I found the Tux work at https://secure.wikimedia.org/wikipedia/commons/wiki/File:Tux-shaded.svg / CC BY-SA 3.0, and the gnu was from CRW_5073.jpg / / CC BY-SA 2.0.
Here’s a smaller version:
I would include the SVG files, but I can’t get Tux to show up on another computer because it was apparently linked instead of embedded. I followed these instructions to embed images that were previously linked, and Inkscape mentioned it needed an updated python-lxml which wasn’t installed but is a package provided by my distribution (so a quick and easy install).
Also, I had to simplify the nodes on the smaller ones because their filesizes were just as big as the largest (4.9MiB)! I got them down to 1.5MiB (Simplify is on the Path menu, and you have to select the objects to be simplified before simplifying).