Micropachycephalosaurus
Encyclopedia
Micropachycephalosaurus (meaning "small thick headed lizard") is a monotypic genus of ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...

n dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

. It lived in Shandong Province, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 during the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 period (between 70.6 and 68.5 million years ago). The incomplete skeleton of the single specimen was found on a cliff southwest of Laiyang
Laiyang
Laiyang city is a city between Yantai and Qingdao, located at the middle of Shandong peninsula, China. Majority of its population are farmers and it is famous for Laiyang Pear...

. It was bipedal and herbivorous, and currently has the longest generic name
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of any dinosaur. Ironically, it was also among the smallest of the dinosaurs, at a little over 1 meter (3.3 feet) long.

The genus contains only the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

, Micropachycephalosaurus hongtuyanensis. Paleontologist Dong Zhiming
Dong Zhiming
Dong Zhiming , from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, is one of China's leading paleontologists. He began working at the IVPP in 1962, learning from Yang Zhongjian who was director at the time...

 originally described it as a member of the Pachycephalosauria
Pachycephalosauria
Pachycephalosauria is a clade of ornithischian dinosaurs. Well-known genera include Pachycephalosaurus, Stegoceras, Stygimoloch, and Dracorex. Most lived during the Late Cretaceous Period, in what is now North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls...

, a group of bipedal dome-headed herbivores. However, re-evaluation of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Pachycephalosauridae by Sullivan in 2006 cast doubt on this assignment. Further study of the original fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 specimens by Butler and Zhao in 2008 also failed to find any characteristics linking Micropachycephalosaurus with the pachycephalosaurs. The one piece of evidence that could provide this link, the supposedly thickened skull roof, was missing from the fossil collection the scientists examined, and so could not be used to support or refute its original classification. Butler and Zhao therefore classified it as an indeterminate member of the Cerapoda
Cerapoda
Neornithischia is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth...

. In 2011, cladistic analysis performed by Butler et al. showed that Micropachycephalosaurus is a basal member of the Ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...

.

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