It was only missing one thing: a shell.

Thanks to the newly discovered fossil of that tiny creature, scientists say they have solved the story of how the turtle got its shell. But this is no Rudyard Kipling fable. It's science.

The not-so "Just So" story, published in the journal Nature on Wednesday, tracks the evolution of the turtle body plan through millions of years of history. By examining fossils that spanned millennia and continents, researchers were able to figure out how the modern turtle's unique shell evolved from what was just a brief expanse of belly bones about 240 million years ago.

The origin of the turtle shell has long bewildered scientists (this was, apparently, the one natural phenomenon Kipling hadn't written a story to explain). Though they had fossils of turtle predecessors from the beginning and the end of the Triassic period, there was little evidence of what happened to ancient turtles during the intervening years.