I didn't bring up sharks. You did. You will have to explain how it came to be that there were sharks wandering around with the marsupials.
Oh good gawd. Go back to your post 426 which was a response to my post 424. I didn't mention either sharks or marsupials in my post. You brought up sharks and I had no idea why you did. Maybe you meant to reply to someone else. I don't have to explain why sharks were wandering around with marsupials. You said "Early placental mammals were driven from Australia by marsupials due to their reproductive superiority." I have no idea why you brought this up. I have no idea about sharks or marsupials except that it seems they would not compete for the same resources.