GMAT Critical Reasoning (CR) | Paleontologists hypothesize that modern birds evolved from the family

Source: McGraw Hill GMAT

Paleontologists hypothesize that modern birds evolved from the family of dinosaurs that included Tyrannosaurus rex. This hypothesis would be strongly supported if evidence that dinosaurs from this family had a body covering resembling feathers could be found, but so far no such evidence has been found.

Which of the following, if true, would most help the paleontologists explain why no evidence of feathered dinosaurs has yet been found?

A. Fossilized dinosaurs have shown
...

---