Search the Community
Showing results for tags 'miguasha'.
Found 3 results
Bothriolepis ("pitted scale" or "trench scale") was the most successful genus of antiarch placoderms with over 100 species found on every continent, including Antarctica . The extinct armored fishes known as placoderms make up what is considered to be the earliest branch of the gnathostome family tree -- the earliest branch of the jawed fishes. Antiarchs are characterized by the fact that their pectoral fins are enclosed in bony tubes (pectoral appendages). Instead of typical fish-like pectoral fins, it bears a pair of rigid arms that are joined at two points. These arms, like the limbs of an arthropod, are articulated by interior muscles. Bothriolepis is a placoderm with a heavily armoured head fused with the thoracic shield. The body was encased in a bony box that had flat sides and bottom and an angled roof. There are two openings through its solidly armoured head -- a keyhole opening along the midline on the upper side for both eyes and nostrils and a mouth on the lower side near the front. The discovey of some undeformed, three-dimensionally preserved specimens led to a review of this fish's morphology. It appears that Bothriolepis had a much more rounded shape than previously thought, and as a direct consequence of the latest reconstructions, it is now believed that its eyes faced forward instead of upward. Bothriolepis does have a slender fish-like tail that extends behind the heavily armored portion but, because it is almost naked with few scales, it is rarely preserved. Placoderms bore heavy bony armor on the head and neck; in the past it has been suspected that there is an unusual joint in the dorsal armor between the head and neck regions; this joint apparently allowed the head to move upwards as the jaw dropped downwards, creating a larger gape. But one of the new discoveries shows there is no indication of mobility between the cephalic and thoracic armors. Bothriolepis had a peculiar spiral, sediment-filled gut and probably grubbed in the mud. It may also have used its pectoral fins to throw sediment (mud, sand or otherwise) over itself. Bothriolepis probably fed on invertebrates such as crustaceans and molluscs or even was a mud-grubber that ingested organic-rich mud for its food. Bothriolepis is the most common fish fossil in the shales and sandstones of the Escuminac Formation (Late Devonian, 380 Ma) on the south shore of the Gaspé Peninsula at Miguasha. Abraham Gesner (1797-1864), the provincial geologist of New Brunswick who discovered the site in 1842, referred to this fossil as "a small species of tortoise with foot-marks". It seems to be certain that there are at least two, with the second species discovered and described in 1924. Named B. traquairi (after the Scottish paleontologist Ramsey Heatly Traquair) the one and only specimen officially assigned to this species has a more slender body than B. canadensis. Because the fossils are found in freshwater sediments, Bothriolepis was originally presumed to have spent most of its life in freshwater rivers and lakes. This idea is now abandoned; many paleontologists now hypothesize that they lived most of their lives in saltwater, and returned to freshwater only to breed. Lit.: Béchard, I., Arsenault, F., Cloutier, R., & Kerr, J. (2014) The Devonian placoderm fish Bothriolepis canadensis revisited with three-dimensional digital imagery. Palaeontologia Electronica, 17(1):1-19 OPEN ACCESS PDF
m.e.clark posted a topic in Fossil IDHello, For academics purpose, I must identify parts of a fine specimen of Bothriolepis canadensis. I've spent a great deal of time trying to find how these parts were called, and couldn't find a convincing answer. One of my guess is that the anterior central structure shown on the pictures is the preorbital recess, but I'm pretty unsure of what would be the two cavities on its side, if it is indeed the preorbital recess. My second interrogation concerns the posterior end, where there are two mores plates, in V shapes. Then again, I have no clue what those might be. Therefore here I am, seeking help from more knowledgeable people on the subject. Thank you!
Taken from my blog: http://redleafz.blogspot.ca/2013/08/miguasha-national-park-quebec-canada.html (I had wished that somebody from la belle province would have posted anything on Miguasha, but I guess I'll be the first =P ) A few weeks ago I took a day trip to our neighboring province of Quebec to check out Miguasha National Park. I've always wanted to check that place since I've started researching fossil localities. Miguasha National Park is what the paleontology community sees as the world's most important paleontological fossil record of the Devonian Period. Most of the main fossil fish groups have been found here, including lobe-finned fish, the antecedent of tetrapods. The park's fossil collection has over 5000+ specimens. The importance of these cliffs and the treasures they hold has put this little community on the map, and eventually became a UNESCO World Heritage Site. For me, seeing this site was important. I've been going to Joggins quite often and appreciated what information that this place was giving out to the world. I wanted to see how this mirror image of an as important site from a different time period would compare with Joggins's. Miguasha (red dot) Me and my friend Ray left Moncton with his little red hybrid Prius early to be able to get to Miguasha at a reasonable time. The drive from Moncton to Campbelton took about 2 hours and a half, and from Campbelton to Nouvelle (Quebec) was about 30 minutes or so. The scenery driving up was gorgeous as you come across the eroded Appalachian mountains and Mount Sugarloaf, an extinct volcano of the same age as the rocks where the fish from Miguasha are found. After crossing the bridge that links the two Canadian provinces, the signage made finding the interpretation center pretty easy. Eusthenopteron foordi ('Prince of Miguasha') The star attraction of Miguasha is Eusthenopteron foordi, also called 'The Prince', which made this place famous. Eusthenopteron is a good example of a transitional animal by having this fish well on its way to evolve into tetrapods. Bothriolepis Another well-known abundant animal found in these cliffs is Bothriolepsis canadensis, a placoderm that had bone forming some sort of armor plating mostly on their head and thorax. The specimens I saw at the Park's interpretation center were exquisite! Silurian fossiliferous limetones (Anticosti Island) Can you spot the trilobites? The exhibits didn't just contain fossils from the area, but also from other parts of the province, and other parts of Canada. They currently have some bone from an Hadrosaur that used to roam Alberta during the Cretaceous. Archaeopteris halliana The Devonian Period was called the 'Age of Fish', but there was also life on land, albeit a bit more desolate and mostly populated by arthropods (primitive insects). Plants like this archaeopteris doted the landscape. This fern-like plant was similar to modern trees, but reproduced by producing spores like many other flora of the Paleozoic. Eusthenopteron foordi Escuminaspis laticeps Escuminaspis laticeps was a bottom feeding fish that was on its way out. They went extinct not long after this period of time. They were similar to the modern lamprey, as these were jawless fish. Bothriolepis canadensis (complete) My friend Ray with Dunkleosteus (cast), which could grow up to 7 meters long The Prince of Miguasha, Eusthenopteron foordi Close up of Eusthenopteron's tail (look at 'em bones) Eusthenopteron showing off its teeth After the guided tour of the interpretation center was done, we went down to the beach. High tide was quickly closing in so we couldn't stay on the beach for too long, just enough to have a quick chat on the past and current digs done at the cliffs. Layers of shale and silt that still hide fish Miguasha's Interpretation Center And that was it. We made our back back to New Brunswick with a quick stop in Campbelton for a late lunch. Looking back, it is easy to see why geologists keep coming to this area. Across the bay, the cliffs of Atholville all the way to Belledune have in them a treasure trove of Devonian fossils just as important as the ones found in Miguasha. I feel that I'll be spending a little bit of time up North in the near future. Till next time, cheers! - Keenan