placoderm
/ˈplækəˌdɜrm/
noun
- An extinct prehistoric fish that had a hard, bony armor covering its head and the front part of its body. Placoderms lived in oceans and rivers hundreds of millions of years ago, before the time of dinosaurs.
- In the ancient seas, the placoderm used its armored plates to protect itself from predators.
- Scientists believe the placoderm was one of the first jawed vertebrates on Earth.
- The museum's fossil collection includes a well-preserved placoderm from the Devonian period.