This is the first kids' book I've seen that makes an honest attempt to explain cladistics: that's a tall order in a book of only forty-eight pages, including front and back matter, especially when about half of the pages are taken up by pictures, and large print is used throughout.
You have to admire Dennis Shealy for making the attempt. In seven short chapters he skims over subjects like evolution, extinction, natural selection, Linnaean and cladistic classification and the dinosaurian ancestry of birds. Unfortunately, in covering so much material so cursorily, something has to give: and what gives is the definition of cladistics, which is described as grouping animals ``based just on traits they have in common'', without emphasising the importance of shared _derived_ characters. It's not exactly a fatal flaw in a book aimed at seven-year-olds, but it should have been easy enough to catch.
There are other minor oversights too: page 26 tells us that the bones of _Deinonychus_ and of modern birds share 22 common traits; then on page 30, that there are twenty-three shared traits.
Still, let's not be picky: this is fine attempt at teaching some complex stuff to kids, and it doesn't do a bad job. It's enhanced by Michael Skrepnick's characteristically fine illustrations: not just beautiful restorations, but helpful skeletal diagrams too, including a complete _Velociraptor_, a modern bird, and detail of their arms.
It's a good attempt at a very difficult book. The Jurassic Park institute is to commended for its ambition.