The Euplacostraca (lit. "true Placostracans") are a clade of herbivorous Diplostoma.
The emergence of the Megalobrachids led many species of Placostracans to extinction, being out-competed for the niche of browser. The surviving species are referred to as the Euplacostracans.
Euplacostracans serve as generalist grazers, feeding on low vegetation. Their feeding tentacles, which are much shorter than those of Archaeoplacostracans, are used to forage through leaves and dig for roots. Otherwise, Euplacostracans are largely identical in anatomy to early Placostracans, serving as slow, bulky herbivores which rely on their thick shell for protection. They are present in both the primitive forest and the steppe.
Early Euplacostracans were roughly identical in size to the first Placostracans. However, the progressive decline of atmospheric oxygen has resulted in the decrease in maximum size, from roughly 50cm to 20cm in height.