Polacanthus
Encyclopedia
Polacanthus, deriving its name from the Ancient Greek
poly-/πολυ- "many" and acantha/ακανθα "thorn" or "prickle", was an early armored, spiked, plant-eating ankylosaur from the early Cretaceous
period. Early depictions often gave it a very vague head as it was only known from the rear half of the creature. It lived 130 to 125 million years ago in what is now western Europe
.
al ornithischian or "bird-hipped" dinosaur. There are not many fossil
remains of this creature, and some important anatomical features, such as its skull, are poorly known.
Polacanthus had a large sacral shield, a single fused sheet of dermal bone over its hips (sacral area) which was not attached to the underlying bone and decorated with tubercles. This feature is shared with other "polacanthine
" (basal
nodosaurids) dinosaurs such as Gastonia
and Mymoorapelta
.
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
poly-/πολυ- "many" and acantha/ακανθα "thorn" or "prickle", was an early armored, spiked, plant-eating ankylosaur from the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period. Early depictions often gave it a very vague head as it was only known from the rear half of the creature. It lived 130 to 125 million years ago in what is now western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
Description
Polacanthus grew to between 4 to 5 m (13.1 to 16.4 ft) long. It was a quadrupedQuadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al ornithischian or "bird-hipped" dinosaur. There are not many fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
remains of this creature, and some important anatomical features, such as its skull, are poorly known.
Polacanthus had a large sacral shield, a single fused sheet of dermal bone over its hips (sacral area) which was not attached to the underlying bone and decorated with tubercles. This feature is shared with other "polacanthine
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
" (basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
nodosaurids) dinosaurs such as Gastonia
Gastonia (dinosaur)
Gastonia is a genus of nodosaurid dinosaur from the Early Cretaceous of North America, around 125 million years ago. Closely related to Polacanthus, it has a sacral shield and large shoulder spikes. It is also the first polacanthine dinosaur to have been mounted for display at the Denver Museum of...
and Mymoorapelta
Mymoorapelta
Mymoorapelta is an ankylosaur from the Late Jurassic Morrison Formation of western Colorado. The taxon is known from portions of a disarticulated skull, parts of three different skeletons and other postcranial remains...
.
Discovery and species
The genus Polacanthus comprises two species from Europe:- Polacanthus foxii was discovered by the Reverend William FoxWilliam Darwin FoxThe Reverend William Darwin Fox was an English clergyman, naturalist, and a 2nd cousin of Charles Robert Darwin.- Early life :...
on the Isle of WightIsle of WightThe Isle of Wight is a county and the largest island of England, located in the English Channel, on average about 2–4 miles off the south coast of the county of Hampshire, separated from the mainland by a strait called the Solent...
in 1865. It was an incomplete skeleton with the head, neck, anterior armour and forelimbs missing. Two other partial skeletons have since been found. The second known specimen was found and excavated by Dr William T. Blows in 1979, and is also in the London Natural History MuseumNatural History MuseumThe Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
. It is the first specimen to show neck vertebrae and anterior armour.
- P. rudgwickensis was named in 1996 by Dr. William T. Blows, after review of some fossil material found in 1985 and thought to have been IguanodonIguanodonIguanodon is a genus of ornithopod dinosaur that lived roughly halfway between the first of the swift bipedal hypsilophodontids and the ornithopods' culmination in the duck-billed dinosaurs...
, which was on display at the Horsham Museum in SussexSussexSussex , from the Old English Sūþsēaxe , is an historic county in South East England corresponding roughly in area to the ancient Kingdom of Sussex. It is bounded on the north by Surrey, east by Kent, south by the English Channel, and west by Hampshire, and is divided for local government into West...
. The material is fragmentary and includes several incomplete vertebrae, partial scapulocoracoid, the distal end of humerusHumerusThe humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
, a nearly complete right tibiaTibiaThe tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
, rib fragments, and two osteoderms. P. rudgwickensis seems to have been about 30% larger than type species P. foxii and differs from it in numerous characters of the vertebrae and dermal armor. It is named after the village of Rudgwick in West SussexWest SussexWest Sussex is a county in the south of England, bordering onto East Sussex , Hampshire and Surrey. The county of Sussex has been divided into East and West since the 12th century, and obtained separate county councils in 1888, but it remained a single ceremonial county until 1974 and the coming...
and was discovered at a Rudgwick Brickworks Company quarry, at the quarry floor in gray-green marlMarlMarl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
beds of the Wessex Formation. BarremianBarremianThe Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
age, approximately 124-132 million years ago.