65 million years ago, a 10-km-wide asteroid slammed into a region in Mexico, leaving a 175-Km crater right in the heart of what would one day become the Mayan domain.
That impact, according to Luiz Alvarez (physicist and Nobel laureate) is what led to the extinction of the dinosaurs and about 70% of all the other species on the planet.
UC Berkley physicist Richard Muller & his graduate student, Robert Rhode found solid, reliable evidence that mass extinctions occur regularly every 62 million to 65 million years. PS: We are now overdue!
This hypothesis is based on a three-year computer analysis of the 542-million-year fossil record compiled by Jack Sepkoski. Sepkoski had classified the fossils of creatures by genus. eg: Felis, a genus that includes cats, bobcats and jaguars. Canis includes dogs,wolves and jackals.
Sepkoski found that the 542-million-year time period covered by his compendium divided into layers roughly 3 million years apart, and he identified the oldest and youngest layers in which each genus appeared. eg: jaguars and other cats had not yet appeared at the time of the dinosaurs extinction, but snakes indeed predate the dinosaurs and will presumably postdate us.
Muller and Rhode found (based on Sepkoski's mammoth compendium) that anywhere between 50 to 90 percent of genera (plural of genus) vanished every 62 million to 65 million years.
Muller's "Nemesis hypothesis"
The Sun, like most stars of its age and ilk, has a companion, probably a barely visible star such as a red or brown dwarf or a black hole. Muller hypothesized that Nemesis's orbit would bring it by every X million years, gravitationally jostling the Sun and destabilizing the solar system...
Muller now believes that every 62 million to 65 million years, the solar system's orbit passes through a region of the milky way that is exceptionally gravitationally dense. He thinks that the sudden and extreme gravitational tugs sets off showers of comets and asteroids that pummel the sun and all the planets,including the Earth.
"Sounds promising :| " - Myriam
inspired by the book: "Apocalypse 2012", Lawrence E. Joseph