I live in southern Ohio, an area referred to geologically as unglaciated, meaning that the ice sheets from the last ice age did not reach here. I am a bit of a reptile buff. In reading I have done about the distribution of reptiles in Ohio, I frequently run into range discussions that mention species that are found in the glaciated area and not the unglaciated, or vice versa. I am simplistically dividing Ohio in glaciated and unglaciated regions, but it’s a little more complicated than that.
Thinking about those glaciers led me to the following thoughts. If most of Ohio was covered by ice during the last ice age, then reptiles, amphibians and insects must have been entirely absent. The unglaciated areas would probably have been too cold for exothermic species to survive as well.
So my questions. When did the glaciation that covered most of Ohio end? I have done a bit of internet reading and have not seen a firm answer on this question. Maybe a firm answer is not possible. Whenever it may have been, does that mean that all of the species of insects, reptiles and amphibians found in Ohio now migrated here since then?