European Palaeobotany and Palynology Conference 2026

During 2016 and 2017 Yale Peabody Museum field expeditions in Petrified Forest National Park, Arizona, Division of Paleobotany had excavations in Crystal Forest, a new fossil plant locality in the Late Triassic Chinle Formation and collected more than 173 Equisetites specimens from a carbonaceous mudstone layer. The Equisetites is represented by well-preserved young shoots, stems, leaf sheaths, and nodal diaphragms. Two types of Equisetites were identified. One type is Equisetites bradyi with relatively thin stems, short free portions of the leaves, and clear commissural grooves gradually expanding upward. The other one is probably a new type with relatively thick stems, long free portions of the leaves, and narrow commissural grooves of almost constant width. In addition to Equisetites specimens, just one conifer leafy shoot megafossil specimen of cf. Pagiophyllum sp. was uncovered in the locality. The Equisetites-dominated, low-diversity assemblage probably indicates the floodplain paleoenvironment where Equisitites grew in shallow parts of streams, ephemeral ponds, and adjacent wetlands. Furthermore, piercing and sucking insect damage (DT77) was noticed in a stem specimen of E. bradyi. This is the first such report of piercing and sucking damage in the Triassic. This type of insect damage was possibly caused by sternorrhynchan hemipterans (scale insects) which might indicate the presence of a dry season in the winter during that time. The charcoal recovered from the carbonaceous mudstone layer also provides direct evidence of ancient wildfire which may support the presence of a dry season.