Wednesday, August 09, 2006

Fieldwork Pt II: Miguasha

There was once a time when there were very few animals living on the land. Vertebrates are pretty much the last animals to march onto land. The time before tetrapods is one of the most interesting for paleontologists and evolutionary biologists because it represents a time when the basic evolution of vertebrates is happening -- from their very origins to their two largest radiations: sarcopterygians ('lobe fins' - including ourselves) and ray-fins (all the most common fish we recognize today. Together, these two groups contain the vast majority of vertebrate diversity. It is also during this time that jaws originated and all kinds of appendages evolve into a diverse array of forms. If we are to single out the most significant site in helping us understand this time it is the greenish coloured cliffs of the Escuminac Formation at Miguasha, Quebec.

Located on the Baie des Chaleurs on the Gaspé Peninsula, the Parc Nationale de Miguasha preserves unbelievably beautiful and complete vertebrate fossils. The most famous of these is probably Eusthenopteron, the icon of children's books on prehistoric life as that fish that crawled from the water. While it is doubtful that Eusthenopteron crawled around on land, it certainly had much in common with the first tetrapods.

These are the cliffs from which it and many other extremely important fossil fishes were found.



I spent at least a few hours of every day, or sometimes the better part of a day out prospecting on the beach and the cliffs. Even with constant patrolling and daily visits by tourists, there are still important specimens to be found -- even lying on the beach. The most common fossil out there is probably the placoderm (or "armored fish") known as Bothriolepis. It's initial discovery was a serious case of "mistaken identity", as it was thought to be a turtle! However, later specimens from Miguasha showed preservation of its soft, unarmored body and tail demonstrating that it was a fish. Recently, a specimen was discovered showing stains on the inside of the ventral shield where the blood vessels had been!

This same locality is also the place where Elpistostege, Tiktaalik's sister-taxon was first recovered. Elpistostege was really the first so-called "fishapod" to be found. Initially, only a partial skull roof was known and was described by T.S. Westoll in 1938. Since then, some more of the skull and body, seen below, have been found and described.



This is the beautiful museum which stands at the top of the cliffs. In my opinion, it probably has one of the finest displays of any museum in all of Canada -- and it's very small. The display is very pedagogical, in a good way. It uses the finest examples of each type of fish that is found at Miguasha to give the visitor a sense of the diversity that exists there. It uses a lot of pictures, specimens and cleverly organized displays to teach the history of the site: both geologically and in terms of the discovery, exploitation and research of the site. Sorry, I haven't got pictures of the displays handy.



In short, this bit of fieldwork was more like a holiday for me. In fact, it wasn't much in the way of fieldwork, since I got more work done in the collections. I really would like to encourage people to check the place out if they ever get the chance. It's a bit out of the way, but if you're at all interested in palaeontology, evolution, or just pretty places, it's well worth the visit.

3 comments:

rwez said...

hey martin,

not a real comment on your article, just a general one: great site! will stay alert on new articles and photos!

rick
--
http://rwez.blogspot.com/

B12 said...

Would you say the beach is one of your favorite places to be?

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