[3] Scolosaurus was named by Franz Nopcsa von Felső-Szilvás in 1928, based on holotype NHMUK PV R.5161, a nearly complete specimen that preserves the entire skeleton except for the distal end of the tail, the right forelimb, the right hindlimb, and the skull.

This specimen consists of a partial skull, both humeri, a caudal vertebra and several osteoderms and was recovered in the Upper Member of the Two Medicine Formation, in Montana, which has been dated at approximately 74 million years.

However, a redescription of Scolosaurus published in 2013 in the Canadian Journal of Earth Sciences by Paul Penkalski and William T. Blows suggested that the genus is a valid taxon.

The biogeographical tree (i.e. the following cladogram) is basically the 50% majority rule tree, except with some of the polytomies resolved according to the results of the maximum agreement subtree:[12] Crichtonpelta Tsagantegia Zhejiangosaurus Pinacosaurus Saichania Tarchia Zaraapelta Dyoplosaurus Talarurus Nodocephalosaurus Ankylosaurus Anodontosaurus Euoplocephalus Scolosaurus Ziapelta The following cladogram is based on a 2017 phylogenetic analysis of the Ankylosaurinae conducted by Victoria Arbour and David Evans.

The cladogram depicts the majority rule (average result) of 10 most parsimonious trees, which each are considered to have the fewest evolutionary steps, thus being the most accurate under the principle of Occam's razor:[13] Zhejiangosaurus luoyangensis Pinacosaurus grangeri Pinacosaurus mephistocephalus Tsagantegia longicranialis Talarurus plicatospineus Nodocephalosaurus kirtlandensis Saichania chulsanensis Zaraapelta nomadis Tarchia kielanae Ziapelta sanjuanensis Euoplocephalus tutus Zuul crurivastator Scolosaurus cutleri Dyoplosaurus acutosquameus Anodontosaurus lambei Ankylosaurus magniventris In 1874, G. M. Dawson excavated specimen USNM 7943 at the Milk River locality of the Frenchman Formation in Alberta.

In 1928, George F. Sternberg, collected specimen USNM 11892, from the Montanazhdarcho holotype locality, high up in the Two Medicine Formation in Glacier County, Montana.

[15] The material, a partial skull, was recovered from channel sandstone sediments that were deposited during the Campanian stage, approximately 74 million years ago.

Lithologies, invertebrate faunas, and plant and pollen data support that the Two Medicine Formation was deposited in a seasonal, semi-arid climate with possible rainshadows from the Cordilleran highlands.

Scolosaurus shared its paleoenvironment with other dinosaurs, such as the duck-billed hadrosaurs Hypacrosaurus, Acristavus, Gryposaurus, Brachylophosaurus, Glishades, Prosaurolophus and Maiasaura, and the ankylosaur Edmontonia.

[19] Volcanic eruptions from the west periodically blanketed the region with ash, resulting in large-scale mortality, while simultaneously enriching the soil for future plant growth.

Fluctuating sea levels also resulted in a variety of other environments at different times and places within the Judith River Group, including offshore and nearshore marine habitats, coastal wetlands, deltas and lagoons, in addition to the inland floodplains.

[21] The excellent vertebrate fossil record of Two Medicine and Judith River rocks resulted from a combination of abundant animal life, periodic natural disasters, and the deposition of large amounts of sediment.

This region preserves the remains of many aquatic amphibians and reptiles, including bivalves, gastropods, frogs, salamanders, turtles, Champsosaurus and crocodilians.

When water was plentiful, the region could support a great deal of plant and animal life, but periodic droughts often resulted in mass mortality.