Evidence from South Africa for a protracted end-Permian extinction on land

Abstract

Earth’s largest biotic crisis occurred during the Permo–Triassic Transition (PTT). On land, this event witnessed a turnover from synapsid- to archosauromorph-dominated assemblages and a restructuring of terrestrial ecosystems. However, understanding extinction patterns has been limited by a lack of high-precision fossil occurrence data to resolve events on submillion-year timescales. We analyzed a unique database of 588 fossil tetrapod specimens from South Africa’s Karoo Basin, spanning ∼4 My, and 13 stratigraphic bin intervals averaging 300,000 y each. Using sample-standardized methods, we characterized faunal assemblage dynamics during the PTT. High regional extinction rates occurred through a protracted interval of ∼1 Ma, initially co-occurring with low origination rates. This resulted in declining diversity up to the acme of extinction near the Daptocephalus–Lystrosaurus declivis Assemblage Zone boundary. Regional origination rates increased abruptly above this boundary, co-occurring with high extinction rates to drive rapid turnover and an assemblage of short-lived species symptomatic of ecosystem instability. The “disaster taxon” Lystrosaurus shows a long-term trend of increasing abundance initiated in the latest Permian. Lystrosaurus comprised 54% of all specimens by the onset of mass extinction and 70% in the extinction aftermath. This early Lystrosaurus abundance suggests its expansion was facilitated by environmental changes rather than by ecological opportunity following the extinctions of other species as commonly assumed for disaster taxa. Our findings conservatively place the Karoo extinction interval closer in time, but not coeval with, the more rapid marine event and reveal key differences between the PTT extinctions on land and in the oceans.

Early evolution of beetles regulated by the end-Permian deforestation

“…Moreover, how terrestrial ecosystems were affected during the EPME is still highly controversial ( Benton and Newell, 2014 ; Gastaldo, 2019 ). Terrestrial tetrapods and plants are considered to have been severely affected by the EPME mostly based on diversity and taxonomic composition ( Benton and Newell, 2014 ; Viglietti et al, 2021 ); however, such mass extinction was questioned by a more comprehensive dataset of plant macro- and microfossils ( Gastaldo, 2019 ; Nowak et al, 2019 ). Similarly, Permian insects are thought to have suffered a significant extinction ( Labandeira and Sepkoski, 1993 ; Béthoux et al, 2005 ; Labandeira, 2005 ; Condamine et al, 2020 ; Condamine et al, 2016 ), but this was not supported by other molecular phylogenetic and fossil record analyses ( Ponomarenko, 2016 ; Dmitriev et al, 2018 ; Montagna et al, 2019 ; Schachat et al, 2019 ).…”

Living fast in the Triassic: New data on life history in Lystrosaurus (Therapsida: Dicynodontia) from northeastern Pangea

“…However, more recent evidence from isotopic and geochemical data produced differing estimates of the degree to which aridity increased in the Karoo Basin, complicating our understanding of seasonal variation in precipitation and resource availability [111,116,117]. Nevertheless, conditions were disruptive enough to have destabilized terrestrial communities and caused a prolonged interval of faunal turnover in southern Pangea during the extinction interval [15,18,118].…”

“…Fluctuating climates accompanied by an overall increase in global temperatures are hypothesized to have forced 70% of terrestrial vertebrate families to extinction [4][5][6][7][8], although plant extinctions were notably damped [9][10][11]. Recovery after the Permo-Triassic extinction has been a topic of intense research, but most studies in the terrestrial realm focus on taxonomic diversity and abundance [12][13][14], or changes in community structure and dynamics following the extinction [6,3,[15][16][17][18]. Few studies have examined how the extremely changed environment of the earliest Triassic impacted growth rate, life history, and longevity of surviving taxa [19][20][21][22].…”

“…Lystrosaurus, a stoutly built dicynodont therapsid that ranged in maximum skull size from approximately 16-39 cm (L. murrayi and L. maccaigi from South Africa, respectively), is one of the hallmark survivors of the Permo-Triassic extinction due to its remarkable abundance in southern Pangean deposits [18,23,24]. The success of Lystrosaurus has been variously attributed to its generalist diet of tough plant material (e.g., [25,26]), broad habitat tolerances [27], a burrowing lifestyle [28], unusual thermal tolerances [29], and a developmentally plastic growth strategy that allowed it to weather extreme ecosystem instability [20,22,30,31].…”

Editorial: Permian Extinctions

“…Gastaldo et al (2020) reconstruct wet-dry and warm-cool oscillations using stable-isotope geochemistry of the recalcitrant soil nodules, concentrated as erosional remnants in fluvial channel-lag deposits. The fluctuation in latest Permian climate occurs across what has been considered, previously, as the pre-EPME Daptocephalus and the post-EPME Lystrosaurus declivis Assemblage Zone (AZ; Viglietti et al, 2021), where Lystrosaurus is designated a "disaster taxon" (Botha-Brink et al, 2016). The term disaster taxon was originally conceived for marine microorganisms that bloomed in the wake of a biological crisis and has become a term strongly attached to mass extinctions.…”