Translation:The little boy knows everything about dinosaurs!
True, but here's the difference. It is not "tous les dinosaures" (all the dinosaurs), then it would have needed the S
It is rather "il sait tout" (he knows everything).
So "tout" is not linked with dinosaurs, it is linked with the verb "he knows"
Does this sentence sound exactly the same as the following? : "Le petit garçon s'est tu sur les dinosaures ! "
Yes. It sounds exactly like that sentence that makes no grammatical sense.
No. tu and tout are pronounced with different vowel sounds. Also the one with tu would never be said because little boys are never silent about dinosaurs. ;-)
"Savoir" deals with knowledge of facts. "Connaître" deals with familiarity.