noun Etymology: K (alternative for C as abbreviation for Cretaceous) + Tertiary Date: 1983 the transition between the Cretaceous and Tertiary periods of geologic time characterized by a mass extinction of many forms of life including the dinosaurs
K-T BOUNDARY
Meaning of K-T BOUNDARY in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012