Polacanthus
Hypothetical reconstruction of live Polacanthus foxii
- Polacanthus foxii Hulke, 1881
- Polacanthus rudgwickensis Blows, 1996
Polacanthus is a genus of bird Beck dinosaur ( Ornithischia ) from the group of Ankylosauria. He lived in the front of about 131-113 million years ago in the Cretaceous in Europe.
Features
Polacanthus reached a length of approximately 4 meters, but so far only the rear parts of the postcranial skeleton and a possible lower jaw are known. He was like all Ankylar by bony plates ( osteoderms ) protected on his body. The most striking feature was about a grown together, shield-like structure over the pool, but in addition also small, round bone plates and bony spines were present.
The exact arrangement of these structures is not known, presumably the spines were mounted on the flanks of the animal. Like all Ankylar he moved away ( Quadrupedie ) on all fours and had a stocky build with short, powerful limbs. The skull is - apart from a possible part of the lower jaw - not known, but it is likely that Polacanthus, like all the better known Ankylar, a herbivore.
Discovery and designation
After Hylaeosaurus Polacanthus was the second Ankylar, which was discovered in the 19th century in England. Fossil finds are known from Dorset, West Sussex and the Isle of Wight, describer was the British scientist Thomas Henry Huxley.
The genus name is derived from the Greek words πολυ-/poly- ( = "a lot" ) and ακανθα / acantha ( = "thorn " or " thorn" ) from. Type species is P. foxii, in 1996, was described by P. rudgwickensis a second type which was probably slightly larger and differed in the construction of the vertebrae and the bone plates of P. foxii.
System
According to some researchers, it is at Hylaeosaurus - mainly from the known, the front half of the body - to the same genus as Polacanthus, accordingly, both types are sometimes incorporated into this genus.
The systematic classification in the Ankylosauria is controversial. Polacanthus is named after the Polacanthidae or Polacanthinae, a group of ankylosauruses that are sometimes incorporated into the Ankylosauridae and sometimes in the Nodosauridae; sometimes they are performed as an independent family. Because of sparse finds a precise classification is difficult Vickaryous M. et al. (2004) list Polacanthus therefore as " incertae sedis Ankylosauria ".