I suddenly wondered: When was the first time that any science fiction writer published a story in which one or more human beings use some form of "time travel technology" to travel back to the era of the dinosaurs, and thus come face to face with one or more dinosaurs, as part of the plot?
I don't care if it was a short story or a full-sized novel. I don't insist you name a story that is still popular today, and gets reprinted on a regular basis. I just want to know who used this exact plot device first, along with the title of the story in which he (or she) did it, and thereby started a trend! (Heck, if it was first used a hundred years ago, in some old silent movie that I've never heard of, instead of in a work of prose fiction, then calling that movie to my attention would be a valid answer!)
Examples of What I Do Not Want:
Someone finds a way to recreate "dinosaurs," more or less, in modern times -- or it happens accidentally, for that matter! Gene splicing, cloning, radioactive mutations triggered by a nuclear war, whatever. (One example of "creating new dinosaurs in my lab" occurred in Jurassic Park, although I think other authors had used much the same idea before Michael Crichton got into the act.)
Someone discovers that some breeds of dinosaurs are still "naturally" alive, somewhere upon the surface of the globe (or down inside the Hollow Earth, or somewhere else entirely), and at least one human explorer comes face to face with some of those dinosaurs, in a story set in "modern" times. (Arthur Conan Doyle's The Lost World immediately springs to mind -- it was published in 1912, and for all I know, it may have been the first story to take that approach.)
Human space explorers, visiting an alien planet, run afoul of gigantic lizards which are very reminiscent of some of the dinosaurs which once existed on Planet Earth. But quite possibly these creatures evolved separately on their own homeworld, and are not genetically related to our own Tyrannosaurus Rex or any other terrestrial breed of dinosaur. (I'm having trouble thinking of a classic example of this approach, but I'm sure it's been done!)
The entire story is set in the distant past, with "cavemen" (or some other sentient lifeform) encountering at least one "dinosaur," but there is no use of the concepts of "time travel" and "people from modern times."
There is something resembling "time travel" within the plot, but the rationale is very much "fantasy" instead of "science fiction." For instance, if the Evil Sorcerer chants a spell, waves his hands in mystic gestures, and magically sends someone else back in time, millions of years, to suddenly appear right in front of a charging Triceratops, then I would not call that story a valid answer to this question. No matter when that story was first published!