Early radioisotopic age constraints on the Campanian formations of the WIB consisted of K–Ar analyses of biotite and feldspar from interbedded bentonites115,116, with assumed uncertainties within the purchase of ± five%, and these analyses are certainly not talked about even more right here. Biotite ages, particularly, are regarded of questionable https://www.generationgenius.com/videolessons/fossil-record-video-for-kids/