Triassic Revolution

Abstract

The Triassic has long been recognized as a time during which marine and terrestrial ecosystems modernized dramatically, and it seems to have been a two-step process. First, recovery from the Permian-Triassic mass extinction (PTME) was a time of extraordinary renewal and novelty, and these processes of change were enhanced, it seems, by the effects of the Carnian Pluvial Episode (CPE). After the CPE, in the oceans, not only did the carbonate factory begin to change towards its modern form, but also arguably the Mesozoic Marine Revolution (MMR) speeded up. When the MMR was proposed it was seen as a process that occurred in the Late Jurassic and Cretaceous, as modern crustaceans, gastropods, and fishes enhanced predator-prey arms races. New evidence from China and elsewhere suggests in fact the MMR was already underway in the Middle and Late Triassic, and so was coincident with Sepkoski’s classic idea that Paleozoic faunas were replaced by Modern marine faunas from the beginning of the Triassic. On land, ongoing competition between synapsids and archosauromorphs through the Triassic was marked by a posture shift from sprawling to erect, and a shift in physiology to warm-bloodedness, with insulating skin coverings of hair and feathers. Dinosaurs, for example, originated in the Early or Middle Triassic, but did not diversify until after the CPE. These arms races, the MMR in the sea, and the endothermy shift in tetrapods, were triggered by the PTME, and then enhanced by the CPE.

A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem

“…Although the Guiyang Biota remains incompletely sampled, it highlights that the slow and stepwise recovery model ( 7 ) after the PTME is not applicable. Further, it fills part of a wide knowledge gap regarding the rise of modern marine ecosystems after the PTME by documenting the early diversification of fishes and decapods, two groups playing a substantial role in present-day marine ecosystems and in prey-predator interactions during the Mesozoic marine revolution ( 6 , 41 ).…”

“…The rise to dominance of the modern evolutionary fauna happened after the Permian-Triassic mass extinction (PTME), also known as the “great dying,” around the Permian-Triassic boundary ~251.9 million years ago (Ma) ( 2 ), which wiped out >80% of marine species ( 3 , 4 ). The subsequent recovery was a major period of evolutionary changes, during which not only did modern marine ecosystems emerge ( 5 ), but the Triassic Revolution began ( 6 ). However, because of the relative scarcity of Early Triassic fossil records for many marine groups, and especially the lack of exceptionally preserved fossil assemblages, the timing and processes of the rise of modern-type marine ecosystems remain poorly understood ( 5 ).…”

Beyond functional diversity: The importance of trophic position to understanding functional processes in community evolution

“…However, this is because the maximum body size of top consumers, not only primary production, has a significant effect on the amount of long versus short chains in a trophic network. For example, the Bathonian and Aptian experienced a level of planktonic diversity that was likely much higher than was experienced by ecosystems of the Triassic (Knoll and Follows, 2016;Benton and Wu, 2022). This high level of production enabled the presence of long chains, as observed in the Bathonian, but the novel presence of very large consumers in the Aptian lead to a greater degree of short chains, or trophic omnivory by top consumers, in this community.…”

The dawn of an Era: New contributions on comparative and functional anatomy of Triassic tetrapods

“…In a world where all continents were united, in a land dominated by hot climates and expansive deserts at its core—while boasting diverse environments along its peripheries—life resiliently endured and even flourished amid several events of climatic changes. Many vertebrate lineages populating current ecosystems, such as birds, testudines, lizards, crocodiles, and mammals, can trace their origins or early diversification events back to the Triassic period (e.g., Dal Corso et al, 2020; Simões et al, 2018; Sues, 2024), and significant events of adaptive radiation were able to forge an unprecedented diversity of body plans and lifestyles during this period (Araújo et al, 2022; Benton & Wu, 2022). Besides (or even explained by) its macroevolutionary significance, the Triassic period is a fertile field of scientific research, and growing attention has been devoted to Triassic tetrapods, whether from an anatomical, ecological, or evolutionary perspective.…”