Pronunciation: pol-a-KAN-thus
Meaning: Many spines
Author/s: Owen/Fox/Anonymous? (1865)
Synonyms: See below
First Discovery: Isle of White, UK
Discovery Chart Position: #23
Polacanthas foxii
Often confused with the remains of Hylaeosaurus, Polacanthus foxii was discovered by Reverend William Fox on the Isle of Wight in 1865. It was missing much of the front end, which was always going to hamper research somewhat, but its rear was distinct from any other dinosaur known at that time and it went on to anchor its own family—Polacanthidae, a name that is shrouded in mystery.
Polacanthidae was first published by Wieland in 1911, ironically during a rant at the unecesssary naming of new families! He thought it was merely a synonym of Marsh's Nodosauridae and the name drifted into obscurity until 1988 when Jim Kirkland ressurected it as Polacanthinae (with an "n") and wrongly credited Wieland as author. Given the uncertainty, it comes as little suprise that both names have been brushed under the carpet, and most paleontologists were content to list polacanthids/ines as basal nodosaurids and leave it at that... at least until 2013 when Yang et al. provided the first official definition as they coined Taohelong.
Like its closest relatives Mymoorapelta and Gastonia, Polacanthus had a "floating" sacral shield - a huge amour plate covering its entire hip area but not attached to the underlying bones. Its neck, shoulders and back were fortified with spikes and armour knobs, and rows of spike-like plates ran the length of its tail. Typically, Polacanthids are like tail-club-less nodosaurids with ankylosaurid heads, and weren't exactly fleet of foot.
A second species of Polacanthus, around 30% bigger than Polacanthus foxii and with a different armour arrangement, was discovered at Rudgwick Brickworks in 1985 and displayed at the Horsham Museum in Sussex, labelled as Iguanodon. It was renamed Polacanthus rudgwickensis in honour of the Brickworks by Dr. William Blows in November 1996, but patiently awaits a new name because it doesn't seem to belong to Polacanthus. (Update: Yup, we were right. The above mentioned critter was renamed Horshamosaurus in 2015).
Polacanthidae was first published by Wieland in 1911, ironically during a rant at the unecesssary naming of new families! He thought it was merely a synonym of Marsh's Nodosauridae and the name drifted into obscurity until 1988 when Jim Kirkland ressurected it as Polacanthinae (with an "n") and wrongly credited Wieland as author. Given the uncertainty, it comes as little suprise that both names have been brushed under the carpet, and most paleontologists were content to list polacanthids/ines as basal nodosaurids and leave it at that... at least until 2013 when Yang et al. provided the first official definition as they coined Taohelong.
Like its closest relatives Mymoorapelta and Gastonia, Polacanthus had a "floating" sacral shield - a huge amour plate covering its entire hip area but not attached to the underlying bones. Its neck, shoulders and back were fortified with spikes and armour knobs, and rows of spike-like plates ran the length of its tail. Typically, Polacanthids are like tail-club-less nodosaurids with ankylosaurid heads, and weren't exactly fleet of foot.
A second species of Polacanthus, around 30% bigger than Polacanthus foxii and with a different armour arrangement, was discovered at Rudgwick Brickworks in 1985 and displayed at the Horsham Museum in Sussex, labelled as Iguanodon. It was renamed Polacanthus rudgwickensis in honour of the Brickworks by Dr. William Blows in November 1996, but patiently awaits a new name because it doesn't seem to belong to Polacanthus. (Update: Yup, we were right. The above mentioned critter was renamed Horshamosaurus in 2015).
(Fox's Many Spines)Etymology
Polacanthus is derived from the Greek "polys" (much, many) and "akantha" (spine, thorn) because of the many spines on its neck, shoulders and tail. The species epithet, foxii, honors Reverend William Fox.
Polacanthus foxii was coined during an 1865 lecture to the British Association that was reproduced pretty much word for word in the Illustrated London News. Written anonymously, the article cites Sir Richard Owen as name-giver, but some suspect that Fox wrote it himself (he gave the lecture) to circumvent the convention that an author does not name a taxon after himself. Barring etiquette, there's nothing to stop anyone from attaching their own name to dinosaurs. But by the by, a corresponding 1865 publication by Owen failed to materialise so some sources credit Thomas Huxley (1867) as official author because he was the first to mention the name in a traceable scientific journal. John W. Hulke was the first to fully describe its remains in 1881.
Apparently, Fox planned to have his friend Alfred Tennyson Christen the find, but his chosen name -- Euacanthus vectianus -- was ultimately rejected. Euacanthus vectianus (Tennyson, 1897).
Polacanthus becklesi. Found on the Isle of White during the nineteenth century and named by Edwin Hennig in honor of collector Samuel Beckles in 1924, Polacanthus becklesi is based on a piece of ilium (hip bone) and several armour plates which have a smoother surface than those of Polacanthus foxii. However, the smoother surface of said armour plates was likely caused by water erosion, and Polacanthus becklesi is universally considered a synonym of Polacanthus foxii.
