As a writer, Bradbury was renowned for his highly lyrical prose. Much of his writing was extremely imagery intensive and flooded with metaphor. "A Sound of Thunder" is no exception.
In this short story featuring a time-travelling safari, Bradbury recreates the world of the late Cretaceous period in extensive detail, down to the sights and sounds:
The jungle was high and the jungle was broad and the jungle was the entire world forever and ever. Sounds like music and sounds like flying tents filled the sky, and those were pterodactyls soaring with cavernous wings, gigantic bats out of delirium and a night fever.
Later, Bradbury introduces the hunters to a Tyrannosaurus Rex, and again, the imagery is extensive, melding together visual impressions and metaphor to create a picture with words:
It came on great oiled, resilient, striding legs. It towered above half of the trees, a great evil god, folding its delicate watchmaker's claws close to its oily reptilian chest. Each lower leg was a piston, a thousand pounds of white bone, sunk in thin ropes of muscle, sheathed over in a gleam of pebbled skin like the mail of a terrible warrior.
Note, however, that the excised portion represents only the beginning of a much longer description which carries forward from this point. For some additional details, Bradbury likens its eyes to "ostrich eggs, empty of all expression save hunger." When running, "it ran with a gliding balletic step, far too poised and balanced for its ten tons."
Sometimes, this imagery depends on the use of contrasts: the dinosaur's overwhelming power is in tension with "its delicate watchmaker claws," much as its "balletic" grace is in tension with its extraordinary weight. In short, Bradbury's intention here is not simply to introduce his characters to a dinosaur, but more importantly, to create in his readers a vivid impression as to what such an experience might actually entail.
Later, when the dinosaur is killed, this same use of imagery is in effect. Bradbury writes,
The monster lay, a hill of solid flesh. Within, you could hear the sighs and murmurs as the furthest chambers of it died, the organs malfunctioning, liquids running a final instant from pocket to sack to spleen, everything shutting off, closing up forever. It was like standing by a wrecked locomotive or a steam shovel at quitting time, all valves being released or levered tight.
Again, note how the preponderance of detail extends beyond the image of the dead dinosaur and also applies to the simile comparing the animal to a destroyed train: he doesn't simply end the simile there, but actually expands on it—the train is "at quitting time" with "all valves being released or levered tight." We have in this passage the visual and auditory details of the dying animal being woven together with this train metaphor, all in order to create a vivid impression of this dying animal.
This is all very representative for Bradbury's overall writing style: he was a writer who delighted in the resources of language itself, which (in many of his stories) often seems just as important as the story being told.