I’m sure someone else can chime in with a better reply.
First, not all dinosaurs have large heads and tiny arms. But you are right that some were like that, like famous Trex for example.
The large head is so that these dinosaurs can have a large mouth. A large mouth means they can attack larger prey with it. That’s beneficial if you are big, because you can eat with one kill as opposed to spending the whole day trying to find enough small prey. It’s also beneficial if most prey available is large.
The small arms are simply because they didn’t need them to hunt or defend themselves, or to move around. The mouth and legs alone were enough as these dinosaurs evolved, and so the advantage of having small arms is that you don’t waste body resources and energy in growing and maintaining unecessary limbs.
I’m sure someone else can chime in with a better reply.
First, not all dinosaurs have large heads and tiny arms. But you are right that some were like that, like famous Trex for example.
The large head is so that these dinosaurs can have a large mouth. A large mouth means they can attack larger prey with it. That’s beneficial if you are big, because you can eat with one kill as opposed to spending the whole day trying to find enough small prey. It’s also beneficial if most prey available is large.
The small arms are simply because they didn’t need them to hunt or defend themselves, or to move around. The mouth and legs alone were enough as these dinosaurs evolved, and so the advantage of having small arms is that you don’t waste body resources and energy in growing and maintaining unecessary limbs.