Nodocephalosaurus (meaning "knob headed lizard") is a monospecific genus of ankylosaurid dinosaur from New Mexico that lived during the Late Cretaceous (late Campanian to early Maastrichtian stage, 73.49 to 73.04 Ma) in what is now the De-na-zin member of the Kirtland Formation.

[2] In 1995, a partial skull of an ankylosaur was discovered weathering out of a grey mudstone a few hundred metres west of a new Parasaurolophus site in the De-na-zin member of the Kirtland Formation, New Mexico.

[1] In 2000, Tracy Ford assigned NMMNH P-20880, a single pup-tent scute with a hollowed-out base, as a potential specimen of Nodocephalosaurus.

[7] In 2016, Gregory S. Paul gave Nodocephalosaurus an estimated length of 4.5 metres (15 feet) and a weight of 1.5 tonnes (3,306 lbs).

[3] Sullivan (1999) originally diagnosed Nodocephalosaurus based on the presence of semi-inflated to bulbous polygonal osteoderms fused to the nasal, frontal and supraorbital regions of the skull, a prominent quadratojugal horn that is directed anteroventrally, and a prominent post-maxillary/lacrimal osteoderm.

[1] However, Arbour & Currie (2015) later diagnosed Nodocephalosaurus based on the presence of a bulbous, ridge-like loreal caputegulum, a quadratojugal horn with an anteriorly positioned apex, conical frontonasal caputegulae with circular bases, lacks V-shaped upraised area of frontals, and a lacrimal caputegulum that is smaller, more square than in Ankylosaurus, Anodontosaurus, Euoplocephalus.

The supraoccipital cannot be distinguished as it is presumably part of a large mass of bone that lies between the skull roof and the occipital condyle.

The parasphenoid is obscured by a parasagittal bony mass that represents part of the skull roof and associated osteoderms of the frontal region.

Due to the overlying osteoderms that are fused to the skull roof, the frontals are not visible in dorsal view.

[1] A rugose osteoderm is present in the posterior region of the parietals where the squamosal horn attaches to the end dorsolateral side of the skull.

The osteoderms of the external surface are characterised by the presence of rugose ornamentation consisting of pits and poorly defined ridges.

As in other ankylosaurids, the region corresponding to the parietal table of the skull consists of a low-relief osteodermal covering.

[1] Nodocephalosaurus shares similar anatomical features with Akainacephalus, such as the lateral orientation of the external nares and the morphology of the supranarial, loreal and frontal caputegulae.

[2] Numerous cranial osteoderms possibly referable to the right side of the skull were recovered which vary in size and shape.

[1] Sullivan (1999) originally considered Nodocephalosaurus to be closely related to Saichania and Tarchia, although this was not based on the result of a phylogenetic analysis but rather the presence of bulbous caputegulae on the skull.

[7] Gastonia Ahshislepelta Aletopelta Liaoningosaurus Cedarpelta Chuanqilong Gobisaurus Shamosaurus Crichtonpelta Tsagantegia "Zhejiangosaurus" Pinacosaurus grangeri Pinacosaurus mephistocephalus Saichania Tarchia Zaraapelta Dyoplosaurus Talarurus Nodocephalosaurus Ankylosaurus Anodontosaurus Euoplocephalus Scolosaurus Ziapelta Wiersma and Irmis (2018) found Nodocephalosaurus to be within a southern Laramidian clade containing Akainacephalus that is nested within Asian taxa rather than other Laramidian taxa and suggested that this clade was a separate biogeographic dispersal event from Asia independent from the main radiation of Laramidian ankylosaurids.

[2] Gobisaurus Zhongyuansaurus Shamosaurus Tsagantegia Crichtonsaurus Pinacosaurus mephistocephalus Zaraapelta Tianzhenosaurus Pinacosaurus grangeri Saichania Tarchia gigantea Nodocephalosaurus Akainacephalus Minotaurasaurus Tarchia kielanae Shanxia Euoplocephalus Oohkotokia Scolosaurus Ziapelta Anodontosaurus Ankylosaurus Dyoplosaurus Describing a new ankylosaurine ankylosaurid Datai in 2024, Xing et al. recovered Nodocephalosaurus as a sister taxon to Talarurus when Zheng et al. (2018) dataset after the deletion of 14 taxa is used.

[13] Nodocephalosaurus is known from the De-na-zin member of the Kirtland Formation which has been dated to the upper-most Campanian to lower-most Maastrichtian stage, 73.49 ± 0.25 to 73.04 ± 0.25 Ma, and may be a taxon unique to the Willow Wash local fauna.

[1][2] The Kirtland Formation consists of interbedded sandstone, siltstone, mudstone, coal and shale.

[23] Non-dinosaur taxa contemporaneous with Nodocephalosaurus include an indeterminate choristodere,[14] the crocodylomorphs Denazinosuchus,[24] Brachychampsa[14] and Leidyosuchus,[14] the turtles Basilemys,[14] Denazinemys,[14] Neurankylus,[14] Plastomenus[14] and Thescelus,[14] and the fishes Melvius[14] and Myledaphus.