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.
When you run cable through any building you first need to consider plenum spaces. Plenum spaces are the open spaces above the ceiling or below the floor that are used for air circulation. Technically, any ductwork is considered a plenum space too.