Cretaceous wildfires and their impact on earth’s ecosystem

Cretaceous wildfires and their impact on earth’s ecosystem

The cretaceous was a geological period that lasted from 145 to 66 million years ago with the dinosaurs still roaming the earth at the time. From the early cretaceous period, the terrestrial sedimentary system of earth preserved charcoal in abundance. This observation infers that fires were widely distributed and very frequent during this period. The cretaceous can also be referred to as a “High Fire” world. This period was marked by high temperatures, seasonally dry climate and higher atmospheric oxygen than current levels. 

These wildfires seem to have left their mark on the archaeological record in the form of charcoal deposits. This increased fire activity can be related to elevated levels of oxygen concentration in the atmosphere ,with the elevation estimated to have been in the range of 21% to 25%. Global temperatures would also have been higher because of the presence of greenhouse effect in the atmosphere. A majority of these fires have been suggested to be groundfires in the range of 250–420-degree Celsius. This widespread activity of the fire would have greatly affected the earth’s vegetation. In addition to stripping the landscape of plants, they also caused disturbance to the environment in which a plethora of dinosaurs, mammals, reptiles and birds lived. The fires would have also affected the fauna through habitat loss. A higher level of plant turnover would also have taken place as the burnt plants returned to the soil. Amongst the various changes that took place in the vegetation during the cretaceous stage, the most prominent was the rise of the angiosperms. Early form of angiosperms was weed like and sustained in extreme conditions. Studies also show angiosperm‐dominated forests became widespread during this time. The extensive fires may have not only helped in their diversification and their spread through environmental disturbance., with a significant number of angiosperms gatherings from the early cretaceous period strongly supporting this hypothesis. 

It has also been speculated that several fires during the cretaceous period would have increased levels of runoff, their exacerbation and erosion leading to spillage of large amounts of phosphorous entering the marine ecosystem. This would have eventually led to plankton bloom and other related anoxic events in the marine ecosystem. The cretaceous wildfires could have also promoted excessive flooding after storms. Studies suggest that catastrophic bone bed accumulations may have been the result of post-fire erosion-depositional systems. This widespread fire activity and its effects continued throughout the late cretaceous period causing various changes in the earth’s ecosystem and actively affecting its diverse inhabitants. 

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