Wahweap Formation

The Wahweap formation is divided into four members, which are listed below with their respective ages: • Last Chance Creek Member: 82.17-81.55 Ma • Reynolds Point Member: 81.55-80.61 Ma • Coyote Point Member: 80.61-79 Ma • Pardner Canyon Member: 79-77.29 Ma ==Paleobiota==

Invertebrates The Wahweap Formation shows a substantial amount of invertebrate activity ranging from fossilized insect burrows in petrified logs to various mollusks that characterize the shell beds. Large fossilized crabs are common at most shell bed sites in the Wahweap, and over 1,900 gastropod specimens (of four likely genera) have been unearthed in the formation's siltstone. Elasmobranchs Osteichthyes Salamanders Dinosaurs Dinosaurs known from the Wahweap include at least 2 species of hadrosaur, at least two ceratopsians and at least one theropod. Mammals an dinosaur digging a primitive mammal out of its burrow, as per the 2010 discovery by Simpson et al. of trace fossils indicating a predator–prey relationship in the Wahweap Formation. A fair number of mammals spanning the lower Campanian are known from the Wahweap as well, including at least 15 genera of multituberculates, cladotherians, marsupials, and placental insectivores. ==Trace fossils==

Trace fossils are also relatively abundant in the Wahweap, and include vertebrate tracks as well as burrow activity. Tracks preserved in the capping sandstone indicate the presence of crocodylomorphs, which had been previously known in this area only from teeth elements, as well as ornithischian dinosaurs. At least one possible theropod track has been identified in this area as well. In 2010 a unique trace fossil from the Wahweap was discovered that indicates a predator–prey relationship between dinosaurs and primitive mammals. The trace fossil includes at least two fossilized mammalian den complexes as well as associated digging grooves presumably caused by a maniraptoran dinosaur. The proximity indicates a case of probable active predation of the burrow inhabitants by the owners of the claw marks. ==See also==