…is a species of rhenanid placoderm (armored fish) that lived in the seas of Early Devonian Germany. In life G.stuertzi lived a similar lifestyle to a modern stargazer, as it lived on the bottom and had upward facing mouth and eyes which allowed it to suction prey that swam over head. Unlike other placoderms G.stuertzi’s armor was made up of a mosaic of unfused bony plates and scales. It also lacked the characteristic tooth plates of other placoderms, instead it had star-shaped tubercle scales which it allowed it to seize other animals.
Heavily armoured piscine torpedoes with fierce teeth roamed the oceans in the early days of fishes, in fact the Devonian era is called the age of fishes by palaeontologists as they had a huge burst of speciation and diversified to fill most marine ecological niches during this time. The now extinct (fortunately) class known as placodermi (plate skin in Greek) was the apex predator of these long gone waters, and thrived from 438 to 358 million years ago, dying out at the end Devonian mass extinction (one of the lesser ones).
…an extinct genus of antiarch placoderms that lived during the late Devonian period. This genus was largely successful with over 100 species that lived throughout the Devonian. Most members of Bothriolepis were freshwater benthic detritivores, although some were probably able to enter saltwater as well. Some paleontologists hypothesize that live salmon they lived their lives in saltwater and returned to freshwater to breed. Like other antiarches Bothriolepis had a heavily armored head that was attached to a thoratic shield. It also had a long pair of pectoral fins, these fins were likely used to lift it off the bottom as its heavy armor would have made it sink when it lost momentum. It might have also used its fins to throw sediment over itself.