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.
The teres major is a small muscle that originates on the lateral inferior angle of the scapula. Since it inserts to the intertubercular groove of the humerus, similar to the latissimus dorsi, it also assists with medial rotation and adduction of the arm. The teres major is known for its strength and stabilization of the shoulder joint, as it is one of the four muscles of the rotator cuff.