Extinction



Foraminifera are single-celled organisms, similar to amoebas, which live in the oceans. Although tiny, they are extremely numerous, and can be found both along the shore, and far out at sea, near the surface and at the immense depths of the oceans. The vast abundance and extent of these creatures means that they are excellent indicators of global environmental changes, so are used by scientists interested in how the climate on Earth may have changed over the past 500 million years. Before the impact event 65 million years ago, scientists found evidence of larger foraminifera living in the oceans, but after the impact, only smaller organisms are seen in the fossil record, indicating that something catastrophic had occurred, causing the extinction of the larger members of this species.

A cross-section through the K-T boundary layers.
Image Above: a cross-section through the K-T boundary layers.

However, the actual cause of the extinction event has been the subject of scientific speculation for some years. Not all scientists agree that it was caused by an asteroid impacting the Earth.

Other suggestions have included:

  • It wasn’t a single event, but a series of unrelated local extinctions
  • The extinction was a slow decline in numbers and diversity, not a catastrophe
  • The extinction was caused by a rapid change in climate from warm and wet to cool and dry
  • The dinosaurs became an evolutionary dead end and could no longer adapt to minor changes in their environment
  • Living things were killed by the effects of massive volcanic eruptions (specifically those in the Deccan region of India)