Micropachycephalosaurus

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Micropachycephalosaurus
Temporal range: Late Cretaceous, Campanian
Micropachycephalosaurus.jpg
Restoration
Micropachycephalosaurus ilium.jpg
Drawing of the ilium
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Ornithischia
Clade: Neornithischia
Clade: Marginocephalia
Genus: Micropachycephalosaurus
Dong, 1978
Species:
M. hongtuyanensis
Binomial name
Micropachycephalosaurus hongtuyanensis
Dong, 1978

Micropachycephalosaurus (meaning "small thick-headed lizard") is an extinct genus of basal marginocephalian dinosaur containing only the type species, Micropachycephalosaurus hongtuyanensis. It lived in China during the Late Cretaceous (Campanian) and was found in the Jiangjunding Formation. [1]

Contents

Micropachycephalosaurus has the longest name of any dinosaur, with 23 letters in the genus name alone, while the full binomial contains 37 letters. [2]

Discovery and naming

The holotype, IVPP V5542 was found on a cliff southwest of Laiyang, Shandong Province, near Hongtuyan train station. [3] The remains were named and described by Dong Zhiming in 1978 as belonging to the new genus and species Micropachycephalosaurus hongtuyanensis, [3] which he incorrectly figured was discovered in the Wangshi Formation.

IVPP V5542 consisted of the left quadrate, a partial tooth row with seven teeth, another partial tooth row with no teeth preserved, a single loose tooth, a partial basioccipital, the centra of three posterior dorsal and two sacral vertebrae, associated with impressions of the neural spines of the posteriormost dorsal and four sacrals, four partial caudal vertebrae preserved in near articulation with associated chevrons, the isolated centra of seven caudals (one with a partial neural arch), a single isolated partial caudal neural arch, a partial left ilium, a left femur, and the proximal portion of the left tibia. [3] [4] Dong (1978) briefly described, but did not figure, a parietal and squamosal that also supposedly belonged to the holotype, [3] but Butler & Zhao (2009) were unable to locate them. [4]

Description

Micropachycephalosaurus likely only grew up to 1 metre (3.3 ft) long when fully grown [1] and it was a bipedal and herbivorous dinosaur. [4]

Classification

Paleontologist Dong Zhiming originally described it as a member of the Pachycephalosauria, a group of bipedal dome-headed herbivores. However, re-evaluation of the family Pachycephalosauridae by Sullivan in 2006 cast doubt on this assignment. [5]

Further study of the holotype 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. [4] A cladistic analysis performed by Butler et al. (2011) showed that Micropachycephalosaurus is a basal member of the Ceratopsia. [6] Phylogenetic analyses by Fonseca et al. (2024) instead recovered this taxon as a basal pachycephalosaur. [7]

Paleoecology

Micropachycephalosaurus was found in the Jiangjunding Formation of the Chinese Wangshi Group. [3] [8] The Jiangjunding formation consists purpley-grey or reddy-brown sandstones or various consistencies, siltstones and conglomerates. The Wangshi group of geologic formations is generally considered to be from the Late Cretaceous, although some regions are older. Based on the discovery of Pinacosaurus , only known elsewhere in the Djadokhta Formation or regions of the same age, the Wangshi Group was presumed to be a similar age of 75-71 million years old. The specific age for the Hongtuya Formation has been identified as 73.5-72.9 mya. As the Hongtuya is directly older than the Jiangjunding, it was identified that Tanius sinensis, a contemporary of Micropachycephalosaurus, lived in the latest Campanian to earliest Maastrichtian by Borinder in 2015. [9]

The Jiangjunding Formation was deposited in a fluvial to lacustrine environment. The climate was warm and humid during the majority of the timespan, although it was beginning to dry out after the Jiangjunding. Taxa that lived alongside Micropachycephalosaurus in the formation include the ankylosaur Pinacosaurus cf. grangeri ; the hadrosaur Tanius sinensis ; intermediate sauropods; intermediate coelurosaurs; and intermediate cheloniids which show similarities to Nanhsiungchelyidae. Multiple localities of dinosaur eggs have also been identified. [9]

See also

Related Research Articles

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Pachycephalosauria is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. With the exception of two species, most pachycephalosaurs lived during the Late Cretaceous Period, dating between about 85.8 and 66 million years ago. They are exclusive to the Northern Hemisphere, all of them being found in North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls. Skulls can be domed, flat, or wedge-shaped depending on the species, and are all heavily ossified. The domes were often surrounded by nodes and/or spikes. Partial skeletons have been found of several pachycephalosaur species, but to date no complete skeletons have been discovered. Often isolated skull fragments are the only bones that are found.

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<i>Prenocephale</i> Extinct genus of dinosaurs

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<i>Tsintaosaurus</i> Hadrosaurid dinosaur from the Late Cretaceous

Tsintaosaurus is a genus of hadrosaurid dinosaur from China. It was about 8.3 metres (27 ft) long and weighed 2.5 tonnes. The type species is Tsintaosaurus spinorhinus, first described by Chinese paleontologist C. C. Young in 1958.

<i>Tanius</i> Extinct genus of dinosaurs

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Ferganocephale is a dubious genus of neornithischian dinosaur. It was from the Middle Jurassic Balabansai Svita of Kyrgyzstan. The type and only species is F. adenticulatum.

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Gongbusaurus is a genus of ornithischian, perhaps ornithopod, dinosaur that lived between about 160 and 157 million years ago, in the Late Jurassic period. A small herbivore, it is very poorly known. Two species have been assigned to it, but as the original name is based on teeth, there is no concrete evidence to connect the two species. Its fossils have been found in China.

<i>Nanshiungosaurus</i> Extinct genus of reptiles

Nanshiungosaurus is a genus of therizinosaurid that lived in what is now Asia during the Late Cretaceous of South China. The type species, Nanshiungosaurus brevispinus, was first discovered in 1974 and described in 1979 by Dong Zhiming. It is represented by a single specimen preserving most of the cervical and dorsal vertebrae with the pelvis. A supposed and unlikely second species, "Nanshiungosaurus" bohlini, was found in 1992 and described in 1997. It is also represented by vertebrae but this species however, differs in geological age and lacks authentic characteristics compared to the type, making its affinity to the genus unsupported.

<i>Nanyangosaurus</i> Extinct genus of dinosaurs

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<i>Alaskacephale</i> Extinct genus of dinosaurs

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Dong Zhiming is a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. He began working at the IVPP in 1962, studying under Yang Zhongjian, who was director at the time. He has described fossil remains of many dinosaurs. He investigated and described the Shaximiao Formation; an important contribution to science since they are composed of Middle Jurassic beds which do not commonly yield fossils.

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The Jiangjunding Formation is a geological formation in Shandong, China whose strata date back to the Campanian-Maastrichtian stages of the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the group.

References

  1. 1 2 Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
  2. "How Dinosaurs Were Named | Scholastic (no longer available)".
  3. 1 2 3 4 5 Z. Dong. (1978). [A new genus of Pachycephalosauria from Laiyang, Shantung]. Vertebrata PalAsiatica 16(4):225-228.
  4. 1 2 3 4 Butler, R.J. & Zhao, Q. (2009). "The small-bodied ornithischian dinosaurs Micropachycephalosaurus hongtuyanensis and Wannanosaurus yansiensis from the Late Cretaceous of China". Cretaceous Research. 30 (1): 63–77. Bibcode:2009CrRes..30...63B. doi:10.1016/j.cretres.2008.03.002.
  5. Sullivan, R.M. (2006). "A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia)." New Mexico Museum of Natural History and Science Bulletin, 35: 347-365.
  6. Richard J. Butler; Jin Liyong; Chen Jun; Pascal Godefroit (2011). "The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China". Palaeontology. 55 (3): 667–683. Bibcode:2011Palgy..54..667B. doi: 10.1111/j.1475-4983.2011.01046.x .
  7. Fonseca, A. O.; Reid, I. J.; Venner, A.; Duncan, R. J.; Garcia, M. S.; Müller, R. T. (2024). "A comprehensive phylogenetic analysis on early ornithischian evolution". Journal of Systematic Palaeontology. 22 (1). 2346577. Bibcode:2024JSPal..2246577F. doi:10.1080/14772019.2024.2346577.
  8. Zhang, J.L.; Wang, Q; Jiang, S.X.; Cheng, X.; Li, N.; Qiu, R.; Zhang, X.J.; Wang, X.L. (2017). "Review of historical and current research on the Late Cretaceous dinosaurs and dinosaur eggs from Laiyang, Shandong" (PDF). Vertebrata PalAsiatica. 55 (2): 187–200.
  9. 1 2 Borinder, N.H. (2015). "Postcranial Anatomy of Tanius Sinensis Wiman, 1929 (Dinosauria; Hadrosauroidea)" (PDF). Examensarbete vid Institutionen för geovetenskaper. Upsala University. ISSN   1650-6553.