title: Hygroscopic motions of fossil conifer cones.
abstract: Conifer cones represent natural, woody compliant structures which move their scales as passive responses to changes in environmental humidity. Here we report on water-driven opening and closing motions in coalified conifer cones from the Eemian Interglacial (approx. 126,000-113,000 years BP) and from the Middle Miocene (approx. 16.5 to 11.5 million years BP). These cones represent by far the oldest documented evidence of plant parts showing full functionality of such passive hydraulically actuated motion. The functional resilience of these structures is far beyond the biological purpose of seed dispersal and protection and is because of a low level of mineralization of the fossils. Our analysis emphasizes the functional-morphological integrity of these biological compliant mechanisms which, in addition to their biological fascination, are potentially also role models for resilient and maintenance-free biomimetic applications (e.g., adaptive and autonomously moving structures including passive hydraulic actuators).
authors.affiliation: Plant Biomechanics Group, Botanic Garden, University of Freiburg, Faculty of Biology, D-79104 Freiburg im Breisgau, Germany.|Freiburg Materials Research Center (FMF), University of Freiburg, D-79104 Freiburg im Breisgau, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Poppinga
authors.affiliation: BASF SE Advanced Materials and Systems Research, D-67056 Ludwigshafen, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Nestle
authors.affiliation: BASF SE Advanced Materials and Systems Research, D-67056 Ludwigshafen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Šandor
authors.affiliation: Department of Orthopedics and Traumatology Heidelberg, Heidelberg University Hospital, D- 69118 Heidelberg, Germany.
authors.forename: Bruno
authors.initials: B
authors.lastname: Reible
authors.affiliation: Plant Biomechanics Group, Botanic Garden, University of Freiburg, Faculty of Biology, D-79104 Freiburg im Breisgau, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Masselter
authors.affiliation: BASF SE Advanced Materials and Systems Research, D-67056 Ludwigshafen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Bruchmann
authors.affiliation: Plant Biomechanics Group, Botanic Garden, University of Freiburg, Faculty of Biology, D-79104 Freiburg im Breisgau, Germany.|Freiburg Materials Research Center (FMF), University of Freiburg, D-79104 Freiburg im Breisgau, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Speck
mesh_terms: D053476:Extinction, Biological; D005580:Fossils; D009038:Motion; D009929:Organ Size; D064028:Tracheophyta / Q000033:anatomy & histology*; D014867:Water; D017155:Wettability
chemical_list: D014867:Water