| Isadia Temporal range: | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | †Eurynotoidiformes |
| Family: | †Eurynotoidiidae |
| Genus: | †Isadia Minikh, 1986 |
| Species | |
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See text | |
Isadia is an extinct genus of prehistoric freshwater ray-finned fish from the order Eurynotoidiformes. It is known from the Permian of European Russia. The genus Amblypterina is partially considered a junior synonym of both Isadia and Kichkassia.
The following species are known:
- I. arefievi Minikh, Arefiev & Golubev, 2015 - Wuchiapingian of Vologda, Russia (Salarevskaya Formation)
- I. aristoviensis Minikh, 1990 (syn: Amblypterina grandicostata) - Capitanian to Wuchiapingian of Vologda & Orenburg, Russia (Vyazovskaya, Kutuluk & Kulchumovskaya Formations)
- I. opokiensis Minikh & Andrushkevich, 2017 - Capitanian to Wuchiapingian of Vologda, Russia (Poldarsky Formation)
- I. suchonensis Minikh, 1986 (syn: Amblypterina pectinata) - Capitanian to Wuchiapingian of Vologda & Orenburg, Russia (Poldarsky & Malokinelskaya Formations)
Based on an extensive review of tooth morphology, Isadia was a herbivorous fish that predominantly fed on algae. I. suchonensis had teeth adapted for shearing off algae in manner similar to a surgeonfish, I. opokiensis & I. arefievi had teeth adapted for scraping algae off rocks similar to certain cichlids, and I. aristoviensis cropped parts of large algae and submerged vascular plants in a manner similar to rabbitfish. Based on this morphology, Isadia can be divided into two evolutionary lineages: one lineage comprising I. suchonensis→I. opokiensis→I. arefievi, and one lineage comprising just I. aristoviensis.
