DEVONIAN PERIOD

References

419.2 - 358.9 Ma YEARS AGO

Although fossil record shows that insects were wingless during the Devonian Period, they mauy have began to appear during the Devonian as winged insects are found early in the next Carboniferous Period.

During the Devonian Period, the Earth had two supercontinents Gondwana and Euramerica.

Placoderm at the time could vary in size from the large Dunkleosteus (10m long) to the Minicrania (2cm long).

DEVONIAN EXTINCTIONS

DEVONIAN PLANT EXPLOSION

ANIMAL LIFE

PLANT LIFE

Fun Facts

MAJOR EVENTS

CLIMATE

WHAT THE WORLD WAS LIKE

DEVONIAN PERIOD

During the late Silurian Period through the Early Devonian, plants were evolving to survive in wetlands. Over time, roots began to spread and started to develop wood around 407 Ma years ago allowing plants to store and transport water using an extra level in xylem which allowed more CO2 to be received while maintaining water. The development of wood allowed plants to grow taller due to its support, and also to spread away from the wetlands as water could be more efficiently used. Eventually Archaeopteris would develop male and female spores, where the female spore would act like a seed containing water and nutrients. This allowed the spread of plants and early trees to spread further from wetlands and cover the planet. At the same time, roots were developing into the ground allowing for taller trees/plants and weathered the soil allowing for more nutrients to be readily available.

Devonian Plant Explosion (438 - 359 Ma Years Ago)

Around 3 main extinction events had occurred towards the end of the Late Devonian Period. Marine life had suffered the largest extinctions during this time where about 70%-80% of invertebrate species went extinct. Some causes are algae which grew too quickly from nutrients being released as land root plants released them into water through soil. The algae would have been blooming yet unable to survive as there was too much competition for resources, therefore much of it would die and cover the ocean floors essentaily killing trilobite and other bottom dwellers. Furthermore, as the forests grew CO2 was being used up in the atmosphere causing a global cooling. This cooling would have made the ocean too cold for living, while alos being oxygen starved.

Extinctions and Impact

During the Silurian Period that preceeded the Devonian Period, the Earth was warming. CO2 was rich in the atmosphere during the Early Devonian but eventually flourishing forests and plant life would cause CO2 levels to decline and cause a cooling event and mass extinction by the end of the Devonian Period. This was most likely caused by CO2 being trapped in the sediment due to the newly emerging forests.Oxygen also rose due to the forests, and some early wildfire is evidenced by charcoal.

DEVONIAN PERIOD CLIMATE

Initially, fungi was all over and covered a large amount of land. Some types of fungi such as Prototaxities would tower in height and provide food for insects. Later in the Devonian Period, forests began to develop. Fossil Record shows that deep rooted plants began to exist in by the end of the Early Devonian. These roots were found to be made of wood and are some of the earliest examples of wood. It is hypothesized that these plants developed wood as a way to transport and hold water. By the late Devonian, Archaeopteris had developed and fossil record finds examples in every continent. Archaeopteris could grow up to 30 meters tall, and were deep rooted. This rooting accelerated soil weathering and allowed plants to take in CO2 more efficiently and caused a boom in early trees. Furthermore, early seeds began to develop as Archaeopteris developed female spores that contained nutrients. With the rise of these tree like plants, fungi began to disappear.

Plant Life

On land, the first insects and arachnid began to appear. As mentioned with marine life, titaalik and other verterbrate species began to appear during this period and fossil record indicates that they had spread throughout the world.

Marine animals included Placoderm which were jawed fish that could grow up to 10 meters long. Placoderm were the main predators of the oceans. During this time many features that whales and sharks would develop. Some species of fish adapted to swimming in shallow waters, and lobe finned fish would pull themselves onto land during the Devonian Period including Tiktaalik. Also, early Sharks began to appear during the Devonian.

Animals During the Devonian

https://ucf-flvc.primo.exlibrisgroup.com/permalink/01FALSC_UCF/a65521/cdi_crossref_primary_10_1016_j_earscirev_2020_103200 https://ucf-flvc.primo.exlibrisgroup.com/permalink/01FALSC_UCF/a65521/cdi_hal_primary_oai_HAL_halsde_00676445v1 https://ucf-flvc.primo.exlibrisgroup.com/permalink/01FALSC_UCF/a65521/cdi_proquest_journals_220811371

References