Provincialization of terrestrial faunas following the end-Permian mass extinction

Abstract

In addition to their devastating effects on global biodiversity, mass extinctions have had a long-term influence on the history of life by eliminating dominant lineages that suppressed ecological change. Here, we test whether the end-Permian mass extinction (252.3 Ma) affected the distribution of tetrapod faunas within the southern hemisphere and apply quantitative methods to analyze four components of biogeographic structure: connectedness, clustering, range size, and endemism. For all four components, we detected increased provincialism between our Permian and Triassic datasets. In southern Pangea, a more homogeneous and broadly distributed fauna in the Late Permian (Wuchiapingian, ∼257 Ma) was replaced by a provincial and biogeographically fragmented fauna by Middle Triassic times (Anisian, ∼242 Ma). Importantly in the Triassic, lower latitude basins in Tanzania and Zambia included dinosaur predecessors and other archosaurs unknown elsewhere. The recognition of heterogeneous tetrapod communities in the Triassic implies that the end-Permian mass extinction afforded ecologically marginalized lineages the ecospace to diversify, and that biotic controls (i.e., evolutionary incumbency) were fundamentally reset. Archosaurs, which began diversifying in the Early Triassic, were likely beneficiaries of this ecological release and remained dominant for much of the later Mesozoic.biogeography | complex networks | macroevolution | biotic recovery | paleoecology M ass extinctions are thought to reshape the composition and ecological structure of communities on a scale unparalleled by background extinction (1, 2). Within the terrestrial realm, the replacement of dinosaur-dominated communities by those of mammals after the end-Cretaceous extinction is perhaps the best-known example of such wholesale faunal reshuffling. By contrast, understanding the effects of the more massive endPermian extinction on terrestrial community structure has been hampered by the paucity of high-quality geographic data, with nearly all studies restricted to sequences from single basins in Russia (3, 4) or South Africa (5-8). Although some broad similarities have emerged, such as the progressive aridification of the two basins (3, 8) and a heightened diversity of temnospondyl amphibians in the recovery interval (9), limited geographic sampling in each hemisphere constrains the ability of paleontologists to distinguish regional patterns from those characteristic of the individual basins. Moreover, these broadly separated areas are uninformative regarding large-scale (i.e., continentlevel) patterns of faunal evolution.Here we examine tetrapod faunal composition in five fossiliferous areas in southern Pangea approximately 5 million years before and 10 million years after the end-Permian mass extinction. We analyze changes in biogeographic structure with four metrics of taxon occurrence data. First, biogeographic connectedness (BC) quantifies the proportion of taxon-locality occurrences relative to the maximum number of such occurrences possible. Thus...

The precise temporal calibration of dinosaur origins

“…The new dates also imply greater uncertainty for the ages of other putative Middle Triassic vertebrate assemblages from South Africa (Cynognathus Assemblage Zone), Zambia (Ntawere Formation), Tanzania (Manda Formation), and Antarctica (upper Fremouw Formation). These assemblages have been particularly influential in the discussion of the origin of dinosauromorphs (15,33), and Triassic biotic provincialization after the end-Permian mass extinction in southern Pangea (13). The Zambian, Tanzanian, and Antarctic assemblages are all correlated to the South African Karoo Basin record using vertebrate biostratigraphy, yet all of these sequences (including the Karoo Basin) are devoid of both published radioisotopic dates and other independent criteria for assessing their age.…”

“…As recently pointed out, analyses of the origin and early diversification of dinosaurs have suffered from an overreliance on low-resolution (both stratigraphic and taxonomic) vertebrate biostratigraphy that obscures real faunal differences in time and space (10). This situation is particularly problematic for Triassic nonmarine communities, where tetrapod composition across Pangea appears to be particularly heterogeneous (11)(12)(13). Without precise independent age control (other than vertebrate biostratigraphic correlations), it is impossible to determine if these faunal differences vary across time, space, or a combination of both.…”

A living fossil tale of Pangaean biogeography

“…The Permo-Triassic mass extinction had a profound and drastic impact on most forms of life on the planet, with an estimated 70% extinction of terrestrial animals. This resulted in a global ecological release that drove species diversification and increased provincialism [76]. In addition, strong biotic provinciality was also related to cyclical climatic modes during the early Mesozoic [77].…”

Late Permian (Lopingian) Terrestrial Ecosystems: A Global Comparison With New Data From the Low Latitude Bletterbach Biota

“…Climate models suggest a temperate to cool, seasonal climate (Yemane, 1994;Rees et al, 2002;Roscher et al, 2008). The faunal assemblage is dominated by dicynodonts (47%) that consist of endothiodonts, emydopoids, cryptodonts, and dicynodontoids, and gorgonopsians (35%), with rare temnospondyls (9%), and a single biarmosuchian and a single therocephalian (Haughton, 1926;Keyser, 1975;Jacobs et al, 2005;Fröbisch, 2009;Kurkin, 2011;Sidor et al, 2013;Kruger et al, 2015). Plant macroremains are mostly represented by Glossopteris leaves, Vertebraria roots and Paracalamites stems.…”

“…The transition from Palaeozoic to Mesozoic plant groups, for example, seems to be globally diachronous (Knoll, 1984;DiMichele et al, 2001;Looy et al, 2014), and late Permian vertebrate communities have been described as highly homogeneous across the whole of Pangaea (Sues and Boy, 1988;Rage, 1988;Milner, 1993;Dilkes and Reisz, 1996;Sues and Munk, 1996) to moderately endemic (Modesto et al, 1999;Modesto and Rybczynski, 2000;Angielczyk and Kurkin, 2003;Sidor et al, 2005;Angielczyk, 2007). Although new discoveries (e.g., Angielczyk and Sullivan, 2008;Smith et al, 2015;Huttenlocker et al, 2015;Benton, 2016;Huttenlocker and Sidor, 2016) and macroevolutionary studies (e.g., Fröbisch, 2009;Sidor et al, 2013) are contributing to a new and more comprehensive picture of late Permian terrestrial life, the geographic patchiness of well-preserved Lopingian ecosystems complicates attempts to outline a coherent, global scenario. Furthermore, a deep understanding of Permian terrestrial ecosystems is especially relevant because this time interval precedes the most severe biotic crisis of Earth history, the end-Permian mass extinction (Benton and Twitchett, 2003).…”