The Tropical Eastern Pacific is unique in that is greatly influenced by flow through the Drake Passage of the Antarctic Circumpolar Current. Changes in the flow can produce wicked climate cycles like ENSO on steroids, IMHO. Because of the huge flow of water and ice, there is a distinctive scour pattern on the eastern side of the Drake Passage.
A very similar scour pattern is in the Southern Caribbean created when South America was likely once located at the southern pole, IMHO, about the same time Canada was located in the tropics.
I haven't look into how the contents shifted and I am sure this has been notice before, but it did inspire a few questions, especially since a "Snowball" Earth seems unlikely, thermodynamically speaking.