Dating back to 1870, this frog skeleton drawing is one of many wonderful drawings from a large book called Reptiles and Birds. This drawing includes the full skeleton of a frog and would be great for students to use in a biology or other science class. I could include the names of the bones and all that sort of stuff, but, for Reusable Art, that would be a bit of overkill. And besides, that would ruin the learning opportunity that this animal skeleton provides.
This image is copyright free and in the public domain anywhere that extends copyrights 70 years after death or at least 120 years after publication when the original illustrator is unknown.