One of my interests is speculative zoology, but I'm not interested about fauna of alien planets. I think it's a very good question that what animals will in the Earth in a few million years.
I'm also very interested in speculative biology! Considering the fact that dinosaurs and prehistoric life is one of my biggest passions, alongside zoos and present day fauna, I like to speculate a bit about how non-avian dinosaurs may have ended up, if not extinct. I really like the Speculative Dinosaur Project, an online, well, project that discussed exactly this. Unfortunately, the university site where the project was hosted stopped maintaining it, so one has to use the Internet Archive to access it. I'd recommend anyone who is interested in the evolutionary history of life to check it out, especially if you like dinosaurs.
Go to Darren Naish's blog Tetrapod Zoology in different incarnations. He was interested in this topic and probably brought together everything what exists.
In the 1980s there was a popular book speculating what the current biota of Earth might evolve into once humans go extinct. I remember whale-sized penguins were one of them. It was popular enough that there was a series of animatronics made for a traveling exhibition like the traveling dinosaur exhibits that go from zoo to zoo. The name of the book and the author elude me. I saw the animatronic show at the San Diego Wild Animal Park in 1991.
After Man: A Zoology of the Future. It was written by the Scottish paleontologist Dougal Dixon: After Man - Wikipedia I own a copy of the book. It's very good: he is an amazing illustrator, and a lot of what he imagines in the book are rodents and lagomorphs that evolve into familiar shapes and ecological niches through convergent evolution. I've also read another one of his books, The New Dinosaurs: An Alternative Evolution, which has similar themes and illustrations exploring a modern day world in which dinosaurs and other giant reptiles never went extinct.
Besides After Man, I also own the DVD set of The Future is Wild. I also highly recommend it; like Dixon's books, it does a great job of combining fascinating creature designs while giving thought to physiology, environmental conditions and successful survival strategies. It breaks up "the future" into three different time periods - 5, 100, and 200 million years from now - and breaks down four different ecosystems from each time period. Each episode also has a range of scientists from different backgrounds discuss relevant biological topics and talk about the likelihood of the organisms the documentary creates. The Speculative Dinosaur Project is the same concept as Dixon's The New Dinosaurs; it's very unfortunate that the project is on a permanent hiatus, as it had a lot of creative potential.
