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Temporal range: Devonian
Parmastega is a prehistoric animal from the Devonian, notable for being a very early tetrapod, dated to the earliest Famennian age (about 372 million years ago), in contrast to later fossils known from late Famennian (365–359 million years ago). These later fossils are considerably younger, by about 30 million years, than the earliest recorded tetrapod footprints, which presented a mystery that Permastega's more recently described morphology from a three dimensional reconstruction has helped provide light on.
One remaining mystery is what exactly it hunted. There were large invertebrates on land but they were not necessarily common. It is faintly possible it hunted other shore-resting early amphibians, but more speculative. It is also possible it hunted sea scorpions that were comfortable on both land and sea.
It was estimated more than a meter in length and lived in Russian lagoons. It had eyes positioned on the top of its head in a crocodilian or mudskipper-like fashion, and had sharp teeth, which together would have made it a capable ambush hunter of the water's edge. Like more recent cousins, it was a gill breather, and had low-lying nostrils that would have been submerged in water to drive water to the gills, but it also possessed a spiracle on the top of its head for breathing air. Spiracles were eventually replaced by ears as nostrils moved upward on tetrapods to breathe air and the spiracles became redundant.
- Beznosov, Pavel A.; Clack, Jennifer A.; Lukševičs, Ervīns; Ruta, Marcello; Ahlberg, Per Erik (October 2019). "Morphology of the earliest reconstructable tetrapod Parmastega aelidae". Nature. 574 (7779): 527–531. doi:10.1038/s41586-019-1636-y. ISSN 1476-4687.
- "Early tetrapods had an eye on the land". Nature. Springer Nature. Retrieved 5 November 2019.