2024/07/25 by Francisco R. Nares, Indah B. Huegele, Steven R. Manchester · 1 voice
Agricultural and Biological Sciences · #Plant Diversity and Evolution #Botany, Ecology, and Taxonomy Studies #Fern and Epiphyte Biology
paper · doi:10.1086/732310
openalex publication_date 2024/07/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Premise of research. The genus Platanites, an extinct platanoid distinctive because of its trifoliolate compound leaves, has previously been documented only from the late Cretaceous and Paleocene of western North America and the Paleocene of western Scotland. Methodology. We examined terminal and lateral leaflets from Eocene sites in western North America in the Green River Formation of Utah, the Aycross Formation of Wyoming, and the Clarno Formation of Oregon. To better visualize anatomical features, we used ammonium chloride (NH4Cl) to coat the surface of some specimens. Pivotal results. Although previously known only from the late Cretaceous and Paleocene, the genus Platanites is now shown to have extended well into the Eocene in the Rocky Mountain and west coastal region of North America. We synonymize the genus Erlingdorfia (known for its lobed lateral leaflets) with Platanites since the type species of Platanites also has lateral leaflets with lobes. We provide an emended diagnosis for Platanites raynoldsii, which ranged from the early Paleocene to the middle Eocene. We present a new combination, Platanites fremontensis (Berry), which is recognized from the Eocene of the Rocky Mountain region, distinguished from the other species by a blunt apex angle on the terminal leaflet as well as the overall lamina shape and moderate interlobal sinuses on both the terminal and lateral leaflets. Conclusions. We found characters of lamina shape, lobe sinus depth, and minor secondary vein bifurcations to be most informative in distinguishing species of this extinct genus. The geographic range and abundance of Platanites appears to have declined in the early Cenozoic, but at least two lineages survived into the middle to late Eocene.