The Jewish holy book, the Torah, permits the consumption of select animals. Only land animals that both “chew the cud” and have cloven hooves are allowed. That means ruminants like cows are on the menu, while pigs are not. Fish with both fins and scales are also permitted. Birds of prey are not to be eaten, along with “creeping things” that crawl the earth and “flying creeping things” (commonly taken to mean “insects” and “flying insects”). However, grasshoppers, beetles, and certain types of locusts are permitted.

But, of course, the animals around today aren’t the same as they were thousands or millions of years ago. The kosher animals of today may not have been around in the ancient past!

So what was? The authors explored numerous eras in a literary piece of time travel.