Dinosaur Extinction

All non‑avian dinosaurs (every dinosaur except the lineage that led to birds) went extinct at the end of the Cretaceous Period, about 66 million years ago.

Main Causes (Current Scientific View)

Most evidence supports a combination of:

Asteroid Impact
- A large asteroid (₁₀ km wide) struck near present‑day Chicxulub in Mexico.
- Impact effects:
  - Massive shock waves and wildfires.
  - Ejection of dust and aerosols into the atmosphere, blocking sunlight.
  - Short‑term global cooling and disruption of photosynthesis.

Volcanic Activity
- Huge volcanic eruptions in the Deccan Traps (modern India) released vast amounts of lava, CO₂, and sulfur gases.
- Likely caused longer‑term climate change, ocean acidification, and environmental stress.

Consequences

Collapse of many food webs, especially those depending on photosynthesis (plants and plankton).
Extinction of non‑avian dinosaurs, large marine reptiles, ammonites, and many other groups.

Survivors

Birds (avian dinosaurs) survived and diversified in the Cenozoic Era.
Many mammals, crocodilians, turtles, lizards, insects, and plants also survived and later diversified.

This extinction event marks the boundary between the Mesozoic and Cenozoic eras and dramatically reshaped life on Earth.