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.
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the amount of life on Earth.Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. This extinction event lasted perhaps as long as 20 million years, and there is evidence for a series of extinction pulses within this period. 2  OrdovicianâSilurian extinction events (End Ordovician or O-S): 450â440 Ma at the Ordovician-Silurian transition.