However, with its sprawling limbs and single temporal fenestra it instead belongs to a lineage sometimes referred to as “mammal-like reptiles”, although we prefer the more accurate term of synapsid.

We used powerful imaging methods to peer inside a 380-million-year-old fossil called Elpistostege from Quebec, Canada, to reveal the oldest fish fingers!

A tooth whorl is a bizarre row of teeth that curls in on itself in a spiral pattern (most famously present in the buzz-saw shark, Helicoprion).

Branchiostoma lanceolatum, a type of lancelet., CC BY-SA Next come those with well organised heads (craniates), and those in which the notochord is replaced by a backbone in adults (vertebrates).

We have a few tantalising fossils representing the earliest known examples of vertebrates, such as Metaspriggina known from Canada, or Haikouichthys from China in rocks more than 500 million years old.

So, whether it be your large brain and broad pelvis from walking around upright, skull with a single opening and bony arch, your fingers, toes, teeth or spinal cord, we humans share many ancient features in our bodies.