Nodosaurus

Nodosaurus textilis is the type and only widely recognized species within the genus Nodosaurus, which gives its name to the family Nodosauridae. Its name translates to "knobbed lizard," referring to the bony nodes that covered its back. The species name textilis describes the woven, fabric-like appearance of this tightly packed armour.

This moderate-sized herbivore grew to about 6 m in length and weighed approximately 3.5 tonnes. It is distinguished from its close relatives, the ankylosaurids, by the absence of a tail club. Instead, nodosaurids had flexible, weaponless tails. To compensate, they often possessed larger lateral spikes, especially on the shoulders, to provide protection along their flanks.

The dinosaur's dorsal armour was made of numerous small osteoderms that formed a shield over its back and tail. Larger, ridged scutes and conical spikes ran along its sides. Evidence from related fossils, such as the exceptionally preserved Borealopelta mummy, indicates that these bony plates were covered in keratinous sheaths. This would have increased the effective size and sharpness of the armour in life.

The skull of Nodosaurus was more pointed than those of its ankylosaurid cousins. Its narrow snout suggests it was a more selective feeder than the broad-beaked ankylosaurines.

During the Cenomanian, Nodosaurus inhabited the coastal environments of the Frontier Formation in Wyoming. These areas were characterized by conifer and fern forests with shallow marine influences. As a low-browsing herbivore, it likely ate ferns, low-lying conifers, and cycads. Its defensive strategy relied on its dense back armour and shoulder spikes. Unlike ankylosaurids, which could actively strike back with a tail club, nodosaurids likely crouched low to the ground when threatened, using their spiked flanks to deter predators.

The discovery of the Borealopelta specimen, a close relative, has provided new insights into nodosaurid biology. It preserved stomach contents, including ferns and charcoal, suggesting the animals fed in areas regrowing after fires. Analysis of its melanosomes also revealed reddish-brown countershading, the most detailed colour reconstruction for any non-avian dinosaur to date.

• YPM 1815 — Marsh's holotype, Yale Peabody Museum.
• AMNH 3736 — referred specimen.
• Borealopelta markmitchelli (close relative, TMP 2011.033.0001) — Royal Tyrrell Museum; preserves intact armour, skin, gut contents, and countershading pigment.

Genus and species count — N. textilis is the only universally accepted species; the genus is somewhat poorly diagnosed by modern standards because the holotype lacks a complete skull. Some workers consider Nodosaurus textilis a nomen dubium, though it remains in active use. Phylogenetic position within Nodosauridae — basal nodosaurid; well-resolved. Defensive strategy — flank-protection-and-crouch model is the dominant interpretation.

Nodosaurus is less famous than Ankylosaurus or even Borealopelta but is the namesake of an important ankylosaur subfamily. The 2017 Borealopelta unveiling at the Royal Tyrrell — a near-perfectly preserved nodosaurid that "looks like a sculpture rather than a fossil" — went viral globally and substantially raised public awareness of nodosaurids generally.

• ankylosauria
• ankylosaurus
• euoplocephalus
• ornithischia

• Lull, R. S. (1921). The Cretaceous armored dinosaur Nodosaurus textilis Marsh. American Journal of Science, 1, 97–126.
• Carpenter, K., & Kirkland, J. I. (1998). Review of Lower and middle Cretaceous ankylosaurs from North America. New Mexico Museum of Natural History and Science Bulletin, 14, 249–270.
• Brown, C. M., et al. (2017). An exceptionally preserved three-dimensional armored dinosaur reveals insights into coloration and Cretaceous predator-prey dynamics. Current Biology, 27, 2514–2521.
• Brown, C. M., et al. (2020). Dietary palaeoecology of an Early Cretaceous armoured dinosaur (Ornithischia; Nodosauridae). Royal Society Open Science, 7, 200305.