Secrets of the Chinle Formation
The sage-brush and cacti-dotted landscape at Zion does not easily render thoughts of lakes, streams, and swamps. During Chinle time, no flowering plants existed, instead, club mosses and ferns grew in freshwater marshes, while horsetails and cycads occupied floodplains. The Chinle Formation’s 220 million-year old paleo-environment featured conifers that grew to 150 feet with 9-foot widths. When they aged and fell or were toppled by erosion and floods, some of the conifers were buried rapidly by sediments. Deprived of oxygen needed for fast decay, the living woody tissues were slowly replaced by minerals and hardened to stone to form petrified wood.
Plants aren’t the only fossil finds from the Chinle Formation at Zion. Within the murky marshes of thick vegetation, a carnivorous creature lurked, heavily protected with armor and built to attack. In this tropical lowland, phytosaurs, with their razor sharp teeth and long snouts were dominant predators. The phytosaur partial fossil shown here includes the occipital condyle, a part of the braincase which articulated with the upper vertebra. Phytosaur teeth have also been found in the Chinle Formation in Zion. Phytosaurs measured up to sixteen feet and, although unrelated, looked similar to a present-day crocodiles.