We can learn about what is going to happen in the future looking at the past. Climate change already happened before. Earth was once very hot and humid and it was also very cold. It comes and goes in cycles, even if nowadays humans are causing the climate to shift several degrees up. Scientists at The University of Edinburgh found that deep water predators during the Jurassic Period thrived as sea levels rose, while those at shallow waters died out.
Scientists look what happened 150 million years ago trying to predict what is going to happen soon. Back then for more than 18 million years, diverse reptile species lived together in tropical waters that stretched from present-day northern France to Yorkshire in the north of England – this area is now known as the Jurassic Sub-Boreal Seaway. As temperatures began to climb, water levels rose, but we don’t know very well, how it affected local food chains and species. Now scientists analysed the shape and size of teeth of these reptiles and found that back then many species were able to co-exist as they didn’t have to compete for food.
Scientists studied these fossil records and found that shallow water predators that used to hunt with their thin, piercing teeth, declined drastically as the sea levels rose. Meanwhile, bigger reptile species, which lived in deeper waters and had broader teeth for crunching and cutting prey, began to thrive. Scientists hypothesize that raising sea levels actually changed the chemical composition of the water, pushing more nutrients towards the bottom of the oceans. They also say that parallels could be drawn between these findings and dolphins and other marine species that are witnessing changes in ocean water chemical composition changes as well as rising sea levels.
Researchers believe that these kind of studies could allow predicting how such changes as, climate change, pollution and rising temperatures, may affect ocean life of today. Davide Foffa, one of the scientists behind this study, said: “Studying the evolution of these animals was a real – and rare – treat, and has offered a simple yet powerful explanation for why some species declined as others prospered. This work reminds us of the relevance of palaeontology by revealing the parallels between past and present-day ocean ecosystems”.
It is very interesting how humble fossilized teeth can tell so much. But this is nowhere near the full story. Scientists can see how the number of bones on the sea floor changed over time. This allows making accurate assumptions about population sizes, which can then be described in the context of environmental changes.
Source: The University of Edinburgh