Both Anisacanthus and Holodiscus are what level of classification?
Holodiscus Holodiscus (syn. "Sericotheca") is a genus of flowering plants in the family Rosaceae, native to the Americas, from southwestern British Columbia, Canada and the western United States south to Bolivia.
Ptyctodontida The ptyctodontids ("folded-teeth") are placoderms of the order Ptyctodontida, containing the family Ptyctodontidae. With their big heads, big eyes, reduced armor and long bodies, the ptyctodontids bore a superficial resemblance to modern day chimaeras (Holocephali). Their armor was reduced to a pattern of small plates around the head and neck. Like the extinct and related acanthothoracids, and the living and unrelated holocephalians, most of the ptyctodontids are thought to have lived near the sea bottom and preyed on shellfish.