Polypterids are the sole survivors of the Order Polypteriformes whose distribution included Africa and South America and can be dated back at least 100 million years in the fossil record. They are among the most primitive of the ray-finned fishes (Actinopterygii) the dominant group of fishes today.
Our story begins some 245 million years ago with a super continent named Pangaea in the Mesozoic era.Which has three periods the oldest triassic(245-208 mya)(short for Millions of Years Ago) then jurassic(208-146 mya) and the cretaceous(145-65 mya)era.
Pangaea (Greek for "all lands") was the supercontinent that existed before plate tectonics separated the major continents.Pangaea was believed to have formed 300 million years ago.The vast ocean that surrounded Pangaea has been named Panthalassa.Pangaea is believed to have broken up about 200-180 mya into two supercontinents Laurasia the continents of the northern hemisphere and Gondwana (originally Gondwanaland) which includes most of the landmasses which make up today's continents of the southern hemisphere, Including Africa and South America.
Gondwana is of intrest to us if you look at the pictures you can see The rift between Africa and South America occurs right in the natural range of the remaining memebers of the Order PolypteriformesThe polypterids.Hope this answers how South America has fossil remains-Anne
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Polypterid fossil record
The polypterid fossil record was for a long time reduced to some scarce, disarticulated bones, mainly scales, found in various African deposits covering a wider area than the actual geographical distribution. With the discovery, on one hand, of polypterid scales, vertebrae, dermal bones of the cranium and dorsal spiny rays in South America and, on the other hand, of scales and numerous dorsal spiny rays in Niger and Sudan, and two articulated fossils in Morocco, the story of the polypteriformes has revealed some of its mysteries. The discovery of isopedine between dentine and bony basal plate in the scales of living and fossil polypterid species is considered a synapomorphy of the group, and has been an important aid in discriminating polypterid scales from other ganoid scales(Fish and Fisheries Volume 2 Issue 2 Page 113 - June 2001)
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