How does Michael Crichton use imagery in The Lost World?

Imagery:

"The triceratops herd moved slowly past the stegosaur, which paid no attention to them. And to the west, rising above a clump of trees, they saw a dozen long, graceful necks of apatosaurs, their bodies hidden by the foliage that they lazily ate. It was a tranquil scene - but it was a scene from another world."

"The wall splintered wide, an eight-inch plank cracking inward, and a raptor stuck his head through, snarling, snapping his jaws."