Why is the Shrike depicted with only two arms on the covers of the first three "Hyperion" novels?

Question

The cover illustrations for the Dan Simmons novels "Hyperion", "The Fall of Hyperion" and "Endymion" all feature depictions of the Shrike with two arms:

However, already in the first novel "Hyperion" it is mentioned dozens of times that the Shrike has FOUR arms.

Only the last cover in the tetralogy, "The Rise of Endymion", gets it right:

Is there a backstory to this? Clearly the illustrator was familiar with the contents of the novels, as the cover paintings depict actual scenes from the story in detail. Did Simmons add the "four arms" attribute as an afterthought? Why was this type of depiction kept for two more novels (by which time surely the author must have noticed that the text and cover art do not match) and then suddenly changed?

Answer 1

I can't find anything specific for the Hyperion series, but in general the cover designer does not always get to read the book before designing the cover - either because the book has not been finished, or because the designer simply doesn't have time to read it all.

E.g. taken from this discussion by some book cover designers:

Ideally you would read the book – key themes and ideas present themselves so readily that way – but it’s important to remember that the book isn’t always written by the time a designer is summoned. Often, we receive only the vague promise of a book, with design work regularly taking place before a title is even settled on

So possibly the cover artist for this series (Gary Ruddell) was given a brief for Hyperion that included a description of some scenes and characters from the book, but that failed to mention that the Shrike had four arms. He probably re-used his original design for the second and third novels. I can't find anything to explain why this changes for the final novel (to show the Shrike with four arms), but the most likely reasons are the author or publisher requested it, or the artist unilaterally decided to correct his earlier mistake.