Yesterday I began writing a little bit about what I do, so if you want to catch up check out Part 1. My goal while I’m at Bristol is to compile a community-level study of tetrapod diversity and to compare it to Mike Benton’s global pattern of tetrapod diversity. I hope that my research will aid our understanding of some ‘big’ questions such as:
1) Is global diversity a reasonable measure of true biodiversity?
2) How did tetrapods diversify? Did they conquer new niches or expand into new habitats?
3) How did mass extinction events effect community structure?
But even more interestingly, this study has an application to our present situation. We are witnessing a biodiversity crisis right now and it is not clear whether it is simply a part of Earth’s natural cycle or massive impact by human presence (though to be honest I lean towards the latter). Studying past communities helps us understand more about our present situation.
The first part of my research covered the Palaeozoic, from the origin of tetrapods about 375 million years ago to about 250 million years ago. At this time there were no birds, no mammals and no dinosaurs. The landscape was dominated by large amphibians and the first reptiles. Amphibians at the time were not like frogs but more like very large salamanders, and the largest of these superficially resembled crocodiles (For example, see my post of Parotosuchus). This period of time ended with the largest mass extinction event, in Earth’s history, the Permo-Triassic event 251 million years ago, when over 90% of Earth’s species went extinct.
During the 125 million years though, a lot of changes took place. I realize this post has gotten long already so I will continue more next week starting with a look at the first tetrapods, who possessed a strange oddity that we rarely see today and one that has changed our understanding of the evolution of life on land. Can you spot this oddity in the image to the right?
Click to view a larger image at http://universe-review.ca/I10-72-Acanthostega.jpg