class Placodermi vs Placodermi

class Placodermi and Placodermi both are nouns.

Word	Noun	Adjective	Verb	Adverb
class Placodermi	Yes	No	No	No
Placodermi	Yes	No	No	No

As nouns, class Placodermi and Placodermi are synonyms defined as:

class Placodermi and Placodermi: extinct group of bony-plated fishes with primitive jaws

class Placodermi (noun)	Placodermi (noun)
extinct group of bony-plated fishes with primitive jaws	extinct group of bony-plated fishes with primitive jaws