Wikipedia
Silurolepis
Silurolepis platydorsalis is the, as yet, only Silurian-aged antiarch placoderm that has been described from (mostly) articulated remains. Although it has been known for several years, it was finally described by Zhang, et al., in 2010. The earliest described placoderm is the yunnanolepid antiarch, Shimenolepis, from Llandovery Hunan. In contrast to S. platydorsalis, Shimenolepis is known only from distinctively ornamented thoracic armor plates that bear anatomic features unique to yunnanolepids.
S. platydorsalis is known from thoracic armor: as the specific name suggests, the dorsal side is very flat.