Cambrian Brachiopod Radiation And Diversity

Both classes are known from the Early Cambrian. In the Cambrian, Calciata were represented by the orders Obolellida, Kutorginida, Craniopsida, Naukatida, and Chileida, in addition to traditional articulates (Orthida and Pentamerida orders). However, their diversity was low, and they became abundant only during the Ordovician to Devonian. Lingulates were much more diverse, and all five orders were present in the Cambrian (figure 16.2). Three of these—Paterinida, Lingulida, and Acrotretida—appeared during the Early Cambrian, the Siphonotretida appeared in the Middle Cambrian, and the Discinida arose at the end of the Cambrian.

Figure 16.2 Generic diversity of calciate and lingulate brachiopods in the Cambrian.

Stages: tom = Tommotian; atd = Atdabanian; bot = Botoman; toy = Toyonian; amg = Amgan; mar = Marjuman; ste = Steptoan; sun = Sunwaptan; dat = Datsonian.

Figure 16.2 Generic diversity of calciate and lingulate brachiopods in the Cambrian.

Stages: tom = Tommotian; atd = Atdabanian; bot = Botoman; toy = Toyonian; amg = Amgan; mar = Marjuman; ste = Steptoan; sun = Sunwaptan; dat = Datsonian.

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