The Extinction and Survival of Dinosaurs

Key vocabulary terms related to the extinction and survival of dinosaurs, along with their definitions.

Mass Extinction

A significant worldwide decrease in biodiversity, where over 50% of species are lost in a short geological timeframe.

Cretaceous-Paleogene (K-Pg) Extinction

An event marking the end of the Mesozoic era, where at least 50% of all species were lost, including nearly all dinosaurs.

Extinction Classification by Severity

Categorization of extinctions into major (50% families, 80-95% species), intermediate (20-30% families, 50% species), and minor (10% families, 20-30% species).

Iridium Anomaly

The elevated levels of iridium found in a clay layer coinciding with the K-Pg boundary, suggesting an extraterrestrial impact.

Impact Event

A significant collision with celestial objects, such as asteroids or comets, that can cause mass extinction through environmental changes.

Shocked Quartz

Quartz that shows characteristic stress features, indicating high-energy impact events such as asteroid collisions.

Tektites

Natural glass formed from melted rock during an impact event, serving as evidence of the K-Pg extinction.

Nuclear Winter

A climatic condition resulting from widespread firestorms following an impact, leading to a decrease in sunlight and global cooling.

Fern Spike

A rapid increase in fern spores in the fossil record following the K-Pg extinction, indicative of ecological recovery post-impact.

Chicxulub Impact Crater

A large impact crater in Mexico believed to be the site of the asteroid impact that caused the K-Pg mass extinction.