Thyestiida

Thyestiida
The Origin of Vertebrates 1908 Fig. 13.— Auchenaspis (Thyestes) verrucosus, natural size. (From Woodward.)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	†Osteostraci
Order:	†Thyestiida Janvier 1996
Families
†Thyestiidae †Tremataspididae

Thyestiida was an order of bony-armored jawless fish in the class Osteostraci.

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

Cladogram

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 has lost the paired fins, possibly as a consequence of an adaptation to burrowing habits.

References

• The origin and early evolution of the Osteostraci (Vertebrata): A phylogeny for the Thyestiida. Robert S. Sansom, Journal of Systematic Palaeontology, Volume 6, Issue 3, 2008, pages 317-332, doi:10.1017/S1477201907002386

External links

• Thyestiida at fossilworks.org (retrieved 21 April 2016)