In the popular mind, mass extinctions are associated with catastrophic events, like giant meteorite impacts and volcanic super-eruptions. But the worldâs first known mass extinction, which took place about 540 million years ago, now appears to have had a more subtle cause: evolution itself. âPeople have been slow to recognize that biological organisms can also drive mass extinction,â said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University.
The pectoralis major (/ËpÉktÉËreÉªlÉ¨s ËmeÉªdÊÉr/) (from Latin: pectus, breast) is a thick, fan-shaped muscle, situated at the chest (anterior) of the human body. It makes up the bulk of the chest muscles in the male and lies under the breast in the female.he pectoralis major (/ËpÉktÉËreÉªlÉ¨s ËmeÉªdÊÉr/) (from Latin: pectus, breast) is a thick, fan-shaped muscle, situated at the chest (anterior) of the human body. It makes up the bulk of the chest muscles in the male and lies under the breast in the female.
Why You Chose Your Major. Topic: Why you chose your major One of toughest decisions many people, and colllege students in particular face are choosing a major and a career. Hopefully when a person chooses their major is they know what they want to do for a life time.Some people do other things from what they studied. Itâs...hy You Chose Your Major. Topic: Why you chose your major One of toughest decisions many people, and colllege students in particular face are choosing a major and a career. Hopefully when a person chooses their major is they know what they want to do for a life time. Some people do other things from what they studied.