What if the American and Oceania continents never existed?

Oceania is not a continent in the geographical sense as it is a water body, the Pacific Ocean, with thousands of tiny islands (too difficult to represent in a large scale map) scattered all over it. It has none of the attributes to be called a continent. At best it is a convenient term of nomenclature by international bodies like UN. To justify the term Oceania, the smallest continent, Australia & the two large islands of New Zealand were added. That makes it even more grotesque.

Being joined by a flimsy 36 mile wide isthmus of Panama, doesn’t make the Americas a singlecontinen t when each large enough to possess all the attributes for a continent. In fact Asia & Africa too are conjoined by a 104 mile wide isthmus of Suez. It is significant that these two isthmuses necessitated digging of two canals to further lend support that each unit separated by the isthmus is minded of continental proportions.

Well there wouldn't be any kangaroos.