While traditionally regarded as a monophyletic clade as the sister taxon to the Ankylosauridae, some analyses recover it as a paraphyletic grade leading to the ankylosaurids.

Nodosaurids, like other ankylosaurians, were small- to large-sized, heavily built, quadrupedal, herbivorous dinosaurs, possessing small, leaf-shaped teeth.

One particularly well-preserved nodosaurid "mummy", the holotype of Borealopelta markmitchelli, preserves a nearly complete set of armor in life position, as well as the keratin covering and mineralized remains of the underlying skin, which indicate reddish pigments in a countershading pattern.

[3][4] The clade Nodosauridae was first informally defined by Paul Sereno in 1998 as "all ankylosaurs closer to Panoplosaurus than to Ankylosaurus," a definition followed by Vickaryous, Teresa Maryańska, and Weishampel in 2004.

[5] Following the publication of the PhyloCode, Nodosauridae needed to be formally defined following certain parameters, including that the type genus Nodosaurus was required as an internal specifier.

[8][9] Corresponding clades are shown in matching colors for clarity, and ⊞ buttons can be clicked to expand nodes: Sauroplites Mymoorapelta Dongyangopelta Gastonia Gargoyleosaurus Hoplitosaurus Polacanthus Peloroplites Taohelong Sauropelta Acantholipan Nodosaurus Niobrarasaurus Ahshislepelta Tatankacephalus Silvisaurus CPC 273 (Aguja Formation specimen) Hungarosaurus Europelta Pawpawsaurus Borealopelta Stegopelta Struthiosaurus languedocensis Struthiosaurus transylvanicus Struthiosaurus austriacus Animantarx Panoplosaurus Patagopelta Texasetes Denversaurus Edmontonia longiceps Edmontonia rugosidens Kunbarrasaurus Paw Paw juvenile Hylaeosaurus Liaoningosaurus Crichtonpelta Chuanqilong Cedarpelta Aletopelta Later-diverging ankylosaurids Sarcolestes Paw Paw juvenile Animantarx Cedarpelta Gargoyleosaurus Hoplitosaurus Niobrarasaurus Polacanthus Texasetes Patagopelta Hylaeosaurus Gastonia burgei Gastonia lorriemcwhinneyae Peloroplites Sauropelta Tatankacephalus Invictarx Silvisaurus Taohelong Europelta Struthiosaurus transylvanicus Struthiosaurus languedocensis Struthiosaurus austriacus Hungarosaurus Pawpawsaurus Tianchisaurus Panoplosaurus Denversaurus Edmontonia longiceps Nodosaurus Edmontonia rugosidens Anoplosaurus Dracopelta Borealopelta Mymoorapelta Stegopelta Vectipelta Dongyangopelta Zhejiangosaurus Ahshislepelta Aletopelta Talarurus Shamosaurinae Ankylosaurinae

[6][11][12][7][13][1] Panoplosaurini is defined as the largest clade containing Panoplosaurus mirus, but not Nodosaurus textilis or Struthiosaurus austriacus, and was named in 2021 by Madzia and colleagues for the group found in many previous analyses, both morphological and phylogenetic.

[6][7][13][1][15] Struthiosaurini is defined as the largest clade containing Struthiosaurus austriacus, but not Nodosaurus textilis or Panoplosaurus mirus, and was named in 2021 by Madzia and colleagues for the relatively stable group found in many previous analyses.