The head-shield and body armor of most traquairaspids form an almond shape. Plates have a distinctive ornamentation of tubercles: this ornamentation is very similar to the plate ornamentation of the heterostracan Weigeltaspis. This similarity of ornamentation creates much confusion over the taxonomical placement of Weigeltaspis, in addition to confusion over whether or not an isolated plate is of Traquairaspis, or of Weigeltaspis. Intact specimens of Weigeltaspis suggest a living animal similar to psammosteids like Drepanaspis.[2] The armor of Phialaspis symmondsi (once considered as species of Traquairaspis[3]) is shaped like a jet plane or paper airplane, with pointed wing-like crests and a dorsal crest near the posterior end of the armor. The body of "Yukonaspis," Traquairaspis angusta, is greatly elongated, based on the holotype, a ventral plate.
Most species of traquairaspids are placed within the type genus Traquairaspis; most of the other genera, such as Phialaspis, Toombsaspis, and "Yukonaspis," have been synonymized into Traquairaspis. Weigeltaspis is sometimes placed within Traquairaspidiformes on account of the plate ornamentation being almost identical to that of Traquairaspis.
^Dineley, DL (1964). "New specimens of Traquairaspis from Canada". Palaeontology. 7 (2): 210–219. "Archived copy"(PDF). Archived from the original(PDF) on 2012-04-25. Retrieved 2015-07-19.{{cite web}}: CS1 maint: archived copy as title (link)
^Tarlo, Halstead. "LB t1965) Psammosteiformes tAgnatha)—A review with descriptions of new material from the Lower Devonian of Poland, II. Systematic Part." Palaeontologia Polonica 15: 168. Pages 20-21
