length of 2 meters it was a rather small pachycephalosaur, at the same time it is one of the most fully preserved representatives of this group. The only species described is G. lattimorei .
features
Goyocephale , like all pachycephalosaurs, was characterized by the thickened roof of the skull, which was formed from the frontal bone and the parietal bone . He is one of the flat-headed representatives of this group, in which the skull roof was not arched and the upper skull window of the temporal region was well developed. For assumptions about the function of this skullcap, see Function of the skullcap in the Pachycephalosauria .
Like many other Pachycephalosauria, Goyocephale had different types of teeth ( heterodontics ). On the premaxillary , the foremost part of the upper jaw, sat three canine-like teeth, of which the rearmost was the largest. Behind it there was a big gap, the teeth of the upper jaw behind were small and had triangular crowns. The foremost tooth of the lower jaw was also canine-like and clearly enlarged; it had a polygonal cross-section and a sharp edge on the outer edge. The remaining teeth of the lower jaw resembled the rear teeth of the upper jaw. The exact function of these teeth is not known, like all pachycephalosaurs, Goyocephale probably had a predominantly plant- based diet , possibly supplemented by insects.
The trunk was built rather stocky, the vertebrae were reinforced by interlocking connections and the pelvis was very wide. The front limbs were short and only about a quarter of the length of the hind limbs. The lower legs were longer than the upper legs, suggesting that these animals reached high speeds. They moved biped (on their hind legs).
Discovery and naming
The fossil remains of Goyocephale were discovered in the Mongolian province of Öwörchangai-Aimag and first described in 1982. The generic name is derived from the Mongolian goyo (= "decorated") and the Greek kephalē (= "head"), a common part of the name of pachycephalosaurs. The type and only known species is G. lattimorei , the specific epithet honors Owen Lattimore , a US professor and Mongolian traveler who was accused of being a spy in the McCarthy era . The finds are dated in the Upper Cretaceous (middle Campanium ) to an age of about 80 to 76 million years.
Systematics
Traditionally, Goyocephale was incorporated within the Pachycephalosauria into the Homalocephalidae, the group of primitive, flat-headed representatives, the best-known representative of which was Homalocephale and who faced the domed-headed, more highly developed Pachycephalosauridae. The "Homalocephalidae" are now considered to be paraphyletic , so they do not represent a natural family group, as the Pachycephalosauridae evolved from them. A cladistic study by T. Maryańska et al. sees Goyocephale as a primeval representative of the Pachycephalosauria and as a sister taxon of the Homalocephaloidea, which include Homalocephale and the dome-headed representatives. However, with the discovery of Dracorex , a flat-headed but highly developed pachycephalosaur, the internal system was shaken. According to R. Sullivan, it is also conceivable that the development from dome-headed to flat-headed animals took place, so that the flat skull is the derived characteristic. There is no generally recognized systematic classification of Goyocephale in Pachycephalosauria.
literature
- Teresa Maryańska , Ralph E. Chapman, David B. Weishampel : Pachycephalosauria. In: David B. Weishampel, Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 464-477.
- Robert M. Sullivan: A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). In: Spencer G. Lucas, Robert M. Sullivan (Eds.): Late Cretaceous Vertebrates from the Western Interior (= New Mexico Museum of Natural History and Science. Bulletin. 35, ISSN 1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 2006, pp. 347–365, digital version (PDF; 4.79 MB) .