The Messinian is the uppermost stage, or age, of the Miocene epoch in the Neogene period of the geologic time scale, spanning from 7.246 to 5.333 million years ago.[1] Defined by the International Commission on Stratigraphy at the base of a reddish sedimentary layer in Oued Akrech, Morocco, coinciding with the first regular appearance of the planktonic foraminifera Globorotalia miotumida and the calcareous nannofossil Amaurolithus delicatus, this stage represents a critical interval of late Miocene paleoenvironmental change.[2]The Messinian is most notably defined by the Messinian Salinity Crisis (MSC), a profound geological event that unfolded primarily between 5.97 and 5.33 million years ago, during which the Mediterranean Sea became increasingly isolated from the Atlantic Ocean due to tectonic restriction of gateways like the Strait of Gibraltar, exacerbated by orbital climate fluctuations and eustatic sea-level variations.[3] This isolation triggered extreme evaporation, transforming the Mediterranean into a series of hypersaline basins that deposited vast evaporite sequences—known as "salt giants"—including thick layers of gypsum, halite, and other salts, with thicknesses exceeding 1–3 kilometers in deep basinal areas.[3] The crisis progressed through distinct stages: an initial phase of gypsum precipitation around 5.97–5.60 Ma, a peak desiccation period marked by halite accumulation and cyclic sedimentation tied to precession-driven climate cycles, and a terminal freshening phase featuring lagoonal-marine (Lago-Mare) facies before the basin's reflooding.[3][4]The consequences of the MSC extended far beyond the Mediterranean, influencing global climate through enhanced carbon sequestration via evaporite formation, which removed significant calcium and bicarbonate ions from seawater and contributed to a 7–10% reduction in atmospheric CO₂ levels, potentially amplifying late Miocene cooling.[3] The crisis culminated in a catastrophic reflooding event at approximately 5.33 Ma—the Zanclean flood—when Atlantic waters breached the Gibraltar sill, rapidly restoring marine conditions and eroding deep canyons across the Mediterranean seafloor, with flow rates estimated at up to 100 million cubic meters per second.[3] Ecologically, the event reshaped Mediterranean biota, driving evolutionary adaptations in marine species and facilitating biotic exchanges between Atlantic, Paratethyan, and Indo-Pacific realms, while leaving a legacy of seismic instability and hydrocarbon resources in the form of salt domes and reservoirs.[5] Ongoing research continues to refine models of the MSC's drivers and impacts, highlighting its role as one of the most extreme paleoceanographic perturbations in Earth's history.[3]
Definition and Nomenclature
Etymology and Historical Naming
The term "Messinian" was introduced by the Swiss geologist and paleontologist Karl Mayer-Eymar in 1867 to designate a stratigraphic unit filling the gap between the Tortonian and Astian stages.[6] It derives from the city of Messina in Sicily, Italy, where Mayer-Eymar studied key post-Tortonian, pre-Astian strata in a small sedimentary basin nearby.[7] This naming reflected the initial focus on marine and evaporitic deposits characteristic of the region, marking the term's origins in local Italian geology.[6]Initially employed as a regional stage within Mediterranean Neogene stratigraphy, the Messinian was rarely used even in Sicily during the late 19th and early 20th centuries, where geologists often preferred terms like "formazione gessoso-solfifera" for similar deposits.[7] By the mid-20th century, its application expanded across the Mediterranean basin as correlations with fossil assemblages strengthened its utility in regional chronostratigraphy.[6] In 1959, the Mediterranean Neogene Committee formally adopted the Messinian as a standard geochronological unit during a meeting in Vienna, solidifying its role in European stratigraphic frameworks.[6]The term's evolution culminated in its international recognition as the uppermost stage of the Mioceneepoch within global chronostratigraphy.[6] This formalization occurred with the ratification of the Global Boundary Stratotype Section and Point (GSSP) by the International Union of Geological Sciences (IUGS) in January 2000, establishing the Messinian's boundaries for worldwide use under the auspices of the International Commission on Stratigraphy (ICS).[6] Prior proposals for neostratotypes, such as those at Pasquasia-Capodarso (Selli, 1960) and Falconara (Colalongo et al., 1979), were evaluated but ultimately replaced by the selected GSSP to ensure global applicability.[6]
Stratotype and Boundaries
The Global Stratotype Section and Point (GSSP) for the base of the Messinian Stage is located at Oued Akrech in Morocco, at coordinates 33.9369°N, 6.8125°W, approximately 7 km southeast of Rabat.[2][8] This GSSP was ratified by the International Union of Geological Sciences (IUGS) in 2000 and is defined at the base of the reddish layer within sedimentary cycle number 15, corresponding to a precession-related eccentricity minimum in the astronomical timescale.[6] The primary correlation criteria include the first regular occurrence (FRO) of the planktonic foraminifer Globorotalia miotumida and the first occurrence (FO) of the calcareous nannofossil Amaurolithus delicatus, within magnetic polarity subchronozone C3Br.1r, providing robust magnetostratigraphic and biostratigraphic markers for global recognition of the Tortonian-Messinian boundary.[6][9]The upper boundary of the Messinian Stage coincides with the base of the overlying Zanclean Stage and is defined by its GSSP at Eraclea Minoa on the southern coast of Sicily, Italy, at coordinates 37.3917°N, 13.2806°E.[10][8] Ratified in 2000, this GSSP is placed at the base of the Trubi Formation, a rhythmically bedded limestone unit, and is marked by the first common occurrence (FCO) of the planktonic foraminifer Globorotalia margaritae.[11] Supporting criteria include the first occurrence (FO) of the calcareous nannofossil Ceratolithus acutus and position within magnetic polarity chronozone C3r, approximately 100 kyr before its top, ensuring precise biostratigraphic and magnetostratigraphic correlation across Mediterranean and global sections.[11][12] These markers facilitate reliable identification of the Miocene-Pliocene boundary without reliance on lithological changes alone.[11]
Stratigraphy and Chronology
Temporal Range
The Messinian stage represents the uppermost division of the Mioceneepoch, spanning approximately 1.913 million years from its base at 7.246 ± 0.005 Ma to its top at 5.333 ± 0.005 Ma, as defined in the 2024 International Chronostratigraphic Chart of the International Commission on Stratigraphy.[13] This temporal range immediately follows the Tortonian stage, which extends from 11.63 Ma to 7.246 Ma, marking the final phase of the Miocene before the transition to the Pliocene Zanclean stage.[13]The precise numerical ages for the Messinian boundaries have been established through high-resolution astronomical tuning, which correlates rhythmic sedimentary cycles in Mediterranean marine sections—such as marls, sapropels, and evaporites—with Milankovitch orbital forcings, including eccentricity, obliquity, and precession cycles. This method, pioneered in studies of the Oued Akrech section in northern Morocco (the Global Stratotype Section and Point for the Messinian base), yields uncertainties on the order of ±0.005 Ma by aligning cycle patterns to the stable La2004 astronomical solution for Earth's orbital parameters. The top boundary at 5.333 Ma corresponds to the base of the Zanclean stage, similarly tuned via cycles in the Faneromeni section on Crete.Complementary radiometric dating using the ⁴⁰Ar/³⁹Ar method on sanidine and biotite from volcanic ash layers interbedded in Messinian sequences has provided independent calibration, confirming the astronomical ages with precisions typically better than ±0.02 Ma and resolving minor discrepancies in early radioisotopic estimates. For instance, ashes from the Ervilia and Venta del Moro formations in Spain yield ages aligning closely with the tuned chronology for the stage's early phases. These integrated approaches ensure robust global correlations for the Messinian, underpinning its placement within the Neogene timescale.[13]
Correlation with Biozones and Mammal Ages
The Messinian stage, spanning approximately 7.25 to 5.33 million years ago, correlates with specific marine biostratigraphic zones defined by microfossils, facilitating global synchronization of Neogene sediments. In the Mediterranean realm, it encompasses the upper part of the planktonic foraminiferal Zone M12 (Globorotalia margaritae s.l. Zone) and the entirety of Zones M13a (G. miotumida Zone) and M13b (G. conomiozea Zone), with the base of the stage marked by the first regular occurrence (FRO) of the G. miotumida group at Oued Akrech, Morocco (the GSSP).[14] Calcareous nannoplankton biozonation places the Messinian within the upper portion of Zone NN12 (Amaurolithus tricorniculatus Zone), particularly subzone CN12b, characterized by the first occurrence of Amaurolithus delicatus.[15] These marine markers enable precise correlation across Tethyan and Atlantic basins, reflecting pre-evaporitic open marine conditions before the salinity crisis.Continental biostratigraphy ties the Messinian to the European Neogene Mammal Zones (MN) late MN12 through MN13, corresponding to the middle to late Turolian European land mammal age, where faunas are dominated by advanced hipparionine horses such as Hipparion species adapted to open woodlands.[16][17] In South America, this interval overlaps the late Huayquerian and early Montehermosan South American Land Mammal Ages (SALMAs), featuring native litopterns and proterotheriids indicative of expanding grasslands and faunal turnover linked to Andean uplift.[18] These mammal correlations, integrated with magnetostratigraphy, confirm the Messinian's alignment with global climatic shifts toward aridity.[17]Dinoflagellate cyst assemblages further refine Messinian correlations, particularly in marginal marine settings, with the influx of Paratethyan species like Galeacysta etrusca marking late-stage events tied to the salinity crisis and regional connectivity.[19] In the Eastern Paratethys, the Messinian equivalents integrate with the Pontian regional stage, encompassing dinocyst zones that reflect freshwater incursions and evaporitic deposition, allowing linkage between Mediterranean and Black Sea records.[20]
Major Geological Events
Messinian Salinity Crisis
The Messinian Salinity Crisis (MSC) represents a pivotal episode of Mediterranean Sea isolation and desiccation during the late Miocene, spanning approximately 5.97 to 5.33 million years ago (Ma). This event unfolded in multiple phases, beginning with the Primary Lower Gypsum (PLG) stage around 5.97 Ma, characterized by marine gypsum precipitation in shallow peripheral basins, followed by halite deposition in deeper central basins from about 5.6 to 5.53 Ma, and concluding with the Upper Gypsum and brackish Lago Mare conditions until 5.33 Ma. The crisis resulted from progressive restriction of Atlantic water inflow through the Gibraltar gateway, driven by a combination of tectonic uplift and glacio-eustatic sea-level lowering, which reduced the sill depth and curtailed exchange between the Mediterranean and the Atlantic Ocean.[21][22]Evaporite sequences formed extensively across the Mediterranean basins during the MSC, accumulating up to several kilometers in thickness and comprising primary lower units of gypsum overlain by upper units dominated by halite and potash salts. In marginal settings, such as the Sorbas Basin in southeastern Spain, cyclic gypsum layers reflect repeated marine incursions and evaporative drawdown, while Sicilian deposits exhibit similar stratified evaporites indicative of fluctuating salinity levels. Deep-basin halite, observed in the Levant and Liguro-Provençal basins via seismic and drilling data, points to prolonged hypersaline conditions and near-total desiccation in the crisis's later stages. These sediments, totaling over 1 million cubic kilometers in volume, were precipitated under increasingly restricted hydrological conditions, with evidence from seismic profiles revealing the deep Messinian Erosional Surface (MES)—an extensive subaerial erosion feature incising underlying Miocene strata by 800–2,000 meters, later onlapped by Pliocene deposits.[21][22]The MSC concluded abruptly with the Zanclean transgression at 5.33 Ma, when tectonic subsidence and a rapid eustatic sea-level rise breached the Gibraltar sill, triggering a catastrophic Atlantic inflow that refilled the desiccated Mediterranean basin in mere months to years. This flooding event, estimated to have involved water volumes exceeding 10^6 km³ cascading at velocities up to 100 km/h, rapidly restored marine conditions and dispersed residual evaporites basin-wide. Seismic and stratigraphic records confirm the erosional unconformity of the MES sealed by this influx, marking the transition to the Pliocene Zanclean stage.[21][22]Recent studies as of 2025 have further refined understanding of the MSC, highlighting the role of river incision and climate-driven erosion in causing drawdowns of up to 1 km in sea level, as well as evidence for contemporaneous desiccation of the Red Sea basin at the crisis's onset. Additional research has provided new evidence supporting the catastrophic nature of the Zanclean megaflood that refilled the Mediterranean.[4][23]
Tectonic and Volcanic Activity
During the Messinian stage of the late Miocene (7.246–5.333 Ma), the Alpine-Himalayan orogeny experienced intensified compressional tectonics across the Mediterranean realm, driven by the ongoing convergence between the African and Eurasian plates. This phase involved significant crustal shortening and thickening, particularly in the western Mediterranean, where slab dynamics led to regional uplift. In the Betic Cordillera of southern Spain and the Rif of northern Morocco, uplift rates reached up to 1000 m by the late Messinian (around 5.3 Ma), triggered by westward slab tearing and detachment beneath these structures, resulting in the transition from marine to continental sedimentation in intramontane basins.[24] This tectonic compression contributed to the partial isolation of the Mediterranean basin, setting the stage for the Messinian Salinity Crisis.[25]Volcanic activity during the Messinian was prominent in rift settings and subduction-related arcs peripheral to the Mediterranean. In the Afar region of Ethiopia, bimodal basalt-rhyolite volcanism initiated around 7 Ma along the southern Afar rift floor, associated with the early stages of continental rifting and the development of the East African Rift system. This included rift-related basaltic flows and large silicic centers (7–5 Ma) aligned along an east-west structural trend, marking a renewal of mafic activity following earlier Miocene events and preceding Plio-Pleistocene escarpment formation.[26] Similarly, in the eastern Mediterranean margins, such as northern Israel, pyroclastic deposits and lava flows recorded ongoing volcanism between 7 and 5 Ma, linked to extensional tectonics and alkali basaltic eruptions in the Levantine region.[27] In the South Aegean volcanic arc, submarine volcanic rocks positioned relative to the Messinian seismic marker indicate early calc-alkaline activity, with broader distribution than subaerial outcrops, reflecting subduction-driven magmatism.[28]In central Europe, the Pannonian Basin and associated Paratethys domains underwent basin inversions and fault reactivation during the Messinian, altering continental sedimentation patterns in the remnant Lake Pannon. Tectonic uplift and subsidence variations, including fault-controlled block movements, produced an Intra-Messinian Unconformity (dated 6–4.18 Ma) and a relative lake-level fall of several hundred meters, leading to spatially variable erosion and progradational sediment shifts.[29] These inversions, part of a broader compressional regime tied to Alpine convergence, uplifted basin margins and tilted depocenters basinward, influencing the deposition of fluvial and lacustrine sequences without direct evaporite formation.[30]
Paleoenvironmental Setting
Paleogeography of the Mediterranean
During the Messinian stage, the Mediterranean basin underwent significant paleogeographic reconfiguration, most notably marked by the progressive closure of the GibraltarStrait. This closure resulted from tectonic uplift driven by the convergence between the African and Eurasian plates, which elevated the Betic-Rifian orogen and restricted Atlantic water inflow, transforming the Mediterranean into a semi-enclosed basin with limited oceanic exchange. The uplift rates, on the order of 1-2 mm/year, were partially offset by fluvial and marine erosion within the strait, sustaining a narrow, shallow corridor for much of the early Messinian before full isolation.[31]The surrounding landmasses further shaped the basin's configuration through ongoing plate interactions. Convergence between the African and Arabian plates contributed to the narrowing of the eastern Mediterranean, as subduction and collision along the Hellenic and Cyprean arcs compressed the basin margins, promoting the development of thrust belts and reducing the overall width of the seaway. In the central Mediterranean, back-arc extension in the Tyrrhenian Sea led to the emergence of volcanic islands, such as precursors to the Aeolian archipelago, amid rifting that fragmented the continental crust and created a complex mosaic of sub-basins separated by shallow sills. These changes, influenced by slab rollback beneath the Apennines, altered circulation patterns and facilitated localized depositional environments.[32]Sediment dispersal patterns reflected the interplay between peripheral orogenic sources and internal basin dynamics. Clastic sediments were primarily supplied from the eroding Alps via rivers like the paleo-Po and Rhône, delivering quartz-rich sands and gravels to the northern Adriatic and Provençal foredeeps, while inputs from the Atlas Mountains in North Africa contributed finer-grained terrigenous material to the western margins through the Betic and Tellian corridors. In contrast, the deep central basins accumulated evaporitic infills due to restricted circulation, with gypsum and halite precipitating in subsiding troughs like the Sicilian and Ionian domains, highlighting the transition from open-marine to restricted conditions.[33]
Climate and Oceanographic Changes
During the Messinian stage (7.246–5.333 Ma), global climate transitioned toward cooler conditions, marked by the expansion of the Antarctic ice sheet (AIS). Benthic oxygen isotope (δ¹⁸O) records from deep-sea cores, such as those from Ocean Drilling Program (ODP) Sites 846 and 926, reveal an enrichment phase from approximately 6.2 Ma to 5.75 Ma, indicating a roughly 50% increase in ice volume due to AIS growth.[34] This cooling trend, part of the broader Miocene Climate Transition, is evidenced by drill core data from Antarctic sites like ODP 1092, 1095, 1165, and AND-1B, which show ice-sheet advances peaking between 6.1 and 5.6 Ma, with sedimentation interruptions linked to glacial erosion.[34] The Messinian Oxygen Isotope High further underscores reduced export of salt from the Mediterranean and heightened cryosphere sensitivity, contributing to a stable cool phase with extended Antarctic ice coverage.[35]In the Mediterranean Basin, the Messinian Salinity Crisis (MSC; 5.971–5.33 Ma) induced profound oceanographic changes, culminating in hypersaline conditions that severely altered water column structure. Modeled scenarios indicate surface water salinities exceeding 100 g/L (approximately 130 psu) during gypsum precipitation phases, driven by restricted Atlantic inflow and intense evaporation.[36] These elevated salinities fostered strong density stratification, with a lighter, fresher surface layer (influenced by limited riverine input) overlying denser, hypersaline deep waters, as reconstructed from evaporite sequences and biomarker analyses in eastern Mediterranean cores.[36] This stratification promoted anoxic conditions in deeper basins, evidenced by organic-rich laminated marls and high total organic carbon (TOC) levels up to 1.31% in pre-MSC deposits (6.457–6.128 Ma), signaling oxygen depletion and enhanced preservation of organic matter.[37] Such meromictic states persisted through crisis phases, limiting vertical mixing and benthic ventilation.[38]Concurrent with Mediterranean isolation, the progressive closure of Tethys remnants intensified monsoon systems in the Indo-Pacific region during the late Miocene. The two-step restriction of the Indian Ocean Gateway, completed by around 13 Ma but with lingering effects into the Messinian, trapped thermal energy in the northwestern Indian Ocean, enhancing upwelling in the Arabian Sea and strengthening the South Asian Monsoon (SAM) to near-modern intensities.[39] This tectonic reconfiguration, inferred from neodymium (Nd) isotope records in sediments from Malta and the Maldives, reduced Tethyan Indian Saline Water (TISW) flux from over 20 Sv to about 2 Sv, altering low-latitude surface water exchange and bolstering monsoonprecipitation.[39] In the eastern Mediterranean, intensified North African monsoon runoff during precession minima is documented by sapropel layers—organic-rich deposits forming from 16 to 13.5 Ma onward—reflecting increased freshwater input, surface freshening, and transient anoxia linked to orbital forcing.[39] These sapropels, such as those in the Faneromeni section (Crete), highlight heightened hydrologic sensitivity to monsoon variability amid Tethys closure.[40]
Biota and Ecosystems
Marine Microfossils and Invertebrates
During the Messinian stage, planktonic foraminifera assemblages in the Mediterranean were dominated by species such as Globorotalia miotumida, which served as a key biostratigraphic marker from the Messinian to the late Messinian, with its first regular appearance defining the base of the Messinian around 7.246 Ma.[2] This species persisted through much of the Messinian but underwent evolutionary changes, including the disappearance of keeled morphotypes and the emergence of non-keeled forms with rounded peripheries, reflecting adaptations to shifting environmental conditions.[41] Its decline occurred during the Messinian Salinity Crisis, marking the end of pre-crisis marine conditions before the Zanclean reflooding.[2] In hypersaline settings associated with the salinity crisis, surviving foraminifera exhibited dwarfed morphologies, with specimens 2-3 times smaller than normal sizes, indicating reduced growth rates under stressed conditions like oxygen depletion and salinity fluctuations.[42]Calcareous nannoplankton provided critical biostratigraphic control during the Messinian, with species like Amaurolithus tricorniculatus and Ceratolithus acutus anchoring zonal schemes; the last occurrence of A. tricorniculatus helped delineate late Messinian intervals, while the first occurrence of C. acutus at around 5.345 Ma signaled the marine reflooding at the Messinian-Zanclean boundary.[43][44] These microfossils maintained relative resilience compared to foraminifera, but their diversity decreased during evaporite deposition phases starting at 5.97 Ma, linked to nutrient shifts, increased restriction, and stratification that favored opportunistic taxa like Braarudosphaera bigelowi.[45]Benthic invertebrate assemblages in marginal evaporite settings were characterized by euryhaline ostracods and mollusks adapted to brackish conditions, with taxa such as Caspiocypris pontica and Rhombocongeria rhomboidea showing tolerance to salinity variations through osmoregulatory mechanisms and high mobility.[46] These groups underwent adaptive radiation in shallowing environments, from sublittoral to littoral zones, with 25 ostracod and 18 mollusk taxa recorded in late Messinian deposits, many shared with Paratethyan faunas.[46]Coral reefs, a key invertebrateecosystem, collapsed due to salinity fluctuations and restricted circulation, transitioning from coral-boundstone to algal-dominated systems with reduced biodiversity, dominated by stress-tolerant Poritesspecies before the full crisis onset.[47]
Terrestrial Flora and Fauna
During the Messinian stage of the late Miocene (approximately 7.246 to 5.333 million years ago), terrestrial ecosystems across Eurasia, Africa, and adjacent regions underwent significant transformations driven by progressive aridification and associated climatic shifts. Pollen records from the Mediterranean borderlands reveal a marked expansion of open habitats, with increased dominance of herbaceous taxa adapted to drier conditions. This shift is exemplified by the proliferation of C4 grasslands, which became more prevalent as atmospheric CO₂ levels declined and seasonal aridity intensified, favoring grasses capable of efficient photosynthesis under water-stressed environments.[48][49]Pollen assemblages from peri-Mediterranean sites, including marine and continental deposits, document a rise in Poaceae (grasses) and Chenopodiaceae (saltbush family) percentages, often exceeding 20-30% of total pollen counts in some sequences, indicating widespread steppe-like vegetation and saline-tolerant flora in response to evaporative concentration during the Messinian Salinity Crisis. These changes reflect a broader trend toward xerophytic (drought-resistant) plant communities, with arboreal pollen (e.g., from conifers like Pinus) diminishing in favor of open-ground indicators, particularly in southern Europe and North Africa. Fossil wood and leaf remains further corroborate this, showing anatomical adaptations for water conservation in woody species bordering these grasslands.[50][51]Mammalian faunas of the Messinian exhibit high diversity and turnover, particularly in Eurasia, where the Pikermian biome—a mosaic of woodlands, grasslands, and savannas—supported large herbivores adapted to mixed feeding strategies. Hipparion horses reached their peak abundance and morphological diversity during this interval, with species like Hipparion cf. primigenium dominating assemblages in sites such as Pikermi (Greece) and Samos (Greece-Turkey border), comprising up to 40% of large mammal fossils in some localities and reflecting exploitation of emerging C4-dominated pastures. Advanced proboscideans, including the tetralophodont gomphothereAnancus arvernensis, also proliferated, with their high-crowned molars suited for abrasive, silica-rich C4 vegetation; Anancus originated in Africa and dispersed northward into Europe by the early Messinian, facilitated by episodic low sea-level stands that exposed land connections across the Mediterranean.[52][53]Rodent communities underwent notable diversification in the MN13 biozone (late Turolian, ~7.3-5.3 Ma), with increased speciation in cricetine and arvicoline lineages across the Iberian and Eastern Mediterranean regions, driven by habitat fragmentation and niche partitioning in aridifying landscapes. In Africa and southern Eurasia, dispersals intensified via the Sicily land bridge during Messinian lowstands, allowing taxa such as primitive bovids and proboscideans to cross from North Africa into Sicily and peninsular Italy, evidenced by shared dental morphologies in fossils from sites like Scontrone (Italy). These migrations contributed to biotic homogenization between African and Eurasian faunas, though many African elements failed to establish long-term populations in Europe due to subsequent isolation.[54][55]Avian and reptilian records from the Messinian are sparser than those of mammals but align with the warming-drying trends, showing adaptations to open, seasonal environments. In the Pikermi assemblage (Greece), reptile fossils include lizards of the family Lacertidae and snakes like colubrines, with vertebral and osteoderm remains indicating ground-dwelling forms suited to steppe habitats; these suggest a decline in forested refugia and expansion of thermophilic species. Similarly, Siwalik Group deposits in northern India and Pakistan yield Messinian-age squamate fossils, including varanid lizards and pythonid snakes, alongside limited avian elements like passerine bird bones, reflecting arid-adapted faunas in monsoon-influenced but increasingly seasonal Asian ecosystems. Overall, these non-mammalian groups underscore a continental trend toward faunas resilient to aridity, with brief climatic references to enhanced seasonality influencing dispersal patterns.[56][57]