DOI: 10.5061/dryad.4xgxd25n0
title: Leaf measurements from New Caledonian conifers

description: Premise: The archipelago of New Caledonia contains one of the world's
 most distinctive biotas. The presence of notable paleoendemic taxa
 suggests Gondwanan vicariance may have played an important role in the
 formation of New Caledonia's biota, but geological evidence indicates
 that the landmass was submerged until the Oligocene and its flora resulted
 from more recent long-distance dispersal events. The lack of a fossil
 record contributes to uncertainties inherent in both interpretations, but
 newly discovered fossil plant assemblages may help to clarify the origins
 of the New Caledonian flora. Methods: We use standard paleobotanical
 techniques to prepare and describe leafy conifer shoots from an early
 Miocene deposit (~19 Ma) on the Pindaï Peninsula of western New Caledonia.
 To determine affinities of the fossil material, we compare it to herbarium
 collections of extant New Caledonian conifers and the broader macrofossil
 record. Results: Fossil leaves contain cellular-level details of leaf
 morphology and epidermis anatomy, which are consistent with the conifer
 family Podocarpaceae, particularly the extant genus Dacrycarpus. Stomata
 in the fossils are arranged in crowded complexes unlike those of any
 described Podocarpaceae taxon, however, and we assign this material to a
 new extinct genus Dacrycarpoides. Conclusions: New Caledonia is a hotspot
 of modern conifer biodiversity and was home to now-extinct lineages as
 well. The presence of extinct conifers on Miocene New Caledonia is
 consistent with floras from neighboring landmasses and highlights the role
 of extinction in shaping the modern flora of New Caledonia and other
 Australasian landmasses.
description: To compare fossil material with living and extinct taxa, we
 examined leaf morphology and epidermal anatomy in published descriptions
 and compilations of Southern Hemisphere conifers in the families
 Araucariaceae, Cupressaceae, and Podocarpaceae (e.g., Florin, 1931;
 Stockey and Ko, 1986; Hill and Brodribb, 1999). We also compared our
 fossil material with herbarium specimens of extant New Caledonian species
 that produce awl-shaped leaves comparable to those of the fossils,
 including <em>Dacrycarpus vieillardii</em> (Parl.) de Laub.,
 several species of <em>Dacrydium </em>Sol. ex G. Forst.
 (<em>D. balansae </em>Brongn. & Gris, <em>D.
 guillauminii</em> J. Buchholz, <em>D. araucaroides</em>
 Brongn. & Gris,), and two species of
 <em>Araucaria</em> Juss. that have relatively small leaves
 (<em>A. bernierii</em> J. Buchholz, <em>A.
 subulata</em> Vieill.). This material was supplied by loan from The
 Huntington Library, Art Museum, and Botanical Gardens in San Marino,
 California, USA.
description: # Leaf measurements from New Caledonian conifers This study describes a
 new fossil conifer genus and species from Miocene sediments on New
 Caledonia. The provided dataset consists of leaf size measurements from
 the fossil taxon and living conifer species on New Caledonia. These data
 were used to compare the fossil taxon to living species and to support our
 taxonomic interpretation of the fossil. ## Description of the data and
 file structure Data consists of 1 csv file of leaf size measurements.
 FileList-NCleafdata.csv Raw data leaf measurement data are provided in
 NCleafdata.csv, a csv spreadsheet consisting of 1928 rows organized into 9
 columns. Each row represents a measurement or set of measurements from an
 individual of a given species s. Columns are as follows: * Taxon: Species
 from which the leaf measurements were made. - Subspecies: In some cases,
 additional subspecies information was provided. * Herbarium_sheet:
 Identification number on the herbarium sheet containing the specimen from
 which the leaf measurements were made (NA- not available) - Leaf_type:
 Describes whether leaves were flattened bifacially (flattening occurs
 parallel the abaxial-adaxial plane) or bilaterally (flattening occurs
 perpendicular to the abaxial-adaxial plane) * BranchID: Identifies the
 branch on a given herbarium specimen from which the leaf measurements were
 made. - Analysis_Order: An identification number used to organize plots of
 the data. * Length_mm: Leaf length, in millimeters (n/a: not available;
 measurement could not be made without destroying the sample). - Width_mm:
 Maximum leaf width, in millimeters (n/a: not available; measurement could
 not be made without destroying the sample). * Thickness_mm: Maximum leaf
 thickness, in millimeters. Thickness is here measured perpendicular to the
 abaxial-adaxial plane. (n/a: not available; measurement could not be made
 without destroying the sample).