Erik Jarvik and the Prince of Miguasha

In 1892, American paleontologist Edward Drinker Cope, well known for his passionate for hunting dinosaur bones, was the first to describe the bone structure of the fins of Eusthenopteron foordi and to recognize the equivalent bones in the skeletons of tetrapods.

Eusthenopteron foordi is nicknamed The Prince of Miguasha, not only because it holds one of the foremost places in the evolution and understanding of vertebrates, but also because it helped bestow worldwide recognition upon Miguasha during the 20th century.

(48 kb)Researchers from all over the world have studied Eusthenopteron, but the Swedes have a special place in the history of this fish. In particular, Professor Erik Jarvik dedicated sixty years of his life to studying Eusthenopteron, and published descriptions that were unequalled in their accuracy and realism. Not only is the skeleton well known, but also such details as the shape of the brain, the placement of the main nerves and blood vessels, the point of insertion of the muscles, etc.

This vast wealth of knowledge is almost entirely due to a single specimen, the famous P.222, which was acquired by the Swedish Natural History Museum in Stockholm. Discovered during dynamite work in preparation for the construction of the Miguasha quay, the Swedes acquired the specimen through Joseph Landry for the sum of $50 Canadian, and it was shipped to Sweden in 1925.

(48 kb)Researchers in Stockholm were thrilled by the incredible preservation of the specimen. At 53 cm long, its body still had a rounded shape and its head was almost complete, with the exception of a small part of the snout that was missing. After removing the fossilized scales from its surface, they could see the entire skeleton inside, held perfectly in place by its shroud of rock. If not for the stony texture, the specimen could have mistaken for a recently killed fish.

(40 kb)Erik Jarvik and his mentor, Erik Stensiö, decided to study the interior of the skull of this exceptional specimen by a process called serial sectioning. The method consisted of grinding away the specimen layer by layer, removing 0.2 mm of the fossil at a time, and drawing the exposed surface. The sectioning gradually wore down the entire skull, but the 530 drawings made during the process allowed researchers to reconstruct the head in three dimensions with wax, and to meticulously study everything on the surface and interior, right down to the tiniest details.

Twenty-five years of work on specimen P.222 provided a virtually complete morphology of Eusthenopteron’s skull, gills, palate bones, nasal capsules, etc. One of the most significant anatomical details revealed by Jarvik’s study was in the snout of the fish. The cross-sections made it possible to observe that the two nasal capsules, the little cavities in the interior of the snout, were not only linked to the outside by external nostrils, but also opened into the interior of the palate via internal nostrils. Identical orifices, called choana, are present in the fossils of primitive tetrapods. The presence of choana in Eusthenopteron strengthens the link between this sarcopterygian fish and terrestrial vertebrates.

Studies continue to this day on Eusthenopteron. Jarvik’s work is now pursued using new research techniques that include scanners and other non-destructive methods, which allow specimens to be preserved intact.

More than 200 articles were published on this species by researchers around the world. Thanks to all this diligent work, Eusthenopteron has the best known anatomy of any vertebrate fossil.