An early record of a vesselless angiosperm from the middle Cenomanian of the Envigne valley (Vienne, Western France)

in IAWA Journal
Restricted Access
Get Access to Full Text
Rent on DeepDyve

Have an Access Token?



Enter your access token to activate and access content online.

Please login and go to your personal user account to enter your access token.



Help

Have Institutional Access?



Access content through your institution. Any other coaching guidance?



Connect

Thousands of silicified wood fragments were recently collected from the middle Cenomanian of Vienne in western France at less than 10 km away from a historical locality where in 1870 the French geologist Alphonse Le Touzé de Longuemar reported silicified wood. The plant assemblage is very diverse, and includes several species of ferns, conifers, and angiosperms. We describe and discuss the systematic affinities of a new vesselless angiosperm. Many of its characters are shared by extant and fossil Winteraceae. Nevertheless, the absence of uniseriate rays makes the anatomy of these specimens unique. Its combination of characters justifies the establishment of a new genus of vesselless fossil angiosperm wood of uncertain affinity, Sherwinoxylon gen. nov.

An early record of a vesselless angiosperm from the middle Cenomanian of the Envigne valley (Vienne, Western France)

in IAWA Journal

Sections

References

  • Angiosperm Phylogeny Group (APG). 2016. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Bot. J. Linn. Soc. 181: 120. https://doi.org/10.1111/boj.12385.

  • Azéma C Durand S Médus J . 1972. Des miospores du Cénomanien moyen. Paléobiologie continentale 3 (4): 154.

  • Baas P Wheeler EA . 1996. Parallelism and reversibility in xylem evolution – a review. IAWA J. 17: 351364. DOI: .

  • Bailey IW . 1944. The comparative morphology of the Winteraceae: III. Wood. J. Arnold Arbor. 25: 97103.

  • Bailey IW . 1957. Additional notes on the vesselless dicotyledon, Amborella trichopoda Baill. J. Arnold Arbor. 38: 374380.

  • Bailey IW Swamy BGL . 1948. Amborella trichopoda Baill., a new morphological type of vesselless dicotyledon. J. Arnold Arbor. 29: 245254.

  • Bourgueil B Cariou E Moreau P Ducloux J . 1976. Carte géologique de la France au 1/50 000. Vouneuil-sur-Vienne. XVIII-26. BRGMOrléans.

  • Carlquist S. 1975. Ecological strategies of xylem evolution. University of California PressBerkeley.

  • Carlquist S. 1981. Wood anatomy of Zygogynum (Winteraceae); field observations. Bull. Mus. Natl. Hist. Nat. 3: 28192.

  • Carlquist S. 1982. Exospermum stipitatum (Winteraceae): observations on wood, leaves, flowers, pollen, and fruit. Aliso 10: 277289.

  • Carlquist S. 1983a. Wood anatomy of Belliolum (Winteraceae) and a note on flowering. J. Arnold Arbor. 64: 161169.

  • Carlquist S. 1983b. Wood anatomy of Bubbia (Winteraceae), with comments on origin of vessels in dicotyledons. Am. J. Bot. 70: 578590. DOI: .

  • Carlquist S. 1987. Presence of vessels in wood of Sarcandra (Chloranthaceae); comments on vessel origins in angiosperms. Am. J. Bot. 74: 17651771. DOI: .

  • Carlquist S. 1988. Wood anatomy of Drimys s. s. (Winteraceae). Aliso 12: 8195.

  • Carlquist S. 1989. Wood anatomy of Tasmannia . Aliso 12: 257275.

  • Carlquist S. 1992. Wood anatomy and stem of Chloranthus; summary of wood anatomy of Chloranthaceae, with comments on relationships, vessellessness, and the origin of monocotyledons. IAWA J. 13: 316. https://doi.org/10.1163/22941932-90000556.

  • Carlquist S. 2000. Wood and bark anatomy of Takhtajania (Winteraceae); phylogenetic and ecological implications. Ann. Mo. Bot. Gard. 87: 317322. DOI: .

  • Carlquist S. 2001. Comparative wood anatomy. Systematic ecological and evolutionary aspects of dicotyledon wood. Ed. 2. Springer-VerlagBerlin.

  • Carlquist S Schneider EL . 2001. Vegetative anatomy of the New Caledonian endemic Amborella trichopoda: relationships with the Illiciales and implications for vessel origin. Pac. Sci. 55: 305312.

  • Carlquist S Schneider EL . 2002. The tracheid–vessel element transition in angiosperms involves multiple independent features: cladistic consequences. Am. J. Bot. 89: 185195. DOI: .

  • Chaney RW Sanborn EI . 1933. The Goshen flora of west central Oregon. Carnegie Institution of Washington PublicationWashington.

  • Chase MW Soltis DE Olmstead RG Morgan D Les DH Mishler BD Duvall MR Price RA Hills HG Qiu YL Kron KA Rettig JH Conti E Palmer JD Manhart JR Sytsma KJ Michael HJ Kress WJ Karol KA Clark WD Hedrén M Gaut BS Jansen RK Kim KJ Wimpee CF Smith JF Furnier GR Strauss SH Xiang QY Plunkett GM Soltis PS Swensen SM Williams SE Gadek PA Quinn CJ Eguiarte LE Golenberg E Learn GH Graham SW Jr Barrett SCH Dayanandan S Albert VA . 1993. Phylogenetics of seed plants: an analysis of nucleotide sequences from the plastid gene rbcL. Ann. Mo. Bot. Gard. 80: 528580. DOI: .

  • Christenhusz MJ Fay MF Chase MW . 2017. Plants of the world: An illustrated encyclopedia of vascular plants. University of Chicago PressChicago.

  • Crane PR Manchester SR Dilcher DL . 1991. Reproductive and vegetative structure of Nordenskioldia (Trochodendraceae), a vesselless dicotyledon from the early Tertiary of the Northern Hemisphere. Am. J. Bot. 78: 13111334. DOI: .

  • Crié L. 1884. Contribution à l’étude de la flore crétacée de l’Ouest de la France. C.R. Acad. Sci. Paris 99: 511513.

  • Dettmann ME Jarzen DM . 1990. The Antarctic/Australian rift valley: Late Cretaceous cradle of northeastern Australasian relicts? Rev. Palaeobot. Palynol. 65: 131144. https://doi.org/10.1016/0034-6667(90)90064-P.

  • Doust AN Drinnan AN . 2004. Floral development and molecular phylogeny support the generic status of Tasmannia (Winteraceae). Am. J. Bot. 91: 321331. DOI: .

  • Doyle JA . 2000. Paleobotany, relationships, and geographic history of Winteraceae. Ann. Mo. Bot. Gard. 87: 303316. DOI: .

  • Doyle JA Endress PK . 2014. Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: ANITA lines and relatives of Chloranthaceae. Int. J. Plant Sci. 175: 555600. https://doi.org/10.1086/675935.

  • Doyle JA Hotton CL Ward JV . 1990. Early Cretaceous tetrads, zonasulcate pollen, and Winteraceae. I. Taxonomy, morphology, and ultrastructure. Am. J. Bot. 7715441557. DOI: .

  • Eklund H Doyle JA Herendeen PS . 2004. Morphological phylogenetic analysis of living and fossil Chloranthaceae. Int. J. Plant Sci. 165: 107151. DOI: .

  • Endress PK . 1986. Floral structure, systematics, and phylogeny in Trochodendrales. Ann. Mo. Bot. Gard. 73: 297324. DOI: .

  • Feild TS Brodribb T Holbrook NM . 2002. Hardly a relict: freezing and the evolution of vesselless wood in Winteraceae. Evolution 56: 464478. https://doi.org/10.1111/j.0014-3820.2002.tb01359.x.

  • Feild TS Zwieniecki MA Brodribb T Jaffré T Donoghue MJ Holbrook NM . 2000. Structure and function of tracheary elements in Amborella trichopoda . Int. J. Plant Sci. 161: 705712. DOI: .

  • Fleury R Polette F Batten DJ Durand M Moreau JD Néraudeau D Strullu-Derrien C Redois F . 2017. Palaeobotanical investigation of a Cenomanian clay lens in Hucheloup Quarry, Maine-et-Loire, NW France: Taxonomic, stratigraphic and palaeoenvironmental implications. Ann. Paleontol. 103: 235250. DOI: .

  • Friis EM Crane PR Pedersen KR . 2011. Early flowers and angiosperm evolution. Cambridge University PressCambridge.

  • Friis EM Pedersen KR Crane PR . 1994. Angiosperm floral structures from the Early Cretaceous of Portugal. Plant Syst. Evol. Suppl. 8: 3149. https://doi.org/10.1007/978-3-7091-6910-0_3.

  • Gabilly J Cariou E . 1997. Poitou Vendée Charentes. Guides géologiques régionaux. Ed. 2. MassonParis.

  • Gasson P Baas P Wheeler E . 2011. Wood anatomy of CITES-listed tree species. IAWA J. 32: 155198. DOI: .

  • Gomez B Coiffard C Dépré E Daviero-Gomez V Néraudeau D . 2008. Diversity and histology of a plant litter bed from the Cenomanian of Archingeay–Les Nouillers (southwestern France). C.R. Palevol. 7: 135144. DOI: .

  • Gomez B Daviero-Gomez V Garcia G Caner L Boura A Barral A Cantinolle P Valentin X . 2018. Silicified plant megafossils from the upper Turonian of Vienne, western France. Earth Environ. Sci. Trans. R. Soc. Edinb. 108: 449457. DOI: .

  • Gomez B Daviero-Gomez V Perrichot V Thévenard F Coiffard C Philippe M Néraudeau D . 2004. Assemblages floristiques de l’Albien-Cénomanien de Charente-Maritime (SO France). Ann. Paleontol. 90: 147159. DOI: .

  • Gottwald H. 1992. Hölzer aus marinen Sanden des oberen Eozän von Helmstedt (Niedersachsen). Palaeontographica B 225: 27103.

  • Gregory M Poole I Wheeler EA . 2009. Fossil dicot wood names: an annotated list with full bibliography. IAWA Journal Supplement 6220 pp.

  • Greguss P. 1955. Identification of living gymnosperms on the basis of xylotomy. Akadémiai KiadoBudapest.

  • Greguss P. 1963. A new homoxylous tree Tetracentronites hungaricum n. sp. The Palaeobotanist 12: 110.

  • Grímsson F Grimm GW Potts AJ Zetter R Renner SS . 2018. A Winteraceae pollen tetrad from the early Paleocene of western Greenland, and the fossil record of Winteraceae in Laurasia and Gondwana. J. Biogeogr. 45: 567581. DOI: .

  • Grimsson F Xafis A Neumann FH Zetter R . 2017. Pollen morphology of extant Winteraceae: a study allowing SEM-based affiliation of its fossil representatives. Acta Palaeobot. 57: 339396. DOI: .

  • Hergert HL Phinney HK . 1954. Trochodendroxylon beckii gen. et sp. nov. from the Tertiary of Oregon. Bull. Torrey Bot. Club 81: 118122. DOI: 10.2307/2481846.

  • Hufford L Crane PR . 1989. A preliminary phylogenetic analysis of the “lower” Hamamelidae. In: Crane PR Blackmore S (eds.) Evolution systematics and fossil history of the Hamamelidae Vol. 1: 175192. Clarendon PressOxford.

  • IAWA Committee. 1989. IAWA List of microscopic features for hardwood identification. IAWA Bull. n.s. 10: 219332.

  • InsideWood. 2004-onwards. Published on the Internet. http://insidewood.lib.ncsu.edu/search [October 2018].

  • Jones TP Rowe NP . 1999. Fossil plants and spores: modern techniques. Geol. Soc. London.

  • Jud NA Rothwell GW Stockey RA . 2010. Paleoecological and phylogenetic implications of Saxicaulis meckertii gen. et sp. nov.: a bennettitalean stem from the Upper Cretaceous of western North America. Int. J. Plant Sci. 171: 915925. DOI: 10.1086/655963.

  • Juignet P Médus J . 1971. Les argiles noires d’Écommoy (Sarthe): Précisions sédimentologiques et palynologiques. Bull. Soc. géol. Fr. 6: 310312.

  • Keating WG Bolza E . 1982. Characteristics properties and uses of timbers. Vol. I. Southeast Asia Northern Australia and the Pacific. Texas A&M University Press.

  • Laing JF . 1975. Mid-Cretaceous angiosperm pollen from southern England and northern France. Palaeontol. 18: 775808.

  • Li HF Chaw SM Du CM Ren Y . 2011. Vessel elements present in the secondary xylem of Trochodendron and Tetracentron (Trochodendraceae). Flora. 206: 595600. https://doi.org/10.1016/j.flora.2010.11.018.

  • Mathiesen J. 1932. Notes on some fossil plants from East Greenland. Medd. Grønl. 85: 162.

  • Médioni R Debrand-Passard S Perna G Weecksteen M . 1974. Carte géologique au 1/50 000. Châtellerault. XVIII-25. BRGMOrléans.

  • Metcalfe CR Chalk L . 1950. Anatomy of the Dicotyledons. The Clarendon PressOxford.

  • Metcalfe CR Chalk L . 1987. Anatomy of the Dicotyledons Second Edition Volume 3. Oxford Scientific Publications.

  • Meylan BA Butterfield BG . 1978. The structure of New Zealand woods. NZ Dept. Sci. Ind. Res. Bull. 222.

  • Mildenhall DC Crosbie YM . 1979. Some porate pollen from the upper Tertiary of New Zealand. New Zeal. J. Geol. Geop. 22: 499508. DOI: 10.1080/00288306.1979.10424159.

  • Nardi R Edlmann A . 1992. Legnami tropicali importati in Italia: anatomia e identificazione. Vol. II. América Latina. Istituto di Assestamento e Tecnología ForestaleFirenze.

  • Néraudeau D Allain R Perrichot V Videt B De Broin F Guillocheau F Philippe M Rage JC Vullo R . 2003. Découverte d’un dépôt paralique à bois fossiles, ambre insectifère et restes d’Iguanodontidae (Dinosauria, Ornithopoda) dans le Cénomanien inférieur de Fouras (Charente-Maritime, sud-ouest de la France). C.R. Palevol. 2: 221230. DOI: .

  • Néraudeau D Perrichot V Batten DJ Boura A Girard V Jeanneau L Nohra YA Polette F Saint Martin S Saint Martin JP Thomas R . 2017. Upper Cretaceous amber from Vendée, north-western France: age dating and geological, chemical, and palaeontological characteristics. Cretac. Res. 70: 7795. https://doi.org/10.1016/j.cretres.2016.10.001.

  • Néraudeau D Perrichot V Colin JP Girard V Gomez B Guillocheau F Masure E Peyrot D Tostain F Videt B Vullo R . 2008. A new amber deposit from the Cretaceous (uppermost Albian-lowermost Cenomanian) of southwestern France. Cretac. Res. 29: 925929. https://doi.org/10.1016/j.cretres.2008.05.009.

  • Néraudeau D Redois F Ballèvre M Duplessis B Girard V Gomez B Daviero-Gomez V Melliere B Perrichot V . 2013. L’ambre cénomanien d’Anjou: stratigraphie et paléontologie des carrières du Brouillard et de Hucheloup (Ecouflant, Maine-et-Loire). Ann. Paleontol. 99: 361374. https://doi.org/10.1016/j.annpal.2013.10.001.

  • Néraudeau D Vullo R Gomez B Perrichot V Videt B . 2005. Stratigraphie et paléontologie (plantes, vertébrés) de la série paralique Albien terminal–Cénomanien basal de Tonnay-Charente (Charente-Maritime, France). C.R. Palevol. 4: 7993. https://doi.org/10.1016/j.crpv.2004.11.008.

  • Page VM . 1968. Angiosperm wood from the Upper Cretaceous of Central California: Part II. Am. J. Bot. 55: 168172. https://doi.org/10.1002/j.1537-2197.1968.tb06957.x.

  • Page VM . 1970. Angiosperm wood from the Upper Cretaceous of central California: III. Am. J. Bot. 57: 11391144. https://www.jstor.org/stable/2441279.

  • Patel RN . 1974. Wood anatomy of the dicotyledons indigenous to New Zealand 4. Winteraceae. N.Z. J. Bot. 12: 1932. https://doi.org/10.1080/0028825X.1973.10430261.

  • Peyrot D Jolly D Barrón E . 2005. Apport de données palynologiques à la reconstruction paléoenvironnementale de l’Albo-Cénomanien des Charentes (Sud-Ouest de la France). C. R. Palevol. 4: 151165. DOI : .

  • Philippe M Cuny G Bashforth A . 2010. Ecpagloxylon mathiesenii gen. nov. et sp. nov., a Jurassic wood from Greenland with several primitive angiosperm features. Plant Syst. Evol. 287: 153165. DOI .

  • Pons D Lauverjat J Broutin J . 1980. Paléoclimatologie comparée de deux gisements du Crétacé supérieur d’Europe occidentale. Mém. Soc. géol. Fr. 139: 151158.

  • Poole I Francis JE . 2000. The first record of fossil wood of Winteraceae from the Upper Cretaceous of Antarctica. Ann. Bot. 85: 307315. https://doi.org/10.1006/anbo.1999.1049.

  • Ren Y Chen L Tian XH Zhang XH Lu AM . 2007. Discovery of vessels in Tetracentron (Trochodendraceae) and its systematic significance. Pl. Syst. Evol. 267: 155161. https://doi.org/10.1007/s00606-007-0563-9.

  • Richter HG Dallwitz MJ . 2000-onwards. Commercial timbers: descriptions illustrations identification and information retrieval. Version: 25th June 2009.

  • Robin N Velasquez M Boura A Garcia G Jauvion C Boiteau JM Gomez B Daviero-Gomez V Valentin X. 2018. The oldest shipworms (Bivalvia, Pholadoidea, Teredinidae) preserved with soft parts (western France): insights into the fossil record and evolution of Pholadoidea. Palaeontol. 61: 905918. https://doi.org/10.1111/pala.12376.

  • Sakala J Selmeczi I Hably L . 2018. Reappraisal of Greguss’ fossil wood types and figured specimens from the Cenozoic of Hungary: Overview, corrected geology and systematical notes. Fossil Imprint 74: 101114. DOI: .

  • Saulnier G Boura A Bernard G Daviero-Gomez V De Franceschi D Pons D Garcia G Boiteau J-M Valentin X . 2018. Diversity in Cenomanian forests: an example from the Envigne Valley (Vienne) France. 10th European Palaeobotany and Palynology Conference Dublin.

  • Schrank E. 2013. New taxa of winteraceous pollen from the Lower Cretaceous of Israel. Rev. Pal. Pal. 195: 1925. http://dx.doi.org/10.1016/j.revpalbo.2013.03.005.

  • Scott RA Wheeler EA . 1982. Fossil woods from the Eocene Clarno Formation of Oregon. IAWA J. 3: 135154. https://doi.org/10.1163/22941932-90000829.

  • Stevenson DW . 1990. Morphology and systematics of the Cycadales. Mem. New York Bot. Gard. 57: 855. http://dx.doi.org/10.21135/893273507.003.

  • Stover LE Partridge AD . 1973. Tertiary and Late Cretaceous spores and pollen from the Gippsland Basin, southeastern Australia. Proc. R. Soc. Victoria. 85: 237286.

  • Suzuki M Joshi L Noshiro S . 1991. Tetracentron wood from the Miocene of Noto Peninsula, Central Japan, with a short revision of homoxylic fossil woods. Bot. Mag. (Tokyo) 104: 3748. DOI: .

  • Swamy BGL Bailey IW . 1950. Sarcandra, a vesselless genus of the Chloranthaceae. J. Arnold Arbor. 31: 117129. https://www.jstor.org/stable/43781355.

  • Takahashi M Herendeen PS Xiao X . 2017. Two early eudicot fossil flowers from the Kamikitaba assemblage (Coniacian, Late Cretaceous) in northeastern Japan. J. Plant. Res. 130: 809826. DOI: .

  • Tanaka S. 2008. Early Cretaceous angiosperm pollen fossils from Hokkaido, northern Japan. Terra Nostra 2: 276277.

  • The Plant List. 2013. Version 1.1. Published on the Internet; http://www.theplantlist.org/ [accessed October 2018].

  • Thomas N Bruhl JJ Ford A Weston PH . 2014. Molecular dating of Winteraceae reveals a complex biogeographical history involving both ancient Gondwanan vicariance and longdistance dispersal. J. Biogeogr. 41: 894904. DOI: .

  • Upchurch GR Dilcher DL . 1990. Cenomanian angiosperm leaf megafossils Dakota Formation Rose Creek locality Jefferson County southeastern Nebraska. U.S. Geol. Survey Bull. 1915.

  • Valentin X Gomez B Daviero-Gomez V Charbonnier S Ferchaud P Kirejtshuk AG Licht A Néraudeau D Vullo R Garcia G . 2014. Plant-dominated assemblage and invertebrates from the lower Cenomanian of Jaunay-Clan, western France. C.R. Palevol. 13: 443454. https://doi.org/10.1016/j.crpv.2014.04.001.

  • Walker JW Brenner GJ Walker AG . 1983. Winteraceous pollen in the Lower Cretaceous of Israel: early evidence of a magnolialean angiosperm family. Science 220 (4603): 12731275. DOI: .

  • Walker JW Walker AG . 1984. Ultrastructure of Lower Cretaceous angiosperm pollen and the origin and early evolution of flowering plants. Ann. Mo Bot. Gard. 71: 464521. https://doi.org/10.2307/2399035.

  • Wheeler EA . 2011. InsideWood - a web resource for hardwood anatomy. IAWA J. 32: 199–211. DOI: .

  • Young DA . 1981. Are the angiosperms primitively vesselless? Syst. Bot. 6: 313330. DOI: .

Figures

  • View in gallery

    Occurrence of vesselless wood in angiosperms. Blue circle = homoxylous or vesselless, black circle = heteroxylous or vessel-bearing. Modified from Angiosperm Phylogeny Group (2016).

  • View in gallery

    – 2: Map of France showing the Vienne department (outline in red), the type locality, Scorbé Clairvaux, is included in the red rectangle. The area represented by this rectangle is magnified in 4. – 3: Two fossil wood samples, a = UP.SCF.17.004, b = UP.SCF.17.007. Scale bars = 3 cm. Multiseriate rays are visible to the naked eye. – 4: Simplified geologic map showing the two new localities: Fouilloux (type locality, Scorbé-Clairvaux) and ‘La Maison Neuve’ (Colombiers) are illustrated by red stars. Jaunay-Marigny represents the historical locality where in 1870 the French geologist A. Le Touzé de Longuemar has reported for the first time silicified wood. Modified from Médioni et al. (1974) and Bourgueil et al. (1976). – 5: Stratigraphic column modified after Gabilly & Cariou (1997): A, claystones and white sandstones of Vierzon (lower Cenomanian); B, green sandstones and C, sandy-claystones of La Pallu (middle Cenomanian); D, plastic claystones and white marlstones with oysters (upper Cenomanian); E, clayey limestones and chalkstones with Inoceramus labiatus (lower Turonian); F, white tufa (micaceous glauconitic chalk, middle Turonian); G–H, altered yellow tufa and clayey sandstones with silicified nodules with plants (Gomez et al. 2019) (upper Turonian). Studied wood remains were collected from the green sandstones and claystones of La Pallu (indicated in B).

  • View in gallery

    Transverse sections of Sherwinoxylon winteroides Boura & Saulnier, sp. nov. – 6: Parenchymatous pith, UP/SCF.17.007. – 7, 8: Homoxylous wood with broad rays, axial parenchyma diffuse-in-aggregates (arrowheads), UP/SCF.17.005. – 9, 10: Thick-walled tracheids; note the indistinct growth rings (arrowheads) marked by 1–3 rows of flattened tracheids with thickened walls, UP/SCF.17.004. – 11: Axial parenchyma diffuse-in-aggregates (arrowheads), UP/SCF. 17.003. – Scale bar 6 = 1 mm, 7 = 2 mm, 8 = 500 μm, 9 & 10 = 250 μm, 11 = 100 μm.

  • View in gallery

    Longitudinal sections of Sherwinoxylon winteroides Boura & Saulnier, sp. nov. – 12 & 13: TLS, exclusively multiseriate rays, UP/SCF.17.004 (12) & UP/SCF.17.003 (13). – 14: TLS, bordered pits in tangential walls of tracheids, UP/SCF.17.003. – 15 & 16: RLS, circular to elliptical often contiguous bordered pits, UP/SCF.17.004. – 17: RLS, rays composed of square cells, with several rows of upright marginal cells, UP/SCF.17.006. – 18: RLS, thick-walled ray cells with simple to weakly bordered pits (funnel-shaped in section), UP/SCF.17.005. – 19: RLS, ray cell pitting, UP/SCF.17.006. – Scale bar 12 = 2 mm, 17 = 500 μm, 13 = 250 μm, 14, 18, 19 = 100 μm, 15, 16 = 50 μm.

Index Card

Content Metrics

Content Metrics

All Time Past Year Past 30 Days
Abstract Views 116 116 5
Full Text Views 59 59 48
PDF Downloads 34 34 28
EPUB Downloads 12 12 12