Early Pennsylvanian Lagerstätte reveals a diverse ecosystem on a subhumid, alluvial fan.

Much of what we know about terrestrial life during the Carboniferous Period comes from Middle Pennsylvanian (~315-307 Mya) Coal Measures deposited in low-lying wetland environments 1-5 . We know relatively little about terrestrial ecosystems from the Early Pennsylvanian, which was a critical interval for the diversification of insects, arachnids, tetrapods, and seed plants 6-10 . Here we report a diverse Early Pennsylvanian trace and body fossil Lagerstätte (~320-318 Mya) from the Wamsutta Formation of eastern North America, distinct from coal-bearing deposits, preserved in clastic substrates within basin margin conglomerates. The exceptionally preserved trace fossils and body fossils document a range of vertebrates, invertebrates and plant taxa (n = 131), with 83 distinct foliage morphotypes. Plant-insect interactions include what may be the earliest evidence of insect oviposition. This site expands our knowledge of early terrestrial ecosystems and organismal interactions and provides ground truth for future phylogenetic reconstructions of key plant, arthropod, and vertebrate groups.