Heterosteus

Heterosteus (also known as Heterostius) is an extinct genus of heterosteid placoderm of the Middle Devonian known from remains discovered in Europe and Greenland. According to Denison, 1978, Heterosteus might have been planktivorous, along with Homosteus, and Titanichthys.

==Name== Heterosteus was originally described in 1837 as species of Trionyx, a softshelled turtle. Also in later studies it was often misidentified and given names like Ichthyosauroides, Asterolepis asmussi and Chelonichthys asmusii. Even in recent studies, it is controversial as to whether to use genus name Heterosteus or Heterostius. According to International Code of Zoological Nomenclature, suffix ‘-ostius’ in scientific name should not be corrected as ‘-osteus’, so some studies use the genus name Heterostius.