In order to propagate the species, most dinosaurs had to lay multiple eggs. They did this to make sure at least some of their babies survived predators and weather events.
Pretty much all dinosaurs lay eggs, so Spinosaurus likely did too.
Why dinosaurs were so big is because in prehistoric times there was no winter. and dinosaurs are lizards and lizards never stop growing. so mixed with humidity and surplus of food the dinosaurs or lizards lived for hundreds of years and grow all that time.
all dinosaurs
Most, if not all, dinosaurs layed eggs.
They did not carry their eggs. Dinosaurs kept their eggs in nests just like modern birds and reptiles.
Dinosaurs are extinct, so they do not lay eggs anymore. They developed from the reptiles but were not reptiles themselves, because they could regulate their body temperature to some extent. Yes. All dinosaurs do beause they are reptiles
they layed eggs
Not all dinosaurs had large feet. Some dinosaurs were small and didn't have big feet.
Dinosaurs roamed the earth between about 235 million years ago and 65 million years ago. So, to answer your question, the best guess would be about 235 million years ago or so. Also dinosaurs laid eggs so they are not actually born but hatched.
All of them
All of them lay eggs.
Dinosaurs laid eggs to reproduce. Carrying offspring until they are born is stressful and challenging for a mother animal, so, excluding mammals and a few reptiles, most animals lay eggs to reproduce. This way, the mother is free of the burden of carrying the offspring while they develop.