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. The close of the Devonian Period is considered to be the second of the âbig fiveâ mass extinction events of Earthâs history. Rather than a single event, it is known to have had at least two prolonged episodes of species depletion and several shorter periods.