7
Heavy and lethal defenses or speed and agility -Ornithischians were masters of survival.
but some were quadrupedal due to their heavy armor.
Those who presented heavy armor like Stegosaurus
and Ankylosaurus primarily
used them for defense.
This order also presents other groups who made it up for the lack of armor with horns like the Triceratops or with high speed like Iguanodons and Parasaurs. A famous group is the group of the Pachycepholausaurs which presented a dome on the head. mainly used for choosing mates or fighting with hostile enemies
A lot of fossils were discovered next to each other which means that this order produced a lot of species that lived in herds like modern-day buffalos.
Triceratops skeleton
Stegosaurs: Tiny Brains & Thagomizers
https://youtu.be/Nsf5xCbZ7us
PBS EONS