Pros: 1  Works equally well in open terrain, under cover or in a gym. 2  Accurate on flat or hilly terrain and when making quick, sharp turns (e.g., when trail running or on an indoor track). 3  Lightweight design is sleeker than most GPS-enabled SDMs.
Definitions for mass extinction. Here are all the possible meanings and translations of the word mass extinction. Wiktionary(0.00 / 0 votes)Rate this definition: mass extinction(Noun) A sharp decrease in the total number of species in a relatively short period of time.
More birds evolved, and reptiles got bigger. Dinosaurs were still dominant, and carnivorous dinosaurs were more prevalent. At the end of the Cretaceous Period, and the end of the Mesozoic Era, came another mass extinction. This extinction is generally called the K-T Extinction.