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 have been five mass extinction events in Earth's history. In the worst one, 250 million years ago, 96 percent of marine species and 70 percent of land species died off. It took millions of years to recover. Nowadays, many scientists are predicting that we're on track for a sixth mass extinction. The world's species already seem to be vanishing at an unnaturally rapid rate. And humans are altering the Earth's landscape in far-reaching ways: We've hunted animals like the great auk to extinction. We've cleared away broad swaths of rain forest.