Toward mammals

Around 225 million years ago, small cynodont relatives combined mammal-like traits in different ways. A 2024 CT study showed a mammalian-style jaw joint arose independently in one lineage. Such relatives and early mammaliaforms should not all be equated with crown mammals: the common ancestor of living mammals and its descendants.

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CO₂280ppm
Temp14.3°C
Sea0m
O₂21%

Annual surface temperature from CESM (T): a model estimate, not a direct observation of the past.

0 Ma: pre-industrial climate/CO₂; modern sea-level and O₂ references.

Data references
CenCO2PIP Consortium vetted productMiller et al. (2020), smoothed Cenozoic sea level relative to modernMills et al. (2023), Evolution of Atmospheric O₂ Through the Phanerozoic, Revisited, Annual Review of Earth and Planetary Sciences 51:253–276Li et al. (2022), CESM surface temperature
Sources & methods

Glacial-interglacial cycles with 120m+ sea level swings. Homo sapiens spread from Africa across the globe, and most megafauna went extinct.

Key Life
🧑Homo sapiens🦣Mammoth🧔Neanderthals
Innovations
  • ›Language and culture
  • ›Agricultural revolution (~10,000 years ago)
  • ›Birth of civilization
Simplified Köppen
Af Rainforest
Am Monsoon
Aw Savanna
BW Desert
BS Steppe
Cf Temperate wet
Cs/Cw Temperate dry
Df Cold wet
Dw Cold dry
ET Tundra
EF Ice
CESM (Li et al. 2022)

Annual model means · 0 Ma: pre-industrial

Full exploration range1,800 Ma → Present
540 Ma → Present
Precambrian
Paleozoic
Mesozoic
Cenozoic
Cambrian
Ordovician
Devonian
Carbonif.
Permian
Triassic
Jurassic
Cretaceous
Paleogene
┆ Data transition · 540 Ma

Present