Dyoplosaurus

Dyoplosaurus (meaning "double-armored lizard") is an extinct genus of ankylosaurid dinosaurs within the subfamily Ankylosaurinae. It is known from the lower levels of the Late Cretaceous Dinosaur Park Formation (latest middle Campanian stage, about 76.5 Ma ago) of Alberta, Canada. It contains a single species, Dyoplosaurus acutosquameus.[1]

Dyoplosaurus
Temporal range: Late Cretaceous, 76.5 Ma
Holotype skull
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Ankylosauridae
Subfamily: Ankylosaurinae
Genus: Dyoplosaurus
Parks, 1924
Species:
D. acutosquameus
Binomial name
Dyoplosaurus acutosquameus
Parks, 1924

History of discovery

Dyoplosaurus was named by William Parks in 1924, based on holotype ROM 784, a partial skeleton including parts of the skull and lower jaws. It was collected from the bottom 10 m of the Dinosaur Park Formation, near what is now the Red Deer River in Alberta, Canada.

Description

Tail of the holotype specimen

The type specimen of Dyoplosaurus was about 4–4.5 m (13–15 ft) long[2] and about 5.8 feet (1.7 m) wide, with a skull measuring 14 inches (35 centimeters) across. Like most other ankylosaurids, it was quadrupedal, ground-dwelling and herbivorous, with an armored body and a bony club on the end of its tail. The club was composed of several armor plates fused together.[3] The tail club possessed by Dyoplosaurus is relatively small and narrow, when compared to that of other ankylosaurids.

Classification

Reconstructed tail and pelvis

In 1971, Walter Coombs proposed that Dyoplosaurus was a junior synonym of Euoplocephalus. The two were since generally assumed to be the same species and thus, former Dyoplosaurus specimens have been identified as Euoplocephalus tutus. However, a redescription of the genus published in 2009 in the Journal of Vertebrate Paleontology claims that the genus is a valid taxon, suggesting that the proposed synonymy was due to the fragmentary nature of the holotype and other specimens of E. tutus.[1] The cladistic analysis performed by Thompson et al., 2011 confirmed this separation.[4] The following cladogram is based on a 2015 phylogenetic analysis of the Ankylosaurinae conducted by Arbour and Currie:[5]

Ankylosaurinae

Crichtonpelta

Tsagantegia

Zhejiangosaurus

Pinacosaurus

Saichania

Tarchia

Zaraapelta

Ankylosaurini

Dyoplosaurus

Talarurus

Nodocephalosaurus

Ankylosaurus

Anodontosaurus

Euoplocephalus

Scolosaurus

Ziapelta

See also

References

  1. Arbour, V. M.; Burns, M. E.; Sissons, R. L. (2009). "A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology. 29 (4): 1117. doi:10.1671/039.029.0405.
  2. Arbour, V.M.; Mallon, J.C. (2017). "Unusual cranial and postcranial anatomy in the archetypal ankylosaur Ankylosaurus magniventris". FACETS. 2 (2): 764–794. doi:10.1139/facets-2017-0063.
  3. Parks, W. A. (1924). "Dyoplosaurus acutosquameus, a new genus and species of armored dinosaur; and notes on a skeleton of Prosaurolophus maximus". University of Toronto Studies Geological Series. 18: 1–35.
  4. Richard S. Thompson; Jolyon C. Parish; Susannah C. R. Maidment; Paul M. Barrett (2011). "Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora)". Journal of Systematic Palaeontology. in press (2): 301–312. doi:10.1080/14772019.2011.569091.
  5. Arbour, V. M.; Currie, P. J. (2015). "Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs". Journal of Systematic Palaeontology. 14 (5): 1–60. doi:10.1080/14772019.2015.1059985.


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