Peloroplites (meaning "monstrous heavy one") is a monospecific genus of nodosaurid dinosaur from Utah that lived during the Late Cretaceous (Cenomanian to lower Turonian stage, 98.2 to 93 Ma) in what is now the Mussentuchit Member of the Cedar Mountain Formation.

[1][2] In 2001, a skeleton of a large nodosaurid from the Cedar Mountain Formation in Emery County, Utah was mentioned by Burge and Bird in a publication about the faunal composition of the Price River II quarry.

More material was obtained and was subsequently described in 2008 by Kenneth Carpenter, Jeff Bartlett, John Bird and Reese Barrick.

The Price River II quarry was previously reported as occurring in the Ruby Ranch Member by Burge and Bird (2001) but was later reported as occurring in the base of the Mussentuchit Member due to the dark, carbonaceous nature of mudstones of the strata.

The Price River II quarry has also produced specimens pertaining to four individuals of a new brachiosaurid, an iguanodontid, associated cranial and postcranial material of Cedarpelta, a turtle and a pterosaur.

[1] Carpenter et al. (2008) suggested that some of the large nodosaurid material from the Ruby Ranch Member of the Cedar Mountain Formation that has been questionably identified as Sauropelta may actually belong to Peloroplites.

If the material does belong to Peloroplites, then it would extend the stratigraphic range based on a specimen described by Warren and Carpenter (2004).

The specimen was obtained from the Poison Strip Sandstone Member of the Cedar Mountain Formation and assigned to Hoplitosaurus by Bodily (1969) based on the morphology of the spines.

[1] However, Gregory S. Paul in 2016 gave a higher estimate of 6 metres (20 feet) and a weight of 2 tonnes (4,410 lbs).

[2] Carpenter et al. (2008) diagnosed Peloroplites based on the lack of premaxillary teeth, occiput sloping forwards and towards the back, the absence of a prominent lateral temporal notch towards the back as in Sauropelta, small and blunt squamosal horns, paroccipital process projecting from the sides, a vertical quadrate that isn’t anteriorly bowed or sloped on the underside of the front, a very short odontoid, a short axis centrum which is as long as it is tall, and similar coracoid to scapula proportions to Animantarx and Edmontonia.

Both sets of prefrontal-lachrymals are triangular in upper and side view and have rugose sculpturing external surfaces that are composed of irregular pits which is especially prominent over the orbits.

The front of the orbit has a faint, shallow groove which extends onto the upper surface of the prefrontal and probably outline the margins between adjoining keratinous scales, a feature also similarly seen in other nodosaurids such as Edmontonia.

The postorbital horncores are conical structures that are very low that project dorsolaterally, which are much less prominent than those of Pawpawsaurus, Sauropelta and Gastonia.

The jugal-quadratojugal horncores appear as low, localized thickening of bone as they are not prominent on the skull unlike Gastonia and Animantarx.

A tooth from a maxillary fragment is similar to some teeth referred to Priconodon and has an extensive wear facet that extends the entire face of the crown as seen in ankylosaurids.

[1] Only the rear portions of the left and right mandibles are preserved and include the articular, angular, surangular and prearticular.

The adductor fossa is large and lateral-medially and is separated from the articular by a wall, both are features that are not seen in Edmontonia or Animantarx.

The diapophysis is short and located at the end of the midline on the centrum which is contrast to Sauropelta as it occurs on the neural arch instead.

Unlike Cedarpelta, Sauropelta and Edmontonia, the articular face of Peloroplites is circular, rather than heart-shaped, hexagonal or horizontally ellipsoid.

The neural arch is anteroposteriorly short, tall and erect which results in the postzygapophyses not reaching the level of the posterior face of the centrum.

In addition, a ridge extends along the transverse process ventrally to the parapophysis located on a short neural arch.

Parts of the humeri are known and enough of the crest remains to show that the humeral shaft is elongated in a similar condition to Sauropelta, Edmontonia, Animantarx, and Gastonia.

As in Sauropelta, the proximal end of the metatarsal is sloped laterally in anterior view and the distal condyles are well developed.

[1] Carpenter et al. (2008) originally placed Peloroplites within Nodosauridae but did not conduct a phylogenetic analysis to determine its exact relationships within the clade.

[6] Rivera-Sylva et al. (2018) placed Peloroplites as sister taxon to Sauropelta, Taohelong and a clade containing more nested taxa.

[7][8] Sauroplites Mymoorapelta Dongyangopelta Gastonia Gargoyleosaurus Hoplitosaurus Polacanthus Peloroplites Taohelong Sauropelta Acantholipan Nodosaurus Niobrarasaurus Ahshislepelta Tatankacephalus Silvisaurus

[4] Antarctopelta Mymoorapelta Hylaeosaurus Anoplosaurus Tatankacephalus Horshamosaurus Gargoyleosaurus Hoplitosaurus Gastonia Peloroplites Polacanthus Struthiosaurus Zhejiangosaurus Hungarosaurus Animantarx Niobrarasaurus Nodosaurus Pawpawsaurus Sauropelta Silvisaurus Stegopelta Texasetes Edmontonia Panoplosaurus Peloroplites is known from the uppermost part of the Cedar Mountain Formation, a layer known as the Mussentuchit Member.

[1] However, other radioistopic datings places the Mussentuchit Member in the Cenomanian to early Turonian age (98.2 ± 0.6 to 93 Ma).

[9] Peloroplites was contemporaneous with the basal hadrosauromorph Eolambia,[10] the brachiosaurid sauropod Abydosaurus,[11] the tyrannosauroid Moros,[12] the carcharodontosaurian Siats, the indeterminate coelurosaur Richardoestesia,[13] the ankylosaurs Animantarx and Cedarpelta,[14][1] the thescelosaurid cf.

Pseudosaurillus, Bothriagenys, Harmodontosaurus, Dicothodon and Primaderma,[17] the snake Coniophis,[17] the amphibian Albanerpeton,[15] the turtles Glyptops and Naomichelys,[15] the mammals Astroconodon, Spalacotherium, Symmetrodontoides, Paracimexomys and Kokopellia,[15] the batoids Ischyrhiza and cf.