I wish I could be as sure about upright hominoids, but picture books for older readers do exist. I managed to capture some on film. And more proof came via a heartening e-mail I received from teacher and blogger Keith Schoch, who kindly gave me permission to share it here (in slightly condensed form):
First of all, I'm a big fan of Boys of Steel: The Creators of Superman. My fourth grade class dug it as well, and what really impressed them was that at first they thought they didn't care about these two guys, but by book's end, they cared a lot! And then when I stumbled upon your site today I thought it was pretty cool to read your About Me and find that this is precisely what you're attempting to do now as a writer. [MTN: This refers to a former version of my About Me in which I explained that I like to write books on people whose achievement is well-known but whose name and back story are not (i.e. everyone knows Superman, few know who created him, when, or why).]
Good, good stuff, Marc. I say that not just as a teacher, but as someone who is constantly poking and prodding other teachers in the upper primary and middle grades to use picture books to enhance their instruction. I conduct workshops on that topic, and also host a blog aimed at teachers of grades 3-8 called Teach with Picture Books. It features summaries, themes, guiding questions, teaching suggestions, cross-curricular extensions, author profiles, and related links.
As a companion site to my workshops, I also put up a static site called Teaching with Picture Books Across the Middle Grades, which offers reasons why teachers of the upper primary and middle grades should be using picture books in their instruction. Many teachers use this site to get their colleagues on board and to squeeze some money out of their administrators for purchasing picture books for the classroom.
You might want to check out a post [in which] your book is featured prominently.