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.
Scientists generally agree that the reason for any mass extinction can be traced to a variety of environmental factors that may have resulted from a triggering event. The extinction that occurred at the end of the Permian period, 250 million years ago, was probably the most severe in Earth's history.