Description

Thursius pholidotus Traquair 1888
Devonian
Lower Caithness Flagstone Group, Achanarras Limestone
Sandwick Fish Bed, Achanarras Horizon, Quoylou, Scotland

Good 165mm fish on 190mm slab. Partial fish on back.

Thursius was a relative of Osteolepis, both belonging to the Order Osteolepiformes, the group of fishes close to the ancestry of tetrapods – the lineage that led to land vertebrates.

This one has nice detail and John says I get a free ice cream if someone buys it today.

The Devonian Period was the block of geologic time during which jawed fishes (osteichthyans, placoderms, acanthodians, and chondrichthyans) greatly diversified while jawless fish groups declined draatically.  The apex predators of the sea had been all invertebrates previously, but in the Devonian, giant armored nightmares with guillotine-like jaws ruled the seas.