red letters indicate the correct answer
1. What was the sail of Ouranosaurus for?
2. What does the arctometatarsalian condition refer to?
metatarsal III pinched proximally
3. What does Sinosauropteryx have that is so unusual?
a down-like or feather-like covering
4. What character was long thought to bar dinosaurs from the ancestry of birds?
the apparent absence of a furcula
5. What is the age of the Hell Creek Formation?
Cretaceous (and maybe a little bit of Tertiary)