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Cisuralian

The Cisuralian Epoch, also known as the Early Permian, represents the initial division of the Permian Period within the Paleozoic Era, extending from 298.9 ± 0.15 Ma to 272.3 Ma.^[1] Named for its type region on the southern slopes of the Ural Mountains in Russia (the cis-Uralian area), it encompasses four chronostratigraphic stages—Asselian (298.9 ± 0.15 to 293.52 ± 0.17 Ma), Sakmarian (293.52 ± 0.17 to 290.1 ± 0.26 Ma), Artinskian (290.1 ± 0.26 to 283.3 ± 0.4 Ma), and Kungurian (283.3 ± 0.4 to 272.3 Ma)—defined primarily by conodont biostratigraphy and global stratotype sections in Kazakhstan and Russia.^[1] This epoch marks a transitional phase in Earth's history, bridging the Carboniferous-Permian boundary with widespread glacial retreat and the onset of more arid continental conditions.^[2] Geologically, the Cisuralian is characterized by significant tectonic activity, including the assembly of the supercontinent Pangea, which influenced sedimentation patterns across equatorial and high-latitude regions.^[3] In Gondwana, marine transgressions and fluvial deposits dominated, while North American basins like the Appalachian recorded igneous events around 280 Ma; globally, low sea levels at the Sakmarian base gave way to rising levels by the Kungurian, fostering diverse shallow-marine environments.^[4] Climate during this time shifted from the peak of the Late Paleozoic Ice Age (LPIA) in the Asselian-Sakmarian, with extensive glaciation in southern Gondwana, to a warming greenhouse regime by the late Kungurian, evidenced by humid conditions in eastern Gondwana and the deglaciation of polar ice sheets.^[2] These changes drove paleogeographic reconfiguration, with cratonic basins accumulating coal-bearing sediments in humid zones and evaporites in emerging arid interiors.^[5] Paleobiologically, the Cisuralian witnessed pivotal evolutionary developments among terrestrial and marine life, setting the stage for Permian dominance. On land, synapsids—early mammal relatives—diversified rapidly, with basal groups like ophiacodontids and edaphosaurids appearing in North America, alongside the emergence of herbivory in amniotes exemplified by the sail-backed Edaphosaurus.^[6] Vascular plants, including conifers and seed ferns, expanded in wetland and floodplain ecosystems, while insects like beetles and flies diversified, enhancing pollination and decomposition roles. In marine realms, brachiopods, bryozoans, and fusulinid foraminifers flourished in warming epicontinental seas, though biodiversity showed provincialism tied to the icehouse-greenhouse transition; conodonts such as Streptognathodus isolatus served as key index fossils for stage boundaries.^[3] Overall, this epoch's biotic innovations and environmental shifts laid foundational patterns for the Middle and Late Permian, preceding the era's mass extinction.^[6]

Nomenclature and definition

Etymology and historical context

The term "Cisuralian" derives from the Latin prefix cis-, meaning "on this side of" or "before," combined with "Uralian," which refers to the western foreland and slopes of the Ural Mountains in Russia and Kazakhstan, the type region for early Permian strata.^[7] This nomenclature highlights the geological units lying west of the main Uralian orogenic belt, distinguishing them from later Permian deposits.^[8] The concept of the Cisuralian emerged from Russian stratigraphic traditions, where the Lower Permian had been delineated since the late 19th century, building on Roderick Murchison's 1841 establishment of the Permian System based on exposures near Perm, Russia.^[9] Russian geologists formalized key stages within this interval—such as the Asselian (proposed 1905), Sakmarian (1920s), Artinskian (1910s), and Kungurian (1920s)—using regional type sections in the Cis-Uralian foreland, emphasizing fusulinid foraminifera and ammonoids for correlation. The specific term "Cisuralian Series" was proposed in 1982 by John B. Waterhouse to unify these stages under a single, geographically descriptive unit, initially excluding the Kungurian, which was added in 1997 to align with the base of the overlying Guadalupian.^[7] This nomenclature shift from the traditional "Lower Permian" to "Cisuralian" aimed to reduce Eurocentric bias and better reflect the global applicability of Russian type sections, facilitating international standardization.^[10] The International Subcommission on Permian Stratigraphy approved the term in 1996, and it was ratified by the International Commission on Stratigraphy as the basal series of the Permian in the updated geological timescale during the early 2000s. Today, the Cisuralian serves as the formal epoch/series for the early Permian (approximately 298.9 to 274.4 Ma), preceding the Guadalupian within the broader Permian structure.^[1]

Stratigraphic boundaries and type sections

The lower boundary of the Cisuralian Epoch marks the Carboniferous-Permian transition and is defined by the Global Stratotype Section and Point (GSSP) in the Aidaralash Member of the Aktasty Formation, located at Aidaralash Creek in the southern Urals of Kazakhstan. This boundary is recognized by the first appearance of the fusulinid foraminifer Pseudoschwagerina, a key biostratigraphic marker for the base of the Permian System, with a calibrated numerical age of 298.9 ± 0.15 Ma based on high-precision U-Pb dating of zircons from ash beds in the section.^[11]^[12] The upper boundary of the Cisuralian corresponds to the base of the Guadalupian Series and Roadian Stage, defined at the GSSP in the Cutoff Formation within Stratotype Canyon, Guadalupe Mountains National Park, Texas, USA. This level is identified by the first appearance of the conodont Jinogondolella nankingensis, providing a precise biostratigraphic correlation, and is dated to 274.4 ± 0.4 Ma through integrated radioisotopic and cyclostratigraphic methods.^[13]^[14]^[1] The Cisuralian thus encompasses a duration of approximately 24.5 million years, bridging a critical interval of post-glacial recovery and climatic stabilization in the late Paleozoic.^[15] Associated lithological changes underscore these boundaries: the lower limit reflects the waning of widespread Carboniferous coal swamps, with diminishing peat accumulation and organic-rich deposits, while the Cisuralian interior features the progressive onset of red beds—hematite-rich sandstones and mudstones signaling increased aridity and oxidation under warmer, drier paleoclimatic regimes.^[16]^[17]

Subdivisions

Global stages

The Cisuralian Epoch is subdivided into four global stages, ratified by the International Commission on Stratigraphy (ICS), which provide a standardized chronostratigraphic framework based primarily on conodont biostratigraphy. These stages span from 298.9 ± 0.15 Ma to 274.4 ± 0.4 Ma, marking the transition from the Late Paleozoic Ice Age to warmer conditions.^[1] The Asselian Stage, the lowermost division, extends from 298.9 ± 0.15 Ma to 293.52 ± 0.17 Ma and is defined by the first appearance datum (FAD) of the "isolated-nodular" morphotype of the conodont Streptognathodus wabaunsensis within the Streptognathodus fusus zone. Its Global Stratotype Section and Point (GSSP) is located at Aidaralash Creek in northern Kazakhstan (50.2458°N, 57.8914°E), 27 m above the base of Bed 19 in a hemipelagic siltstone sequence. This stage represents the initial phase of Permian marine recovery following the Carboniferous-Permian boundary extinction, with secondary correlations supported by the termination of the ammonoid lineage Prouddenites-Uddenites and the base of the fusulinid Sphaeroschwagerina vulgaris-S. fusiformis Zone.^[18] The Sakmarian Stage follows, lasting from 293.52 ± 0.17 Ma to 290.1 ± 0.26 Ma, and is marked by the FAD of the conodont Mesogondolella monstra. The GSSP is established at 55.4 m in Bed 26/3 of the Usolka section, Southern Urals, Russia (53.9247°N, 56.7287°E), in a carbonate-siliciclastic succession. This interval signifies a transition to post-glacial warming, with evidence of reduced ice volume and rising sea levels influencing global sedimentation patterns.^[19]^[20] The Artinskian Stage spans 290.1 ± 0.26 Ma to 283.3 ± 0.4 Ma and is defined by the FAD of the conodont Sweetognathus asymmetricus within the Sweetognathus merrilli zone. Its GSSP is positioned 1.2 m above the base of Bed 4b in the Dal'ny Tulkas section, Southern Urals, Russia (53.88847°N, 56.51615°E), in shallow-marine limestones. This stage encompasses the Artinskian Warming Event around 287 Ma, characterized by a rapid shift to greenhouse conditions, increased aridity in Euramerica, and biotic turnover favoring drought-tolerant flora.^[21] The Kungurian Stage, the uppermost Cisuralian division, ranges from 283.3 ± 0.4 Ma to 274.4 ± 0.4 Ma and remains the only Permian stage without a ratified GSSP as of 2025, with candidates including the Mechetlino Quarry section in the Southern Urals, Russia, and the Pequop Mountains, Nevada, USA. Proposed markers include the FAD of the conodont Neostreptognathodus pnevi or Jinogondolella nankingensis, bounding the stage amid ongoing proposals for formal definition. This period marks the end of major icehouse conditions, with deglaciation and atmospheric CO₂ rise driving the final collapse of the Late Paleozoic Ice Age.^[22] Global standardization of these stages relies on correlations with ammonoid and fusulinid biostratigraphy, which complement conodont zones for interregional matching. Ammonoid genera such as Artinskia and Prokionoceras aid Sakmarian-Artinskian boundary identification, while fusulinids like Pseudoschwagerina and Parafusulina provide robust markers across Tethyan and Gondwanan sections, enabling precise alignment despite provincial variations.

Regional series and stages

In North America, the Cisuralian is subdivided into the Wolfcampian and Leonardian series, which correspond to the global stages from the Asselian through the Kungurian. The Wolfcampian series encompasses the Asselian, Sakmarian, and early Artinskian stages, while the Leonardian series includes the late Artinskian and Kungurian stages. These regional series are defined based on lithostratigraphic units in the Permian Basin of west Texas and New Mexico, where marine and terrestrial deposits reflect a mix of carbonate platforms and basinal shales. The type locality for the Wolfcamp Formation, the basal unit of the Wolfcampian series, is in the Glass Mountains of Brewster County, western Texas, where it consists of a diverse sequence of shales, limestones, and sandstones up to several hundred meters thick, marking a regional unconformity at its base.^[23]^[24]^[25] In Europe and Russia, regional stages in the Cisuralian vary by basin, with the Donets Basin featuring subdivisions that include equivalents to the Tournaisian-like lower boundaries transitioning into Permian sequences, though the bulk aligns with Asselian through Kungurian equivalents. Local stages such as the Sterlitamakian, named after exposures near Sterlitamak in the southern Urals, correspond to parts of the Sakmarian and Artinskian, characterized by ammonoid zones like Andrianovia sakmarae and dominated by carbonate and clastic deposits in platform settings. The Kungurian stage retains its global name in Russian stratigraphy but is regionally tied to evaporitic and reefal facies in the broader East European Platform. These subdivisions are formalized through body stratotypes in the Ural Mountains, aiding precise boundary definitions.^[26]^[27]^[28] In Gondwana, correlations to the Cisuralian rely on lithostratigraphic groups like the Ecca Group in South Africa, which spans the Asselian to Sakmarian stages and consists of shales, sandstones, and coal measures deposited in post-glacial fluvial-deltaic environments. The lower Ecca Group, including the Verbrande Berg Formation, yields detrital zircon ages constraining it to Sakmarian-Asselian intervals, with palynological assemblages supporting ties to early Permian global events. Similar successions in other Gondwanan basins, such as the Godavari Graben in India, show comparable palynofloras indicative of Asselian-Sakmarian age.^[29]^[30]^[31]^[32] Correlating these regional series to the global Cisuralian stages faces challenges from fossil provincialism, particularly in fusulinids, brachiopods, and ammonoids, which exhibit strong biogeographic separation between North American, Eurasian, and Gondwanan realms, leading to divergent biostratigraphic schemes. This endemism complicates direct faunal matching, as seen in the distinct biotic provinces of North America during the Cisuralian. Resolution has advanced through integrated methods like magnetostratigraphy, which identifies polarity chrons for cross-continental alignment, and chemostratigraphy, using carbon and oxygen isotope profiles to link sections despite biotic differences. These tools, combined with radiometric dating, enable robust correlations, such as aligning the Wolfcampian with Uralian stages via shared magnetic susceptibility patterns.^[33]^[34]^[35]^[36]

Geological context

Paleogeography

During the Cisuralian Epoch, the progressive assembly of the supercontinent Pangaea continued through the ongoing collision between the northern landmass of Laurussia and the southern continent of Gondwana, which progressively closed the Rheic Ocean basin. This diachronous process, initiated in the late Carboniferous, reached its later stages in the early Permian, with subduction along the southern margin of Laurussia driving the convergence and resulting in the formation of extensive orogenic belts along their margins.^[37] By the Asselian stage, the core of Pangaea was largely coalesced, though final adjustments persisted into the Sakmarian and Artinskian. Paleogeographic reconstructions place Laurussia in equatorial to low-latitude positions, spanning much of the northern hemisphere with its western portion (Laurentia) oriented toward the Panthalassic Ocean and its eastern margins facing the narrowing remnants of the Rheic Ocean. In contrast, Gondwana occupied predominantly southern high-latitude realms, where glacial deposits indicative of polar ice sheets are preserved in basins such as the Karoo and Paraná, reflecting the waning phases of the Late Paleozoic Ice Age.^[38] These positions highlight a latitudinal contrast that influenced global circulation patterns, with Laurussia's tropical settings fostering carbonate platforms and Gondwana's polar to subpolar environments supporting diamictites and tillites.^[39] Paleomagnetic data from Gondwanan sequences indicate an approximate 10° northward drift of the continent during the Cisuralian, at rates of around 0.4° per million years, shifting its northern margins from high southern latitudes toward more temperate zones by the Kungurian.^[40] Concurrently, the Paleotethys Ocean experienced significant narrowing due to northward subduction beneath Eurasia, while the initiation of closure in the Uralian seaway—through tectonic uplift and gateway restriction in the southern Urals—began isolating boreal marine realms by the Sakmarian.30500-9) These dynamic configurations profoundly affected sedimentation, particularly along peri-Gondwanan shelves, where terranes like the South China Block developed extensive carbonate platforms and mixed siliciclastic-carbonate sequences in response to epeiric sea incursions and detrital influx from eroding continental margins.^[2]

Tectonics and orogenies

The Cisuralian epoch was marked by significant tectonic activity associated with the final stages of Pangea assembly, including major orogenic events that deformed the supercontinent's margins and interior. These processes involved continental collisions and the closure of remnant Paleozoic ocean basins, leading to widespread deformation across Laurussia, Gondwana, and intervening terranes. Key orogenies during this time reshaped paleogeography through thrust faulting, metamorphism, and uplift, with effects persisting into the Guadalupian.^[41] The Alleghenian orogeny represented the culmination of convergence along the eastern margin of Laurussia with Gondwana, active from the late Carboniferous through the early Permian (approximately 335–265 Ma). This transpressive collision produced extensive fold-and-thrust belts, forming the Appalachian Mountains in North America and correlative Ouachita-Marathon ranges in the south. Deformation involved dextral-oblique shortening, with peak activity in the Cisuralian involving the docking of Gondwanan terranes against the Laurentian margin, resulting in polyphase folding and low- to medium-grade metamorphism.^[41]^[42] Contemporaneously, the Hercynian or Variscan orogeny deformed central and southern Europe as well as North Africa, driven by the collision between Laurussia and Gondwanan fragments during the late Paleozoic. This event, peaking in the Carboniferous but extending into the Cisuralian, involved subduction and continental collision that uplifted the Variscan Mountains, with associated nappe structures and granitic intrusions spanning from Iberia to the Bohemian Massif. Post-collisional extension in the early Permian led to basin formation and magmatism within the orogenic belt.^[43]^[44] In the eastern regions, the Uralian orogeny progressed through the closure of the Uralian Ocean between Baltica and the Kazakhstania-Siberia assembly, with major deformation from the Devonian to Permian but intensifying in the Cisuralian. This arc-continent collision uplifted the Ural Mountains via obduction of ophiolitic complexes and foreland thrusting, creating a linear orogenic belt over 2,000 km long. The process involved northward subduction and final suturing around 290–270 Ma, marking the completion of Pangea's eastern margin.^[45] Associated with these orogenies was widespread calc-alkaline magmatism in the orogenic belts, characterized by intermediate to felsic volcanism and plutonism linked to subduction and post-collisional extension. In the Variscan domain, Cisuralian andesites and rhyolites erupted in rift-related settings, reflecting lithospheric delamination and mantle upwelling. Similarly, in the Appalachian-Variscan system, high-K calc-alkaline suites formed arc-like signatures despite the collisional context. This magmatism contributed to the formation of intracratonic rift basins, such as the Permian Basin in North America, where extensional tectonics superimposed on compressional stresses created subsiding depocenters filled with syntectonic sediments.^[46]^[47]^[48] These tectonic events influenced global sea levels through isostatic adjustments, as orogenic loading depressed foreland basins while erosion and rebound elevated hinterlands. The assembly-related shortening reduced ocean basin volumes, contributing to a net eustatic fall of tens of meters during the Cisuralian, modulated by sediment redistribution and dynamic topography. Reduced tectonic forcing in some regions allowed for more stable accommodation space, though overall Pangean collisions promoted long-term regression.^[49]^[50]

Paleoenvironment

Climate trends

The Cisuralian epoch began with the peak of the Late Paleozoic Ice Age during the Asselian and Sakmarian stages, characterized by extensive glaciation centered over Gondwana. Glacial deposits, such as those of the Dwyka Group in southern Africa, record diamictites and tillites indicative of ice sheets that covered vast areas, with the apex of glaciation occurring from approximately 299 to 293 Ma.^[51]^[52] This glacial maximum led to a significant eustatic sea-level drop of 100–200 m, driven by the locking of water in continental ice sheets.^[53] A marked shift occurred during the Artinskian stage with the Artinskian Warming Event around 290 Ma, involving rapid deglaciation linked to rising atmospheric CO₂ levels from enhanced volcanism, including activity from the Choiyoi Province and other arcs.^[54]^[55] This event accelerated the transition toward warmer conditions, reducing ice volume in Gondwana and initiating a broader shift from icehouse to greenhouse climate. By the Kungurian stage, the climate had evolved into a full greenhouse state, with pronounced aridification in the interiors of the assembling supercontinent Pangaea, as evidenced by widespread evaporite deposits and redbed formations.^[2]^[56] Oxygen isotope (δ¹⁸O) records from brachiopod shells and other proxies indicate an overall warming of approximately 5°C across the Cisuralian, from cooler glacial temperatures averaging ~13°C globally in the early Asselian to ~18°C by the late Kungurian.^[57] This warming facilitated the intensification of a global megamonsoon system, driven by the Pangaean configuration of a large, low-latitude landmass that enhanced seasonal temperature contrasts and moisture transport.^[58]^[59]

Sedimentation and sea levels

During the early Cisuralian (Asselian to Sakmarian), sedimentation in southern high latitudes was dominated by glacial deposits, including tillites and diamictites, reflecting the persistence of the Late Paleozoic Ice Age with ice sheets covering parts of Gondwana.^[60] These coarse-grained, poorly sorted sediments accumulated in subglacial, ice-marginal, and proglacial environments, often interbedded with dropstones in finer-grained marine or lacustrine deposits, indicating episodic ice advance and retreat.^[61] In the mid-Cisuralian (Artinskian to early Kungurian), depositional environments shifted toward arid conditions in equatorial basins, characterized by extensive evaporites and red beds formed under fluctuating sea levels and increased evaporation rates.^[62] These sediments, including gypsum, halite, and hematitic sandstones, filled subsiding intracratonic basins, with the Solikamsk Basin in Russia exemplifying restricted marine conditions leading to thick evaporite sequences up to several kilometers in thickness.^[63] By the late Kungurian, sedimentation featured expansive carbonate platforms along the margins of the Paleo-Tethys Ocean, where warm, shallow waters promoted the growth of reefs and lagoons dominated by fusulinids and brachiopods.^[64] Concurrently, coal formation declined markedly in northern hemispheric regions, such as Euramerica and northern Cathaysia, as peat mires gave way to more oxidized, red-bed-dominated fluvial and lacustrine systems due to warming and drying climates.^[65] Eustatic sea-level changes throughout the Cisuralian were influenced by Gondwanan ice volume fluctuations, with a prominent lowstand during the Asselian–Sakmarian due to peak glaciation, followed by a rise through the Artinskian and Kungurian driven by deglaciation and the Artinskian Warming Event, culminating in a highstand that flooded continental shelves and promoted widespread carbonate and shale deposition.^[66] Representative formations include the Wellington Formation in the North American midcontinent, comprising red beds, shales, and thin evaporites deposited in playa-lake and sabkha settings during the Leonardian (late Artinskian to Kungurian).^[67] Similarly, the Phosphoria Formation in the western United States records phosphorite-rich marine sediments in an upwelling-influenced shelf environment, with beds up to 300 meters thick reflecting nutrient-rich waters during the late Cisuralian.^[68]

Life and evolution

Marine biodiversity

The Cisuralian epoch, spanning the early Permian from approximately 298.9 to 274.4 million years ago, featured diverse marine ecosystems dominated by invertebrate groups adapted to shallow shelf and reef environments. Fusulinid foraminifers, such as the genus Schwagerina, were particularly abundant, serving as key biostratigraphic markers and reaching their peak diversity during the Artinskian stage, with widespread species like Schwagerina moelleri occurring across Tethyan, Uralian, and Boreal regions.^[69]^[70] Rugose corals also flourished in reef settings, contributing to complex bioherms alongside sponges and algae, with colonial forms enhancing structural diversity in warm, tropical waters. Shelf environments supported thriving communities of brachiopods, particularly productids, which formed dense assemblages filtering nutrients from nutrient-rich waters, alongside bryozoans that encrusted substrates in colonial growth forms.^[71] Ammonoids, including genera like Uraloceras in Boreal settings, exhibited coiled shells suited to nektonic lifestyles and provided insights into biostratigraphy across marine basins.^[72] Marine reptiles were absent from Cisuralian assemblages, with vertebrate components limited to early chondrichthyans—such as sharks with specialized teeth—and primitive osteichthyans inhabiting reef fringes and lagoons.^[73]^[74] Marine provincialism was pronounced, distinguishing Tethyan realms in equatorial low latitudes—characterized by diverse fusulinids and corals—from cooler Boreal realms in higher latitudes, with limited faunal exchange fostering endemicity.^[70]^[75] Toward the Kungurian stage, diversity declined sharply due to expanding anoxic conditions in ocean basins, linked to elevated pCO₂ and restricted circulation, impacting shelf biotas and setting the stage for biotic turnover.^[76]^[77]

Terrestrial ecosystems

During the Cisuralian, terrestrial ecosystems in Gondwana were dominated by Glossopteris flora, consisting of arborescent gymnosperms that formed extensive lowland forests in swampy to deltaic environments across southern continents.^[78] These forests, characterized by leaves, fertile organs like Lidgettonia, and in situ roots (Vertebraria), supported diverse plant communities adapted to cool-temperate, seasonally wet conditions.^[78] In contrast, Laurussian ecosystems experienced the decline of Carboniferous coal swamps, driven by increasing aridity and the transition from wetland lycopsid- and pteridosperm-dominated mires to drier landscapes.^[79] This shift facilitated the rise of walchian conifers, such as Walchia piniformis, which became prominent in seasonal tropical floodplains, forming low-diversity woodlands alongside peltasperms like Supaia in red-bed deposits of the Abo Formation.^[80] Vertebrate faunas featured pelycosaur synapsids as key components, with Dimetrodon serving as the primary apex predator in North American terrestrial ecosystems, preying on smaller tetrapods through its heterodont dentition and ziphodont teeth adapted for capturing and processing diverse prey.^[81] Reaching lengths of up to 3.5 meters and weighing 100–150 kg, these carnivores dominated swampy and floodplain habitats for approximately 25 million years.^[82] Temnospondyl amphibians, such as rhinesuchids, occupied riparian and non-marine aquatic zones, exhibiting swimming and bottom-walking behaviors in shallow lagoons and fluvial settings, where they acted as dominant predators on fish and invertebrates.^[83] Insect communities saw the emergence of Coleoptera (beetles) and Diptera (flies), marking early diversification amid shifting vegetation.^[84] The first North American Permian beetle, Permocoleus wellingtonensis, from the Wellington Formation, represents the Permocoleidae family and indicates a global distribution of early coleopterans in upland and floodplain habitats.^[85] Upland red-bed environments, prevalent in equatorial regions, supported sparse vegetation including lycopsids in poorly drained depressions, with evidence of early soil formation through paleosols in fluvial sequences that preserved woody debris and indicated periodic wildfires.^[86] These settings reflected a transition to more arid conditions, contrasting with wetland biomes.^[87] Biogeographic provinces highlighted contrasts between Euramerican and Cathaysian floras: Euramerican assemblages shifted to conifer-rich, seasonally dry communities by the earliest Permian, while Cathaysian floras in North China retained wetland elements like coal swamps into the middle Permian, sharing genera with Euramerican origins before diverging due to regional isolation.^[79]

Key evolutionary events

During the Cisuralian Epoch, synapsids underwent a significant radiation, marked by a transition from sphenacodontid-dominated faunas in the Asselian and Sakmarian stages to increased diversity including edaphosaurids by the Artinskian stage.^[88] Sphenacodonts, primarily carnivorous forms like Dimetrodon, were prominent in early Cisuralian ecosystems but began to decline as edaphosaurids, such as Edaphosaurus, diversified, representing an early shift toward herbivorous adaptations within eupelycosaurian synapsids.^[89] This diversification reflected broader ecological partitioning, with edaphosaurids exploiting plant resources in increasingly arid environments. By the Kungurian stage, precursors to therapsids emerged, including basal forms that foreshadowed the more mammalian-like features of later therapsids, setting the stage for their dominance in the Guadalupian.^[90] Insect diversification accelerated in the early Cisuralian, with the appearance of the oldest definitive beetle fossils in the late Asselian or early Sakmarian, dated to approximately 295 million years ago. These fossils, assigned to Coleopsis archaica from deposits in Germany, represent the earliest unequivocal evidence of Coleoptera, characterized by elytral venation patterns distinct from earlier ambiguous insect impressions.^[91] This event signals the onset of beetle radiation within the broader Permian insect fauna, coinciding with expanding terrestrial habitats that supported arthropod proliferation. A major floral turnover occurred across the Cisuralian, involving the decline of Carboniferous-era arborescent lycopsids such as lepidodendrids (Lepidodendron and relatives) and their replacement by seed ferns (pteridosperms) and early gymnosperms like conifers and cordaitaleans. Lepidodendrids, once dominant in wetland forests, became scarce by the Sakmarian stage due to drying climates and habitat shifts, allowing seed-bearing plants to dominate upland and seasonal environments.^[92] This transition marked a pivotal macroevolutionary change, enhancing vascular plant adaptability to aridity through seed dispersal and contributing to the stabilization of Permian terrestrial ecosystems.^[93] The Cisuralian also featured Olson's Extinction, a minor mass extinction event around 273 million years ago at the Kungurian-Roadian boundary, which disproportionately affected early tetrapods including amphibians and basal reptiles. This event led to the disappearance of diverse varanopid and other small carnivorous forms, creating ecological vacancies filled by emerging therapsids and parareptiles.^[94] Although less severe than later Permian crises, it represented a key turnover in terrestrial vertebrate assemblages.^[95] Parallel to these changes, the Cisuralian witnessed the onset of increased herbivory among tetrapods, building on Late Carboniferous origins but expanding markedly in diversity and ecological impact. Early herbivores like edaphosaurids and captorhinids proliferated, with multiple independent evolutions of dental and digestive adaptations for processing fibrous vegetation, such as multiple tooth rows and shearing mechanisms.^[96] By the Artinskian and Kungurian, herbivorous lineages achieved greater body sizes and biomass, influencing plant community structure and accelerating the selective pressures on Cisuralian floras.^[97] This trend underscored the epoch's role in establishing more complex trophic interactions on land.

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Jan 1, 2018 · The Lower Permian (Cisuralian Series) conodont zonation is derived ... Astronomical tuning using cyclothems would suggest an age of 297.2 Ma (Fig.
[17]
Radioisotopic calibration of the Guadalupian (middle Permian) series
The Roadian Stage, according to this model, possesses a numerical age for the base of 272.95 ± 0.5 Ma, and for the top of 268.8 ± 0.5 Ma. Non-platform elements ...
[18]
(PDF) The Permian Period - ResearchGate
... GSSP, and the boundary between the Carboniferous. and Permian Periods. p0100 The strata of Late Paleozoic age at Aidaralash Creek were. deposited on a narrow ...
[19]
Climatic and biotic changes around the Carboniferous/Permian ...
Silicification instead of coalification was the dominant fossilisation process during red-beds deposition. Even drier, possibly semi-arid climate may be ...
[20]
High-precision U-Pb age constraints on the Permian floral turnovers ...
Feb 5, 2021 · The results indicate that the predominance of continental red beds, climate aridification, and the disappearance of coals and characteristic ...
[21]
GSSP for Asselian Stage - International Commission on Stratigraphy
The base of the Permian System, Cisuralian Series and Asselian Stage is defined 27m above the base of Bed 19, Aidaralash Creek, northern Kazakhstan.
[22]
International Commission on Stratigraphy
- **GSSP for Sakmarian Stage:**
[23]
https://pubs.usgs.gov/sir/2013/5109/pdf/sir2013-5109.pdf
[24]
International Commission on Stratigraphy
### GSSP for Artinskian Stage Summary
[25]
Base-Kungurian Working Group - Permian Stratigraphy
The Kungurian Stage is the only stage that has not been ratified with a Global Stratotype Section and Point within the Permian System. In 2012 there was a ...
[26]
[PDF] Scientific Investigations Report 2013–5109
western North America from Neoproterozoic through early. Mesozoic time. Regional ... Early Permian (Wolfcampian to early Leonardian) provides a plausible.
[27]
Geolex — Wolfcamp publications - National Geologic Map Database
Aug 28, 2025 · Wolfcamp series in Glass Mountains, [Brewster County], western Texas, is represented by sequence of diverse lithologies and includes regional unconformity.
[28]
[PDF] Centennial of the Wolfcamp Formation, #70305 (2017).
Nov 27, 2017 · Location map of Glass Mountains, West Texas, and type locality of the Wolfcamp Formation, along with stratigraphic chart showing position of ...
[29]
Early Permian (Cisuralian) zonations of foraminifers and conodonts ...
The late Tastubian corresponds to the Synar- tinskia principalis and the Sterlitamakian to the Andrianovia sakmarae ammonoid zones (Chuvashov et al., 2002b; Fig ...
[30]
[PDF] Global time scale and regional stratigraphic reference scales of
Donets (T.I. Nemyrovska). The Tournaisian Stage in the Donets Basin is composed of marine carbonates, 90–200 m thick. Its basal parts are absent, and its ...
[31]
[PDF] SUBCOMMISSION ON PERMIAN STRATIGRAPHY ...
The southern Ural Mountain region is the type area of the. Cisuralian Series, comprising the Asselian, Sakmarian, Artinskian and Kungurian stages. The ...
[32]
[PDF] The Early Permian fossil record of Gondwana and its relationship to ...
The Ecca Group which has the highest δ13Corganic values is thought to have been, at least in part, deposited during the earliest Asselian. Further study. The ...
[33]
A review of the palynostratigraphy of Gondwanan Late ...
Aug 6, 2025 · Palynological records of the Early Permian icehouse-greenhouse transition (Ecca Group, South Africa). Conference Paper. Apr 2013.
[34]
A case study of northern Namibian late Palaeozoic sedimentary rocks
Jan 12, 2022 · Inferred by youngest detrital zircon U−Pb ages the Verbrande Berg Formation (lower Ecca Group) yields a Sakmarian to Asselian maximum ...
[35]
Early Permian (Asselian-Sakmarian) Palynoflora from Chintalapudi ...
Aug 7, 2025 · PDF | This article integrates palynological, palaeobotanical and palynofacies analysis to evaluate the stratigraphy, palaeovegetation and.<|separator|>
[36]
Micromorphic brachiopods from the early Permian (Kungurian) of ...
Nov 1, 2024 · Throughout the Cisuralian, different biotic provinces (mainly composed of fusulinids and brachiopods) were established in North America: Exotic, ...Missing: subdivisions | Show results with:subdivisions
[37]
Late Paleozoic–early Mesozoic continental biostratigraphy
Other cross correlations have been aided by magnetostratigraphy, chemostratigraphy and a growing database of radioisotopic ages. A synthetic nonmarine ...Missing: challenges provincialism
[38]
[PDF] Shift in the Paradigm for GSSP Boundary Definition - ScholarWorks
Apr 3, 2018 · Importantly, some correlation tools, such as magnetostratigraphy, astronomic calibration, chemostratigraphy, and magnetic susceptibility are ...
[39]
The Permian timescale: an introduction - Lyell Collection
Nov 23, 2017 · In the non-marine Permian realm, much progress has been made in correlation, especially using palynomorphs, megafossil plants, conchostracans ...
[40]
From supercontinent to superplate: Late Paleozoic Pangea's inner ...
The first phase of the collision between Gondwana and Laurussia formed the supercontinent Pangea ~330 Ma. However, the interior of Pangea remained tectonically ...
[41]
Low-latitude climate change linked to high-latitude glaciation during ...
These climatic conditions at low latitudes recorded high-latitude Gondwana glaciation events during the Asselian-early Sakmarian and the late Sakmarian-early ...<|separator|>
[42]
Upper Paleozoic glacigenic deposits of Gondwana: Stratigraphy and ...
The aim of the present research is to define the stratigraphic setting and the environmental interpretation of a poorly studied Lower Permian glacigenic ...
[43]
Pangea and the Lower Mantle - AGU Journals
Sep 3, 2019 · ... Gondwana-Land-Laurasia collision had not yet begun. It then migrated northward at a steady 0.4°/Myr rate until it reached its equatorial ...
[44]
Alleghanian Orogeny - an overview | ScienceDirect Topics
Alleghanian orogeny is defined as the final orogenic event that occurred from the Middle Mississippian to the Middle Permian (335–265 million years ago), ...
[45]
Alleghanian (Appalachian) orogeny, a product of zipper tectonics
Aug 6, 2025 · The Appalachian orogenic cycle culminated in the Late Mississippian to Permian Alleghenian orogeny, which involved continent-continent ...
[46]
Late Paleozoic climate transition from a long-term carbon cycle ...
The orogeny linked to the consolidation of Pangea is named the Variscan Orogeny in southern/central Europe (also often termed Hercynian) displaying peak ...
[47]
Early Permian post-collisional magmatism induced by extensive ...
Sep 15, 2025 · The tectonic re-equilibration after the Variscan orogeny coincided with widespread early Permian post-collisional magmatism in southern Europe.
[48]
The evolution of the Uralian orogen - Lyell Collection
The Uralian orogen is located along the western flank of a huge (>4000 km long) intracontinental Uralo-Mongolian mobile belt. The orogen developed mainly ...
[49]
Cisuralian calc-alkaline magmatism in the Herrera Unit of the Iberian ...
Jul 12, 2022 · During the Lower Permian, intense calc-alkaline magmatism of intermediate-felsic composition occurred in the SW domain of the European Variscan ...
[50]
(PDF) Origin and significance of the Permian high-K calc-alkaline ...
Aug 6, 2025 · In the above context, the calc-alkaline affinity and the orogenic-like signature of the Permian magmatism might result from extensive ...
[51]
West Texas (Permian) Super Basin, United States: Tectonics ...
Jun 15, 2021 · The West Texas Super Basin is a complex Paleozoic basin built on a varied Proterozoic crust. After Cambrian rifting, regional subsidence began ...ABSTRACT · INTRODUCTION · TECTONIC AND... · PETROLEUM SYSTEMSMissing: Cisuralian | Show results with:Cisuralian
[52]
Plate Tectonics and Sea Level Change | EARTH 107
The tectonic processes at work on the Earth influence the size of ocean basins and, therefore, sea level in many, complex ways. The following list gives an ...
[53]
Orbitally-paced coastal sedimentary records and global sea-level ...
Under reduced tectonic forcing, diminished crustal disturbance and enhanced accommodation continuity likely facilitated the preservation of such sedimentary ...
[54]
A new stratigraphic framework built on U-Pb single-zircon TIMS ...
Jan 4, 2018 · One of the main challenges in reconstructing late Paleozoic ice age glaciation history is the ability to accurately correlate geologic records ...
[55]
(PDF) Late Paleozoic Glacial Events and Postglacial Transgressions ...
The LPIA is believed to be the longest and most geographically widespread ice age along the Phanerozoic, widely recognized in Gondwana deposits from the Visean ...Missing: Cisuralian | Show results with:Cisuralian
[56]
Sequence Stratigraphic and Geochemical Records of Paleo-Sea ...
The basin was affected by multiple Gondwanan glacial episodes (C1–C4), which occurred between 320 and 300 Ma, leading to high-amplitude (100–200 m) glacio- ...
[57]
Volcanic CO2 emissions from subduction of the tropical Paleo ...
Jun 15, 2025 · Peak volcanism from this arc system is concomitant with the early warming event at 290−280 Ma. Considering the prevailing carbonate ...
[58]
Linkage of paleolake to climate change during the Early Permian ...
Here we present a pilot study on the Early Permian Artinskian warming (ca. 290 Ma) during the Late Paleozoic Ice Age (LPIA), using comprehensive records of ...
[59]
[PDF] Carbon and strontium isotope stratigraphy of the Permian
Aug 16, 2023 · Another factor that may relate to decreased silicate weathering is the increasing aridification of the Pangean continental interior (e.g. ...
[60]
https://www.researchgate.net/publication/235926597_A_paleoclimatic_review_of_southern_South_America_during_the_late_Paleozoic_A_record_from_icehouse_to_extreme_greenhouse_conditions
[61]
Climate of the Supercontinent Pangea | The Journal of Geology
Numerous climate models predict that the geography of the supercontinent Pangea was conducive to the establishment of a "megamonsoonal" circulation.
[62]
Provenance of Permian eolian and related strata in the North ...
Dec 28, 2018 · (2) The Pangean monsoon strengthened as the Permian icehouse receded, resulting in increasing ease of transport of sediment from the west as ...
[63]
(PDF) A paleoclimatic review of southern South America during the ...
Aug 6, 2025 · During the Bashkirian–earliest Cisuralian (terminal glacial stage), glacial deposits disappeared almost completely in the western retroarc ...
[64]
[PDF] Journal of Sedimentary Research - NSF PAR
Jun 2, 2021 · This study evaluates the sedimentology, stratigraphy, and flow directions of the glaciogenic, Asselian–Sakmarian (Early Permian) Pagoda ...
[65]
The Permian System in Kansas--Subdivisions--Leonardian
Apr 27, 2010 · In general the lower part of the Wellington is gray anhydritic mudrock interbedded with anhydrite; the middle part, the thickest, is mostly red ...
[66]
Salt-pillow formation during inversion of evaporite-filled half graben
Sedimentary infill of the Polish Basin starts with the Rotliegend (Cisuralian – lower Lopingian) clastics and Zechstein (upper Lopingian) evaporites and ...
[67]
Facies and Carbon Isotope Variations during the Kungurian (Early ...
The late Paleozoic ice age, which lasted for nearly 100 million years, is the longest-lived ice age of the Phanerozoic [1,2,3]. Many studies have been ...
[68]
Unveiling the evolution of the Kungurian (Cisuralian) flora in the ...
This stepwise transition gradually spread from western to eastern Pangea, reaching Cathaysia during the middle Permian, with the palaeotropical coal forests ...
[69]
Sequence stratigraphy, basin morphology and sea-level history for ...
Jan 9, 2017 · Thus, melting ice caps and the associated major sea-level rise would account for the widespread flooding of the palaeo-land surface that ...<|control11|><|separator|>
[70]
Lakes, Loess, and Paleosols In the Permian Wellington Formation of ...
Oct 1, 2013 · The provenance, transport and depositional processes of the voluminous Permian redbeds of the Midcontinent, however, remain largely undefined.
[71]
[PDF] The Phosphoria, Park City and Shedhorn Formations in the Western ...
The Phosphoria formation of Permian age consists mainly of chert, carbonaceous mudstone, and phosphorite at the type locality in southeastern Idaho.
[72]
[PDF] Cisuralian and Guadalupian global paleobiogeography of fusulinids in
Cisuralian stages, showing faunal similarities among stations. Color indicates bioregion. 950 classification. 951. Page 46. 46. 952. Figure 5. Cluster ...
[73]
Cisuralian and Guadalupian global paleobiogeography of fusulinids in response to tectonics, ocean circulation and climate change
**Summary of Narrowing of Paleotethys Ocean and Initiation of Uralian Seaway Closure During Cisuralian**
[74]
Global Distribution and Character of Permian Biomes Based on ...
Aug 10, 2025 · We present data on the occurrences of Permian brachiopod families comprising the genera of 54 families, plus corals and fusulinids, ...
[75]
CISURALIAN AMMONOID GENUS URALOCERAS IN NORTH ...
Mar 3, 2017 · In North America, the ammonoid Uraloceras Ruzhentsev occurs in Cisuralian (Lower Permian) strata of the northern Yukon Territory, ...
[76]
Chondrichthyans from the base of the Irati Formation (Early Permian ...
Aug 6, 2025 · The fossils already disclosed are Chondrichthyes teeth and spines, Osteichthyes teeth, scales and bone parts and tetrapods bone parts ... ...
[77]
Permian–Triassic Osteichthyes (bony fishes): diversity dynamics and ...
Nov 27, 2014 · Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the ...
[78]
The Permian timescale: an introduction - Lyell Collection
In 1841, Murchison coined the term Permian for strata in the Russian Urals. Recognition of the Permian outside Russia and Central Europe soon followed, but ...
[79]
Volcanism-driven synchronous terrestrial and marine anoxia during ...
Our results show that Kungurian anoxia occurred synchronously in both marine and freshwater settings, as it did in the stratigraphically younger Toarcian (T- ...
[80]
A major anomaly in the carbon cycle during the late Cisuralian ...
The Kungurian (late Cisuralian) is associated with elevated atmospheric pCO2 levels and numerous substantial changes in the ocean and terrestrial systems, ...
[81]
South African Lagerstätte reveals middle Permian Gondwanan ...
Oct 30, 2022 · The iconic plant Glossopteris, an arborescent gymnosperm, dominated these floras in the lowlands of Gondwana for over 50 million years, from its ...
[82]
The relationship between Euramerican and Cathaysian tropical ...
Evidence from Euramerica demonstrates extinction of this kind of wetland biota by the earliest Permian and the development of drier floras including conifer ...Missing: provinces | Show results with:provinces
[83]
A low diversity, seasonal tropical landscape dominated by conifers ...
A low diversity, seasonal tropical landscape dominated by conifers and peltasperms: Early Permian Abo Formation, New Mexico ... Walchian conifers (Walchia ...
[84]
Hidden dental diversity in the oldest terrestrial apex predator ...
Feb 7, 2014 · Dimetrodon and other sphenacodontids are the first terrestrial vertebrates to have strong heterodonty, massive skulls and well-developed labio- ...
[85]
Introduction to the Pelycosaurs
Pelycosaurs are the earliest, most primitive synapsids, a group characterized by a single dermal opening in the skull permitting muscle attachment to the jaw.Missing: Cisuralian | Show results with:Cisuralian
[86]
Unique trackway on Permian Karoo shoreline provides evidence of ...
Mar 29, 2023 · Large-bodied temnospondyl amphibians were the dominant predators in non-marine aquatic ecosystems from the Carboniferous to the Middle Triassic.Missing: riparian | Show results with:riparian
[87]
Review The evolution of insect biodiversity - ScienceDirect.com
Oct 11, 2021 · Phylogenomics has provided a new framework for reconstructing insect evolutionary history, resolving their position among the arthropods and some long-standing ...
[88]
Permocoleus, New Genus, the First Permian Beetle (Coleoptera ...
Permocoleus wellingtonensis, new genus and new species, is based on an elytron from the Permian Wellington Formation of Oklahoma and is the only Paleozoic ...Missing: Permocoleidae | Show results with:Permocoleidae
[89]
Vegetation ecology of Early Pennsylvanian alluvial fan and ...
Distal alluvial fan environments, where braided stream and leveé/splay sedimentation predominated, were covered by similar vegetation, together with lycopsids ...
[90]
Late Palaeozoic red beds elucidate fluvial architectures preserving ...
Nov 19, 2019 · Fluvial red beds containing anatomically preserved large woody debris shed new light on seasonally dry biomes of the Pennsylvanian–Permian ...
[91]
The early evolution of synapsids, and the influence of sampling on ...
Aug 6, 2025 · Diversity recovered during the Artinskian and Kungurian, coinciding with the radiation of Caseidae, although other families begin to decline. A ...
[92]
Predatory synapsid ecomorphology signals growing dynamism of ...
Feb 17, 2024 · We find a major morphofunctional shift in synapsid carnivory between the early and middle Permian, via the addition of new feeding modes.Missing: sphenacodonts edaphosaurs
[93]
Early–middle Permian Mediterranean gorgonopsian suggests an ...
Dec 17, 2024 · Phylogeny and a detailed timeline for the origin and early radiation of therapsids. Currently, no definitive early Permian therapsids are known ...
[94]
Evolution of the elytral venation and structural adaptations in the ...
The oldest definitive beetle, Coleopsis archaica gen. et sp. nov., is described from the earliest Permian (Asselian or early Sakmarian) of Germany ...
[95]
Carboniferous Lepidodendraceae and Lepidocarpaceae - jstor
Regionalization of these floras continued to develop into the Permian, with a general decline of arborescent lycopods and an associated rise of gymno- sperms.
[96]
Ecological and evolutionary responses of terrestrial arthropods to ...
Jun 6, 2023 · ... floral turnover is of tremendous relevance. Yet, the phenomena of ... Xeromorphic plants dominated Euramerican floras by the early Permian ...
[97]
Olson's Extinction and the latitudinal biodiversity gradient of ...
Apr 5, 2017 · The terrestrial vertebrate fauna underwent a substantial change in composition between the lower and middle Permian. The lower Permian fauna ...Missing: Artinskian | Show results with:Artinskian
[98]
Permian tetrapod extinction events - ScienceDirect.com
Olson's gap remains a hiatus in the global record of Permian tetrapods equivalent to part of the Kungurian-Roadian. Across the gap, eupelycosaur-dominated ...
[99]
Origins and early evolution of herbivory in tetrapods - PubMed
The first herbivorous tetrapods date from the Late Carboniferous, about 300 million years ago. By the Late Permian, continental ecosystems of `modern' aspect ...
[100]
A new Carboniferous edaphosaurid and the origin of herbivory in ...
Apr 5, 2023 · However, herbivory becomes more widespread among tetrapods in the Early Permian with a greater volume of high-fibre herbivores. Melanedaphodon ...