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.
Mass Extinction in the Fossil Record. Mass extinctions are apparent in the fossil record wherever some sort of organism virtually disappears from the geologic column above a certain layer. One of the most well-known mass extinctions is the disappearance of the dinosaurs and a number of other organisms at the K-T boundary.