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66-421: The field is formed by a late Pliocene lava plateau. Several volcanoes formed under the influence of ice and are constructed by lava flows and hyaloclastite , these are so-called tuyas which form by eruptions of volcanoes into ice. Ice meltwater floods may have accompanied this activity. The youngest dated volcanic centre was active 48,000 ± 20,000 years ago, but some lava flows may be even younger. The field

132-469: A monotreme , appeared. The predatory South American phorusrhacids were rare in this time; among the last was Titanis , a large phorusrhacid that migrated to North America and rivaled mammals as top predator. Other birds probably evolved at this time, some modern (such as the genera Cygnus , Bubo , Struthio and Corvus ), some now extinct. Alligators and crocodiles died out in Europe as

198-599: A few volcanoes have hosted persistent or near-persistent lava lakes during recent decades: The lava lakes at Ambrym volcano disappeared after a large eruption in December 2018. For many years, Kīlauea had two persistent lava lakes: one in the Halemaʻumaʻu vent cavity within the summit caldera , and another within the Puʻu ʻŌʻō cone located on the east rift zone of the volcano. In May 2018, both of these lava lakes disappeared as

264-406: A large neocortex relative to body mass and stone tool manufacture. Improvements in dating methods and in the use of climate proxies have provided scientists with the means to test hypotheses of the evolution of human ancestors. Early hypotheses of the evolution of human traits emphasized the selective pressures produced by particular habitats. For example, many scientists have long favored

330-409: A lava lake at the 1983–1984 Puʻu ʻŌʻō eruption of Kilauea displayed cyclic behaviour with a period of 5–20 minutes; gas "pierced the surface" of the lake, and the lava rapidly drained back down the conduit before the onset of a new phase of lake activity. The behaviour observed is influenced by the combined effects of pressure within the reservoir, exsolution and decompression of gas bubbles within

396-429: A particular habitat. The change to a cooler, drier, more seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, and grasslands spread on all continents (except Antarctica). Eastern Africa in particular saw a huge expansion of C 4 grasslands. Tropical forests were limited to

462-585: A red colour. Based on geochemistry, the magma formed at depths of 80 kilometres (50 mi). Volcaniclastic rocks were originally considered to be tuffs. Cumulates and xenoliths from the mantle have been found at some volcanoes. Volcanic activity in the Azas Plateau commenced during the Late Pliocene. Activity continued into the Holocene . Before volcanism of the Azas Plateau started, volcanism occurred in

528-557: A result of increased activity in Kīlauea's east rift zone. The lava lake at Halemaʻumaʻu returned in December 2020, after Kīlauea's first eruption in over two years. The lava lake solidified after the eruption ended in May 2021, but returned again when eruptive activity at Halemaʻumaʻu resumed on September 29, 2021. Following the 2021 eruption, three more occurred on January 5, 2023; June 7, 2023; and September 10, 2023. As of January 2024, Halemaʻumaʻu

594-953: A tight band around the equator, and in addition to dry savannahs , deserts appeared in Asia and Africa. Both marine and continental faunas were essentially modern, although continental faunas were a bit more primitive than today. The land mass collisions meant great migration and mixing of previously isolated species, such as in the Great American Interchange . Herbivores got bigger, as did specialized predators. In North America, rodents , large mastodons and gomphotheres , and opossums continued successfully, while hoofed animals ( ungulates ) declined, with camel , deer , and horse all seeing populations recede. Three-toed horses ( Nannippus ), oreodonts , protoceratids , and chalicotheres became extinct. Borophagine dogs and Agriotherium became extinct, but other carnivores including

660-632: A tributary of the Yenisei River , crosses the field. The field lies within the Tuva Republic of Russia in a remote area where access is difficult. The volcanoes were first described between 1850 and 1900. It is part of the Tuva volcanic province of the Baikal Rift Zone , which is linked to a hotspot that has raised the terrain as high as 3,000 metres (9,800 ft). Activity in the rift zone started in

726-479: A variety of volcanic systems, ranging from the basaltic Erta Ale lake in Ethiopia and the basaltic andesite volcano of Villarrica , Chile, to the unique phonolitic lava lake at Mt. Erebus , Antarctica. Lava lakes have been observed to exhibit a range of behaviours. A "constantly circulating, apparently steady-state" lava lake was observed during the 1969–1971 Mauna Ulu eruption of Kīlauea , Hawaiʻi. By contrast,

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792-439: Is 2,648 metres (8,688 ft) and was affected by glacial erosion. Sorug-Chushku-Uzu 1 kilometre (0.62 mi) north of Shivit-Taiga is 2,525 metres (8,284 ft) high. Some volcanoes have been affected by landsliding, gully formation and glaciation after their formation. Likewise, the field has been affected by erosion, forming deep valleys with glacier deposits. The Azas Plateau was affected by an ice sheet which formed on

858-407: Is a cone that formed exposed in the air. The cone is accompanied by a maar with a lake to the south, and a lava flow from the cone reached 10 kilometres (6.2 mi) in length. Shivit-Taiga with a length of over 10 kilometres (6.2 mi) and a height of 500 metres (1,600 ft) is among the biggest volcanoes in the world that formed beneath ice, but Derby-Taiga may be even larger depending on how

924-540: Is a key finding of research into a lake-sediment core obtained in Eastern Siberia, which is of exceptional importance because it has provided the longest continuous late Cenozoic land-based sedimentary record thus far. During the late Zanclean, Italy remained relatively warm and humid. Central Asia became more seasonal during the Pliocene, with colder, drier winters and wetter summers, which contributed to an increase in

990-451: Is formed by several layers of hyaloclastite and lava flows and displays a prominent "winged" topography. The hyaloclastite layers were formerly considered to be tuffs and reach thicknesses of 8 metres (26 ft). Pillow lavas also exist. A system of ancient valleys formed by floods are found near to Derbi-Taiga. Ulug-Arginskii ( 52°23′18″N 98°23′7″E  /  52.38833°N 98.38528°E  / 52.38833; 98.38528 )

1056-628: Is located in southern Siberia , between the East Sayan Mountains and the Todzha basin. There it covers a surface area of 2,000 square kilometres (770 sq mi) west of Lake Baikal, at an altitude of 2,000 metres (6,600 ft). Volcanic landforms include cones, lava fields , tuyas, and other volcanic structures including scoria cones , volcanic dykes , volcanic necks and volcanic vents . Other landforms are cirques and U-shaped valleys left by previous glaciations . The Bii Khem river,

1122-535: Is not erupting and the lava lake is no longer active. Nyiragongo's lava lake has usually been the largest and most voluminous in recent history, reaching 700 meters wide in 1982, although Masaya is believed to have hosted an even larger lava lake at the time of the Spanish conquest , being 1,000 meters wide in 1670. The lava lake at Masaya came back in January 2016. In addition to the aforementioned persistent lava lakes,

1188-688: Is the epoch in the geologic time scale that extends from 5.33 to 2.58 million years ago (Ma). It is the second and most recent epoch of the Neogene Period in the Cenozoic Era . The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene,

1254-567: The Hardangervidda plateau to 1200 m in the Early Pliocene. In Southern Sweden similar movements elevated the South Swedish highlands leading to a deflection of the ancient Eridanos river from its original path across south-central Sweden into a course south of Sweden. The Pliocene is bookended by two significant events in the evolution of human ancestors. The first is the appearance of

1320-676: The Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive native ungulate fauna, though other South American lineages like its predatory mammals were already extinct by this point and others like xenarthrans continued to do well afterwards. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters decreasing temperatures in

1386-555: The Netherlands the Pliocene is divided into these stages (old to young): Brunssumian C, Reuverian A, Reuverian B, Reuverian C, Praetiglian , Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian . The exact correlations between these local stages and the International Commission on Stratigraphy (ICS) stages is not established. During the Pliocene epoch (5.3 to 2.6 million years ago (Ma)),

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1452-471: The North Atlantic and North Pacific Ocean beds. Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have accelerated on the disappearance of forests and the spread of grasslands and savannas. During the Pliocene the earth climate system response shifted from a period of high frequency-low amplitude oscillation dominated by

1518-741: The Oligocene and reached its maximum during the Miocene . Together with the Oka Plateau, the Azas Plateau forms the East Sayan province of the Baikal Rift Zone. Activity in the Azas Plateau has been influenced by a tectonic graben in the area. The Azas Plateau is the largest lava field in the Tuva volcanic province. The Jom-Bolok volcanic field may be related to the Azas Plateau. A large lava field with thicknesses of c. 250 metres (820 ft) formed during

1584-489: The hominin Australopithecus anamensis in the early Pliocene, around 4.2 million years ago. The second is the appearance of Homo , the genus that includes modern humans and their closest extinct relatives, near the end of the Pliocene at 2.6 million years ago. Key traits that evolved among hominins during the Pliocene include terrestrial bipedality and, by the end of the Pliocene, encephalized brains (brains with

1650-634: The savannah hypothesis . This proposes that the evolution of terrestrial bipedality and other traits was an adaptive response to Pliocene climate change that transformed forests into more open savannah . This was championed by Grafton Elliot Smith in his 1924 book, The Evolution of Man , as "the unknown world beyond the trees", and was further elaborated by Raymond Dart as the killer ape theory . Other scientists, such as Sherwood L. Washburn , emphasized an intrinsic model of hominin evolution. According to this model, early evolutionary developments triggered later developments. The model placed little emphasis on

1716-493: The weasel family diversified, and dogs and short-faced bears did well. Ground sloths , huge glyptodonts , and armadillos came north with the formation of the Isthmus of Panama. The latitudinal diversity gradient among terrestrial North American mammals became established during this epoch some time after 4 Ma. In Eurasia rodents did well, while primate distribution declined. Elephants , gomphotheres and stegodonts were successful in Asia (the largest land mammals of

1782-465: The 41,000-year period of Earth's obliquity to one of low-frequency, high-amplitude oscillation dominated by the 100,000-year period of the orbital eccentricity characteristic of the Pleistocene glacial-interglacial cycles. During the late Pliocene and early Pleistocene, 3.6 to 2.6 Ma, the Arctic was much warmer than it is at the present day (with summer temperatures some 8 °C warmer than today). That

1848-421: The Baikal Rift Zone have erupted the same rocks. These rocks are alkaline and their texture is aphyric . Minerals contained in the rocks include augite , clinopyroxene , olivine , plagioclase , titanium -containing magnetite and nepheline in the more alkaline rocks. The total volume of volcanic rocks is about 600 cubic kilometres (140 cu mi). Hematite is present in the rocks and gives many tuyas

1914-549: The Bii-Khem valley are even younger than the Ulug-Arginskii volcano. It is possible that when eruptions in the Azas Plateau occurred beneath ice, they caused floods of glacial meltwater called Jokulhlaup ; corresponding landforms have been found at Derbi-Taiga and Shivit-Taiga volcanoes. Pliocene The Pliocene ( / ˈ p l aɪ . ə s iː n , ˈ p l aɪ . oʊ -/ PLY -ə-seen, PLY -oh- ; also Pleiocene )

1980-623: The Cretaceous and the early Cenozoic . This may have contributed to further cooling of the oceans worldwide. The Pliocene seas were alive with sea cows , seals , sea lions , sharks and whales . Lava lake Lava lakes are large volumes of molten lava , usually basaltic , contained in a volcanic vent, crater , or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (sometimes referred to as frozen lava lakes ). Lava lakes can form in three ways: Lava lakes occur in

2046-580: The Earth's climate became cooler and drier, as well as more seasonal, marking a transition between the relatively warm Miocene to the cooler Pleistocene . However, the beginning of the Pliocene was marked by an increase in global temperatures relative to the cooler Messinian . This increase was related to the 1.2 million year obliquity amplitude modulation cycle . By 3.3-3.0 Ma, during the Mid-Piacenzian Warm Period (mPWP), global average temperature

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2112-417: The East Sayan mountains during the Pleistocene. When volcanoes erupt into ice, the ice melts and volcanic structures named tuyas can form in meltwater lakes. Runny lavas can form such edifices, which tend to have steep slopes, only when trapped within ice. During tuya activity, the subaqueous activity forms hyaloclastite and when the activity occurs in the air lava flows are formed, including lava deltas. Some of

2178-411: The Late Pliocene, when the largest eruptions took place. These flows reached a thickness of approximately 250 metres (820 ft). Nine volcanoes bearing evidence of having formed beneath ice are found in the southeastern part of the field. Volcanoes on the plateau are about 400–600 metres (1,300–2,000 ft) high and have the form of tables. Ash cones formed on the individual edifices. The lava flows on

2244-579: The Oka plateau. The Azas trough formed in the Miocene-Pliocene. The first volcanic activity beginning 2 million years ago formed voluminous lava flows from fissure vents . Later the activity focused on deep-seated lineaments. Volcanic activity between 1.65 - 1.75 mya occurred beneath ice in the ancient valleys of the Bii Khem river. In the middle-late Pleistocene volcanism occurred in the southeastern parts of

2310-503: The Pliocene also included the Gelasian Stage, which lasted from 2.59 to 1.81 Ma, and is now included in the Pleistocene. As with other older geologic periods, the geological strata that define the start and end are well-identified but the exact dates of the start and end of the epoch are slightly uncertain. The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between

2376-613: The Pliocene contains the Dacian (roughly equal to the Zanclean) and Romanian (roughly equal to the Piacenzian and Gelasian together) stages. As usual in stratigraphy, there are many other regional and local subdivisions in use. In Britain , the Pliocene is divided into the following stages (old to young): Gedgravian, Waltonian , Pre-Ludhamian, Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian, Pastonian and Beestonian . In

2442-503: The Pliocene were such proboscideans as Deinotherium , Anancus , and Mammut borsoni , ) though proboscidean diversity declined significantly during the Late Pliocene. Hyraxes migrated north from Africa. Horse diversity declined, while tapirs and rhinos did fairly well. Bovines and antelopes were successful; some camel species crossed into Asia from North America. Hyenas and early saber-toothed cats appeared, joining other predators including dogs, bears, and weasels. Africa

2508-533: The Western Atlantic, assemblages of bivalves exhibited remarkable stasis with regards to their basal metabolic rates throughout the various climatic changes of the Pliocene. The Pliocene was a high water mark for species diversity among Caribbean corals. From 5 to 2 Ma, coral species origination rates were relatively high in the Caribbean, although a noticeable extinction event and drop in diversity occurred at

2574-531: The abundance of C 4 plants across the region. In the Loess Plateau , δ13C values of occluded organic matter increased by 2.5% while those of pedogenic carbonate increased by 5% over the course of the Late Miocene and Pliocene, indicating increased aridification. Further aridification of Central Asia was caused by the development of Northern Hemisphere glaciation during the Late Pliocene. A sediment core from

2640-718: The climate cooled. Venomous snake genera continued to increase as more rodents and birds evolved. Rattlesnakes first appeared in the Pliocene. The modern species Alligator mississippiensis , having evolved in the Miocene, continued into the Pliocene, except with a more northern range; specimens have been found in very late Miocene deposits of Tennessee . Giant tortoises still thrived in North America, with genera like Hesperotestudo . Madtsoid snakes were still present in Australia. The amphibian order Allocaudata became extinct. In

2706-401: The conduit and, potentially, exsolution of bubbles within the magma reservoir. Superimposed upon this is the effect of bubbles rising through the liquid, and coalescence of bubbles within the conduit. The interactions of these effects can create either a steady-state recirculating lake, or a lake level that periodically rises and then falls. Persistent lava lakes are a rare phenomenon. Only

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2772-475: The early-mid Pliocene (5 Ma – 3 Ma), after three-million-year intervals with modern or glacial ice volume became longer and collapse occurs only at times when warmer global temperature coincide with strong austral summer insolation anomalies. Continents continued to drift , moving from positions possibly as far as 250 km from their present locations to positions only 70 km from their current locations. South America became linked to North America through

2838-558: The end of this interval. Oceans continued to be relatively warm during the Pliocene, though they continued cooling. The Arctic ice cap formed , drying the climate and increasing cool shallow currents in the North Atlantic. Deep cold currents flowed from the Antarctic. The formation of the Isthmus of Panama about 3.5 million years ago cut off the final remnant of what was once essentially a circum-equatorial current that had existed since

2904-542: The field. Some dates obtained on edifices in the Azas Plateau are 725,000 ± 50,000 - 760,000 ± 50,000 years for Derbi-Taiga, 600,000 - 560,000 years for Kadyr-Sugskii, 600,000 - 290,000 for some volcanoes surrounding Derbi-Taiga, 350,000 - 290,000 for Yurdawa between Derbi-Taiga and Shivit-Taiga, 225,000 ± 50,000 for Ploskii, 150,000 ± 50,000 for Kokhemskii, 130,000 ± 40,000 - 110,000 ± 000 for Shivit-Taiga, 75,000 ± 40,000 for Priozernyi, 60,000 ± 40,000 for Sorug-Chushku-Uzu and 48,000 ± 20,000 for Ulug-Arginskii. Some lava flows in

2970-543: The first time since the Cretaceous , with North American rodents and primates mixing with southern forms. Litopterns and the notoungulates , South American natives, were mostly wiped out, except for the macrauchenids and toxodonts , which managed to survive. Small weasel-like carnivorous mustelids , coatis and short-faced bears migrated from the north. Grazing glyptodonts , browsing giant ground sloths and smaller caviomorph rodents , pampatheres , and armadillos did

3036-413: The influence of seasonal variation. More recent research has emphasized the variability selection hypothesis, which proposes that variability in climate fostered development of hominin traits. Improved climate proxies show that the Pliocene climate of east Africa was highly variable, suggesting that adaptability to varying conditions was more important in driving hominin evolution than the steady pressure of

3102-545: The northern South China Sea shows an increase in dust storm activity during the middle Pliocene. The South Asian Summer Monsoon (SASM) increased in intensity after 2.95 Ma, likely because of enhanced cross-equatorial pressure caused by the reorganisation of the Indonesian Throughflow. In the south-central Andes , an arid period occurred from 6.1 to 5.2 Ma, with another occurring from 3.6 to 3.3 Ma. These arid periods are coincident with global cold periods, during which

3168-724: The now-separated Atlantic Ocean. Africa 's collision with Europe formed the Mediterranean Sea , cutting off the remnants of the Tethys Ocean . The border between the Miocene and the Pliocene is also the time of the Messinian salinity crisis . During the Late Pliocene, the Himalayas became less active in their uplift, as evidenced by sedimentation changes in the Bengal Fan . The land bridge between Alaska and Siberia ( Beringia )

3234-504: The onset of continental glaciation in the Arctic, suggesting that vegetation changes in Australia during the Pliocene behaved similarly to during the Late Pleistocene and were likely characterised by comparable cycles of aridity and humidity. The equatorial Pacific Ocean sea surface temperature gradient was considerably lower than it is today. Mean sea surface temperatures in the east were substantially warmer than today but similar in

3300-400: The opposite, migrating to the north and thriving there. The marsupials remained the dominant Australian mammals, with herbivore forms including wombats and kangaroos , and the huge Diprotodon . Carnivorous marsupials continued hunting in the Pliocene, including dasyurids , the dog-like thylacine and cat-like Thylacoleo . The first rodents arrived in Australia. The modern platypus ,

3366-602: The position of the Southern Hemisphere westerlies shifted northward and disrupted the South American Low Level Jet, which brings moisture to southeastern South America. From around 3.8 Ma to about 3.3 Ma, North Africa experienced an extended humid period. In northwestern Africa, tropical forests extended up to Cape Blanc during the Zanclean until around 3.5 Ma. During the Piacenzian, from about 3.5 to 2.6 Ma,

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3432-505: The recent", referring to the essentially modern marine mollusc fauna. In the official timescale of the ICS , the Pliocene is subdivided into two stages . From youngest to oldest they are: The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene. In the system of In the Paratethys area (central Europe and parts of western Asia)

3498-499: The region was forested at irregular intervals and contained a significant Saharan palaeoriver until 3.35 Ma, when trade winds began to dominate over fluvial transport of pollen. Around 3.26 Ma, a strong aridification event that was followed by a return to more humid conditions, which was itself followed by another aridification around 2.7 Ma. From 2.6 to 2.4 Ma, vegetation zones began repeatedly shifting latitudinally in response to glacial-interglacial cycles. The climate of eastern Africa

3564-518: The scene. Bears, dogs and weasels (originally from North America) joined cats, hyenas and civets as the African predators, forcing hyenas to adapt as specialized scavengers. Most mustelids in Africa declined as a result of increased competition from the new predators, although Enhydriodon omoensis remained an unusually successful terrestrial predator. South America was invaded by North American species for

3630-431: The size is measured. Shivit-Taiga covers a surface of 100 square kilometres (39 sq mi) and is 500 metres (1,600 ft) high. This edifice is a stratovolcano and it features two craters with diameters of 250 metres (820 ft) and 100 metres (330 ft). Lava lakes formed in two craters on the volcano. Shivit-Taiga too is accompanied by a topography that indicates that ancient floods passed there. Kokhemskii

3696-400: The surrounding environment. Anthropologists tended to focus on intrinsic models while geologists and vertebrate paleontologists tended to put greater emphasis on habitats. Alternatives to the savanna hypothesis include the woodland/forest hypothesis, which emphasizes the evolution of hominins in closed habitats, or hypotheses emphasizing the influence of colder habitats at higher latitudes or

3762-510: The table-shaped volcanoes also display rounded hollows. Many volcanoes appear to be part of a lineament. Volcanism may be influenced by strike-slip faults associated with the Jom-Bolok fault . Individual volcanoes in the Azas Plateau volcanic field include the Derbi-Taiga tuya ( 52°22′15″N 98°14′8″E  /  52.37083°N 98.23556°E  / 52.37083; 98.23556 ), which

3828-685: The tuyas in the Azas Plateau may have formed through complex eruptive processes. Based on the tuyas of the Tuvan field, it has been determined that ice thicknesses in the area exceeded 700 metres (2,300 ft) and that at least three different ice ages occurred in the field. The tuyas in the Azas plateau have been compared to volcanic edifices in the Valles Marineris on Mars . Non-tuya volcanic ice interaction landforms are also found, such as Albine-Bondok, Charash-Dag and Sagan which are subglacial mounds. Glaciation

3894-504: The warmer Miocene and the relatively cooler Pleistocene. The upper boundary was set at the start of the Pleistocene glaciations. Charles Lyell (later Sir Charles) gave the Pliocene its name in Principles of Geology (volume 3, 1833). The word pliocene comes from the Greek words πλεῖον ( pleion , "more") and καινός ( kainos , "new" or "recent") and means roughly "continuation of

3960-495: The west. This condition has been described as a permanent El Niño state, or “El Padre.” Several mechanisms have been proposed for this pattern, including increased tropical cyclone activity . The extent of the West Antarctic Ice Sheet oscillated at the 40 kyr period of Earth's obliquity. Ice sheet collapse occurred when the global average temperature was 3 °C warmer than today and carbon dioxide concentration

4026-470: Was 2–3 °C higher than today, while carbon dioxide levels were the same as today (400 ppm). Global sea level was about 25 m higher, though its exact value is uncertain. The northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma. The formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in

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4092-425: Was already in progress under marine isotope stage 5 (127,000 - 71,000 years ago) and by the stage 4 (71,000 - 57,000 years ago) it was continuous over the Azas Plateau. Glacier retreat was underway by the isotope stage 3 (57,000 - 24,000 years ago), when some volcanoes formed in the air. Volcanism is overall basaltic , volcanic rocks erupted by the Azas Plateau include basalt and trachybasalt . Other volcanoes in

4158-506: Was at 400 ppmv. This resulted in open waters in the Ross Sea . Global sea-level fluctuation associated with ice-sheet collapse was probably up to 7 meters for the west Antarctic and 3 meters for the east Antarctic. Model simulations are consistent with reconstructed ice-sheet oscillations and suggest a progression from a smaller to a larger West Antarctic ice sheet in the last 5 million years. Intervals of ice sheet collapse were much more common in

4224-480: Was dominated by hoofed animals, and primates continued their evolution, with australopithecines (some of the first hominins ) and baboon-like monkeys such as the Dinopithecus appearing in the late Pliocene. Rodents were successful, and elephant populations increased. Cows and antelopes continued diversification and overtook pigs in numbers of species. Early giraffes appeared. Horses and modern rhinos came onto

4290-452: Was first flooded near the start of the Pliocene, allowing marine organisms to spread between the Arctic and Pacific Oceans. The bridge would continue to be periodically flooded and restored thereafter. Pliocene marine formations are exposed in northeast Spain , southern California , New Zealand , and Italy . During the Pliocene parts of southern Norway and southern Sweden that had been near sea level rose. In Norway this rise elevated

4356-541: Was very similar to what it is today. Unexpectedly, the expansion of grasslands in eastern Africa during this epoch appears to have been decoupled from aridification and not caused by it, as evidenced by their asynchrony. Southwestern Australia hosted heathlands , shrublands , and woodlands with a greater species diversity compared to today during the Middle and Late Pliocene. Three different aridification events occurred around 2.90, 2.59, and 2.56 Ma, and may have been linked to

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