The Carboniferous period, spanning 358.9 to 298.9 million years ago, was a time of extensive coal formation and life diversification on land. This era saw the rise of vast coal forests, seed plants, and early amniotes, setting the stage for future evolution.

Divided into the Mississippian and Pennsylvanian subperiods, the Carboniferous witnessed major climate shifts and continental reconfigurations. These changes led to the formation of the Appalachian Mountains and the assembly of Pangaea, shaping Earth's geography and biodiversity.

Carboniferous period overview

• The Carboniferous period, spanning from 358.9 to 298.9 million years ago, was a significant time in Earth's history characterized by extensive coal formation, diversification of life on land, and major climate changes
• This period witnessed the formation of vast coal forests, the evolution of seed plants, and the appearance of early amniotes and reptiles

Division into Mississippian and Pennsylvanian subperiods

• The Carboniferous is divided into two subperiods: the Mississippian (358.9 to 323.2 million years ago) and the Pennsylvanian (323.2 to 298.9 million years ago)
• The Mississippian is characterized by the development of extensive shallow seas, the diversification of marine life, and the emergence of early tetrapods
• The Pennsylvanian is marked by the formation of vast coal swamps, the evolution of seed plants, and the appearance of early amniotes and reptiles

Timespan and duration of Carboniferous

• The Carboniferous period lasted for approximately 60 million years, from 358.9 to 298.9 million years ago
• It follows the Devonian period and precedes the Permian period in the Paleozoic era

Paleogeography of Carboniferous

• The Carboniferous period witnessed significant changes in the configuration of continents and the formation of major mountain ranges, setting the stage for the assembly of the supercontinent Pangaea

Configuration of continents

• During the Carboniferous, the continents were in the process of assembling into the supercontinent Pangaea
• Laurussia, formed by the collision of Laurentia (North America) and Baltica (Europe), was located in the northern hemisphere
• Gondwana, a large landmass consisting of present-day South America, Africa, Australia, Antarctica, and India, was situated in the southern hemisphere

Appalachian Mountains formation

• The Carboniferous period saw the formation of the Appalachian Mountains, a major mountain range in eastern North America
• The Appalachian Mountains formed as a result of the collision between Laurussia and Gondwana during the assembly of Pangaea
• The mountain-building event, known as the Alleghenian orogeny, led to the uplift and deformation of sedimentary rocks, creating the Appalachian fold belt

Pangaea assembly

• The Carboniferous marked a significant step in the assembly of the supercontinent Pangaea
• The collision of Laurussia and Gondwana, along with the accretion of smaller landmasses, led to the formation of a single, large landmass
• The assembly of Pangaea had profound effects on global climate patterns, ocean circulation, and the distribution of life on Earth

Carboniferous climate

• The Carboniferous period experienced significant climate changes, including glaciation in the southern hemisphere and warm, humid conditions in the equatorial regions

Glaciation in southern hemisphere

• During the Carboniferous, extensive glaciation occurred in the southern hemisphere, particularly in Gondwana
• Glacial deposits and evidence of ice sheets have been found in present-day South America, Africa, Australia, and Antarctica
• The glaciation led to significant changes in sea level, with periods of glacial advance resulting in lowered sea levels and glacial retreat causing sea level rise

Equatorial climate conditions

• The equatorial regions during the Carboniferous experienced warm, humid conditions favorable for the growth of lush vegetation
• High atmospheric carbon dioxide levels and the absence of polar ice caps in the northern hemisphere contributed to the greenhouse climate
• The warm, moist climate supported the development of extensive coal forests, dominated by lycopsids, sphenopsids, and pteridosperms

Climate impact on flora and fauna

• The Carboniferous climate had a significant impact on the distribution and evolution of flora and fauna
• The warm, humid conditions in the equatorial regions supported the growth of dense coal forests, providing habitats for a diverse array of plant and animal life
• The glaciation in the southern hemisphere influenced the distribution of marine and terrestrial organisms, with some groups adapted to colder conditions while others were restricted to warmer regions

Carboniferous flora

• The Carboniferous period is known for its extensive coal forests, which were dominated by lycopsids, sphenopsids, and pteridosperms

Extensive coal forests

• Vast coal forests developed during the Carboniferous, particularly in the equatorial regions
• These forests were characterized by a high diversity of plant life, including lycopsids, sphenopsids, pteridosperms, and early seed plants
• The warm, humid climate and high atmospheric carbon dioxide levels supported the growth of these dense, swampy forests

Lycopsids, sphenopsids, and pteridosperms

• Lycopsids, such as Lepidodendron and Sigillaria, were dominant plants in the Carboniferous coal forests
• These plants were characterized by their tall, tree-like growth forms, with scaly bark and leaves arranged in spirals
• Sphenopsids, including Calamites and Sphenophyllum, were also common in the coal forests, with jointed stems and whorled leaves
• Pteridosperms, or seed ferns, were a diverse group of plants that bore seeds but retained fern-like foliage

Evolution of seed plants

• The Carboniferous period witnessed the evolution and diversification of seed plants
• Seed plants, such as Cordaites and early conifers, developed adaptations that allowed them to reproduce using seeds rather than spores
• The evolution of seeds provided plants with a more efficient means of dispersal and the ability to survive in a wider range of environments
• The appearance of seed plants set the stage for the eventual dominance of gymnosperms and angiosperms in the Mesozoic and Cenozoic eras

Carboniferous fauna

• The Carboniferous period saw a significant diversification of animal life, both in the oceans and on land

Diversification of insects

• Insects underwent a major diversification during the Carboniferous, with the appearance of many new groups and the evolution of flight
• Carboniferous insects included early forms of dragonflies (Meganeura), cockroaches, and mayflies
• The warm, humid climate and abundant plant life provided ideal conditions for insect diversification

Giant arthropods and amphibians

• The Carboniferous period is known for its giant arthropods, such as the massive millipede-like Arthropleura and the large dragonfly-like Meganeura
• These arthropods reached sizes much larger than their modern counterparts, likely due to the high oxygen levels in the atmosphere
• Amphibians also thrived during the Carboniferous, with the appearance of large, predatory forms such as Eryops and the snake-like Ophiderpeton

Early amniotes and reptiles

• The Carboniferous witnessed the appearance of early amniotes and reptiles, which laid the foundation for the evolution of modern reptiles, birds, and mammals
• Early amniotes, such as Hylonomus and Paleothyris, developed the ability to lay eggs on land, reducing their dependence on water for reproduction
• The first true reptiles, such as Petrolacosaurus, appeared during the late Carboniferous, exhibiting adaptations for a fully terrestrial lifestyle

Carboniferous coal deposits

• The Carboniferous period is named for the extensive coal deposits that formed during this time, which are of great economic significance

Formation process of coal

• Coal deposits formed from the remains of the dense vegetation that grew in the Carboniferous swamps and forests
• As plants died and accumulated in swampy environments, they were buried by sediments and subjected to high pressure and temperature over millions of years
• The process of coalification transformed the plant material into peat, lignite, bituminous coal, and eventually anthracite coal, depending on the degree of alteration

Distribution of coal deposits

• Carboniferous coal deposits are found on all continents, with major reserves in North America, Europe, Asia, and Australia
• The distribution of coal deposits is closely related to the paleogeography of the Carboniferous, with most deposits occurring in regions that were once part of the equatorial coal forests
• Significant coal basins include the Appalachian Basin in the United States, the Donets Basin in Ukraine, and the Bowen Basin in Australia

Economic significance of coal

• Carboniferous coal deposits are of immense economic importance, serving as a major source of energy for industrial and domestic use
• Coal has been a key factor in the development of modern industries, including steel production, electricity generation, and chemical manufacturing
• The exploitation of Carboniferous coal deposits has played a significant role in shaping the global economy and has had far-reaching environmental and social impacts

Carboniferous mass extinction

• The Carboniferous period witnessed significant changes in biodiversity, including the recovery from the Late Devonian extinction and the onset of the Carboniferous-Permian extinction event

Late Devonian extinction recovery

• The Late Devonian extinction, which occurred prior to the Carboniferous, had a significant impact on marine life, particularly reef-building organisms and trilobites
• During the early Carboniferous (Mississippian), marine ecosystems gradually recovered, with the diversification of new groups such as crinoids, bryozoans, and brachiopods
• The recovery of marine life set the stage for the development of extensive reef systems and the colonization of new ecological niches

Carboniferous-Permian extinction event

• The late Carboniferous to early Permian witnessed a gradual decline in biodiversity, known as the Carboniferous-Permian extinction event
• This extinction event primarily affected marine invertebrates, such as trilobites, rugose and tabulate corals, and some groups of brachiopods and bryozoans
• The causes of the Carboniferous-Permian extinction are not fully understood but may include changes in sea level, climate, and ocean chemistry

Causes and consequences of extinctions

• The Carboniferous-Permian extinction event is thought to have been caused by a combination of factors, including glaciation, changes in ocean circulation, and fluctuations in sea level
• The extinction of certain marine groups, such as trilobites and rugose corals, led to the restructuring of marine communities and the rise of new dominant groups
• The ecological changes associated with the Carboniferous-Permian extinction event set the stage for the evolution and diversification of life in the Permian period

Carboniferous reef environments

• The Carboniferous period saw the development of extensive reef systems, which supported a high diversity of marine life

Abundance of reef-building organisms

• Carboniferous reefs were constructed by a variety of organisms, including rugose and tabulate corals, stromatoporoids, and calcareous algae
• These reef-building organisms thrived in the warm, shallow seas that characterized much of the Carboniferous, particularly during the Mississippian subperiod
• The abundance of reef-building organisms led to the formation of large, complex reef structures that provided habitats for a wide range of marine life

Reef types and distribution

• Carboniferous reefs occurred in various forms, including fringing reefs, barrier reefs, and atolls
• Reefs were widely distributed across the shallow seas that covered much of the continents during the Carboniferous
• Major reef systems have been identified in North America (e.g., the Mississippian Madison Limestone), Europe (e.g., the Carboniferous Limestone of the British Isles), and Asia (e.g., the Carboniferous reefs of China)

Reef ecology and biodiversity

• Carboniferous reefs supported a high diversity of marine life, including invertebrates, fish, and early sharks
• Reef environments provided a variety of ecological niches, allowing for the coexistence of numerous species with different feeding strategies and life habits
• The complex structure of reefs also offered protection from predation and environmental stresses, contributing to the high biodiversity observed in these ecosystems

Carboniferous ocean chemistry

• The Carboniferous period witnessed significant changes in ocean chemistry, which had important implications for marine life and sediment deposition

Anoxic conditions in oceans

• During the Carboniferous, particularly in the Mississippian subperiod, some parts of the oceans experienced anoxic conditions, characterized by low oxygen levels in the water column
• Anoxia was likely caused by a combination of factors, including high organic matter input from the continents, sluggish ocean circulation, and warm global temperatures
• Anoxic conditions had a profound impact on marine life, with only certain groups (e.g., some brachiopods and bivalves) able to tolerate the low-oxygen environments

Black shale deposition

• The anoxic conditions in the Carboniferous oceans led to the deposition of black shales, which are dark-colored, organic-rich sedimentary rocks
• Black shales form in oxygen-depleted environments where the decay of organic matter is slowed down, allowing for the preservation of organic carbon
• Carboniferous black shales are important source rocks for hydrocarbons (oil and gas) and can provide valuable insights into the ocean chemistry and environmental conditions of the time

Geochemical proxies for ocean chemistry

• Geochemical proxies, such as stable isotope ratios and trace element concentrations, can be used to reconstruct the ocean chemistry of the Carboniferous period
• Carbon and oxygen isotope ratios from marine carbonates (e.g., brachiopod shells) can provide information on the global carbon cycle and ocean temperature
• Trace element concentrations (e.g., molybdenum, vanadium) in black shales can be used to infer the redox conditions of the oceans and the extent of anoxia

Carboniferous as foundation for Permian

• The Carboniferous period set the stage for the evolution and diversification of life in the Permian, through a combination of evolutionary innovations and environmental changes

Transition to Permian period

• The transition from the Carboniferous to the Permian period was marked by significant changes in climate, paleogeography, and biotic composition
• The amalgamation of Pangaea led to the formation of large, continental landmasses and the development of new terrestrial environments
• The gradual aridification of the climate during the late Carboniferous and early Permian had a profound impact on the distribution and evolution of flora and fauna

Evolutionary innovations in Carboniferous

• The Carboniferous period witnessed several key evolutionary innovations that would have far-reaching consequences for life in the Permian and beyond
• The evolution of seed plants, particularly the appearance of early conifers and cycads, set the stage for the dominance of gymnosperms in the Permian
• The appearance of amniote eggs allowed early tetrapods to become fully terrestrial, paving the way for the diversification of reptiles and synapsids in the Permian

Carboniferous influence on Permian biota

• Many of the major groups that would dominate the Permian, such as reptiles, synapsids, and insects, had their origins in the Carboniferous period
• The ecological and evolutionary changes that occurred during the Carboniferous, such as the diversification of seed plants and the colonization of new terrestrial environments, had a profound influence on the composition and structure of Permian ecosystems
• The extinction events of the late Carboniferous and early Permian also played a role in shaping the biotic composition of the Permian, by removing some groups and creating opportunities for others to diversify