What did Earth look like in the Cretaceous? (143.1–66 Ma)

Key events of this period

• Early Flowering Plants

  130 Ma

  Clear early flowering-plant fossils appear in the Early Cretaceous, around 140–130 million years ago. Their actual origin may be older: fossil and DNA analyses yield different dates, with a 2026 study favouring the latest Jurassic. The timing remains debated.

  References: Integrated analysis of fossils and molecular divergence time estimates a latest Jurassic origin of angiosperms (2026) · Phylogenomics and the rise of the angiosperms (2024)

• Angiosperm Radiation

  100 Ma

  Between about 130 and 100 million years ago, flowering plants diversified rapidly, with new ecological opportunities for insects. Their rise was not simultaneous everywhere: dominance of vegetation developed unevenly and continued into the Cenozoic. Pollination was part of this changing web of relationships, not a single proven cause of the radiation.

  References: The angiosperm radiation played a dual role in the diversification of insects and insect pollinators (2024) · Vast DNA tree of life for plants revealed by global science team (Kew, 2024)

• Oceanic Anoxic Event 2

  94 Ma

  Around 94 million years ago, Oceanic Anoxic Event 2 expanded oxygen-poor waters and left organic-rich sediments in a warm world. Volcanism and nutrient cycling are leading explanations; the event does not mean every ocean became completely oxygen-free at once.

  References: Oceanic Anoxic Event 2 triggered by Kerguelen volcanism

• Western Interior Seaway

  90 Ma

  Around 90 million years ago, a shallow seaway covered parts of central North America. At extensive stages, it linked Arctic waters with the Gulf of Mexico and separated western and eastern land areas. Its shorelines repeatedly advanced and retreated; marine fossils remain in rocks such as Colorado’s Mancos Shale.

  References: Cretaceous Period — National Park Service · Geodiversity Atlas—Greater Yellowstone I&M Network Index — National Park Service · Paleontology at Yucca House — National Park Service

• Madagascar and India drift apart

  88 Ma

  Separation developed around 88 million years ago. Volcanic rock ages provide key evidence; the breakup did not happen in one day. After the split, around 72–66 million years ago, India’s Rajasaurus and Madagascar’s Majungasaurus were close dinosaur relatives, not the same species or direct ancestors. As India moved north, lemur ancestors are inferred to have arrived much later from Africa, roughly 60–50 million years ago. The date is uncertain and the proposed rafting route is unknown.

  References: Storey et al. (1995), Timing of hot spot-related volcanism and the breakup of Madagascar and India · Natural History Museum — Rajasaurus · Krause et al. (2007), Majungasaurus: introduction and overview · Poux et al. (2005), Asynchronous colonization of Madagascar by the four endemic clades of primates, tenrecs, carnivores, and rodents