During the Precambrian, the area of northeastern Utah now occupied by the Uinta Mountains was a shallow sea which was home to simple microorganisms. During the Paleozoic, most of Utah was covered by a shallow sea. The life of Utah during the Cambrian period included brachiopods and trilobites like Elrathia. Cambrian fossils are known from Antelope Springs, the House Range, Millard County in west central Utah. Other Paleozoic marine life included algae, brachiopods, corals, snails, sponges, and trilobites. Marine conditions continued into the Carboniferous. Almost every kind of marine invertebrate could be found in Utah at this time. Fish were also present. This age is the best documented among the state's fossil record. Later, during the Permian period, eastern Utah resembled the modern Sahara desert. Sediments deposited here are now known as the Cedar Mesa Formation. One spectacular fossil trackway from this formation documents a possible predation event that occurred hundreds of millions of years ago. One small trackway of the ichnogenus Stenichnus, left by an early reptile like a protorothyrid or a primitive amphibian like a microsaur, proceeds for a short distance before disappearing when its tracks meet a trackway left by a larger animal. These larger tracks of the ichnogenus Anomalopus were likely left by a predatory pelycosaur who may have eaten the Stenichnus trackmaker.