Thyestiida is an order of bony-armored jawless fish in the extinct vertebrate class Osteostraci.

The osteostracans reconstructed here belong to the major clade Cornuata, whose generalised morphology is exemplified by the zenaspidid Zenaspis (bottom left). Some highly derived head-shield morphologies are exemplified by the benneviaspidids Hoelaspis (top right) and Tauraspis (top left), or the thyestiid Tremataspis (bottom right). The latter, of the family Tremataspididae, has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits.
Thyestiida
Thyestiida Illemoraspis Procephalaspis Auchenaspis Thyestes Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
ThyestiidaIllemoraspis Procephalaspis Auchenaspis Thyestes Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Illemoraspis
Procephalaspis Auchenaspis Thyestes Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Procephalaspis
Auchenaspis Thyestes Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Auchenaspis
Thyestes Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Thyestes
Witaaspis Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Witaaspis
Tremataspidoidea Saaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis Kiaeraspidoidea Didymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
TremataspidoideaSaaremaspis Tyriaspis Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis
Saaremaspis
Tyriaspis
Aestiaspis Dartmuthia Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis
Aestiaspis
Dartmuthia
Timanaspis Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis
Timanaspis
Oeselaspis Tremataspis Dobraspis Sclerodus Tannuaspis
Oeselaspis Tremataspis
Oeselaspis
Tremataspis
Dobraspis Sclerodus Tannuaspis
Dobraspis
Sclerodus Tannuaspis
Sclerodus
Tannuaspis
KiaeraspidoideaDidymaspis Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Didymaspis
Kiaeraspis Norselaspis Nectaspis Axinaspis Acrotomaspis Gustavaspis
Kiaeraspis
Norselaspis
Nectaspis Axinaspis Acrotomaspis Gustavaspis
Nectaspis
Axinaspis Acrotomaspis Gustavaspis
Axinaspis
Acrotomaspis Gustavaspis
Acrotomaspis
Gustavaspis
Cladogram, according to Sansom, 2009

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