Ordofisiyaan
Appearance
Ordofisiyaan (Af-Ingiriisi: Ordovician), kaas oo ah kan labaad ee lixdii xilli ee Balyuuzoik iyo xilli koror, oo ka soo jeeda 485.4 ± 1.9 ilaa 443.8 ± 1.5 milyan sano ka hor, muddo ku saabsan 41.6 milyan oo sano. Waxa ka horreeya Kambriyan, waxa ku xiga Siluriyaanka.
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