Question: Do scientists know for sure what caused the PETM to come to an end? (There are several hypotheses; one provided in this video and one provided in the Lecture Tutorial). Need Assignment Help? Select all that apply. Group of answer choices Not for certain but one hypothesis with evidence in the fossil record is that large quantities of carbon were removed by the sudden death of arctic ferns. Yes we do know for certain that the cause of the cooling was due to large quantities of carbon being removed by the sudden death and burial of dinosaurs. Yes, we do know that the warming oceans of the PETM cause an explosion of the foraminifera population. They removed CO2 from the oceans and the atmosphere to build their shells. The removal of the CO2 by the forams led to the cooling. Not for certain but we do know that large quantities of carbon had to have been added to cause the temperature to go down. Not for certain however we do know that the weathering and erosion of the newly formed Himalayan mountains removed tremendous quantities of carbon dioxide from the atmosphere. Not for certain but we do know that large quantities of carbon had to have been removed to cause the temperature to go down.