The American black bear lived during the same period as short-faced bears (Arctodus simus and A. pristinus) and the Florida spectacled bear (Tremarctos floridanus). These Tremarctine bears evolved from bears that had emigrated from Asia to North America 7â8 ma.
A plenum space is a part of a building that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows, usually at greater than atmospheric pressure.
Each pleural cavity is lined by a pleural membrane that is composed of two layers. The visceral pleura surrounds the outside of the lung. The parietal pleura lines the inside of the chest wall and extends over the diaphragm.These membranes secrete a lubricating fluid, which allows for free movement of the lungs against the chest wall when we breathe.ach lung is contained within a pleural cavity. Each pleural cavity is defined by a space surrounding each lung and is lined by a pleural membrane. The pleural membrane is made up of two layers. These layers can be illustrated in a transverse section of the thoracic cavity.