- "Once there was a little dinosaur called a Maiasaur, who lived with his mother. One day, he told his mother, "I wish I were special like the other dinosaurs. If I were a T. rex, I could chomp with my ferocious teeth!" "But if you were a T. rex," said his mother, "how would you hug me with your tiny little arms?" "I wish I were an Apatosaurus," said the little dinosaur, "so with my long neck I could see high above the treetops." "But if you were an Apatosaurus," said his mother, "how would you hear me in the treetops when I told you I love you? What makes you so special, little Maiasaur?" said his mother. "Is it your ferocious teeth or long neck or pointy beak? What makes you special is out of all of the different dinosaurs in the big, wide world, you have the mother who is just right for you and who will always love you.""
- —The Runaway Dinosaur book[src]
Dinosaurs are a diverse group of reptilian animals, most of which are believed to be extinct by the end of the Prehistoric Era and the time of humans. Despite this, some dinosaurs interacted with humans due to time travel.
In the Prehistoric Era, the time-stranded Ray Palmer was forced to survive in the world dominated by dinosaurs, encountering at least one female Tyrannosaurus Rex (which he nicknamed Gertrude) and possibly a male as well. Ray was confronted by Gertrude before he was rescued by Nate Heywood and Mick Rory.
When the Waverider crash-landed back in the same era, Ray led Nate and Amaya Jiwe to retrieve a component of the ship, which had ironically ended up in Gertrude's nest. When Gertrude came across them later, Amaya used the Anansi Totem to use the spirit of a T-Rex to communicate with the female Rex, resulting in Gertrude leaving them in peace. 
At some point of time a few fossil skeletons of dinosaurs were dug up and placed in Fernbank Museum of Natural History in Atlanta, which also had at least two full-sized sculptures of the dinosaurs located at the front of it. Aside from museums, dinosaurs were also immortalized in literature, with Barry Allen's favorite book as a kid being "The Runaway Dinosaur". 
- "A Feast of Friends" (fossil skeletons and full-sized sculptures)
- "The Runaway Dinosaur" (mentioned)
DC's Legends of Tomorrow
Behind the scenes
- Dinosaurs are a diverse group of animals of the clade Dinosauria (sub-group of clade Dinosauromorpha, class Reptilia), that first appeared during the Triassic period. Today, only theropoda, the saurischian dinosaur group, remains, represented by Aves - birds.
- Although a number of deistic religions in real world deny the existence of dinosaurs, ironically enough dinosaurs on Earth One were first seen depicted in Constantine, a show which also established the existence of God in the shared multiverse, implying that both deistic and evolutionary assumptions regarding the world's prehistory are correct on some level in the multiverse.
- In Supergirl episode "Alex" , when Maggie asked Alex to name their dog, Alex said 'Yeah, um... Let's name her Gertrude.'