title: The first fossil of a bolbitidoid fern belongs to the early-divergent lineages of Elaphoglossum (Dryopteridaceae).
abstract: •
  
  
  OBJECTIVE
  Closing gaps in the fossil record and elucidating phylogenetic relationships of mostly incomplete fossils are major challenges in the reconstruction of the diversification of fern lineages through time. The cosmopolitan family Dryopteridaceae represents one of the most species-rich families of leptosporangiate ferns, yet its fossil record is sparse and poorly understood. Here, we describe a fern inclusion in Miocene Dominican amber and investigate its relationships to extant Dryopteridaceae.•
  
  
  METHODS
  The morphology of the fossil was compared with descriptions of extant ferns, resulting in it being tentatively assigned to the bolbitidoid fern genus Elaphoglossum. This assignment was confirmed by reconstructing the evolution of the morphological characters preserved in the inclusion on a molecular phylogeny of 158 extant bolbitidoid ferns. To assess the morphology-based assignment of the fossil to Elaphoglossum, we examined DNA-calibrated divergence time estimates against the age of the amber deposits from which it came.•
  
  
  RESULTS
  The fossil belongs to Elaphoglossum and is the first of a bolbitidoid fern. Its assignment to a particular section of Elaphoglossum could not be determined; however, sects. Lepidoglossa, Polytrichia, and Setosa can be discounted because the fossil lacks subulate scales or scales with acicular marginal hairs. Thus, the fossil might belong to either sects. Amygdalifolia, Wrightiana, Elaphoglossum, or Squamipedia or to an extinct lineage.•
  
  
  CONCLUSIONS
  The discovery of a Miocene Elaphoglossum fossil provides remarkable support to current molecular clock-based estimates of the diversification of these ferns.
authors.affiliation: University of Munich (LMU), Systematic Botany and Mycology, Menzinger Str. 67, 80638 Munich, Germany.
authors.forename: Josmaily
authors.initials: J
authors.lastname: Lóriga
authors.affiliation: University of Göttingen, Courant Research Centre Geobiology, Goldschmidtstraße 3, 37077 Göttingen, Germany.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Schmidt
authors.affiliation: New York Botanical Garden, Bronx, New York 10458-5126 USA.
authors.forename: Robbin C
authors.initials: RC
authors.lastname: Moran
authors.affiliation: University of Munich (LMU), Systematic Botany and Mycology, Menzinger Str. 67, 80638 Munich, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Feldberg
authors.affiliation: Botany Department, Natural History Museum, London, UK.
authors.forename: Harald
authors.initials: H
authors.lastname: Schneider
authors.affiliation: University of Munich (LMU), Systematic Botany and Mycology, Menzinger Str. 67, 80638 Munich, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Heinrichs
mesh_terms: D005075:Biological Evolution; D018744:DNA, Plant; D019143:Evolution, Molecular; D029624:Ferns / Q000033:anatomy & histology / Q000235:genetics*; D005580:Fossils; D010802:Phylogeny
chemical_list: D018744:DNA, Plant
keywords: Dominican amber; Elaphoglossum; Miocene; Polypodiales; ancestral state reconstruction; bolbitidoid fern; eupolypods I; fossil fern