The Paleogene Period: Rebirth and Transformation After the Dinosaurs
The Paleogene Period, spanning approximately 66 to 23 million years ago, marks the beginning of the Cenozoic Era — the “Age of Mammals.” Following the catastrophic Cretaceous–Paleogene (K–Pg) extinction event, which wiped out around 75% of all species including the non-avian dinosaurs, Earth entered a phase of recovery, renewal, and profound transformation.
The Paleogene is divided into three epochs:
Paleocene (66–56 million years ago)
Eocene (56–33.9 million years ago)
Oligocene (33.9–23 million years ago)
Across this 43-million-year span, Earth experienced dramatic changes in climate, continental drift, vegetation, and animal evolution. The world transitioned from hot, tropical conditions to the cooler, drier environments that would later define the Neogene.
For Australia and Victoria, this period was foundational: it saw the breakup of Gondwana, the isolation of the Australian continent, the birth of new landscapes, and the evolution of early marsupials and plants that would later define Australia’s unique ecosystems.
Global Geological Context
Continental Drift and Plate Movements
During the Paleogene, the Earth’s continents continued to drift toward their modern positions (Scotese, 2015):
Australia and Antarctica separated, initiating the formation of the Southern Ocean and setting up a global system of cold ocean currents.
India collided with Asia, giving rise to the Himalayas and altering global atmospheric circulation.
South America remained isolated, while North America drifted northward toward Europe.
These tectonic shifts dramatically reshaped global climate systems, creating new coastlines, mountain ranges, and ocean basins.
Volcanism and Basin Formation
Intense volcanic activity accompanied continental rifting in the Southern Hemisphere.
In Victoria, early volcanic and sedimentary processes formed the Otway and Gippsland Basins, laying down marine sediments rich in fossils (Joyce, 2010).
These basins later became vital for understanding Paleogene marine environments and for modern petroleum resources.
Climate: From Greenhouse to Icehouse
Paleocene Warmth
The Paleocene began with a greenhouse world — warm, humid, and rich in vegetation. There were no permanent polar ice caps, and tropical forests reached the poles (Zachos et al., 2001).
Eocene Heat Peak
Around 50 million years ago, during the Eocene Climatic Optimum, global temperatures reached their highest levels of the Cenozoic.
Rainforests covered much of the planet, and early primates and mammals flourished.
Fossil evidence from Antarctica shows temperate forests and marsupials living near the South Pole (McGowran et al., 2004).
Oligocene Cooling
Beginning around 34 million years ago, the Earth cooled rapidly.
The formation of the Antarctic Circumpolar Current isolated Antarctica climatically, leading to the first permanent polar ice sheets (Zachos et al., 2001).
This event marked the transition from the greenhouse world of the early Paleogene to the icehouse world of the Neogene.
Flora and Vegetation
Global Trends
The Paleogene saw the rise of angiosperms (flowering plants), which diversified rapidly following the extinction of the dinosaurs.
Forests were dominated by tropical and subtropical species such as palms, magnolias, and ferns in the Paleocene and Eocene.
As climates cooled in the Oligocene, deciduous trees and grass precursors spread, laying the foundation for later grassland ecosystems.
Australia’s Paleogene Flora
Fossil pollen and leaf imprints from Victoria and South Australia indicate widespread rainforests during the Paleocene and Eocene (Christophel & Greenwood, 1989).
By the Oligocene, eucalypts, acacias, and casuarinas began to emerge — the ancestors of today’s dominant Australian flora.
This botanical evolution reflects Australia’s drift toward higher latitudes and the onset of drier, more seasonal climates.
Faunal Evolution
Mammalian Expansion
The extinction of dinosaurs opened ecological niches for mammals, which diversified rapidly across continents:
Early primates, horses, elephants, bats, and whales evolved in the Paleogene.
Whales (cetaceans) transitioned from land-dwelling ancestors to fully aquatic species by the Eocene.
In Europe and North America, ungulates (hoofed mammals) became dominant grazers.
Australian Evolution
Isolated from other landmasses, Australia developed a unique marsupial-dominated ecosystem.
Fossil sites from the Oligocene, such as the Riversleigh World Heritage Area (Queensland), preserve early marsupials, monotremes, and birds (Archer & Hand, 2006).
Ancestors of koalas, kangaroos, and possums evolved in this period, adapting to forested environments.
Marine Life
The Southern Ocean teemed with life — whales, seals, sharks, and giant penguins.
Marine deposits in Victoria’s Otway and Gippsland Basins contain fossils of corals, shells, and marine mammals that flourished in warm Eocene seas.
The Paleogene in Victoria
Geological Evolution
During the Paleogene, Victoria was largely underwater, covered by shallow seas that deposited limestone, shale, and sandstone.
As sea levels fluctuated, coastal plains and river systems began forming.
Early volcanic activity in western Victoria produced small basaltic flows that foreshadowed the later volcanic fields of the Neogene (Joyce, 2010).
Climate and Ecosystems
Warm Eocene climates supported dense rainforests across Victoria, similar to those found in present-day Queensland.
The transition to Oligocene cooling led to the decline of these forests and the emergence of open woodlands and sclerophyll plants (Christophel & Greenwood, 1989).
Fossil Record
Marine fossils from the Torquay and Port Phillip regions document Victoria’s shifting shoreline during the Paleogene.
Plant fossils show the evolution of eucalypts and the onset of aridity — a defining feature of later Australian environments.
Global and Cultural Significance
The Paleogene established the planetary systems that define the modern Earth — from ocean currents and continental configurations to climate patterns and ecosystems.
It was a period of:
Climate regulation: The development of the Antarctic ice sheet permanently altered global weather cycles.
Biological innovation: Mammals, birds, and flowering plants diversified into nearly all ecological niches.
Geological foundation: Continental drift reconfigured landmasses and created new oceanic gateways.
In a deeper cultural sense, the landscapes shaped during the Paleogene became the ancestral grounds of later Aboriginal nations. The volcanoes, river systems, and coastlines that formed during this time are central to Dreaming stories that describe the creation of land, fire, and life (Neale, 2017; Rose, 1996).
Conclusion
The Paleogene Period was an era of rebirth — a time when the Earth, scarred by extinction, renewed its life systems and laid the foundation for the world we inhabit today.
For Victoria and Australia, it marked the dawn of geological and biological isolation, the emergence of distinctive ecosystems, and the creation of landscapes that would later sustain human culture. From the warmth of the Paleocene rainforests to the cooling of the Oligocene, the Paleogene captures Earth’s remarkable ability to adapt, evolve, and renew.
References
Archer, M., & Hand, S. (2006). The Evolution of Australia’s Fauna. Sydney: UNSW Press.
Christophel, D. C., & Greenwood, D. R. (1989). “Changes in vegetation and climate through the Tertiary of southeastern Australia.” Review of Palaeobotany and Palynology, 58, 99–129.
Joyce, E. B. (2010). The Western Victorian Volcanic Plains: A Field Guide to the Newer Volcanics Province. Geological Society of Australia.
McGowran, B., Li, Q., Cann, J., & Padley, D. (2004). The Cenozoic of the Australian Southern Margin: Evolution of a Rifted Continent. Journal of Australian Earth Sciences, 51, 125–145.
Neale, M. (2017). Songlines: The Power and Promise. Canberra: National Museum of Australia.
Rose, D. B. (1996). Nourishing Terrains: Australian Aboriginal Views of Landscape and Wilderness. Canberra: Australian Heritage Commission.
Scotese, C. R. (2015). The Paleomap Project: Paleogeographic Maps of the Paleogene Period. University of Texas.
Zachos, J., Pagani, M., Sloan, L., Thomas, E., & Billups, K. (2001). “Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present.” Science, 292(5517), 686–693.
Written, Researched and Directed by James Vegter 07/10/2025
Magic Lands Alliance
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