Lanarkia
Lanarkia is a genus of extinct thelodont agnathan which existed in what is now Scotland and Canada during the upper Silurian period.
Description
Lanarkia were very small fish around 30-45 cm in length that would have been possible prey to eurypterids.The scales of Lanarkia spinulosa likely served an anti-parasite role, similar to modern sharks which form large groups and cruise at slow to medium speeds. Lanarkia lanceolata preserves scales with a generalized form, similar to modern sharks which swim slowly in open deep-water environments. Lanarkia horrida has an unusual combination of small and larger pointed scales. They could have served a generalist or anti-predator role, though juvenile small-spotted catsharks use similar scales on their tail to rasp at food.