[7] The Lower Triassic series is coeval with the Scythian Stage, which is today not included in the official timescales but can be found in older literature.
[11] A third extinction event occurred at the Olenekian-Anisian boundary, marking the end of the Early Triassic epoch.
The pole-to-equator temperature gradient was temporally flat during the Early Triassic and may have allowed tropical species to extend their distribution poleward.
[20][21][22] On the other hand, an alternative hypothesis proposes these Early Triassic climatic perturbations and biotic upheavals that inhibited the recovery of life following the P-T mass extinction to have been linked to forcing driven by changes in the Earth's obliquity defined by a roughly 32.8 thousand year periodicity with strong 1.2 million year modulations.
The massive extinctions that ended the Permian Period (and with that the Paleozoic Era) caused extreme hardships for the surviving species.
In the southern part of the supercontinent, it co-occurred with the non-mammalian cynodonts Galesaurus and Thrinaxodon, early relatives of mammals.
[36] The flora was gymnosperm-dominated at the onset of the Triassic, but changed rapidly and became lycopod-dominated (e.g. Pleuromeia) during the Griesbachian-Dienerian ecological crisis.
[25][20] Floral diversity was overall very low during the Early Triassic, as plant life had yet to fully recover from the Permian-Triassic extinction.
The regional prevalence of MISS is attributable to a decrease in bioturbation and grazing pressure as a result of aridification and temperature increase.
[40] The disappearance of MISS later in the Early Triassic has been interpreted as a signal of increased bioturbation and recovery of terrestrial ecosystems.
[39] In the oceans, the most common Early Triassic hard-shelled marine invertebrates were bivalves, gastropods, ammonoids, echinoids, and a few articulate brachiopods.