Biostratigraphic table for Orkney indicating the range for arthrodira:
Ranging from a few centimeters to several meters in length, these fishes were very important inhabitants of the lake system and the rivers. They are all “armoured” with big overlapping bony plates often with many tiny tubercles on the outside.
Kwikwi:modern armoured catfish from South America
The head and body were connected with a joint like structure. This probably made
movement of the head more independent from the body. Almost the same structure
can be found today in recent armoured (actinopterygii) catfish. This is a case
of a structure reinvented in evolution by a completely different group of