placoderm
/ˈplækədɜːm/noun
1- a fossil fish of the Devonian period, having the front part of the body encased in broad flat bony plates盾皮鱼。
1.1
- Class Placodermi: several orders.盾皮鱼纲：数目。
词源
mid 19th cent.: from Greek plax, plak- 'flat plate' + derma 'skin'.