Where Did the Ostracoderms Come from?

Galeaspida lived in shallow, fresh water and marine environments during the Silurian and Devonian times (430 to 370 million years ago) in what is now Southern China, Tibet and Vietnam.

Are ostracoderms Gnathostomes?

' How- ever, current vertebrate phylogenies suggest that most, if not all, 'ostracoderms' are in fact jawless stem gnathostomes, which retain certain features that were once regarded as unique to the cyclos- tomes, such as gill pouches or lack of horizontal semicircular canal.

When did ostracoderms first appear on Earth?

Ostracoderms (shell-skinned) are any of several groups of extinct, primitive, jawless fishes that were covered in an armour of bony plates. They appeared in the Cambrian, about 510 million years ago, and became extinct towards the end of the Devonian, about 377 million years ago.