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Fossil floras of western Canada

The Late Cretaceous and Paleocene megafloras of Alberta

The sedimentary deposits in Alberta preserve rich assemblages of Late Cretaceous dinosaurs and Paleocene mammals. These animals are typically reconstructed to have lived in either savannah woodlands or lush forest ecosystems, growing under warm and wet regional climates; however, quantitative palaeobotanical data to support the existence of these regional climates and forest ecosystems in Alberta are comparatively rare or lacking entirely. This research proposes to answer several questions. First, what was the climate of Alberta during the Late Cretaceous and Paleocene? Second, what was the composition of the forests in Alberta? Lastly, what was the floral diversity – i.e., the relative abundance of the different plant taxa and lifeforms – of these ancient ecosystems? Prior studies describing Alberta Late Cretaceous and Paleocene floras focused primarily on taxonomic and systematic description of detached organs, or whole-plant reconstructions. While these studies are useful for understanding evolution within plant lineages, they offer only a narrative interpretation of the environments and vegetation character that Late Cretaceous and Paleocene animals lived.

The Late Cretaceous and early Eocene megafloras of British Columbia

The Late Cretaceous Nanaimo Group, as well as the plant-bearing Late Cretaceous deposits from Northern British Columbia, preserve fossil evidence of forest ecosystems growing during an important warm interval in Earth history. These fossil megafloral deposits offer an opportunity to provide deeper insight into terrestrial climate and ecosystem evolution in British Columbia during the Late Cretaceous, and additional deep-time context for terrestrial climate and ecosystem evolution in North America. The Eocene plant fossil deposits of Interior British Columbia represent a natural archive of plant biota growing at high altitudes during the globally warm Eocene epoch. These fossil plant deposits document evidence of important temperate plant families that gave rise to our modern forest ecosystems.

Fossil floras of the Canadian Arctic

Recent taxonomic descriptions of late Paleocene to early Eocene fossil plants from Ellesmere and Axel Heiberg islands (see West et al. 2019) provide a systematic framework for evaluating the floristic character of the late Paleocene and early Eocene Arctic fossil floras from Ellesmere and Axel Heiberg islands. This systematic framework will underpin new paleoecological and paleoclimatological analyses, which will focus on reconstructing the vegetative character of the early Eocene Arctic fossil megafloras (e.g., evergreen vs. deciduousness, canopy strata, insect leaf herbivory interactions, and vegetation diversity). In addition, the middle Eocene megafloras from Axel Heiberg Island will be investigated as these floras represent a direct continuum from the older late Paleocene and early Eocene floras from Ellesmere and Axel Heiberg islands. Analysis of these plant fossils presents an opportunity to investigate changes to high latitude forest ecosystems as a result of Eocene global climate change. Plant fossils will be used to reconstruct Eocene climate and high-latitude terrestrial ecosystems. In addition, the fossil flora will be similarly organized into a systematic framework and described for comparative purposes, which builds on previous work.

Forest evolution through deep time

Modern temperate forests in North America were influenced by the warm global climate of the early Cenozoic and share a biogeographic lineage with eastern Asia and Europe. Globally warm climates of the early Paleogene likely facilitated an exchange in biota between climatic zones. The lush late Paleocene – early Eocene forests in western Canada and the Arctic reflect this mixture of biogeographic lineages. These forests were comprised of floral elements from contemporaneous mid- and low-latitude ecosystems, pan-Arctic taxa, and taxa endemic to the Canadian Arctic. The Canadian mid- and high-latitude floras present a unique opportunity to study the biogeographic relationships between these and other coeval floras, which will provide insight on the development of our modern forest ecosystems.

Chemical fossils and plants

Plant leaf waxes and terpenoids, chemical fossils preserved in terrestrial sediments, will be used to reveal the presence and relative distribution of conifers and angiosperms across these ancient landscapes. This project focuses on constraining plant carbon isotope fractionation for localities where fossil plants are found and paleoprecipitation estimates are known. Carbon isotope fractionation in plants has been linked to increasing pCO2 and latitude. This work, in collaboration with Dr. Aaron Diefendorf (UCincinnati), will investigate these proposed connections to search for a causal relationship.

The Deep-Time Intermodel Comparison Project (DeepMIP)

Predictions of future climate, essential for safeguarding society and ecosystems, are underpinned by numerical models of the Earth system.  These models are routinely tested against, and in many cases tuned towards, observations of the modern Earth system.  However, the model predictions of the climate of the end of this century lie largely outside of this evaluation period, due to the projected future CO2 forcing being significantly greater than that seen in the observational record.  Indeed, recent work reconstructing past CO2 has shown that the closest analogues to the 22nd century, in terms of CO2 concentration, are tens of millions of years ago, in ‘Deep-Time’.

DeepMIP is dedicated to conceiving, designing, carrying out, analysing, and disseminating, an international effort to improve our understanding of Deep Time climates.

I am a member of DeepMIP.

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