| 单词 | Petalichthyida | 
| 释义 | Petalichthyida [´ped·ǝ·lik`thē·ǝ·dǝ]  PALEONTOLOGY A small order of extinct dorsoventrally flattened fishes belonging to the class Placodermi; the external armor is in two shields of large plates.  | 
	
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