RISE OF THE ANGIOSPERMS

Florissantia sp., from the Allenby Formation, Princeton, BC

Plant fossils are found coast-to-coast in Canada, from 45-million-year-old mosses in British Columbia to fossil forests on Axel Heiberg and Ellesmere islands in the Canadian Arctic.

The early angiosperms developed advantages over contemporary groups — rapid reproductive cycles —  which made them highly efficient, adapting well to "weedy" growth. These modifications, including flowers for the attraction of insect pollinators, proved advantageous in many habitats.

Interaction between plant and pollinator has been a driving force behind the astounding diversification of both flowering plants and insects.

Some of the earliest known flowering plants are found in northeastern British Columbia coalfields. Late Cretaceous (about 101–66 million years ago) floras of the Dawson Creek area of British Columbia, and Milk River, Alberta, reveal increasing dominance by angiosperms. These fossils, while generally resembling some living angiosperms, represent old, extinct families, and their relationships to living groups remain unclear.

At the end of the Cretaceous, the climate cooled, inland seas covering much of western Canada drained, and dinosaurs became extinct. At the boundary between the Cretaceous and Paleogene is evidence of extinction amongst land plants, too. During this interval of mass extinction, the Earth was struck by a massive meteorite. The fallout from this impact is preserved in boundary sediments in southern Saskatchewan as a pale clay, rich in rare earth elements such as iridium.

In the early Paleogene period (66–56 million years ago), we entered the age of mammals. Paralleling the rise of mammals is the rise of modern flora, which consists overwhelmingly of flowering plants.

Early Paleogene fossils are found over much of Alberta —  Red Deer River, Lake Wabamun coalfields and Robb to Coal Valley coalfields —  and southern Saskatchewan —  Eastend area to Estevan coalfield —  to as far north as Ellesmere Island. These floras reveal a variety of flowering plants, including members of the sycamore, birch and walnut families, but the most abundant fossil plants are the katsuras and the dawn redwood, now native only to southeastern Asia.

In the mid-Paleogene period (56–34 million years ago) brief climatic warming coincided with the rapid diversification of flowering plants. Eocene fossils in British Columbia (Princeton, Kamloops and Smithers areas) reveal increasing numbers of modern plant families, with extinct species of birch, maple, beech, willow, chestnut, pine and fir.

Exceptionally well-preserved fossil forests found on Axel Heiberg and Ellesmere islands in the Canadian Arctic illustrate clearly the contrast between modern Canadian vegetation and the floras of a much warmer past. These fossil forests, 40 to 60 million years old, consist of large stumps, many over 1 m in diameter, preserved where they grew, still rooted in ancient soil.

Thick mats of leaf litter that formed the forest floor reveal the types of plants inhabiting the forests. Lush redwood and cypress swamps covered the lowlands, while the surrounding uplands were dominated by a mixed conifer and hardwood forest resembling that of modern eastern North America. Even accounting for continental drift, these forests grew well above the Arctic Circle, and bear witness to a time in Canada's past when a cold arctic climatic regime did not exist.

Around 45-50 million years ago, during the middle Eocene, a number of freshwater lakes appeared in an arc extending from Smithers in northern British Columbia, south through the modern Cariboo, to Kamloops, the Nicola Valley, Princeton and finally, Republic, Washington.

The lakes likely formed after a period of faulting created depressions in the ground, producing a number of basins or grabens into which water collected — imagine gorgeous smallish lakes similar to Cultus Lake near Chilliwack, British Columbia.

Fossilized wood permineralized in fine-grained sediment

The groaning Earth, pressured by the collision of tectonic plates produced a series of erupting volcanoes around the Pacific Northwest. These spouting volcanoes blew fine-grained ash into the atmosphere and it rained down on the land.

The ash washed into the lakes and because of its texture, and possibly because of low water oxygen levels on the bottoms that slowed decay beautifully preserved the dead remains of plant, invertebrate, and fish fossils —  some in wonderful detail with fascinating and well-preserved flora.

Near the town of Princeton, British Columbia, we see the results of that fine ash in the many fossil exposures. The fossils you find here are Middle Eocene, Allenby Formation with a high degree of detail in their preservation. Here we find fossil maple, alder, fir, pine, dawn redwood and ginkgo material. The Allenby Formation of the Princeton Group is regarded as Middle Eocene based on palynology (Rouse and Srivastava, 1970), mammals (Russell, 1935; Gazin, 1953); freshwater fishes (Wilson, 1977, 1982) and potassium-argon dating (Hills and Baadsgaard, 1967).

Several species of fossilized insects can be found in the area and rare, occasional fossil flowers and small, perfectly preserved fish. More than 50 flowers have been reported (Basinger, 1976) from the Princeton chert locality that crops out on the east side of the Similkameen River about 8 km south of Princeton, British Columbia.

The first descriptions of fossil plants from British Columbia were published in 1870–1920 by J.W. Dawson, G.M. Dawson, and D.P. Penhallow. Permineralized plants were first described from the Princeton chert in the 1970s by C.N. Miller, J.F. Basinger, and others, followed by R.A. Stockey and her students. W.C. Wehr and K.R. Johnson revitalized the study of fossils at Republic with the discovery of a diverse assemblage in 1977.

In 1987, J.A. Wolfe and Wehr produced a United States Geological Survey monograph on Republic, and Wehr cofounded the Stonerose Interpretive Center as a venue for public collecting. Systematic studies of the Okanagan Highlands plants, as well as paleoecological and paleoclimate reconstructions from palynomorphs and leaf floras, continue to expand our understanding of this important Early Eocene assemblage.

One of the sister sites to McAbee, the Driftwood Canyon Provincial Park Fossil Beds, offers an honours system for their site. Visitors may handle and view fossils but are asked to not take them home. Both Driftwood Canyon and McAbee are part of that arc of Eocene lakebed sites that extend from Smithers in the north, down to the fossil site of Republic Washington, in the south. The grouping includes the fossil sites of Driftwood Canyon, Quilchena, Allenby, Tranquille, McAbee, Princeton and Republic. Each of these localities provides important clues to our ancient climate.

Eocene Plant Fauna / Eohiodon Fish Fossil / McAbee

The fossils range in age from Early to Middle Eocene. McAbee had a more temperate climate, slightly cooler and wetter than other Eocene sites to the south at Princeton, British Columbia, Republic in north-central Washington, in the Swauk Formation near Skykomish and the Chuckanut Formation of northern Washington state. The McAbee fossil beds consist of 30 metres of fossiliferous shale in the Eocene Kamloops Group.

The fossils are preserved here as impressions and carbonaceous films. We see gymnosperm (16 species); a variety of conifers (14 species to my knowledge); two species of ginkgo, a large variety of angiosperm (67 species); a variety of insects and fish remains, the rare feather and a boatload of mashed deciduous material. Nuts and cupules are also found from the dicotyledonous Fagus and Ulmus and members of the Betulaceae, including Betula and Alnus.

We see many species that look very similar to those growing in the Pacific Northwest today. Specifically, cypress, dawn redwood, fir, spruce, pine, larch, hemlock, alder, birch, dogwood, beech, sassafras, cottonwood, maple, elm and grape. If we look at the pollen data, we see over a hundred highly probable species from the site. Though rare, McAbee has also produced spiders, birds (and lovely individual feathers) along with multiple specimens of the freshwater crayfish, Aenigmastacus crandalli.

For insects, we see dragonflies, damselflies, cockroaches, termites, earwigs, aphids, leafhoppers, spittlebugs, lacewings, a variety of beetles, gnats, ants, hornets, stick insects, water striders, weevils, wasps and March flies. The insects are particularly well-preserved. Missing are the tropical Sabal (palm), seen at Princeton.

200 km to the south, fossil leaves and fish were first recognized at Republic, Washington, by miners in the early 1900s. We find the impressive Ensete (banana) and Zamiaceae (cycad) at Eocene sites in Republic and Chuckanut, Washington. Many early workers considered these floras to be of Oligocene or Miocene age. C.A. Arnold described Canadian occurrences of conifers and Azolla in the 1950s. Palynological studies in the 1960s by L.V. Hills, G.E.Rouse, and others and those of fossil fish by M.V.H. Wilson in the 1970–1980s provided the framework for paleobotanical research at several key localities.

With the succession of ice ages that swept down across North America in the Pleistocene, there were four intervening warm periods. These warmer periods help many species, including the genus Oenothera, enjoy four separate waves of colonization — each hybridizing with the survivors of previous waves. This formed the present-day subsection Euoenothera. The group is genetically and morphologically diverse and contains some of the most interesting of the angiosperms.

Today, there are about 145 species of herbaceous flowering plants in the genus Oenothera, all native to the Americas. It is the type genus of the family Onagraceae. We know them by many names — evening primrose, suncups, and sundrops  —  but they are not closely related to the true primroses (genus Primula).

Oenothera flowers are pollinated by insects, such as moths and bees. One of the most interesting things I've learned (thank you, Jim Barkley) is a clever little evolutionary trait exhibited by the beach evening primrose, Oenothera drummondil. These lovelies can actively sense and respond to the buzzing of bees. Marine Veits et al. were able to show that this species has evolved to respond to the sound of bees by producing nectar with a higher sugar concentration, certainly yummy by bee standards — therein attracting more pollinators and increasing the plant species reproductive success.

David R. Greenwood, Kathleen B. Pigg, James F. Basinger, and Melanie L. DeVore: A review of paleobotanical studies of the Early Eocene Okanagan (Okanogan) Highlands floras of British Columbia, Canada, and Washington, USA.

Sauquet H, von Balthazar M, Magallón S, et al. The ancestral flower of angiosperms and its early diversification. Nat Commun. 2017;8:16047. Published 2017 Aug 1. doi:10.1038/ncomms16047

Marine Veits  Itzhak Khait  Uri Obolski, et al. Flowers respond to pollinator sound within minutes by increasing nectar sugar concentration. https://doi.org/10.1111/ele.13331

Photo: Pictured above is a beautiful example of Florissantia sp., an extinct species of angiosperm from Eocene outcrops near Princeton, British Columbia. It is one of the best-preserved specimens I've seen from the Allenby. Florissantia can be found in western North America outcrops dating from the Eocene to the Oligocene, 56 to 23 million years ago.

GRATIFYING GASTROPODA

Gastropods, or univalves, are the largest and most successful class of molluscs. They started as exclusively marine but have adapted well and now their rank spends more time in freshwater than in salty marine environments.

Many are marine, but two-thirds of all living species live in freshwater or on land. Their entry into the fossil record goes all the way back to the Cambrian.

Slugs and snails, abalones, limpets, cowries, conches, top shells, whelks, and sea slugs are all gastropods. They are the second-largest class of animals with over 60,000–75,000 known living species. The two beauties you see here are Turritella, a genus of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae. They hail from the Paris Basin and have tightly coiled shells, whose overall shape is basically that of an elongated cone. The name Turritella comes from the Latin word turritus meaning "turreted" or "towered" and the diminutive suffix -ella.

Many years ago, I had the pleasure of collecting in the Paris Basin with a fellow named Michael. I had stalked the poor man from Sunday market to Sunday market, eventually meeting up with him in the town of Gordes. He graciously shared his knowledge of the local fossil localities from the hills south of Calais to Poitiers and from Caen to the Rhine Valley, east of Saarbrücken. I deeply regret losing my notebook from that trip but cherish the fossils and memories.

The Paris Basin has many fine specimens of gastropods. These molluscs were originally sea-floor predators, though they have evolved to live happily in many other habitats. Many lines living today evolved in the Mesozoic. The first gastropods were exclusively marine and appeared in the Upper Cambrian (Chippewaella, Strepsodiscus). By the Ordovician, gastropods were a varied group present in a variety of aquatic habitats. Commonly, fossil gastropods from the rocks of the early Palaeozoic era are too poorly preserved for accurate identification. Still, the Silurian genus Poleumita contains fifteen identified species.

Most of the gastropods of the Palaeozoic belong to primitive groups, a few of which still survive today. By the Carboniferous, many of the shapes we see in living gastropods can be matched in the fossil record, but despite these similarities in appearance the majority of these older forms are not directly related to living forms. It was during the Mesozoic era that the ancestors of many of the living gastropods evolved.

In rocks of the Mesozoic era, gastropods are more common as fossils and their shells often very well preserved. While not all gastropods have shells, the ones that do fossilize more easily and consequently, we know a lot more about them. We find them in fossil beds from both freshwater and marine environments, in ancient building materials and as modern guests of our gardens.

SKØKKENMØDDINGER

Johnny Scow's Kwakwaka'wakw Kwakiutl House, 1918

Many First Nations sites were inhabited continually for centuries.

The day-to-day activities of each of these communities were much like we have today. Babies were born, meals were served and life followed a natural cycle. 

As coastal societies lived their lives they also left their mark. There are many communities thriving today but we have lost some to time, plague and disease. For those that have been abandoned or gone quiet, we see the remnants of a once thriving village through their totems, skeletons of buildings—and most always through discarded shells and scraps of bone from their food.

These refuse heaps contain a wealth of information about how that community lived, what they ate and what environmental conditions looked like over time. They also provide insight into the local gastronomic record on diet, species diversity, availability and variation.

This physical history provides a wonderful resource for archaeologists in search of botanical material, artifacts, broken cooking implements and my personal favourite, mollusc shells. Especially those formed from enormous mounds of bivalves and clams. We call these middens. Left for a period of time, these unwanted dinner scraps transform through a process of preservation.

Shell middens are found in coastal or lakeshore zones all over the world. Consisting mostly of mollusc shells, they are interpreted as being the waste products of meals eaten by nomadic groups or hunting parties. Some are small examples relating to meals had by a handful of individuals, others are many metres in length and width and represent centuries of shell deposition. In Brazil, they are known as sambaquis, left between the 6th millennium BCE and the beginning of European colonization.

European shell middens are primarily found along the Atlantic seaboard and in Denmark from the 5th millennium BCE (Ertebølle and Early Funnel Beaker cultures), containing the remains of the earliest Neolithisation process (pottery, cereals and domestic animals).

Younger shell middens are found in Latvia (associated with Comb Ware ceramics), Sweden (associated with Pitted Ware ceramics), the Netherlands (associated with Corded Ware ceramics) and Schleswig-Holstein (Late Neolithic and Iron Age). All these are examples where communities practised a mixed farming and hunting/gathering economy.

On Canada's west coast, there are shell middens that run for more than 1 kilometre (0.62 mi) along the coast and are several meters deep. The midden in Namu, British Columbia is over 9 metres (30 ft) deep and spans over 10,000 years of continuous occupation.

Shell middens created in coastal regions of Australia by Indigenous Australians exist in Australia today. Middens provide evidence of prior occupation and are generally protected from mining and other developments. One must exercise caution in deciding whether one is examining a midden or a beach mound. There are good examples on the Freycinet Peninsula in Tasmania where wave action currently is combining charcoal from forest fire debris with a mix of shells into masses that storms deposit above high-water mark.

Shell mounds near Weipa in far north Queensland are claimed to be middens but are actually shell cheniers, beach ridges re-worked by nest mound-building birds. The midden below is from Santa Cruz, Argentina. We can thank Mikel Zubimendi for the photo.

Some shell middens are regarded as sacred sites, such as the middens of the Anbarra of the Burarra from Arnhem Land, a historical region of the Northern Territory of Australia —  a vast wilderness of rivers, rocky escarpments, gorges and waterfalls.

The Danish use the term køkkenmøddinger, coined by Japetus Steenstrup, a Danish zoologist and biologist, to describe shell heaps and continues to be used by some researchers.

So what about these ancient shells is so intriguing? Well, many things, not the least being their ability to preserve the past. Shells have a high calcium carbonate content.

Calcium carbonate is one of my favourite chemical compounds. It is commonly found in rocks —  as the minerals calcite and aragonite, most notably as limestone, which is a type of sedimentary rock consisting mainly of calcite —  and is the main component of pearls, snails, eggs and the shells of marine organisms. About 4% of the Earth's crust is made from calcium carbonate. It forms beautiful marbles and the 70 million-year-old White Cliffs of Dover — calcium carbonate as chalk made from the skeletons of ancient algae.

Time and pressure leach the calcium carbonate, CaCO3, from the surrounding marine shells and help embalm bone and antler artifacts that would otherwise decay. Much of what we know around the modification of natural objects into tools comes from this preservation. The calcium carbonate (CaCO3) in the discarded shells tends to make the middens alkaline, slowing the normal rate of decay caused by soil acidity and leaving a relatively high proportion of organic material —  food remnants, organic tools, clothing, human remains — to sift through and study.

Calcium carbonate shares the typical properties of other carbonates. In prepping fossil specimens embedded in limestone, it is useful to know that limestone, itself a carbonate sedimentary rock, reacts with stronger acids. If you paint the specimen with hydrochloric acid, you'll hear a little fizzling sound as the limestone melts and carbon dioxide is released: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l). I tend to use a 3-5 molar solution, then rinse with plain water.

Calcium carbonate reacts with water saturated with carbon dioxide to form the soluble calcium bicarbonate. Bone already contains calcium carbonate, as well as calcium phosphate, Ca2, but it is also made of protein, cells and living tissue. Decaying bone acts as a sort of natural sponge that wicks in the calcium carbonate displaced from the shells. As protein decays inside the bone, it is replaced by the incoming calcium carbonate, making the bone harder and more durable.

The shells, beautiful in their own right, make the surrounding soil more alkaline, helping to preserve the bone and turn dinner scraps into exquisite scientific specimens for future generations.

ECHINODERMATA: CRINOIDS

This lovely specimen is Zeacrinites magnoliaeformis, an Upper Mississippian-Chesterian crinoid found by Keith Metts in the Glen Dean Formation, Grayson County, Kentucky, USA.

Crinoids are unusually beautiful and graceful members of the phylum Echinodermata. They resemble an underwater flower swaying in an ocean current. But make no mistake they are marine animals. Picture a flower with a mouth on the top surface that is surrounded by feeding arms. Awkwardly, add an anus right beside that mouth. That's him!

Crinoids with root-like anchors are called Sea Lilies. They have graceful stalks that grip the ocean floor. Those in deeper water have longish stalks up to 3.3 ft or a meter in length.

Then there are other varieties that are free-swimming with only vestigial stalks. They make up the majority of this group and are commonly known as feather stars or comatulids. Unlike the sea lilies, the feather stars can move about on tiny hook-like structures called cirri. It is this same cirri that allows crinoids to latch to surfaces on the seafloor. Like other echinoderms, crinoids have pentaradial symmetry. The aboral surface of the body is studded with plates of calcium carbonate, forming an endoskeleton similar to that in starfish and sea urchins.

These make the calyx somewhat cup-shaped, and there are few, if any, ossicles in the oral (upper) surface called a tegmen. It is divided into five ambulacral areas, including a deep groove from which the tube feet project, and five interambulacral areas between them. The anus, unusually for echinoderms, is found on the same surface as the mouth, at the edge of the tegmen.

Crinoids are alive and well today. They are also some of the oldest fossils on the planet. We have lovely fossil specimens dating back to the Ordovician.