Randall Munroe, a former NASA roboticist who nows draws clever geeky webcomics at XKCD, used data from Vaclav Smil's The Earth's Biosphere: Evolution, Dynamics, and Change ("plus a few other sources") to create a visualization of all of Earth's land mammals, which include us, by weight. It does certainly put things in perspective, especially when you compare wild land mammals to us and our livestock and pets.
If you want the exact numbers behind this graph, you'll have to get Smil's book (I'm sure your local public library has it).
Interesting trivia that is included as alt-text in the original image: "Bacteria still outweigh us thousands to one--and that's not even counting the several pounds of them in your body."
Here are some previous XKCD comics that we featured on TreeHugger:
- Radiation Dose Chart by XKCD
- Cold waves used to be more frequent, and now that we're not used to them, they seem worse
- XKCD webcomic shows how thick ice was over North-American cities 21,000 years ago
- XKCD on BP Oil Spill (Featuring Michael Bay!)
- How Deep are Lakes and Oceans? (Educational Webcomic!)
- Tesla Roadster Featured in Popular XKCD Comic
- Why The Word Sustainable is Becoming Unsustainable
- What if all subways in North-America were connected?