Are any dinosaurs still alive today?

Yes. In an evolutionary sense, birds are a living group of dinosaurs because they descended from the common ancestor of all dinosaurs. Other than birds, however, there is no scientific evidence that any dinosaurs, such as Tyrannosaurus, Velociraptor, Apatosaurus, Stegosaurus, or Triceratops, are still alive. These, and all other non-avian dinosaurs became extinct at least 65 million years ago at the end of the Cretaceous Period.

Many shared evolutionary characteristics can be found in the skeletons of birds and other dinosaurs. One can follow the development of these evolutionary innovations by following along the evolutionary tree of dinosaurs from larger groups into successively smaller ones.

Birds' hips have a hole in the hip socket, just like all other dinosaurs. This feature was inherited from the common ancestor of dinosaurs and allowed dinosaurs to walk with an upright posture. Next, the bones of birds are hollow, and the hind feet of birds have three toes that point forward and one toe that points backwards, just like the hollow bones and three-toed feet inherited from the common ancestor of all meat-eating or theropod dinosaurs, including Tyrannosaurus.

Finally, the wrist of birds is built around a crescent-shaped bone called the semi-lunate carpal, just as the wrist of Velociraptor is. This wrist bone was inherited from the common ancestor of birds, Velociraptor, and other dinosaurs that belong to the group called maniraptors. As documented by these characteristics, birds evolved from the first dinosaur, the first theropod dinosaur, and the first maniraptor. So scientifically, birds are members of all of these groups of dinosaurs.

So, in an evolutionary sense, birds are a living group of dinosaurs, and although no nonavian dinosaurs, such as Tyrannosaurus or Triceratops, still exist, dinosaurs are not extinct! You see dinosaurs flying around in the sky and perching in trees every day!