Hylaeosaurus
Hylaeosaurus | |
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Holotype NMH R3775 | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | †Ornithischia |
Clade: | †Thyreophora |
Clade: | †Ankylosauria |
Clade: | † Euankylosauria
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Family: | †Nodosauridae |
Genus: | †Hylaeosaurus Mantell, 1833 |
Species: | †H. armatus
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Binomial name | |
†Hylaeosaurus armatus Mantell, 1833
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Synonyms | |
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Hylaeosaurus (
Hylaeosaurus was one of the first dinosaurs to be discovered, in 1832 by
Hylaeosaurus was about five metres long. It was an armoured dinosaur that carried at least three long spines on its shoulder.
History of discovery
The first Hylaeosaurus fossils were discovered in the Grinstead Clay Formation, West Sussex. On 20 July 1832, fossil collector Gideon Mantell wrote to Professor Benjamin Silliman that when a gunpowder explosion had demolished a quarry rock face in Tilgate Forest, several of the boulders freed showed the bones of a saurian. A local fossil dealer had assembled the about fifty pieces, described by him as a "great consarn of bites and boanes". Having doubts about the value of the fragments, Mantell had nevertheless purchased the pieces and soon discovered they could be united into a single skeleton, partially articulated. Mantell was delighted with the find because previous specimens of Megalosaurus and Iguanodon had consisted of single bone elements. The discovery in fact represented the most complete non-avian dinosaur skeleton known at the time. He was strongly inclined to describe the find as belonging to the latter genus, but during a visit by William Clift, the curator of the Royal College of Surgeons of England museum, and his assistant John Edward Gray, he began to doubt the identification. Clift was the first to point out that several plates and spikes were probably part of a body armour, attached to the back or sides of the rump.[2] In November 1832 Mantell decided to create a new generic name: Hylaeosaurus. It is derived from the Greek ὑλαῖος, hylaios, "of the wood". Mantell originally claimed the name Hylaeosaurus meant "forest lizard", after the Tilgate Forest in which it was discovered.[3] Later, he claimed that it meant "Wealden lizard" ("wealden" being another word for forest), in reference to the Wealden Group, the name for the early Cretaceous geological formation in which the dinosaur was first found.[4]
On 30 November Mantell sent the piece to the
Hylaeosaurus is the most obscure of the three animals used by Sir Richard Owen to first define the new group Dinosauria, in 1842, the other genera being Megalosaurus and Iguanodon. Not only has Hylaeosaurus received less public attention, despite being included in the life-sized models by Benjamin Waterhouse Hawkins placed in the Crystal Palace Park, it also never functioned as a "wastebasket taxon". Owen in 1840 developed a new hypothesis about the spikes; noting they were asymmetrical he correctly rejected the notion they formed a row on the back but incorrectly assumed they were gastralia or belly-ribs.
The original specimen, recovered by Gideon Mantell from the
Several finds from the mainland of Britain have been referred to Hylaeosaurus armatus.[8][9] However, in 2011 Paul Barrett and Susannah Maidment concluded that only the holotype could with certainty be associated with the species, in view of the presence of Polacanthus in the same layers.[10]
Additional remains have been referred to Hylaeosaurus, from the Isle of Wight, (the Ardennes of) France,[11] Bückeberg Formation, Germany,[12] Spain[13] and Romania.[14] The remains from France may actually belong to Polacanthus and the other references are today also considered dubious.[6][15] However, possible remains were reported from Germany in 2013: a spike, specimen DLM 537 and the lower end of a humerus, specimen GPMM A3D.3, which were referred to a Hylaeosaurus sp.[16]
Later species
Hylaeosaurus armatus Mantell 1833 is currently considered the only valid
Sometimes bones from the Hylaeosaurus material have later been made separate species. In 1928
Description
Gideon Mantell originally estimated that Hylaeosaurus was about 7.6 metres (25 ft) long, or about half the size of the other two original dinosaurs, Iguanodon and Megalosaurus. At the time, he modelled the animal after a modern lizard. Modern estimates range up to 6 metres (20 ft) in length.[24] Gregory S. Paul in 2010 estimated the length at 5 metres (16 ft), the weight at 2 tonnes (2.0 long tons; 2.2 short tons).[25] Some estimates are considerably lower: in 2001 Darren Naish e.a. gave a length of 3–4 metres (9.8–13.1 ft).[15]
Many details about the build of Hylaeosaurus are unknown, especially if the material is strictly limited to the holotype. Maidment gave two
In 2001 the skull and lower jaws remains were described by
Several distinguishing traits were established in 2020. On the shoulder blade, there is a sharp angle of 120° between the acromion and the proximal plate. The acromial process is shelf-shaped instead of thumb-like or folded, from a point positioned at a third from the top edge projecting obliquely to below and sideways instead of strictly laterally. The top edge of the proximal plate is curved sideways. The sides of the centra of the neck vertebrae show a horizontal ridge. Apart from these autapomorphies, the undersides of the side processes of the back vertebrae are exceptionally concave.
The spines at the shoulder are curved to the rear, long, flattened, narrow and pointed. Their underside shows a shallow trough. The front spine is the longest at 42.5 centimetres; to the rear the spines become gradually shorter and wider. A fourth spine, of about the same build but more forward-pointing, is present immediately behind the skull. In 2013 Sven Sachs and Jahn Hornung suggested a configuration in which there were five lateral neck spines, the new German spine having a morphology adapted to fit in the third position.[16]
Phylogeny
Hylaeosaurus was the first
A 2012 study finding Hylaeosaurus to be a basal nodosaurid but not a polacanthine is shown in this cladogram:[27]
Nodosauridae |
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It was defined as a non-ankylosaurine
In one of two phylogenetic analyses by Xing et al. (2024) Hylaeosaurus is resolved as a non-euankylosaur ankylosaur. Below is a simplified cladogram from that study. Zheng et al. (2018) dataset + Datai (14-taxon deletion):[29]
See also
References
- .
- ^ a b Dennis R. Dean, 1999, Gideon Mantell and the Discovery of Dinosaurs, Cambridge University Press, 315 pp
- ^ Mantell, Gideon Algernon (1833). "Observations on the remains of the Iguanodon, and other fossil reptiles, of the strata of Tilgate Forest in Sussex". Proceedings of the Geological Society of London. 1: 410–411.
- ^ Mantell, G.A., 1838, The Wonders of Geology or a Familiar Exposition of Geological Phenomena, 2 vols, Relfe and Fletcher, London
- ^ G.A. Mantell. 1833. The Geology of the South-East of England. Longman Ltd., London
- ^ S2CID 129624992.
- ^ Thomas J. Raven; Paul M. Barrett; Stuart B. Pond & Susannah C.R. Maidment. 2020. "Osteology and Taxonomy of British Wealden Supergroup (Berriasian–Aptian) Ankylosaurs (Ornithischia, Ankylosauria)". Journal of Vertebrate Paleontology. 40(4): e1826956
- ^ .
- ^ Barrett, P.M. (1996). "The first known femur of Hylaeosaurus armatus and reidentification of ornithopod material in The Natural History Museum, London". Bulletin of the Natural History Museum, Geology Series. 52: 115–118.
- ^ a b Barrett, P.M. and Maidment, S.C.R., 2011, "Wealden armoured dinosaurs". In: Batten, D.J. (ed.). English Wealden fossils. Palaeontological Association, London, Field Guides to Fossils 14, 769 pp
- ^ Corroy, G (1922). "Les reptiles néocomiens et albiens du Bassin de Paris". Comptes Rendus de l'Académie des Sciences de Paris. 172: 1192–1194.
- ^ Koken, E (1887). "Die Dinosaurier, Crocodiliden und Sauropterygier des norddeutschen Wealden". Geologische und Palaeontologische Abhandlungen. 3: 311–420.
- .
- ^ E. Posmosanu, 2003, "The palaeoecology of the dinosaur fauna from a Lower Cretaceous bauxite deposit from Bihor (Romania)". In: A. Petculescu & E. Stiuca (eds.), Advances in Vertebrate Paleontology: Hen to Panta. Romanian Academy, "Emil Racovita" Institute of Speleology, Bucarest pp. 121-124
- ^ a b Naish, D. and Martill, D.M., 2001, "Armoured Dinosaurs: Thyreophorans". In: Martill, D.M., Naish, D., (editors). Dinosaurs of the Isle of Wight. Palaeontological Association Field Guides to Fossils 10. pp. 147–184
- ^ PMID 23560099.
- ^ Mantell, G.A. 1844. The Medals of Creation: or first lessons in geology and in the study of organic remains. London Volume 2, pp. 587-876
- ^ Romer, A.S. 1956. Osteology of the Reptiles. University of Chicago Press, Chicago
- ^ Coombs, W. 1971. The Ankylosauria. Ph.D. thesis, New York: Columbia University
- .
- ^ Nopcsa, F., 1928, "Palaeontological notes on Reptiles", Geologica Hungarica, Series Palaeontologica, tomus, 1, -Pasc. 1, p. 1-84
- ^ a b Coombs, W.P. (1978). "The families of the ornithischian dinosaur order Ankylosauria". Palaeontology. 21 (1): 143–170.
- ^ Blows, W.T. (1987). "The armoured dinosaur Polacanthus foxi from the Lower Cretaceous of the Isle of Wight". Palaeontology. 30 (3): 557–580.
- ISBN 978-1-84028-152-1.
- ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 228
- ^ Carpenter, K., 2001, "Skull of the polacanthid ankylosaur Hylaeosaurus armatus Mantell, 1833, from the Lower Cretaceous of England", pp 169–172 In: Carpenter, K. (ed.). The armored dinosaurs. Indiana University Press, Bloomington and Indianapolis, 525 pp
- S2CID 86002282.
- ^ PMID 29487376.
- ^ ISSN 2292-1389.