Past Mass Extinctions The Sixth Mass Extinction •It is thought that Earth is experiencing its sixth mass extinction with disease and human activity taking a devastating toll on vulnerable species. •Mass Extinction: a global event in which species of many types, plant and animal, die out in a short period of time.

•There have been five mass extinctions in known geological history. •Past mass extinctions tended to wipe out the dominate species. Leaving a new one in its place. Mass Extinction Impact of Human Activity •Hunting and habitat destruction are examples of human activities that have wiped out other species •more then 539 species have become extinct since the 17th century and 33% of animal and plant life in America are vulnerable to premature extinction •and 29% of known plant species is threatened with extinction. •Ordovician-Silurian About 443m years ago, a quarter of all marine families were wiped out by fluctuating sea levels as glaciers formed and melted. Late Devonian About 359m years ago, a fifth of marine families were wiped out, alongside more than half of all marine genera.

Endangered Animals - FREE Presentations in PowerPoint format, Free Interactives. Extinction is forever! Dance House Vol 1 Nexus Download Torrent here. In time, all species become extinct: Background Extinction: continuous low level of extinction. Extinction Rate:% of species lost per year or 0.0001% before man became involved. Mass Extinction: 5 mass extinctions – 50-95% of species were lost; but afterwards, biodiversity returned; causes.

Permian-Triassic worst mass extinction 251m years ago, killing 96% of all species. •End of Triassic About 200m years ago, lava floods erupting created lethal global warming, killing a half of marine life.

Cretaceous-Tertiary 65m years ago, extinction of nearly a fifth of land vertebrate, and nearly half of all marine animals. •Humans are the direct cause of ecosystem stress and species destruction in the modern world through transformation of the landscape, overexploitation of species, pollution, and the introduction of alien species. •Human impact on the planet is a similar to the Cretaceous cometary collision. • injections of debris into the atmosphere that global temperatures plummeted and photosynthesis was severely inhibited -- wreaked havoc on the living systems of Earth, which is precisely what we are doing to the planet right now. Yeh Dil Aashiqana Full Movie Free Download Hd. 95-98% of the virgin forests have been destroyed since the 17th century 96% of the virgin southeastern coastal plains are gone along with 98% of the tall grass prairie in the Midwest. 99% of Califonia's native grassland, 91% of its wetlands, and 85% of its red woods are gone. 90% of Hawaii's dry forest and grasslands have disappeared 81% of the nation's fish communities have been disturbed by human activities and more than half of the country's original wetlands have been destroyed.