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.
A large extinction event often represents an accumulation of smaller extinction events that take place in a relatively brief period of time. The first known mass extinction in earth's history was the Great Oxygenation Event 2.4 billion years ago. The event led to the loss of most of the planet's obligate anaerobes. The five largest extinction events in earth's history since are these: