You probably got the Rare Triceratops DNA from the 8 hour, 12 hour, or 24 hour battle arena incubators or any incubators you might have purchased. I am fairly certain that each rare and higher dinosaur and maybe even some common dinosaurs will only start spawning in the wild once you reach a certain level or higher. You are only level 6, so you probably won’t start seeing the rare Triceratops until around 8 or 9 if my memory serves me correctly, and it will get slightly more common with each level you gain. I’m level 11 and there are still some days where I don’t see any, but other days I might find 4 or 5. The rare Triceratops only spawns during the daytime under normal circumstances (meaning you may find one at night if there is a “nest”), while the Triceratops Gen 2 spawns at night and is very common.
It may not even be possible to find a rare or epic in the wild before you have created it. I would love to know for sure, so if any of you have found in the wild a rare or epic that you have not yet created, please let me know!