Polacanthus, (meaning "many spines")[1] is a genus of early armored, herbivorous ankylosaurian dinosaur from the early Cretaceous period of England. Polacanthus was an ornithopod dinosaur. It lived 130 to 125 million years ago in what is now western Europe.[2] Its type species Polacanthus foxii was named after a fossil find on the Isle of Wight in 1865. There are not many fossil remains of this creature, and some important anatomical features, such as its skull, are poorly known. Early depictions often gave it a very generic head as it was only known from the rear half of the creature. It grew to about 5 metres (16 ft) long. Its body was covered with armour plates and spikes. It probably was a basal member of the Nodosauridae.
Discovery and species[]
The genus Polacanthus have two species from Europe: the type species Polcanthus foxii and Polacanthus rudgwickensis.
Description[]
Polacanthus was a medium-sized ankylosaur. In 2010, Gregory S. Paul estimated its length at five metres, its weight at two tonnes.[3] Its legs are relatively long for an ankylosaur, with a right femur length of 555 millimetres with the holotype.
In 2011 Barrett indicated two possible unique traits, autapomorphies: the floor of the neural canal is deeply cut by a groove with a V-shaped transverse profile; the caudal spikes have triangular bases in side view and narrow points.[4]
Phylogeny[]
Fox in 1865 assigned Polacanthus to the Dinosauria, Huxley in 1870[5] and Hulke in 1881 assigned it to the Scelidosauridae. Its exact affinities were not well understood, until Coombs in 1978 placed in the Nodosauridae within a larger Ankylosauria.[6] In 1996 Kenneth Carpenter refined this to the Polacanthinae.[7] An alternative hypothesis, first suggested by Tracy Lee Ford in 2000,[8] is that there existed a clade Polacanthidae below the Nodosauridae + Ankylosauridae node.
A more conventional analysis from 2012,[9] in which Polacanthos foxii and P. rudgwickensis were not recovered as sister species, is shown by this cladogram:
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Gallery[]
In the Media[]
- Polacanthus appears in BBC Walking with Dinosaurs, traveling with Iguanodon herds for mutual protection.
- Polacanthus is featured in Dinosaur King.
Notes[]
- ↑ Liddell & Scott (1980). Greek-English Lexicon, Abridged Edition. Oxford University Press, Oxford, UK. ISBN 0-19-910207-4.
- ↑ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
- ↑ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 229
- ↑ Barrett, P.M. and Maidment, S.C.R. 2011. "Wealden armoured dinosaurs". In: Batten, D.J. (ed.). English Wealden fossils. Palaeontological Association, London, Field Guides to Fossils 14, 769 pp
- ↑ T.H. Huxley, 1870, "On the classification of the Dinosauria, with observations on the Dinosauria of the Trias", Quarterly Review of the Geological Society of London 26: 32-51
- ↑ W.P. Coombs, 1978, "The families of the ornithischian dinosaur order Ankylosauria", Palaeontology 21(1): 143-170
- ↑ K. Carpenter, J. I. Kirkland, C. Miles, K. Cloward, and D. Burge, 1996, "Evolutionary significance of new ankylosaurs (Dinosauria) from the Upper Jurassic and Lower Cretaceous, Western Interior", Journal of Vertebrate Paleontology 16(3, supplement):25A
- ↑ T.L. Ford, 2000, "A review of ankylosaur osteoderms from New Mexico and a preliminary review of ankylosaur armor", In: S.G. Lucas and A.B. Heckert (eds.), Dinosaurs of New Mexico. New Mexico Museum of Natural History and Science Bulletin 17, pp 157-176
- ↑ Richard S. Thompson, Jolyon C. Parish, Susannah C. R. Maidment and Paul M. Barrett, 2012, "Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora)", Journal of Systematic Palaeontology 10(2): 301–312
References[]
- Blows WT (2001). "Dermal Armor of Polacanthine Dinosaurs". In Carpenter, Kenneth(ed). The Armored Dinosaurs. Indiana University Press. pp. 363–385. ISBN 0-253-33964-2.
- Carpenter K (2001). "Phylogenetic analysis of the Ankylosauria". In Carpenter, Kenneth(ed). The Armored Dinosaurs. Indiana University Press. pp. 455–484. ISBN 0-253-33964-2.