''Hoplitosaurus'' (meaning "

Hoplite Hoplites ( ) ( ) were citizen-soldiers of Ancient Greek city-states who were primarily armed with spears and shields. Hoplite soldiers used the phalanx formation to be effective in war with fewer soldiers. The formation discouraged the sold ...

lizard") was a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of armored

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

related to ''

Polacanthus ''Polacanthus'', deriving its name from the Ancient Greek polys-/πολύς- "many" and akantha/ἄκανθα "thorn" or "prickle", is an early armoured, spiked, plant-eating ankylosaurian dinosaur from the early Cretaceous period of England. In ...

''. It was named from a partial skeleton found in the

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...

-age

Lower Cretaceous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker * Lower (surname) * Lower Township, New Jersey *Lower Receiver (firearms) * Lower Wick Gloucestershire, England See also * Nizhny {{Disambiguation ...

Lakota Formation The Lakota Formation is a sequence of rocks of early Cretaceous (Berriasian to Barremian) age from Western North America. Located in South Dakota, the name of the formation is derived from the Lakota people, Lakota Native Americans in the United ...

of Custer County,

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

. It is an obscure genus which has been subject to some misinterpretation of its damaged remains. Although there was a push to synonymize it with ''Polacanthus'' in the late 1980s-early 1990s, ''Hoplitosaurus'' has been accepted as a valid albeit poorly known genus in more recent reviews.

History and Taxonomy

The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, USNM 4752, was discovered in 1898 by

Nelson Horatio Darton Nelson Horatio Darton (December 17, 1865 – February 28, 1948) was a geologist who worked for the United States Geological Survey. He was born in Brooklyn, New York, started working in his uncle's drug business at thirteen years old, and be ...

, near Buffalo Gap Station, and consisted of

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s, caudal

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e, part of a right

scapulocoracoid The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula. The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions. The scapula is commonly known as the ''shoulde ...

, parts of both

humeri The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of ...

, a right

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

, and a variety of

armor Armour (Commonwealth English) or armor (American English; see American and British English spelling differences#-our, -or, spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, e ...

(including tall spines).Lucas, F.A. (1901). A new dinosaur, ''Stegosaurus marshi'', from the Lower Cretaceous of South Dakota. ''Proceedings of the United States National Museum'' 23(1224):591-592.Gilmore, C.W. (1914). Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus ''Stegosaurus''. ''United States National Museum Bulletin'' 89:1-136. Frederic Augustus Lucas described it briefly in 1901 as a new species of ''

Stegosaurus ''Stegosaurus'' (; ) is a genus of herbivorous, four-legged, armored dinosaur from the Late Jurassic, characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails. Fossils of the genus have been fo ...

'', but soon gave the material its own genus.Lucas, F.A. (1902). Paleontological notes. The generic name ''Omosaurus''. A new generic name for ''Stegosaurus marshi''. ''Science'', new series 16(402):435.

Charles W. Gilmore Charles Whitney Gilmore (March 11, 1874 – September 27, 1945) was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum (now the N ...

fully described the material in 1914. William T. BlowsBlows, W.T. (1987). The armoured dinosaur ''Polacanthus foxi'' from the Lower Cretaceous of the Isle of Wight. ''Palaeontology'' 30(3):557-580. and

Javier Pereda-Suberbiola Javier may refer to: Arts, entertainment, and media * Javier, in video game '' Advance Wars: Dual Strike'' * Javier Rios, a character in the Monsters, Inc. franchise. * ''Javier'' (album), a 2003 album by the American singer Javier Colon, known a ...

Pereda-Suberbiola, J. (1991). Nouvelle évidence d'une connexion terrestre entre Europe et Amérique du Nord au Crétacé inférior: ''Hoplitosaurus'' synonyme de ''Polacanthus'' (Ornithischia: Ankylosauria). ''C.R. Academie Science, Paris'' 313:971-976.

rench The Rench is an eastern tributary of the Rhine in the Ortenau in Central Baden, Germany. It rises on the southern edge of the Northern Black Forest at Kniebis near Bad Griesbach im Schwarzwald. The source farthest from the mouth is that of ...

/ref>Pereda-Suberbiola, J. (1994). ''Polacanthus'' (Ornithischia, Ankylosauria), a transatlantic armoured dinosaur from the Early Cretaceous of Europe and North America. ''Palaeontographica Abteilung'' A 232(4-6):133-159. both considered the genus to be the same as ''

'', creating the new combination ''Polacanthus marshii'', but this has since been rejected.Carpenter, K., and Kirkland, J.I. (1998). Review of Lower and middle Cretaceous ankylosaurs from North America. In: Lucas, S.G., Kirkland, J.I., and Estep, J.W. (eds.). ''Lower and Middle Cretaceous Terrestrial Ecosystems''. ''New Mexico Museum of Natural History and Science Bulletin'' 14:249-270. Ken Carpenter and James Kirkland noted that many of the resemblances between the two were more widely distributed among ankylosaurs than previously thought, or were based on damage to the bones, such as some femoral characters. However, its similarity to ''Polacanthus'' has been noted since Lucas renamed it in 1902, the two being most similar in armor, although ''Hoplitosaurus'' lacks the sacral shield of armor found in ''Polacanthus''. Today, both are considered to be polacanthine or polacanthid

ankylosaurs Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with Armour (zoology), armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short ...

,Carpenter, K. (2001). Phylogenetic analysis of the Ankylosauria. In: Carpenter, K. (ed.). ''The Armored Dinosaurs''. Indiana University Press:Bloomington, 455-483. depending on classification preference (see for exampl

, or ankylosaurians of uncertain relationships.Vickaryous, M.K., Maryańska, T., and Weishampel, D.B. (2004). Ankylosauria. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria'' (second edition). University of California Press:Berkeley, 363-392.

Paleobiology

Gilmore described the animal as being about 1.2 m (4 ft) tall at the hips. It would have been a

quadruped Quadrupedalism is a form of locomotion in which animals have four legs that are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four legs is said to be a quadruped (fr ...

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

, eating low to the ground; armor was its main defense. Blows (2001) reconsidered the armor in light of new data on polacanthine dinosaurs, and found it to fall into the following categories:Blows, W.T. (2001). Dermal armor of the polacanthine dinosaurs. In: Carpenter, K. (ed.). ''The Armored Dinosaurs''. Indiana University Press:Bloomington, 363-385. *

Pectoral Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectora ...

spines * Presacral spines *Splates (spine+plate) from the sacral region *Tall, asymmetric, hollow-based

caudal Caudal may refer to: Anatomy * Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism * Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into th ...

plates *Small to large solid-based, ridged ossicles (filling spaces)

References

External links

Polacanthidae
at

Tree of Life The tree of life is a fundamental archetype in many of the world's mythology, mythological, religion, religious, and philosophy, philosophical traditions. It is closely related to the concept of the sacred tree.Giovino, Mariana (2007). ''The ...

{{Taxonbar, from=Q139951 Nodosauridae Dinosaur genera Barremian dinosaurs Taxa named by Frederic Augustus Lucas Fossil taxa described in 1902 Dinosaurs of the United States