Research ArticlePALEONTOLOGY

Fossil scales illuminate the early evolution of lepidopterans and structural colors

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Science Advances  11 Apr 2018:
Vol. 4, no. 4, e1700988
DOI: 10.1126/sciadv.1700988
  • Fig. 1 Wings and scales of Jurassic Lepidoptera and extant Micropterigidae.

    (A to C) A. mane from the Lower Jurassic of Dorset in England, NHMUK In. 59397. (B and C) SEM images of wing scales. (D to F) Lepidopteran specimen from the Upper Jurassic of Karatau in Kazakhstan, PIN2239/607. (E) Enlargement of forewing in (D), SEM image. (F) Cover scale overlapping ground scale, SEM image. (G to I) Lepidopteran specimen from the Lower Jurassic of Grimmen in Germany, LGA1500. (H) Enlargement of forewing in (G), SEM image. (I) Enlargement of forewing scale in (H), SEM image; note that it is an impression fossil and represents an imprint of the original structure. (J to L) Forewing of extant micropterigid moth (M. aruncella). (K) Enlargement of forewing in (J), SEM image. (L) Enlargement of forewing scale in (K), SEM image. (M) Interpretative sketch of herringbone ultrastructure; the regions between the parallel ridges (red) display a striking herringbone pattern formed by oblique-longitudinal parallel crests (green) superimposed on closely spaced parallel crossribs (yellow). Cr, crossrib; Cs, cover scale; Gs, ground scale; Hb, herringbone crest; Pr, parallel ridge. Scale bars, 1 mm (A, D, and G), 0.5 mm (J), 50 μm (E), 20 μm (B, C, F, H, and K), and 1 μm (I and L). Photo credit: B.W., Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences. Used with permission.

  • Fig. 2 Optical modeling showing the photonic response of a simplified fused cover scale structure.

    (A) Three-dimensional schematic of the “unit cell” representing the two-dimensional “U-shaped” structure for which simulations were performed, showing the parallel ridges that run longitudinally along the abwing scale surface. Extending the unit cell gives the periodic structure shown at the top left. (B) Reflectance spectra (for excitation at normal incidence) illustrating zeroth-order diffraction (thin-film interference–like; solid lines) and first-order diffraction (dashed lines) for TE (blue lines) and TM (red lines) polarization states. Together, the TE and TM spectra produce the unpolarized response (black lines). (C) The unpolarized zeroth-order response as a function of increasing angle of incidence, with the region enclosed by the red rectangle shown in (D). (E) International Commission on Illumination color chart with the unpolarized zeroth-order spectrum in (B) represented by the black dot illustrating the broadband color produced by the structure in (A).

  • Fig. 3 Tarachoptera from mid-Cretaceous Burmese amber.

    (A to D) K. brevicostata, female, NIGP164785. (B and C) Forewing scales; note the tubercles and setae on wing membrane. (D) Scale reconstruction. (E to H) K. brevicostata, male, NIGP164786. (E) CLSM images of forewing scales detached from the forewing. (F) Interpretative sketch of cross section of scale. (G) CLSM image of cross section of forewing scales. (H) TEM image of cross section of a forewing scale. Scale bars, 0.5 mm (A), 0.1 mm (B), 50 μm (C), 40 μm (E), 20 μm (G), and 2 μm (H). Photo credit: B.W., Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences. Used with permission.

  • Fig. 4 Evolutionary history and paleodistribution of Amphiesmenoptera.

    (A) Simplified phylogeny of Amphiesmenoptera (47, 55, 56). (B) Paleogeographic distribution of Jurassic lepidopterans on a Middle Jurassic (approximately 170 Ma ago) geographic map (60). Branches representing Lepidoptera are red. Gray vertical bars represent possible wing vestiture apomorphies: 1, single-layer covering; 2, fused scale with simple microstructure; 3, ridges ending in apical scale margin; 4, fused scale with herringbone crests; 5, type 1 bilayer covering; 6, ridges extending beyond apical scale margin; 7, scale arrangement clustered; 8, hollow scales present; 9, interridge plates present; 10, herringbone crests absent. Jurassic lepidopteran scales in clastic sediments are indicated with yellow vertical bars: 1, Early Jurassic of England (195 Ma ago); 2, Early Jurassic of Grimmen, Germany (181.5 Ma ago); 3, Middle Jurassic of Daohugou, China (165 Ma ago); 4, Late Jurassic of Karatau, Kazakhstan (160 Ma ago).

  • Table 1 Measurements of Mesozoic forewing scales.

    FL, forewing length; CSL, cover scale length; CSW, cover scale width; GSL, ground scale length; GSW, ground scale width.

    SpecimenTaxonomyFL (mm)CSL (μm)CSW (μm)GSL (μm)GSW (μm)Age and locality
    Kinitocelis brevicostataTarachoptera4.530−5015−20NoneNoneMid-Cretaceous Burmese amber
    A. maneArchaeolepidae5.5100−11036−4276−8226−33Early Jurassic; United Kingdom
    LGA968? Eolepidopterigidae4.7200−23070−80140−16060−70Early Jurassic; Germany
    LGA2150? Eolepidopterigidae4.7200−23070−80140−16060−70Early Jurassic; Germany
    LGA1500? Eolepidopterigidae4.9200−23065–80UnknownUnknownEarly Jurassic; Germany
    Mesokristensenia sinicaMesokristenseniidae6.195−11035–43UnknownUnknownMiddle Jurassic; China
    PIN2239/607? Eolepidopterigidae5.2100−11048–5366−7235−43Late Jurassic; Kazakhstan

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/4/e1700988/DC1

    fig. S1. Jurassic Lepidoptera from United Kingdom and China.

    fig. S2. SEM image of forewing scales on Kazakhstan specimen PIN2239/607.

    fig. S3. Jurassic Lepidoptera from Germany.

    fig. S4. SEM image of forewing scales on Grimmen specimen LGA1500.

    fig. S5. Reflectance color maps.

    fig. S6. Structural color of extant Micropterigidae.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Jurassic Lepidoptera from United Kingdom and China.
    • fig. S2. SEM image of forewing scales on Kazakhstan specimen PIN2239/607.
    • fig. S3. Jurassic Lepidoptera from Germany.
    • fig. S4. SEM image of forewing scales on Grimmen specimen LGA1500.
    • fig. S5. Reflectance color maps.
    • fig. S6. Structural color of extant Micropterigidae.

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