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.
There's really only one cause of mass extinctions: Something occurs in the environment that overwhelms the ability of the species to tolerate it. Mass extinctions differ from gradual extinctions in that there is not enough time for natural selection to produce a genetic response (which fails if extinction ensues.)