The Mesozoic era (∼252 to 66 million years ago) was a key interval in Earth's evolution toward its modern state, witnessing the breakup of the supercontinent Pangaea and significant biotic innovations like the early evolution of mammals. Plate tectonic dynamics drove a fundamental climatic transition from the early Mesozoic supercontinent toward the Late Cretaceous fragmented continental configuration. Here, key aspects of Mesozoic long-term environmental changes are assessed in a climate model ensemble framework. We analyze so far the most extended ensemble of equilibrium climate states simulated for evolving Mesozoic boundary conditions covering the period from 255 to 60 Ma in 5 Myr timesteps. Global mean temperatures are generally found to be elevated above the present and exhibit a baseline warming trend driven by rising sea levels and increasing solar luminosity. Warm (Triassic and mid-Cretaceous) and cool (Jurassic and end-Cretaceous) anomalies result from pCO₂ changes indicated by different reconstructions. Seasonal and zonal temperature contrasts as well as continental aridity show an overall decrease from the Late Triassic-Early Jurassic to the Late Cretaceous. Meridional temperature gradients are reduced at higher global temperatures and less land area in the high latitudes. With systematic sensitivity experiments, the influence of paleogeography, sea level, vegetation patterns, pCO₂, solar luminosity, and orbital configuration on these trends is investigated. For example, long-term seasonality trends are driven by paleogeography, but orbital cycles could have had similar-scale effects on shorter timescales. Global mean temperatures, continental humidity, and meridional temperature gradients are, however, also strongly affected by pCO₂. This unique paleogeographic constellation shaped global climate patterns during Permian, Triassic, and Early Jurassic times, with the most prominent feature purportedly being pronounced monsoonal circulation patterns, also termed “megamonsoon” (Kutzbach & Gallimore, 1989 ; Parrish, 1993 ; Wang et al., 2014 ). The symmetric arrangement of huge landmasses, further enlarged by low sea levels, around the warm equatorial Tethys Sea provided optimum conditions for this phenomenon and contributed to an overall strongly seasonal climate (Parrish, 1993 ). However, only few climate model‐based studies have been conducted that can represent long‐term climatic changes during the Mesozoic in a continuous and consistent framework. These include Donnadieu et al. ( 2006a ) and Donnadieu et al. ( 2009 ), who performed coupled climate‐biogeochemistry‐vegetation simulations for seven Mesozoic timeslices, and found, among other things, that the fragmentation of Pangaea induced increasingly humid conditions with higher weathering CO 2 drawdown, which alone would have caused an overall cooling through the Mesozoic. Chaboureau et al. By systematically varying paleogeography, sea level, vegetation patterns, solar luminosity, the orbital 3.4 Zonal Temperature Contrasts Our simulations suggest the existence of considerable zonal climatic contrasts prior to the breakup of Pangaea, as can be inferred from the simulated SAT patterns and the distribution of arid regions (pink hatches, see Section 3.5 for explanation) in Figures 4a and 4b : High temperatures and humid conditions are inferred for the tropical latitudes of eastern Pangaea, in contrast to its western low‐ to mid‐latitudes, where temperatures are generally lower and arid regions are more extended. To systematically characterize the evolution of zonal temperature contrasts on the continents through the Mesozoic, the deviation of local annual mean SATs from their zonal mean values is calculated. For two selected timeslices of the P pCO2_1000ppm pathway, the resulting patterns are shown in Figures 6a and 6b . As described above, the eastern tropics and the western mid‐ to high‐latitudes of Pangaea are warmer by up to ∼8°C compared to the respective western or eastern regions (Figure 6a ). For the fragmented late Cretaceous continental configuration, these east–west contrasts are reduced (Figure 6b ). In the low latitudes, dry regions are extended during the Triassic–Middle Jurassic, especially in western Pangaea (see Figure 4 ), but successively disappear in the further course, which indicates the establishment of more continuous tropical humid conditions. The relative portion of global arid land area on the P pCO2_1000ppm pathway (Figure 7b ) peaks in the latest Triassic and continuously decreases into the Late Cretaceous. In agreement with Chaboureau et al. ( 2014 ), the fraction of arid land is found to decrease with warming from elevated pCO 2 . Considering these difficulties and the limitations of the employed climate model, a comprehensive assessment that takes into account the various boundary conditions is beyond the scope of this study. It can still be noted, that Cao et al. ( 2018 ) found a statistical Mesozoic–Cenozoic trend from an unimodal to a bimodal zonal distribution in the evaporite occurrence data of Boucot et al. ( 2013 ). Our simulations suggest that this could express the establishment of a more consistent tropical humid belt and two arid belts during the fragmentation of Pangaea (see Figure 4d ), which could have displaced evaporite formation from equatorial regions especially in the eastern Panthalassa margin. Reconstructed maximum high‐ and low‐stand paleogeographies for each time‐interval could be particularly useful. Depending on the respective model set‐up, deep‐time paleoclimate simulations require information on various boundary conditions, including paleogeography, pCO 2 , vegetation patterns, solar constant S 0 , and orbital configuration. In agreement with previous work (e.g., Donnadieu et al., 2006a ; Donnadieu et al., 2009 ; Valdes et al., 2020 ), we find that these critically affect Earth's climatic evolution through the Mesozoic.

Pangaea or Pangea ( pan-JEE-ə) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous period approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. Pangaea was C-shape Pangaea experienced widespread faulting during the Triassic, also accompanied by a substantial reduction of the… Pangaea existed as a supercontinent for 160 million years, from its assembly around 335 Ma (Early Carboniferous) to its breakup 175 Ma (Middle Jurassic). During this interval, important developments in the evolution of life took place. The seas of the Early Carboniferous were dominated by rugose corals, brachiopods, bryozoans, sharks, and the first bony fish. Life on land was dominated by lycopsid forests inhabited by insects and other arthropods and the first tetrapods. By the time Pangaea broke up, in the Middle Jurassic, the seas swarmed with molluscs (particularly ammonites), ichthyosaurs, sharks and rays, and ray-finned bony fishes, while life on land was dominated by forests of cycads and conifers in which dinosaurs flourished and in which the first true mammals had appeared. The evolution of life in this time reflected the conditions created by the assembly of Pangaea. The union of most of the continental crust into one landmass reduced the extent of sea coasts. Increased erosion from uplifted continental crust increased the importance of floodplain and delta environments relative to shallow marine environments. Continental assembly and uplift also meant increasingly arid land climates, favoring the evolution of amniote animals and seed plants, whose eggs and seeds were better adapted to dry climates. The early drying trend was most pronounced in western Pangaea, which became a center of the evolution and geographical spread of amniotes. Coal swamps typ Pangaea or Pangea ( pan-JEE-ə) was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous period approximately 335 million years ago, and began to break apart about 200 million years ago, at the end of the Triassic and beginning of the Jurassic. Pangaea was C-shaped, with the bulk of its mass stretching between Earth's northern and southern polar regions and surrounded by the superocean Panthalassa and the Paleo-Tethys and subsequent Tethys Oceans. Pangaea is the most recent supercontinent to have existed and was the first to be reconstructed by geologists. Pangaea experienced widespread faulting during the Triassic, also accompanied by a substantial reduction of the Central Pangean Mountains by the Middle Triassic. The Cimmerian terranes, that had detached from Gondwana in the early Permian drifted northwards during the Triassic, increasing the expanse of the Neo-Tethys Ocean which had formed from this event while shrinking the Paleo-Tethys. The largest delta plain in Earth's geological history — the Triassic Boreal Ocean Delta Plain formed in Northern Pangaea during this period. Pangaea existed as a supercontinent for 160 million years, from its assembly around 335 Ma (Early Carboniferous) to its breakup 175 Ma (Middle Jurassic). During this interval, important developments in the evolution of life took place. The seas of the Early Carboniferous were dominated by rugose corals, brachiopods, bryozoans, sharks, and the first bony fish. Life on land was dominated by lycopsid forests inhabited by insects and other arthropods and the first tetrapods. By the time Pangaea broke up, in the Middle Jurassic, the seas swarmed with molluscs (particularly ammonites), ichthyosaurs, sharks and rays, and ray-finned bony fishes, while life on land was dominated by forests of cycads and conifers in which dinosaurs flourished and in which the first true mammals had appeared. The evolution of life in this time reflected the conditions created by the assembly of Pangaea. The union of most of the continental crust into one landmass reduced the extent of sea coasts. Increased erosion from uplifted continental crust increased the importance of floodplain and delta environments relative to shallow marine environments. Continental assembly and uplift also meant increasingly arid land climates, favoring the evolution of amniote animals and seed plants, whose eggs and seeds were better adapted to dry climates. The early drying trend was most pronounced in western Pangaea, which became a center of the evolution and geographical spread of amniotes. Coal swamps typically form in perpetually wet regions close to the equator. The assembly of Pangaea disrupted the Intertropical Convergence Zone and created an extreme monsoon climate that reduced the deposition of coal to its lowest level in the last 300 million years. During the Permian, coal deposition was largely restricted to the North and South China microcontinents, which were among the few areas of continental crust that had not joined with Pangaea. The extremes of climate in the interior of Pangaea are reflected in bone growth patterns of pareiasaurs and the growth patterns in gymnosperm forests. The lack of oceanic barriers is thought to have favored cosmopolitanism, in which successful species attain wide geographical distribution. Cosmopolitanism was also driven by mass extinctions, including the Permian–Triassic extinction event, the most severe in the fossil record, and also the Triassic–Jurassic extinction event. These events resulted in disaster fauna showing little diversity and high cosmopolitanism, including Lystrosaurus, which opportunistically spread to every corner of Pangaea following the Permian–Triassic extinction event. On the other hand, there is evidence that many Pangaean species were provincial, with a limited geographical range, despite the