''Thyestes'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of

osteostracan The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, ...

agnatha Agnatha (; ) or jawless fish is a paraphyletic infraphylum of animals in the subphylum Vertebrata of the phylum Chordata, characterized by the lack of jaws. The group consists of both extant taxon, living (Cyclostomi, cyclostomes such as hagfish ...

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

whose fossils are found in Middle to Late Ludlow-aged marine strata of Late

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

. Individuals of ''Thyestes'' superficially resembled ''

Cephalaspis ''Cephalaspis'' (from , 'head' and , 'shield') is a possibly monotypic genus of extinct osteostracan agnathan vertebrate. It was a trout-sized detritivorous fish that lived in the early Devonian. Description Like its relatives, ''Cephalaspi ...

'', but were more closely related to ''

Auchenaspis ''Auchenaspis salteri'' is an extinct species of Osteostraci, armored jawless fish of the order (biology), order Thyestiida from the Late Silurian of England. In England, ''A. salteris fossils are found in extreme abundance in the Lower Old ...

'' and ''

Tremataspis ''Tremataspis'' is a genus of an extinct osteostracan agnathan from the Silurian period of what is now Estonia. ''Tremataspis'' was about in length, and had an armored shield covering its head. Compared with its relatives, the shield was unus ...

''.

References

Osteostraci genera Silurian fish of Europe {{Paleo-jawless-fish-stub