Polacanthus
From Ancient Greek polys (πολύς, 'many') and akantha (ἄκανθα, 'thorn' or 'prickle'), meaning 'many thorns', referring to the numerous spikes on its body
Polacanthus is an extinct genus of ankylosaurian dinosaurs from the early Cretaceous (130-125 million years ago) of England. Several species have been named in the genus Polacanthus, but only the type species, Polacanthus foxii, is currently seen as valid. There are not many fossil remains of this dinosaur, and some important anatomical features, such as its skull, are poorly known. It grew to about 4-5 meters (13-16 ft) long. Its body was covered with armor plates and spikes. It may be a basal member of the Nodosauridae or part of a separate family, the Polacanthidae.
Diagnosis
- Long armor-plates of bone covering body except back
- Large bony shield protecting back
- Spine-like bones running along sides of body and tail
Species
Polacanthus foxii Fox, 1866
Type species
Named for the Reverend William Fox, who discovered the holotype specimen on the Isle of Wight in 1865.
- Holotype
- BMNH R175 , Natural History Museum
- Material
- Skeletal remains from Wealden beds of Isle of Wight including torso, tail (5 feet), legs (4 feet), armor plates (0.5-4 inches diameter), and spine-like bones along body and tail (up to 15 inches long, 7 lbs)
- Horizon
- Wessex Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
- Locality
- Barnes High, Isle of Wight, United Kingdom
Synonyms of the genus
| Name | Type | Reason |
|---|---|---|
| Euacanthus | nomen nudum | Proposed by Tennyson but ultimately rejected; the name remains a nomen nudum referable to Polacanthus. |
| Vectensia | junior subjective | Named in 1982 without a specific epithet; subsequently treated as a nomen nudum and tentatively referred to Polacanthus. |
References
- Fox, W. (1866). On a new Wealden saurian named Polacanthus. Report of the British Association for the Advancement of Science, Birmingham 1865: 56. fox1866a
-
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the hip height estimate, and the appearance features.
jones2026a