Phacopida
From Freepedia
| Phacopida | ||||||||
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| Image:SilurianTrilobite.jpg Dalmanites limulurus, a trilobite of the suborder Phacopina | ||||||||
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| Suborders | ||||||||
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Phacopida is an order of trilobite that lived from the Ordovician to the Devonian. It is made up of a morphologically diverse group of related suborders.
The origin of the Phacopida order is uncertain. The three suborders Phacopina, Calymenina, and Cheirurina all share a distinctive protaspis (developmental stage lacking segments). This sort of similarity in development suggests phylogenetic unity. The suborder Calymenina is the most primitive of the Phacopida order and shares some characteristics with the order Ptychopariida, though it is not included in the subclass Libristoma.
Phacops rana and Dalmanites limulurus are two of the most well-known members of this order.
