Oxygen depletion triggered mass extinction in ocean's similar to todays
https://www.upi.com/Science_News/2019/03/28/Oxygen-depletion-triggered-mass-extinction-in-oceans-similar-to-todays/6441553787756/?ts_=19 Source Cited: www.upi.com Sign in to see full entry.
![Associated Content](http://www.associatedcontent.com/user/8835/mandaleesrc="http://www.associatedcontent.com/images/house_ads/cp-sp6.gif" border="0"></a>){kind=link}