Fantastical Fish-a-pod’s Fish Fingers

It’s here, it’s here, Elpistostege is finally here!

What or who is Elpistostege, I hear you ask? Elpistostege is an ancient beastie that roamed the earth some 380 million years ago throughout parts of what is today Quebec in Canada. When fossils were first described it was thought they belonged to an ancient amphibian, before further finds suggested it was in fact a fish. The transition from fish (in the water) to the first land animals (with limbs and digits) was surely one of the greatest ever “steps” in evolution, and Elpistostege is perfectly placed to help us understand it.

10 years ago, Prof Richard Cloutier from Université du Québec à Rimouski, discovered a new specimen of Elpistostege, and for the first time a complete skeleton of this animal was uncovered! The fossil is 1.6 m long and preserves a complete head, vertebral column and all the fins right up to the tail.

Richard invited some of the Flinders University Palaeontology group to work with him and his team in Canada on this exciting new fossil, which is where I come in (along with John Long and Mike Lee). The fossil was CT scanned at the University of Texas High-Resolution X-ray Facility so that detailed 3-D modelling of its skeleton could be done.

Via this painstaking 3-D modelling of the scans (it took me months and months!), we revealed the internal bones of the pectoral skeleton (arm) including the presence of a humerus, radius, ulna, rows of carpal bones (e.g. your wrist bones), and other smaller bones (digits!). We have found the first fish fingers!

Excitingly, the digits are still contained within a fish fin. And as John and Richard put it in their recent Conversation article “This suggests the fingers of vertebrates, including of human hands, first evolved as rows of digit bones in the fins of Elpistostegalian fishes.” So next time you shake hands with someone (will we be doing that again?) or take a sip from a champagne flute (I’ll be doing that tonight), you know who you have to thank.

Read the full article in Nature here: https://www.nature.com/articles/s41586-020-2100-8.pdf

• Hear my radio interview on The Wire, with Lachlan McPherson here.