The Class Placodermi is further organized into finer groupings including:
- Order (4): Arthrodira · Petalichthyida · Ptyctodontida · Rhenanida
- Species: ZipcodeZoo has pages for 48 species and subspecies in the Class Placodermi.
Arthrodira is an order of extinct armoured jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. [more]
The Petalichthyida was an order of small, flattened placoderm fish. They were typified by their splayed fins, and numerous tubercles that decorated all of the plates and scales of their armor. They reached a peak in diversity during the Early Devonian and were found throughout the world, particularly in Europe (especially in Germany), North America, Asia, South America, and Australia. The petalichthids Lunaspis and are among the best known. There was an independent diversification event that occurred in what is now Southern China, producing a handful of unique genera that were once placed in their own order, "Quasipetalichthyida," named after the first discovered species there, Quasipetalichthys haikouensis. Soon after the Petalichthids' diversification, they went into a decline, until the last few species were exterminated along with the rest of the placoderms during the Late Devonian extinction event. [more]
More info about the Order Rhenanida may be found here.
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