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| Chaco Canyon is also known for it paleontological resources. The Cliff House Sandstone yields trace fossils. These traces called Ophiomorphia nodosa are fossilized burrows of a shrimp-like crustacean known as Callianasa major. The traces have a round, nodular texture from particles pasted to the sides of the passages, and the passages form interconnected networks. Iron minerals have replace the original nodular particles (probably sand mixed with fecal material and uneaten remains of the crustaceans prey) . The nodular pattern is reminiscent of corn and must have been intriguing to the ancestral Chacoans who must have frequently marveled at they features that occur practically everywhere where the Cliffhouse Sandstone is exposed. The crustaceans lived in shallow sandy seabed in a coastal setting along the coast in the Western Interior Seaway about 70 million years ago. That seaway vanished as the Rocky Mountains began to rise in the region 70 to 65 million years ago. |
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