The Cenozoic Era: The Age of Mammals and the Shaping of Modern Earth
The Cenozoic Era, spanning from approximately 66 million years ago to the present, marks the most recent major chapter in Earth’s geological history. Following the catastrophic Cretaceous–Paleogene (K–Pg) extinction event, which eliminated around 75% of all species, including non-avian dinosaurs, the Cenozoic heralded an age of renewal, adaptation, and diversification — the Age of Mammals (Zachos et al., 2001).
Divided into the Paleogene (66–23 Ma), Neogene (23–2.6 Ma), and Quaternary (2.6 Ma–present), the Cenozoic witnessed profound shifts in climate, ocean circulation, plate tectonics, and biodiversity. It was during this era that continents drifted into their modern positions, global climates cooled dramatically, and mammals, birds, and flowering plants came to dominate ecosystems.
For Australia, and particularly Victoria, the Cenozoic shaped the continent’s identity: the rifting from Antarctica, the rise of volcanic provinces, and the formation of river systems and fertile plains that later supported complex Aboriginal societies.
Geological and Tectonic Transformations
Throughout the Cenozoic, Earth’s surface underwent dynamic restructuring through plate motion and orogeny (Scotese, 2015).
India collided with Asia, uplifting the Himalayas and altering atmospheric circulation.
The Andes, Alps, and Rockies continued to rise under compressional tectonics.
Australia separated from Antarctica approximately 45 million years ago, forming the Southern Ocean and allowing the development of the Antarctic Circumpolar Current (ACC) — a key factor in global cooling (McGowran et al., 2004).
Tectonic uplift and subsidence across southern Australia created sedimentary basins such as the Otway, Murray, and Gippsland, where marine sediments preserved a record of environmental and climatic change (Joyce, 2010).
This reconfiguration of continents and oceans established the climatic and geological framework for modern Earth.
Climate Evolution: From Greenhouse to Icehouse
The Cenozoic climate shifted from the warm greenhouse conditions of the early Paleogene to the icy oscillations of the Quaternary.
Paleogene Warmth
In the Paleocene and Eocene, Earth’s atmosphere contained high concentrations of greenhouse gases, sustaining lush global rainforests and temperate vegetation even near the poles (Zachos et al., 2001). The Eocene Climatic Optimum (≈50 Ma) was one of the warmest intervals in the Cenozoic.
Oligocene Cooling
Around 34 Ma, the opening of the Tasmanian Gateway and the initiation of the ACC isolated Antarctica thermally, resulting in the first permanent polar ice sheets and the onset of the modern “icehouse” climate regime (McGowran et al., 2004).
Neogene Aridification
The Miocene (23–5 Ma) initially brought mild warming, followed by cooling and drying as ice volumes increased. In Australia, this triggered the retreat of rainforests and the spread of grasslands and sclerophyll vegetation (Christophel & Greenwood, 1989).
Quaternary Glacial Cycles
Over the past 2.6 million years, Earth’s climate has oscillated between glacial and interglacial phases driven by orbital forcing (Milankovitch cycles). These fluctuations profoundly influenced human evolution, migration, and ecosystem dynamics (Zachos et al., 2001).
Flora: The Rise of Modern Vegetation
The Cenozoic marks the ascendancy of angiosperms (flowering plants) and the evolution of modern biomes.
Early Paleogene forests were dominated by tropical species such as magnolias and laurels.
As climates cooled, deciduous forests and grasses expanded, giving rise to savannas and steppe ecosystems (Christophel & Greenwood, 1989).
In Australia, rainforest dominance gave way to eucalypts, wattles (Acacias), and banksias, plants adapted to nutrient-poor soils and recurrent fire (Hill, 1994).
By the late Neogene, the distinctive sclerophyll forests and grasslands of modern Victoria were established.
Faunal Evolution: The Age of Mammals
Global Developments
The extinction of dinosaurs opened ecological space for mammals to radiate and diversify (Archer & Hand, 2006).
The Paleogene saw the emergence of primates, whales, elephants, bats, and ungulates.
The Neogene introduced modern grazers and carnivores; elephants, horses, and felids spread across continents.
By the Quaternary, many present-day species, including humans, evolved.
Australia’s Unique Evolution
Isolated since the Paleogene, Australia developed an ecosystem dominated by marsupials and monotremes.
Fossil evidence from the Riversleigh World Heritage Area and southern Victoria reveals early kangaroos, koalas, and wombats.
Giant marsupials such as Diprotodon and Thylacoleo carnifex emerged during the Pleistocene (Archer & Hand, 2006).
Bird and reptile diversity also expanded; emus, cockatoos, and giant goannas reflect long adaptive histories in shifting climates.
Marine fossils from the Otway and Gippsland Basins record ancient whales, sharks, and molluscs in Eocene and Miocene seas (Joyce, 2010).
The Cenozoic in Victoria
Volcanism and Landscape Formation
The Western Victorian Volcanic Plains, stretching from Ballarat to Portland, formed during the late Neogene and Quaternary, creating over 400 eruption points such as Budj Bim, Mount Napier, and Tower Hill (Joyce, 2010). These eruptions produced fertile basalt soils that later sustained Aboriginal aquaculture and agriculture — notably the Gunditjmara eel-trap systems now World Heritage-listed (UNESCO, 2019).
Rivers, Coasts, and Basins
Repeated marine transgressions and regressions shaped Victoria’s coastlines — Bellarine Peninsula, Port Phillip Bay, and Western Port. Inland, erosion and sedimentation formed major rivers such as the Barwon, Moorabool, and Glenelg, vital for Aboriginal livelihoods and cultural identity (Neale, 2017).
Climate and Ecology
Victoria’s ecosystems evolved alongside global cooling: from warm Eocene rainforests to open Miocene woodlands, to the grassy plains and wetlands of the Quaternary. These transformations created diverse habitats that supported complex ecological networks still visible today.
Cultural and Deep-Time Connections
While the Cenozoic predates humanity, its landscapes underpin Aboriginal Country and cultural knowledge. Geological processes such as volcanism, sedimentation, and erosion are mirrored in Dreaming stories of creation, transformation, and ancestral beings (Rose, 1996).
Budj Bim, the ancestral being of Gunditjmara Country, represents the creative volcanic force that shaped the land.
The Great Dividing Range, uplifted during the Cenozoic, appears in many southeastern creation narratives.
Aboriginal oral histories thus encode a deep-time environmental awareness that aligns with geological science, revealing long continuity between human culture and Earth history.
Global Context and Human Emergence
During the late Cenozoic, the stage was set for human evolution.
Early hominins such as Australopithecus afarensis arose in Africa during the Miocene and Pliocene (Begun, 2004).
The Quaternary saw the emergence of Homo erectus, Neanderthals, and Homo sapiens, whose adaptability was shaped by glacial–interglacial variability.
Humans migrated out of Africa and reached Australia by around 65,000 years ago, adapting to environments formed through millions of years of Cenozoic transformation.
Conclusion
The Cenozoic Era encapsulates Earth’s modern transformation — from a post-extinction recovery to the complex, interconnected biosphere we inhabit today. It shaped the continents, climates, and ecosystems that define life on Earth and laid the geological and cultural foundations of Victoria and Australia.
For Aboriginal peoples, these landscapes are not relics of the past but living Country, where deep geological time converges with ancestral story and identity. The Cenozoic stands as both a geological epoch and a testament to Earth’s resilience and renewal.
References
Archer, M. & Hand, S. (2006) The Evolution of Australia’s Fauna. Sydney: UNSW Press.
Begun, D. R. (2004) ‘The earliest hominins: morphology and ecology’, Annual Review of Anthropology, 33, pp. 345–368.
Christophel, D. C. & Greenwood, D. R. (1989) ‘Changes in vegetation and climate through the Tertiary of southeastern Australia’, Review of Palaeobotany and Palynology, 58, pp. 99–129.
Hill, R. S. (1994) History of the Australian Vegetation: Cretaceous to Recent. Cambridge: Cambridge University Press.
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’, Australian Journal of Earth Sciences, 51, pp. 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) Paleomap Project: Paleogeographic Maps of the Cenozoic Era. University of Texas.
UNESCO (2019) Budj Bim Cultural Landscape World Heritage Nomination. Paris: UNESCO.
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), pp. 686–693.
Written, Researched and Directed by James Vegter 16/09/2025
Magic Lands Alliance
Sharing the truth of Indigenous and colonial history through film, education, land and community.
Copyright of MLA – 2025
Magic Lands Alliance acknowledge the Traditional Owners, Custodians, and First Nations communities across Australia and internationally. We honour their enduring connection to the sky, land, waters, language, and culture. We pay our respects to Elders past, present, and emerging, and to all First Peoples communities and language groups. This article draws only on publicly available information; many cultural practices remain the intellectual property of communities.