Heterostraci

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Heterostraci Temporal range: Wenlock[1]–Late Devonian, 433–359 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Panamintaspis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Infraphylum:	Agnatha
Class:	†Pteraspidomorphi
Subclass:	†Heterostraci Lankester 1868
Orders
Cardipeltida Corvaspidida Cyathaspidiformes Pteraspidiformes Lepidaspidida Tesseraspidida Tolypelepidida Traquairaspidiformes

Heterostraci (Ancient Greek, ἕτερος+ὄστρακον "those [with] a different shell" [-i is pl. of -us]) is an extinct subclass of pteraspidomorph, Ostracoderm, jawless vertebrate that lived primarily in marine and estuary environments. Heterostraci existed from the mid-Ordovician to the conclusion of the Devonian.