20. The answer is 1 (Precambrian)
21. The answer is 4 (Pennsylvanian)
22. The answer is 2 (Bony Fishes, Dinosaurs, and Mammals)
23. The answer is 2 (Reptiles)
The animal prepares for the hibernation ahead of time gathering food and eating so that it can sleep for the extended period of time without leaving
It couldn't be analysed chemically because it's chemical composition is to complex. It would be hard for us to analyse them because once it has been removed from the organism, it ends as protoplasm only.