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.
Report Abuse. The plenum is the duct right on top of the furnace. A furnace has 2 ducts. Cold air is sucked-in through the return duct. The air is heated in the furnace and pushed through the plenum, which is the duct on top of furnace.Tam22 Â· 7 years ago. Thumbs up.he plenum is the sheet metal box on top of the furnace that connects the furnace to the rest of the duct work.