6.2 Neogene period
10 min read•august 20, 2024
The period, spanning from 23.03 to 2.58 million years ago, marked significant changes in Earth's climate, geography, and life forms. This second period of the Cenozoic Era saw the expansion of , diversification of mammals, and evolution of early hominins.
Divided into the and epochs, the Neogene witnessed trends, sea level fluctuations, and tectonic events. These changes shaped modern ecosystems, leading to the emergence of C4 plants, grazing mammals, and the foundation for human evolution.
Neogene period overview
- The Neogene period is the second period of the Cenozoic Era, spanning from 23.03 million years ago to 2.58 million years ago
- It follows the Paleogene period and is succeeded by the Quaternary period
- The Neogene period witnessed significant changes in climate, geography, and biotic evolution that shaped the modern world
Miocene and Pliocene epochs
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- The Neogene period is divided into two epochs: the Miocene (23.03 to 5.333 million years ago) and the Pliocene (5.333 to 2.58 million years ago)
- The Miocene epoch is characterized by warmer climates, the expansion of grasslands, and the diversification of mammals
- The Pliocene epoch saw a gradual cooling trend, the emergence of modern biomes, and the evolution of early hominins
Neogene climate and geography
- The Neogene period experienced significant climatic and geographic changes that influenced the distribution and evolution of flora and fauna
- These changes included global cooling, sea level fluctuations, and tectonic events that altered landscapes and created new habitats
Miocene climatic optimum
- The occurred around 17 to 15 million years ago, characterized by warm temperatures and high sea levels
- This period supported the expansion of tropical and subtropical forests and the diversification of plant and animal species adapted to these environments
Mid-Miocene disruption
- The , around 14 million years ago, marked a shift towards cooler and drier conditions
- This event led to the expansion of grasslands and savannas, particularly in the Northern Hemisphere, and the evolution of grazing mammals
Late Miocene cooling
- The late Miocene, from around 11 to 5 million years ago, saw a gradual cooling trend and increasing aridity
- This period witnessed the further expansion of grasslands, the evolution of in plants, and the diversification of mammals adapted to open environments
Messinian salinity crisis
- The occurred during the late Miocene, around 6 million years ago, when the Mediterranean Sea became isolated from the Atlantic Ocean
- This event led to the desiccation of the Mediterranean basin, the deposition of thick evaporite layers, and significant changes in the regional climate and biota
Pliocene climate
- The Pliocene epoch was characterized by a gradual cooling trend, with intermittent warm periods
- The global climate was generally warmer and more humid than the present, with higher sea levels and a reduced extent of polar ice caps
- The Pliocene climate supported the expansion of grasslands and savannas, as well as the evolution of modern biomes and ecosystems
Neogene flora and fauna
- The Neogene period witnessed significant changes in flora and fauna, driven by climatic and geographic factors
- The diversification and evolution of plants and animals during this period laid the foundation for modern ecosystems and biodiversity
Miocene flora
- The Miocene epoch saw the expansion of grasslands and savannas, particularly in the Northern Hemisphere, due to increasing aridity and cooling temperatures
- C4 photosynthesis evolved in plants during the late Miocene, enabling them to thrive in warm, dry conditions
- Examples of Miocene flora include the spread of grasses (Poaceae), the diversification of legumes (Fabaceae), and the evolution of succulent plants (Cactaceae)
Pliocene flora
- The Pliocene epoch witnessed the further expansion of grasslands and savannas, as well as the development of modern biomes and plant communities
- The cooler and drier climate favored the evolution of plants adapted to seasonal changes and water stress
- Examples of Pliocene flora include the spread of C4 grasses, the diversification of herbaceous plants, and the evolution of modern tree genera (Quercus, Pinus)
Miocene fauna
- The Miocene epoch saw the diversification of mammals, particularly those adapted to grassland and savanna habitats
- This period witnessed the evolution of large herbivores (, , ), carnivores, and primates
- Examples of Miocene fauna include the giant ground sloth (), the (Smilodon), and the early horse ()
Pliocene fauna
- The Pliocene epoch was characterized by the continued diversification of mammals and the emergence of modern faunal assemblages
- This period saw the evolution of early hominins, as well as the spread of megafauna adapted to cooler climates
- Examples of Pliocene fauna include the woolly mammoth (), the giant short-faced bear (), and the early hominin ()
Mammalian evolution in the Neogene
- The Neogene period witnessed significant evolutionary changes in mammals, driven by climatic and environmental factors
- Key mammalian groups, such as proboscideans, perissodactyls, artiodactyls, , and primates, underwent diversification and adaptation to new habitats
Proboscidean diversity and distribution
- Proboscideans, including elephants and their relatives, diversified during the Neogene period
- The Miocene epoch saw the evolution of various proboscidean lineages, such as gomphotheres, mammutids, and deinotheres, adapted to different habitats and diets
- During the Pliocene, proboscideans spread to new regions, including Africa, Asia, and the Americas, and evolved into modern forms like the woolly mammoth (Mammuthus primigenius)
Perissodactyl evolution
- Perissodactyls, including horses, rhinoceroses, and tapirs, underwent significant evolutionary changes during the Neogene
- The Miocene epoch witnessed the diversification of equids, with the evolution of grazing adaptations and the emergence of the modern horse lineage (Equus)
- Rhinoceroses and tapirs also evolved and spread to new regions during the Miocene and Pliocene, adapting to various habitats and climates
Artiodactyl diversification
- Artiodactyls, including cattle, deer, and pigs, diversified during the Neogene in response to the expansion of grasslands and savannas
- The Miocene saw the evolution of various artiodactyl lineages, such as bovids, cervids, and suids, with adaptations for grazing and browsing
- During the Pliocene, artiodactyls continued to evolve and spread to new regions, with the emergence of modern genera and species
Carnivoran adaptations
- Carnivorans, including cats, dogs, and bears, underwent evolutionary adaptations during the Neogene to exploit new prey resources and habitats
- The Miocene witnessed the evolution of saber-toothed cats (Machairodontinae), adapted for hunting large prey in open environments
- During the Pliocene, carnivorans continued to diversify, with the emergence of modern lineages like wolves, foxes, and big cats
Primate evolution and hominins
- Primates, including monkeys, apes, and early hominins, evolved and diversified during the Neogene period
- The Miocene saw the evolution of various primate lineages, such as the first apes (Proconsulidae) and the ancestors of modern monkeys and gibbons
- The Pliocene witnessed the emergence of early hominins, such as Ardipithecus and Australopithecus, setting the stage for human evolution
Neogene mass extinctions and turnovers
- The Neogene period experienced several and faunal turnovers, driven by climatic and environmental changes
- These events shaped the composition and distribution of flora and fauna, leading to the emergence of modern ecosystems
Mid-Miocene extinction events
- The mid-Miocene disruption, around 14 million years ago, coincided with extinctions and faunal turnovers in various regions
- This event affected marine and terrestrial ecosystems, with the decline of reef-building corals and the turnover of mammalian faunas in Europe and Asia
Late Miocene extinctions
- The late Miocene, particularly the Messinian stage, witnessed significant extinctions and faunal changes
- The Messinian salinity crisis in the Mediterranean region led to the extinction of many marine species and the turnover of terrestrial faunas
- and aridification also contributed to the decline and extinction of various mammalian lineages
Pliocene extinctions and faunal changes
- The Pliocene epoch saw further extinctions and faunal turnovers, particularly during the Pliocene-Pleistocene transition
- Cooling climates and the onset of glacial-interglacial cycles led to the extinction of many species adapted to warmer conditions
- The Pliocene also witnessed the turnover of mammalian faunas, with the decline of archaic forms and the spread of modern lineages
Neogene marine life
- The Neogene period witnessed significant changes in marine ecosystems, driven by climatic, oceanographic, and evolutionary factors
- Marine biota adapted to changing conditions, with the evolution of new species and the restructuring of marine communities
Miocene marine biota
- The Miocene epoch saw the diversification of various marine groups, such as mollusks, echinoderms, and foraminifera
- Reef ecosystems flourished during the Miocene climatic optimum, with the expansion of coral reefs and associated marine life
- The mid-Miocene disruption and the Messinian salinity crisis led to extinctions and turnover in marine faunas
Pliocene marine ecosystems
- The Pliocene epoch witnessed the recovery and restructuring of marine ecosystems following the Messinian salinity crisis
- Cooler climates and changes in ocean circulation patterns influenced the distribution and composition of marine biota
- The Pliocene saw the evolution of modern marine species and the establishment of present-day marine biogeographic patterns
Evolution of marine mammals
- Marine mammals, including cetaceans (whales, dolphins) and pinnipeds (seals, sea lions), underwent significant evolution during the Neogene
- The Miocene epoch saw the diversification of various cetacean lineages, such as baleen whales (Mysticeti) and toothed whales (Odontoceti)
- Pinnipeds also evolved and diversified during the Miocene and Pliocene, adapting to different marine habitats and climates
Neogene geological events and processes
- The Neogene period was characterized by significant geological events and processes that shaped the Earth's surface and influenced biotic evolution
- These events included tectonic activity, volcanic episodes, and sea level fluctuations
Tectonic activity and orogeny
- The Neogene witnessed ongoing tectonic activity and mountain building (orogeny) in various regions
- The formation of the Himalayan-Tibetan plateau intensified during the Miocene, influencing regional and global climate patterns
- Other notable tectonic events included the uplift of the Andes, the opening of the Gulf of California, and the collision of the African and Eurasian plates
Volcanic episodes and impacts
- Volcanic activity and impacts from extraterrestrial bodies occurred during the Neogene, affecting climate and biota
- The Miocene epoch saw significant volcanic eruptions, such as the Columbia River Basalt Group in North America and the Yellowstone hotspot
- The Pliocene witnessed the formation of the Yellowstone Caldera and the eruption of the Huckleberry Ridge Tuff
Sea level fluctuations
- The Neogene period experienced significant sea level fluctuations, driven by changes in global climate and ice volume
- The Miocene climatic optimum was characterized by high sea levels, leading to the expansion of shallow marine habitats and the diversification of marine biota
- The late Miocene and Pliocene saw a gradual fall in sea levels, punctuated by short-term fluctuations related to glacial-interglacial cycles
Neogene fossil record and localities
- The Neogene period has a rich and diverse fossil record, providing insights into the evolution and paleoecology of flora and fauna
- Numerous fossil localities around the world have yielded important Miocene and Pliocene fossils, contributing to our understanding of this period
Key Miocene fossil sites
- The Miocene epoch has several notable fossil localities, such as the Messel Pit in Germany, known for its exceptionally preserved fossils of early Miocene plants and animals
- The Siwalik Hills in Pakistan and India have yielded a rich record of Miocene mammals, including early primates and proboscideans
- The Ashfall Fossil Beds in Nebraska, USA, preserve a unique assemblage of Miocene mammals killed by volcanic ash
Important Pliocene fossil localities
- The Pliocene epoch also has significant fossil sites, such as the Turkana Basin in Kenya, which has yielded fossils of early hominins and a diverse mammalian fauna
- The Hagerman Fossil Beds in Idaho, USA, are known for their well-preserved Pliocene horses and other mammals
- The Yushe Basin in China has provided insights into Pliocene mammalian evolution and biogeography in Asia
Taphonomy and preservation in the Neogene
- Taphonomy, the study of how organisms become fossilized, plays a crucial role in understanding the Neogene fossil record
- Various taphonomic processes, such as burial, diagenesis, and weathering, influence the preservation and distribution of Neogene fossils
- Exceptional preservation, such as that found in Lagerstätten like the Messel Pit, provides detailed insights into the anatomy and paleoecology of Neogene organisms
Transition to the Quaternary
- The end of the Neogene period marks the transition to the Quaternary, a time of significant climatic and biotic changes
- This transition is characterized by the onset of glacial-interglacial cycles and the evolution of modern ecosystems and species
Pliocene-Pleistocene boundary
- The Pliocene-Pleistocene boundary, set at 2.58 million years ago, marks the beginning of the Quaternary period
- This boundary is defined by the appearance of the planktonic foraminifer Globorotalia truncatulinoides in marine sediments
- The Pliocene-Pleistocene boundary coincides with significant changes in global climate, sea levels, and biotic turnover
Onset of glacial-interglacial cycles
- The transition from the Pliocene to the Pleistocene is marked by the onset of large-scale glacial-interglacial cycles
- These cycles, driven by variations in Earth's orbital parameters (Milankovitch cycles), led to the repeated growth and decay of continental ice sheets
- The onset of glacial-interglacial cycles had profound impacts on global climate, sea levels, and the distribution and evolution of flora and fauna
- The Quaternary period, which follows the Neogene, is characterized by the continued influence of these glacial-interglacial cycles on Earth's ecosystems and biota
Key Terms to Review (32)
Adaptive Radiation: Adaptive radiation is an evolutionary process in which organisms rapidly diversify into a wide variety of forms and species, often when they colonize a new environment or after a mass extinction. This phenomenon allows groups of related species to adapt to different ecological niches, showcasing their ability to exploit various resources and habitats.
Arctodus simus: Arctodus simus, commonly known as the giant short-faced bear, is an extinct species of bear that lived during the late Pleistocene epoch in North America. This species is notable for its remarkable size and adaptations that suggest it was a fast and agile predator, which connects to its ecological role during the Neogene period as a dominant carnivore in its environment.
Artiodactyls: Artiodactyls, also known as even-toed ungulates, are a group of hoofed mammals characterized by having an even number of toes on each foot, typically two or four. This group includes animals like deer, pigs, and cattle, which are significant in understanding evolutionary adaptations during the Neogene period as they evolved in response to changing environments and diverse ecosystems.
Australopithecus afarensis: Australopithecus afarensis is an extinct hominin species that lived approximately 3.9 to 2.9 million years ago in East Africa, known for its small brain size and bipedal locomotion. This species is crucial for understanding the evolutionary transition from early primates to modern humans, showcasing both ape-like and human-like traits, and helping to illuminate the timeline of human evolution during the Neogene period.
C4 Photosynthesis: C4 photosynthesis is a metabolic pathway that enables plants to efficiently fix carbon dioxide in warm and dry environments, reducing photorespiration and improving water-use efficiency. This process is especially significant in tropical and subtropical regions, where it allows certain plants, such as maize and sugarcane, to thrive under high temperatures and light intensity.
Carnivorans: Carnivorans are a group of mammals belonging to the order Carnivora, primarily characterized by their meat-eating habits, though some species also have omnivorous diets. This diverse group includes familiar animals such as dogs, cats, bears, and weasels, which have evolved various adaptations for hunting and feeding on other animals. During the Neogene period, carnivorans saw significant diversification and expansion across different ecosystems, becoming key players in their respective environments.
David Jablonski: David Jablonski is a prominent paleontologist known for his extensive research on macroevolution, biodiversity, and the fossil record. His work has significantly contributed to understanding how environmental changes and extinction events shape the evolution of life on Earth. He is especially recognized for integrating ecological concepts into paleontological studies, particularly in relation to the Neogene period.
Expansion of grasses: The expansion of grasses refers to the significant increase in grassland ecosystems that occurred during the Neogene period, particularly in the Miocene epoch. This shift led to a transformation of terrestrial landscapes, influencing both climate and biodiversity, as well as the evolution of various herbivorous mammals that adapted to these new habitats.
Global cooling: Global cooling refers to a significant decrease in Earth's average surface temperature over a prolonged period. This phenomenon has been associated with various climatic events and geological periods, influencing the evolution of life and ecosystems. Throughout Earth's history, global cooling has played a critical role in shaping both terrestrial and marine environments, leading to major shifts in biodiversity and species distribution.
Grasslands: Grasslands are vast ecosystems characterized by dominant grasses, few trees, and a rich diversity of herbaceous plants. These regions play a crucial role in the environment, supporting a wide range of wildlife and influencing global carbon cycles, especially during the Neogene period when significant climate changes shaped their evolution and distribution.
Late miocene cooling: Late Miocene cooling refers to a significant drop in global temperatures that occurred during the late Miocene epoch, roughly between 11 to 5 million years ago. This climatic shift marked a transition toward more arid conditions and was instrumental in shaping the evolutionary trajectory of both flora and fauna, as many species adapted to changing environments or faced extinction due to habitat loss.
Mammuthus primigenius: Mammuthus primigenius, commonly known as the woolly mammoth, is a species of mammoth that roamed the northern parts of North America, Europe, and Asia during the late Pleistocene epoch. This iconic animal is significant for its adaptations to cold environments and its eventual extinction during the Holocene, which marks a pivotal transition in Earth's climatic and biological history.
Marine environments: Marine environments refer to ecosystems that are dominated by saltwater, including oceans, seas, and coastal regions. These environments play a crucial role in the global climate, biodiversity, and the geological processes that contribute to the fossil record. They are vital for understanding various aspects of paleontology, particularly in relation to fossilization processes, periods of geological time, and the evolution of specific organisms.
Mass extinction events: Mass extinction events are significant and rapid decreases in biodiversity on Earth, characterized by the extinction of a large number of species in a relatively short geological time frame. These events have profound effects on ecosystems, leading to shifts in the dominance of certain groups of organisms and altering the trajectory of evolutionary processes. They are crucial for understanding fossil preservation, geologic time units, and the history of life on Earth.
Mastodon: Mastodon refers to a large, extinct elephant-like mammal that roamed North America, Europe, and Asia during the late Cenozoic Era, particularly thriving in the Neogene period. These fascinating creatures belonged to the family Mammutidae and were characterized by their long tusks and a more robust body compared to their distant relatives, the woolly mammoth. Mastodons lived in a variety of habitats, including forests and grasslands, and are important for understanding prehistoric ecosystems and the impact of climate change on megafauna.
Megatherium: Megatherium, commonly known as the giant ground sloth, was a large herbivorous mammal that roamed South America during the Late Pleistocene and early Holocene epochs. This massive creature was notable for its impressive size, reaching up to 6 meters long and weighing over a ton, making it one of the largest terrestrial mammals of its time. The Megatherium played a significant role in the ecosystems of the Neogene period, particularly in shaping vegetation and interacting with other species.
Merychippus: Merychippus is an extinct genus of horse that lived during the late Miocene epoch, approximately 20 to 10 million years ago. This species is significant as it represents a key evolutionary stage in the development of modern horses, showcasing important adaptations for grazing and a shift in lifestyle as grasslands expanded during the Neogene period.
Messinian Salinity Crisis: The Messinian Salinity Crisis refers to a significant geological event during the late Miocene epoch, characterized by the dramatic evaporation of the Mediterranean Sea, leading to an increase in salinity and the deposition of thick salt layers. This crisis had profound impacts on marine life and sedimentation patterns, fundamentally altering the Mediterranean ecosystem and its connectivity to the Atlantic Ocean.
Mid-miocene disruption: The mid-miocene disruption refers to a significant climatic and ecological shift that occurred during the mid-Miocene epoch, around 14 to 12 million years ago. This period was marked by drastic changes in global temperatures, sea levels, and biodiversity, which had profound effects on terrestrial and marine ecosystems.
Miocene: The Miocene is a geological epoch that lasted from about 23 million to 5.3 million years ago, forming the first part of the Neogene period. During this time, the Earth underwent significant climatic changes, leading to the expansion of grasslands and the diversification of mammal species. It played a crucial role in shaping both terrestrial ecosystems and the evolutionary trajectory of mammals.
Miocene Climatic Optimum: The Miocene Climatic Optimum refers to a significant period during the Miocene epoch, approximately 16 to 11 million years ago, characterized by warmer global temperatures and high levels of biodiversity. This climatic phase saw the expansion of forests and grasslands, influencing the evolution and distribution of many plant and animal species, and played a crucial role in shaping the ecosystems that would follow in later periods.
Neogene: The Neogene is a geologic period that spans from about 23 million to 2.6 million years ago, marking a significant phase in Earth's history characterized by major climate changes and the evolution of modern flora and fauna. This period is divided into two epochs: the Miocene and the Pliocene, which saw the rise of many mammalian species and important geological developments that shaped the planet's surface and ecosystems.
Perissodactyls: Perissodactyls are a group of hoofed mammals characterized by an odd number of toes, with the most prominent being the third toe. This order includes animals like horses, rhinoceroses, and tapirs, which evolved during the Paleogene and diversified significantly during the Neogene period. Their unique limb structure and adaptations for herbivory allowed them to thrive in various ecological niches, making them essential components of their ecosystems.
Pliocene: The Pliocene is a geological epoch that lasted from about 5.3 to 2.6 million years ago, marking the final period of the Neogene period before the onset of the Quaternary. This epoch is characterized by significant climatic changes and the diversification of mammals and birds, along with the establishment of modern ecosystems.
Primate evolution: Primate evolution refers to the adaptive changes and diversification of primates, a group that includes lemurs, monkeys, apes, and humans, over millions of years. This evolutionary process involved various morphological, behavioral, and ecological adaptations in response to changing environments during key geological periods, including the Neogene. Understanding primate evolution provides insights into the origins of human traits and behaviors, as well as the ecological dynamics that shaped primate diversity.
Proboscideans: Proboscideans are a group of large mammals known for their elongated trunks, which are versatile appendages used for a variety of functions including feeding, grasping, and social interactions. This group primarily includes elephants and their extinct relatives like mammoths and mastodons. The evolution and diversity of proboscideans during the Neogene period reflect significant ecological changes and adaptations to varying environments.
Radiation of mammals: The radiation of mammals refers to the rapid diversification and evolutionary expansion of mammals into a wide variety of forms and ecological niches, which primarily occurred after the extinction of the dinosaurs at the end of the Cretaceous period. This event allowed mammals to evolve from small, nocturnal creatures into the dominant land vertebrates, leading to the emergence of many distinct groups such as primates, cetaceans, and ungulates during the Neogene period.
Radiometric dating: Radiometric dating is a scientific method used to determine the age of materials by measuring the radioactive decay of isotopes within them. This technique is crucial for establishing timelines in geology and paleontology, linking fossil records and geological events to specific time periods.
Saber-toothed cat: The saber-toothed cat, often exemplified by the species Smilodon, was a prehistoric carnivore known for its elongated canine teeth and robust build. These distinctive features allowed it to be a powerful predator during the Neogene period, adapting to various environments as it hunted large herbivores. The saber-toothed cat is significant for understanding the evolution of carnivorous mammals and the dynamics of prehistoric ecosystems.
Speciation: Speciation is the evolutionary process by which populations evolve to become distinct species. It involves the divergence of genetic lineages, often triggered by factors like geographical separation, ecological niches, or reproductive barriers, leading to the formation of new species. Understanding this concept helps explain the diversity of life on Earth and how different organisms adapt to their environments over time.
Stratigraphy: Stratigraphy is the branch of geology that studies rock layers (strata) and layering (stratification), primarily to understand the temporal and spatial relationships of geological formations. This field provides crucial insights into the Earth's history, including fossil records, which aid in understanding the processes of fossilization and preservation, and how these layers relate to different geological time units and significant periods in Earth's history.
William D. Hamilton: William D. Hamilton was a prominent British evolutionary biologist known for his groundbreaking work in the field of sociobiology and evolutionary theory, particularly in relation to kin selection. His ideas about how natural selection operates not just on individuals but also on genes laid the foundation for understanding social behavior in animals and humans alike. Hamilton's theories have profoundly influenced how we think about evolution, altruism, and the social structures within species.