The end-Permian mass extinction, 252 million years ago, represents the greatest loss of biodiversity in the history of life on the planet. The extinction was likely driven by greenhouse and toxic gas emissions and an extreme temperature rise triggered by volcanic eruption of the Siberian Traps (located today in Russia) followed by stagnant oceans and low oxygen conditions. Baking and burning of coal, carbonate, and evaporite deposits during Siberian Traps emplacement released additional greenhouse and toxic gases into the atmosphere. Volatile environmental conditions continued into the 5 million-year-long Early Triassic interval where additional carbon isotope excursions are interpreted to represent subsequent volcanic eruptions. Additional eruptive events prompted extreme temperature perturbations of the surface ocean, reaching up to 40°C, reducing temperature gradient driven ocean circulation, and propagating oxygen minimum zones. Following the initial mass extinction event, the marine ecosystem experienced additional community restructuring events in response to extreme climate change intervals. Currently, anthropogenic greenhouse gas production is outpacing the rate of atmospheric carbon input modeled for the end-Permian mass extinction, signaling that environmental change in the modern world may be even more devastating to today’s ecosystems than the biotic crisis 252 million years ago. ❧ New insights into high resolution paleoecological, sedimentological, and geochemical data in the Early Triassic highlight a complex ecological response that varies across ocean basin, water depth, and latitudinal gradient. Intrinsic conditions including metabolic rate and hypoxic or high temperature tolerance determined which marine organisms thrived or died as environmental conditions shifted. A modified recovery rubric was used as an evaluation mechanism to compare and contrast the restructuring of sea floor communities throughout the Early Triassic. In both the Panthalassic and Tethys Ocean basins opportunistic or “disaster taxa” were the most abundant members of the marine community directly following the mass extinction and in low oxygen environments. The periodic resurgence of low oxygen conditions throughout the Early Triassic resulted in decreased diversity and abundance of seafloor-dwelling fauna and the dominance of “disaster” groups like microbialites, microconchids, and flat bivalves. During intervals of extreme sea surface temperature, miniature gastropods prevailed, possibly due to their metabolic flexibility, whereas echinoderms were often excluded by these deleterious conditions. The pace and pattern of recovery varied among ocean basins. The marine organisms of the Tethys Ocean, represented by deposits from the Italian Dolomites, experienced a more rapid recovery, including increased taxonomic diversity and ecological complexity within the first 1 million years following the initial extinction event. This was likely due to well-oxygenated conditions in the shallow marine environments of this region. Additional set-backs to the recovery of the sea-floor dwelling fauna included increased humidity and terrestrial run-off about 2 million years after the end-Permian mass extinction which inundated the seafloor and smothered diverse communities. ❧ In the open ocean, ammonoid cephalopods showed booms and busts in taxonomic diversity corresponding to carbon isotope excursions throughout the Early Triassic. In the polar, Boreal Ocean, ammonoids quickly diversified to fill a variety of ecological niche space represented by Westermann Morphospace including hypothetical planktonic forms, vertical migrants, and fast-moving predators. During each loss of taxonomic diversity, there was no selection against a particular shell shape, and new ammonoid communities rapidly repopulated shape disparity. In the tropics, a significantly higher proportion of ammonoid species diversity occupied streamlined shell shapes, likely representing rapid swimming abilities and higher metabolic rates. These potential predators may have taken advantage of expansive equatorial oxygen minimum zones as their modern relatives, coleoid squid, do today. ❧ The marine fauna of the Early Triassic exhibited a dynamic response to sudden and extreme environmental change. In the aftermath of the mass extinction event, communities were predominantly reconstructed by organisms tolerant to hyperthermals and hypoxic conditions. At the equator, extreme sea surface temperature and oxygen minimum zones selected for high temperature tolerant microgastropods and fast-moving ammonoids. The recovery from the end-Permian mass extinction was not slow and step-like. Instead, the invertebrate communities of the Early Triassic were highly malleable, changing their composition rapidly in response to new challenges from continuous environmental perturbations.