I’m going to have to agree with Almaron. All Styracosaurus in LBT look the same because, being nameless background characters with extremely minor roles, there is no need to give each individual a unique design, and not doing so is also cheaper and reduces the risk of continuity issues (e.g., a character changing color between shots). The ones in the pics can’t all be the same character, because the one in Pterano’s group was implicitly killed with all of the others. (The one in the second picture and one of those in the third are likely the same, though, as well as the one that was seen getting stuck under a tree root later on.) However, if you think of the characters in LBT as being played by actors, the same Styracosaurus extra could be very well be playing all the parts.
Actually, it’s not entirely correct to say that they all look exactly alike. Here’s a screenshot from LBT XI that shows three of them (one on the upper left and the others in the upper right-hand corner), all with different colors:
Adding on to Almaron’s list:
Gallimimus/Troodon (Rainbow Faces) are always green with blue stripes (also blue on the top of the head and snout) and yellow-sided snouts, sometimes with a thin red stripe on the snout as well.
Velociraptor (Fast Biters) vary in color, being green, blue, maroon, or tan. They always have stripes, though. (If you consider the raptors from LBT III to be a different design of the same species, then they come in orange as well.)
Diplodocus have also been seen to be a pinkish color (as seen in Campion’s third image), as well as green.
Saurolophus (Swimmers) are usually brown or grayish brown, though Ducky’s father(?) was shown as teal at the end of LBT V.
Pteranodon (Flyers) varied somewhat in color in the earlier films, but in LBT VII and beyond, nearly all of the background ones were brown and tan.
Archaeopteryx were green in LBT VII, but yellow with purplish-fringed wings and tails in LBT IX and beyond.
Bellydraggers are almost always some shade of green (with a couple of brownish ones in “The Amazing Threehorn Girl”)
Iguanodon are green with a line of darker green spots on the sides of their necks.
Archelon (sea turtles) tend to be light green.
Kentrosaurus are reddish orange with yellow plates and spikes.
Brachiosaurus are generally purple or blue, or somewhere inbetween.
Stegosaurus (Spiketails) are usually brownish green with brown plates, though the herd from LBT VIII showed a much wider variety of colors.
Ophthalmosaurus (Mo’s species) have yellow undersides with purple backs and orange, red, or maroon markings.
Struthiomimus (Egg Stealers) are tan, with brown or grayish brown backs, and bands on their legs and spots along their sides of the same color.
Tyrannosaurus (Sharpteeth) come in shades of green, brown, and gray.
