Here we continue with the coverage of the jawless fish specifically the Anaspida as we see representatives of two larger families; the Tahulalepididae and the Birkeniidae.
The two genera of the Tahulalepidae are little studied outside of the fact that the two of them date roughly to the Ludfordian Stage of the early Silurian Period 423.0 mya or so.
The other family the Birkeniidae which contains four genera the most well known one which gave the family (and by extension order Birkeniiformes) Birkenia. This genus first emerged in the Telychian stage of the Middle Silurian 438.5 mya and lasted according to some records until the very earliest parts of the Lochkovian stage of the early Devonian 419 mya
Left to Right:
Top Row: Tahulalepis elongituberculata, Trimpleylepis concatenata
Second Row: Vilkitskilepis valentinae, Ctenopleuron nerepisense
Third Row: Tahulalepis kingi, Birkenia elegans
Bottom Row: B. robusta, B. campbelli
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