Trochodendraceous fruits and foliage in the miocene of western North America
Two fossil fruit types and at least one fossil leaf type representing Trochodendraceae are recognized from the middle Miocene Cascadia flora of western Oregon, USA. Trochodendron rosayi sp. nov., known also from the middle Miocene of eastern Oregon and northern Idaho, is based on long-pedicelled, apically dehiscent capsular fruits with 7–9 persistent outcurved styles, very similar to the extant monotypic east Asian species T. aralioides. Concavistylon kvacekii gen. et sp. nov. is named for a racemose infructescence bearing shortly pedicellate, apically dehiscent capsules with 4 to 5 persistent incurved styles arising from the basal 1/3 of the fruit. Leaves associated at the Moose Mountain locality are recognized as Trochodendron postnastae sp. nov. They have basally acrodromous venation with a prominent midvein bracketed by a pair of strongly ascending basal secondaries and are thought to correspond to the T. rosayi fruits. These new occurrences demonstrate that greater diversity was present among fossil Trochodendraceae than previously recognized during the Miocene in western North America.
Biological and Environmental Sciences
Manchester, S.R., Pigg, K., & Devore, M.L. (2018). Trochodendraceous fruits and foliage in the miocene of western North America. Fossil Imprint, 74(1-2), 45-54.