Tuesday, 25 September 2018
By the time these ammonites were being buried in sediment, Wrangellia, the predominately volcanic terrane that now forms Vancouver Island and the Queen Charlotte Islands, had made its way to the northern mid-latitudes.
Within the basal part of the sequence, sedimentary beds are found interbedded with lapilli and crystal-tuffs. They include maroon tuffaceous sandstone, orange-grey sandstone, granule sandstone and conglomerate. Ammonites are found alongside gastropods and pelecypods. The Bonanza group is estimated to be at least 1000 metres thick.
We did a fossil field trip up there a few years ago. The site is quite small and the window to collect was limited so we were keen to see what had been exposed.
The drive up the mountain was thrilling as there had just been heavy rains and the road was washed out and narrowed until it was barely the width of our wheel base and then narrower further to be just shy of the width of the vehicle -- thrilling to say the least.
So scary that my passengers all got out as there was a good chance of going over the edge. I was going by some hand written notes and a wee map on a napkin that should have read, "park at the bottom and hike up," Ah, glorious fossils.
Graham Beard from Qualicum Beach was the fellow who showed me the site and drew the wee map for me. I cannot recall everyone on the trip, but Perry Poon was there (he shot a video of the drive up that he described as thrilling. I've never seen it but would like to one day) and so was Patricia Coutts with her lovely doberman. She and I had just done a trip up to Goldbridge where the cliff we were on had turned into a landslide into a ravine so she was feeling understandably cautious about the power of Mother Nature.
As I recall, I wasn't in my ordinary vehicle but a rental because my car had been stolen the weekend I'd headed to Jurassic Point to visit fossil sites with John Fam and Dan Bowen. Fortuitous really, as they stole my car but I'd unloaded my precious fossil collecting gear out of the trunk the day before.
Picture the angle, the hood of my jeep riding high and hiding what remained of the road beneath and a lovely stick shift that made you roll backwards a wee bit with every move to put it into gear. So, without being able to see the very narrow path beneath, I had to just keep going.
Both Perry and Patricia helped with filling in the pot holes so my tires would have something to grip. I bent the frame on the jeep heading up and had some explaining to do when I returned it to the car rental place.
The Memekay site yielded a mix of ammonites, gastropods and bivalves. Many of them poorly preserved.
Once up, I had to drive the whole thing again back down. Solo, as no one wanted to chance it. But well worth the effort as we found some great fossils and with them more information on the paleontology and geology of Vancouver Island.
Saturday, 22 September 2018
When we envision fish, we generally picture large eyes, gills, a well-developed mouth. The earliest animals that we classify as fish appeared as soft-bodied chordates who lacked a true spine. While they were spineless, they did have notochords, a cartilaginous skeletal rod that gave them more dexterity than the cold-blooded invertebrates who shared those ancient seas and evolved without a backbone. Fish would continue to evolve throughout the Paleozoic, diversifying into a wide range of forms. Several forms of Paleozoic fish developed external armour that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many species, including sharks, became formidable marine predators rather than just the prey of arthropods.
Fishes in general respire using gills, are most often covered with bony scales and propel themselves using fins. There are two main types of fins, median fins and paired fins. The median fins include the caudal fin or tail fin, the dorsal fin, and the anal fin. Now there may be more than one dorsal, and one anal fin in some fishes.
The paired fins include the pectoral fins and the pelvic fins. And these paired fins are connected to, and supported by, pectoral and pelvic girdles, at the shoulder and hip; in the same way, our arms and legs are connected to and supported by, pectoral and pelvic girdles. This arrangement is something we inherited from the ancestors we share with fishes. They are homologous structures.
When we speak of early vertebrates, we're often talking about fishes. Fish is a term we use a lot in our everyday lives but taxonomically it is not all that useful. When we say, 'fish' we generally mean an ectothermic, aquatic vertebrate with gills and fins.
Fortunately, many of our fishy friends have ended up in the fossil record. We may see some of the soft bits from time to time, as in the lovely fossil fish found in concretion in Brazil, but we often see fish skeletons. Vertebrates with hard skeletons had a much better chance of being preserved. In British Columbia, we have lovely two-dimensional Eocene fossil fish well-represented from the Allenby of Princeton and the McAbee Fossil Beds. We have the Tiktaalik roseae, a large freshwater fish, from 375 million-year-old Devonian deposits on Ellesmere Island in Canada's Arctic. Tiktaalik is a wonderfully bizarre creature with a flat, almost reptilian head but also fins, scales and gills. We have other wonders from this time. There are also spectacular antiarch placoderms, Bothriolepsis, found in the Upper Devonian shales of Miguasha in Quebec.
There are fragments of bone-like tissues from as early as the Late Cambrian with the oldest fossils that are truly recognizable as fishes come from the Middle Ordovician from North America, South America and Australia. At the time, South America and Australia were part of a supercontinent called Gondwana. North America was part of another supercontinent called Laurentia and the two were separated by deep oceans.
Thursday, 20 September 2018
The graptolites are now classed as hemichordates (phylum Hemichordata), a primitive group which probably shares a common ancestry with the vertebrates.
In life, many graptolites appear to have been planktonic, drifting freely on the surface of ancient seas or attached to floating seaweed by means of a slender thread. Some forms of graptolite lived attached to the sea-floor by a root-like base. Graptolite fossils are often found in shales and slates. The deceased planktonic graptolites would sink down to and settle on the sea floor, eventually becoming entombed in the sediment and are thus well preserved.
Graptolite fossils are found flattened along the bedding plane of the rocks in which they occur. They vary in shape, but are most commonly dendritic or branching (such as Dictoyonema), saw-blade like, or "tuning fork" shaped, such as Didymograptus murchisoni.
Sunday, 16 September 2018
Sunday, 2 September 2018
The fine-grained shales from the Burgess were once part of the ancient landmass known as Laurentia, the ancient geologic core of the North American continent, and are home to some of the most diverse and well-preserved fossils in the world. The sedimentary shales here contain fossils that open a window to marine life some 508 million years ago.
The site is made up of a few quarries and includes the Stephen Formation (Mount Wapta and Mount Field) and the upper Walcott quarry with its Phyllopod Bed. There is also a lower quarry named for Professor Piercy Raymond who opened the site in 1924.
It is one of the rare locations in the world where both soft tissues and hard body parts have been fossilized amidst the layers of black shale that form Fossil Ridge and the surrounding areas.
Discovered 109-years ago in 1909 by Charles D. Walcott, the site has continued to wow scientists and the community at large year after year. Charles was in Canada after losing his first wife to a train crash in Connecticut. He met Mary Morris Vaux, an amateur naturalist from a wealthy family and this new love and her interest in the wilds of Canada had brought him back.
Walcott was a geologist, paleontologist and administrator of the Smithsonian Institution in Washington, DC, USA. He was an expert in Cambrian fossils for his time. A company man, he joined the US Geological Survey in 1879 and rose to become a director in 1894. He served as President of the American Association for the Advancement of Science in 1923 and was an advisor to President Theodore Roosevelt.
Picture the world at this time. Coca-Cola sold their first soft drink, in Germany, Wilhelm Roentgen developed the first x-ray and it was a year before the United States Supreme Court ruled that "separate but equal" public facilities for whites and blacks ought to be legal.
So, up and coming Walcott was up exploring in the Rockies and stopped to rest his horse. Always a rock man, he had his hammer handy and split some likely blocks. They contained trilobites and other arthropods now famous from the site.
While he recognized the significance of the site, it wasn’t until 1960 through the work of Alberot Simonella and others that the Burgess received the scientific attention it deserved.
In 1967, Harry Whittington initiated the Cambridge Project to re-open the Burgess files and build on the work of his predecessors. He brought two grad students on board to do the heavy lifting as a means to publish or perish. Simon Conway Morris (Worms) and Derek Briggs (Arthropods) completed the trio and together they formed the foundation of what was to become some of the most significant work of our time.
Imagine the first paleontologists working on these weird and wonderful specimens. Wondering at the strange and unlikely creatures made real before their eyes. It is a rare and exquisite thing to see soft-bodied organisms fossilized.
Every year, a new species or magnificent specimen is unearthed. In 2011, a hiker discovered a rare fossil of Ovatiovemis, a genus of filter-feeding lobopodians. Picture a marine worm with nine arms waving to you. Yep, that’s him. The specimen she found is now described as Ovatiovermis cribratus and is one of only two known specimens of Oviatiovermis from the Burgess.
This important site in the Canadian Rockies has been awarded protection as a UNESCO World Heritage Site (1981) in recognition of the exceptional fossil preservation and diversity of the species found here.
With countless hours of research and study, we now know the Burgess Shale contains the best record we have of Cambrian animal fossils. It reveals the most complete record of creatures that proliferated the Earth showcasing the Cambrian explosion 545 to 525 million years ago.
It was a time of oceanic life in all it's splendor. The land may habe been inhospitable, barren and uninhabited but our oceans were teeming with new species. Great soft fine-grained mudslides slid onto an ecosystem in a deep-water basin.
Millions of years later, this unlikely event was revealed to us through the fossils preserved at Burgess.