Cracking the coelacanth code: Living version of HMNS fossil has genome sequenced

The coelacanth — a “living fossil” believed to have hardly changed over the last 300 million years — has finally had its genome sequenced by European researchers.

courtesy of wiki media
The deep-sea fish was the inspiration for the famous 1954 film Creature from the Black Lagoon and is well-represented here at HMNS, where we have three examples on display: a Devonian fossil, a Cretaceous specimen and a model like the one sequenced.

Researchers sorted through nearly 3 billion DNA bases to conclude that the coelacanth’s four fleshy fins were likely the early predecessors of limbs.

Although the coealcanth is related to early tetrapods — the first creatures to make the transition from the ocean to land — a comparison of the coelacanth genome with the DNA profiles of lungfish and other modern land-based animals led scientists to conclude that lungfish were the closer relative.

Coelacanths have been notoriously difficult to study, having been assumed extinct until an African fisherman caught the living fossil in 1938. Since then, only a few hundred specimens have been found.

Continue the investigation yourself at our Morian Hall of Paleontology, and see why this mysterious fish has kept researchers rapt for so long.

Living Fossils Living Large

Madagascar Hissing Cockroaches

Frances and I were asked if we would set up a living fossils table for the HMNS’s annual Dino Days celebration that took place here last week. Not having had any history or paleontology classes I was a little clueless as to which of our living animals would fit into the category of living fossils, other than our alligator.

We did some research and what we read lead us in several directions for what it means to be a living fossil. Some animals, like the echidna and platypus, are nicknamed living fossils because they exhibit “primitive” characteristics – like oviparity, or egg-laying, in mammals. The overall consensus is that a living fossil is an organism that originally lived during the time of the dinosaurs (or even predates them), has remained unchanged morphologically and appears the same as a species otherwise only known from the fossil record, has no close living relatives and has survived major extinction events.

Chambered Nautilus

There are several examples that fit this description: the crocodilians, horseshoe crabs, turtles, opossums, salamanders, roaches, millipedes, dragonflies, and the nautilus. These are some of the critters we have in our collection and you can also add ferns, ginkgos, gar fish and the coelacanth to the list. There remains a healthy debate over which plants or animals can and should be included. I have included some pictures of our fossils, both living and non-living at the end of this entry.

All in all, we had a great time in sharing our casts, skins, skulls and live animals with everyone who came up to the table during Dino Days. Hope to see you there next November!

Dino Days Baby Gator

Tiger Salamander - too cute

Fossilized crocodilian scute and modern scutes

Volunteers manned the Touch Tank giving visitors a chance to touch these little fellows - Horseshoe Crabs.

Cast of fossil turtle shell