Describer

Mantell, 1833

Time

Cretaceous Early Valanginian Hauterivian Barremian

Classification

Ornithischia Thyreophora Eurypoda Ankylosauria Nodosauridae

Diet

Herbivore

Fossilsite

Wealden Beds (Tunbridge Wells sand/Grinstead Clay) West Sussex, East Sussex, Wealden Beds (Wessex Formation, Vectis Formation, ?Ferruginous Sands) Isle of Wight, England; unnamed unit, Ardennes, France

Length

3 > 5 meter

Info

Genus - Typespecies

Hylaeosaurus armatus (Mantell, 1833) = Polacanthoides (Nopcsa, 1928) Vectensia (Delair, 1982)

Hylaeosaurus armatus = Hylosaurus mantelli (Fitzinger, 1840) Hylaeosaurus oweni (Mantell, 1844) Polacanthoides ponderosus (Nopcsa, 1929) > Polacanthus foxii (Hulke, 1881)

2 fragmentary posrcranial skeletons with dermal isolated postcranial elements and armor plates.

Hylaeosaurus armatus is a moderate to large (length 3 to 5 m) characterized by a scapular spine that slants obliquely across the entire scapular blade. This feature together with absence of a prespinous fossa makes H.armatus the most primitive known nodosaurid (Coombs, 1971,1978; Sereno, 1986).

Hylaeosaurus consited of the front half of the skeleton embedded in a large piece of stone. The fossil was first described by Gideon Mantell and somewhat later by dr Richard Owen, and along with Megalosaurus and Iguanodon, was one of the founding members of Owen\\\'s Dinosauria.

This fossil which is now in the Britisch museum (Natural History) has, unfortunately, never been prepared out of the stone in which its is embedded. Nevertheless, the parts which are exposed seem to show an animal with rows of large, curved plates running down its back.

In an 1832 presentation before the Geological Society, Mantell originally explained the name as \\\"forest lizard,\\\" alluding to Tilgate Forest where the first specimen was unearthed. However, in later published works he gave the meaning as \\\"Wealden lizard.\\\" The British geologist Peter Martin invented the name \\\"Wealden\\\" in 1828 for the Early Cretaceous sands and clays found in the once-forested Weald (\\\"wood\\\") region of southern England.).

Describing the cranial part of an articulated skeleton with an associated fragmentary skull (BMNH R3775) founded beneeth the remains of Polacanthus (Mantell, 1833) Carpenter, 2001, observed that the postorbital horn is small, triangular and comparable with that of the pokacanthid Gargoyleosaurus, and there is a prominent rim along the rostral edge of the quadrate, e feature also found in the nodosaurid Animantarx, this and other similarities between the the skull of Hylaeosaurus and Gargoyleosaurus indicated to Carpenter a close affinity between these genera, supporting the referral of the former to the Polacanthidae.