Humans like to celebrate anniversaries during their lifetimes in fives and tens, which I like to think is a direct reflection of a much longer evolutionary heritage. For instance, why fives and tens, and not, say, threes or sevens? Look at your hands and feet, count your fingers and toes, and see what totals you get for each appendage (yakuza excluded). These numbers are a result of our having descended from synapsids (“mammal-like reptiles”) that likewise had five digits on each end of four limbs. In fact, all mammals are synapsids, and the last common ancestor synapsids shared with dinosaurs and other egg-laying reptiles was more than 300 million years ago. Humans and most other mammals don’t lay eggs (albeit, some placental mammals like to hatch from eggs), but a few still do – monotremes, such as platypuses and echindnas – thus demonstrating a lingering trait of this reptilian ancestry.
So it was this week that I was reminded of a five-year anniversary, the evolutionary history of mammals, and our long-lost connection to dinosaurs, thoughts that all coincided as they were triggered by remembering the Dinosaur Dreaming dig site in Victoria, Australia.
No, these people are not incarcerated and carrying out their sentences by cracking rocks all day in the summer sun. They actually are: volunteers at the annual Dinosaur Dreaming dig site in coastal Victoria, Australia; looking for fossils of Cretaceous dinosaurs, mammals, turtles, and other animals; and very much enjoy doing this. Really.