''Parmastega'' is an extinct genus of

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

from the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

, dated to the earliest

Famennian The Famennian is the latter of two faunal stages in the Late Devonian Epoch. The most recent estimate for its duration estimates that it lasted from around 371.1 million years ago to 359.3 million years ago. An earlier 2012 estimate, still used b ...

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 ''Parmastegas 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.

Description

''Parmastegas maximum length is estimated to be around 130 centimeters. Its eyes are positioned on the top of its head similarly to modern-day crocodilians, indicating that it likely spent a lot of time looking out above the water's surface while the rest of its body stayed submerged. It possesses sharp teeth including a pair of sharp fangs and rows of marginal teeth on adsymphysial plate, which together would have made it a capable ambush hunter along the water's edge. The question of what exactly it was hunting remains a mystery, as large terrestrial invertebrates were not unheard of but still rare at the time. ''Parmastega'' made its home in shallow freshwater lagoons in what is now Russia. Like other basal Stegocephalians, it breathed primarily through gills, possessing low-lying nostrils that would have remained submerged to drive water to the gills. In addition, it also possessed a spiracle on the top of its head for breathing air in poorly oxygenated or otherwise poor water conditions, not unlike modern

Teleosts Teleostei (; Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts ), is, by far, the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Teleo ...

using a

labyrinth organ The Anabantoidei are a suborder of anabantiform ray-finned freshwater fish distinguished by their possession of a lung-like labyrinth organ, which enables them to breathe air. The fish in the Anabantoidei suborder are known as anabantoids or lab ...

in a similar fashion.

Etymology

The generic name ''Parmastega'' is derived from the Komi word ''parma,'' a term describing the forested hill landscape typical of the region in which the fossils were discovered, and ''stégi,'' the Greek for roof referring to the roof of the skull''.''

References

{{Taxonbar, from=Q72212587 Transitional fossils Fossil taxa described in 2019 Fossils of Russia Devonian tetrapods Famennian genus first appearances

Description

Etymology

See also

References