Schedule Slip: The genus list hasn't been updated since January 2012.
Science Marches On: Befalls the book itself, but the author, being a paleontologist, was savvy enough to set up the supplementary site to avert this. Word of God has said that an updated edition of the book itself may also be written eventually.
The faceless, scaly Deinocheirus is a good example; in 2014, a complete skeleton of Deinocheirus was discovered, showing that it was a huge, goose-like animal fully covered in feathers.
This is also given a nod by the fact that several of Luis Rey's paintings in this book are updated versions of some of his older ones.
Lampshaded frequently in the text as well. The author says this is part of what makes paleontology so fun and frustrating at the same time.