Maastrichtian Stage

What happened during this time?

• The Maastrichian ends with a 6-mile-wide bolide impact that brings massive global environmental disturbance, causing the extinction of large land and sea vertebrates

  • This bolide impacted the Yucatán Peninsula 

  • This event, called the Chicxulub impact, killed off most large animals, including all non-avian dinosaurs

  • It is assumed that the impact ejected dust and dirt into the atmosphere, triggering an "impact winter," which is a period of prolonged cooling during which global temperatures plummeted

  • Research examining proxies for mean annual air temperature (MAAT) before and after K-Pg boundary indicates little prolonged variation in temperatures (O'Connor et al., 2023), therefore no impact winter

• Evidence shows that a second asteroid, 450–500m wide and traveling at 72,000 km per hour, impacted the Atlantic Ocean near the western coast of the country of Guinea. (Nicholson et al., 2024)

• Research by Cox and Keller (2023) analyzed all the data from the end-Cretaceous to pinpoint the cause of the mass extinction

  • While not conclusive, the model suggested that the outpouring of climate-altering gases from the Deccan Traps alone could have been sufficient to trigger the global extinction

  • The Traps had been erupting for roughly 300,000 years before the Chicxulub asteroid

  • During their nearly 1 million years of eruptions, the Deccan Traps are estimated to have pumped up to 10.4 trillion tons of carbon dioxide and 9.3 trillion tons of sulfur into the atmosphere

• Evidence of global disruption of plant communities at the K–Pg boundary ((Vivi, Raine, and Hollis 2001; Wilf and Johnson 2004; Nichols and Johnson 2008).

  • Extinctions are seen both in studies of fossil pollen, and fossil leaves.

  • In North America, the data suggest massive devastation and mass extinction of plants at the K–Pg boundary sections; approximately 57% of plant species became extinct. 

  • In high southern hemisphere latitudes, such as New Zealand and Antarctica, the mass die-off of flora caused no significant turnover in species but dramatic and short-term changes in the relative abundance of plant groups.

• A series of large volcanic eruptions began forming at 66.25 Ma. 

  • The remnants of these lava flows are known as  the Deccan Traps in west-central India

  • This series of eruptions may have lasted less than 30,000 years in total, covering an area as large as 1.5 million km², approximately half the size of modern India.