Many years ago I discovered a unique field guide in the Minneapolis airport bookshop. .....Flattened Fauna, A field guide to common animals of roads, streets and highways.
The author describes 36 reptile, avian and mammal remains after compression, mainly by really big trucks. He he says that the animals are most sincerely dead, so dead that even the flies have lost interest.
Grey squirrels are very flat except for the long bushy tail which is usually the only identifying characteristic as it waves in the slipstream of passing trucks so it's not really suitable for cooking.