Lower part of a stem of the lycopod plant Pleuromeia
The Induan stage was introduced into scientific literature by Russian stratigraphers in 1956, who divided the Scythian stage that was used by Western stratigraphers into the Induan and Olenekian stages. The Induan stage is named for the Indus region of India. The Russian subdivision of the Lower Triassic then slowly replaced the one used in the West.
The top of the Induan stage (the base of the Olenekian) is at the first appearance of ammonite species Meekoceras gracilitatis.
Though the Induan is an unusually short age at this point in the geologic timescale, its million years' extent still contains five ammonite biozones in the boreal domain and four ammonite biozones in the Tethyan domain.
Much of the supercontinentPangea remained almost lifeless, deserted, hot, and dry. In higher latitudes, the flora during the Griesbachian was gymnosperm dominated but became lycopod dominated (e.g. Pleuromeia) in the Dienerian. This change reflects a shift in global climate from cool and dry in the Griesbachian to hot and humid in the Dienerian and points to an extinction event during the Induan, just ca. 500'000 years after the end-Permian mass extinction event. It led to the extinction of the Permian Glossopteris flora.
The lystrosaurids (below) and the proterosuchids (below) were the only groups of land animals to dominate during the Induan stage. Other animals, such as the ammonoids, insects, and the tetrapods (cynodonts, amphibians, reptiles, etc.) remained rare and terrestrial ecosystems did not recover for some 30 million years. Both the seas and much of the freshwater during the Induan were anoxic, predominantly during the Dienerian subage.Microbial reefs were common, possibly due to lack of competition with metazoanreef builders as a result of the extinction.
Triadobatrachus is an extinct genus of salientian frog-like amphibians, including only one known species, Triadobatrachus massinoti. It is the oldest member of the frog lineage known, and an excellent example of a transitional fossil.
The largest land reptile during the Early Triassic period, equivalent in size to today's Komodo dragons. It looked somewhat similar to a primitive crocodile, and shared many of their modern features like long jaws, powerful neck muscles, short legs and a lengthy tail, while retaining several of its own unique features such as its long legs, and hooked shaped mouth.
Once believed to be a proterosuchid, this taxon is now believed to have been intermediate between advanced non-archosauriform archosauromorphs such as Prolacerta, and basal archosauriforms such as Proterosuchus. This genus is also notable being one of the most complete Australian Triassic reptiles known.
Originally classified as a rauisuchid, Tsylmosuchus has more recently been interpreted as an indeterminate archosauriform. Tsylmosuchus occurred throughout the Olenekian age. Some of the strata from which Tsylmosuchus has been found are Induan in age, making it one of the earliest archosaurs.
A cat-sized cynodont. Many scientists suggest that the pits on the skull indicate that Thrinaxodon had whiskers and, therefore, probably had a covering of fur. There are suggestions that it was warm-blooded. Even so, it still laid eggs.
^Yin Hongfu, Zhang Kexin, Tong Jinnan, Yang Zunyi und Wu Shunbao: '"The Global Stratotype Section and Point (GSSP)of the Permian-Triassic Boundary." Episodes, 24(2): 102-114, Beijing 2001 ISSN0705-3797.
^ abWare et al. (2015): High-resolution biochronology and diversity dynamics of the Early Triassic ammonoid recovery: the Dienerian faunas of the Northern Indian Margin. Palaeogeography, Palaeoclimatology, Palaeoecology 440:363-373 https://doi.org/10.1016/j.palaeo.2015.09.013
^Hochuli et al. (2016): Severest crisis overlooked--Worst disruption of terrestrial environments postdates the Permian-Triassic mass extinction. Scientific Reports 6:28372 https://doi.org/10.1038/srep28372
^Foster et al. (2020): Suppressed competitive exclusion enabled the proliferation of Permian/Triassic boundary microbialites. The Depositional record 6. 1-13. https://doi.org/10.1002/dep2.97
^Romano et al. (2016): Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolutionBiological Reviews 91:106-147 https://doi.org/10.1111/brv.12161
^Smithwick F.M., and Stubbs T.L. (2018): Phanerozoic survivors: Actinopterygian evolution through the Permo-Triassic and Triassic-Jurassic mass extinction events. Evolution 72:348-362. https://doi.org/10.1111/evo.13421<
Brack, P.; Rieber, H.; Nicora, A. & Mundil, R.; 2005: The Global boundary Stratotype Section and Point (GSSP) of the Ladinian Stage (Middle Triassic) at Bagolino (Southern Alps, Northern Italy) and its implications for the Triassic time scale, Episodes 28(4), pp. 233-244.