Well, for starters, they are

That’s right, dinosaurs do still exist, and they are everywhere – in the form of birds. That adorable little sparrow on your windowsill? Dinosaur. The noisy myna disturbing your morning coffee? Dinosaur. Pigeons, geese, hawks, you name it – they’re all descendants of large, two-legged, non-avian dinosaurs called theropods, which, according to Scientific American, adapted certain dino features (like feathers) into the birds we see today and “whose members include the towering Tyrannosaurus rex and the smaller velociraptors”.
We wouldn’t have recognised them

Say that species-extinction asteroid hadn’t hit Mexico 66 million years ago and life on Earth had continued apace. Well-known dinosaurs like the Triceratops “would be totally different than anything we know from the fossil record,” science writer Brian Switek wrote in The Guardian. Why? They, too, would have continued to adapt. “There might even be new groups of dinosaurs that didn’t exist during the Mesozoic era. The present Earth wouldn’t be a hodgepodge of old favourites, but an entirely different mix of unknown dinosaurs,” wrote Switek.
In fact, we might never have seen them at all

Why? It’s likely that, with a preponderance of dinosaurs remaining on our planet, humans and many other mammals would not have had the chance to evolve into existence. “Even though mammals thrived in the shadow of the dinosaurs, they did so at small size,” writes Switek. “And even though the very first primates had evolved by the end of the dinosaurian reign, they had more in common with a tree shrew than with you or me…[dinosaurs] would have undoubtedly continued to influence mammalian evolution.”
Would these 21 of the world’s cutest and most adorable wildlife have existed if dinosaurs still roamed the planet?