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Table 1 Measurements and estimations of eyes proprieties in studied samples of polychelidan with preserved ommatidia

From: On the sighted ancestry of blindness – exceptionally preserved eyes of Mesozoic polychelidan lobsters

    d: Eye diameter (μm) a: Om-matidia size (μm) Ommatidia shape Approximation of eye geometry used n: Longest row of ommatidia Opening angle of ommatidia (degree) se: Surface of eye (μm²) so: surface of one ommatidium (μm²) Number of ommatidia
   Formula applied → Measured   Flat \( \frac{d}{a} \) nul, by definition \( \pi \times {\left(\frac{d}{2}\right)}^2 \) Quadrate: \( \frac{se}{so} \)
Age Species ↓ Specimen ↓ Hemispheric \( \frac{\pi \times d}{2\times a} \) \( \frac{180}{n} \) \( 2\pi \times {\left(\frac{d}{2}\right)}^2 \) Hexagonal: \( \begin{array}{l}3\sqrt{3}\hfill \\ {}2\hfill \end{array}\times {\left(\begin{array}{l}a\hfill \\ {}2\hfill \end{array}\right)}^2 \)
Late Jurassic Rosenfeldia oppeli SMNS 66004 3,400 53 Hexagonal Flat 64 0.00 9,079,203 1,824 4,976
Hemispheric 101 1.79 18,158,406 9,953
Palaeopentacheles roettenbacheri SMNS 67903 1,100 35 Quadratic Flat 31 0.00 950,332 1,225 776
Hemispheric 49 3.65 1,900,664 1,552
Palaeopolycheles longipes SMNS 63724 4,200 50 Quadratic Flat 84 0 13,854,424 2,500 5,542
Hemispheric 132 1.36 27,708,847 11,084
Knebelia totoroi SMNS 67916 7,200 67.5 Quadratic Flat 107 0 40,715,041 4,556 8,936
Hemispheric 168 1.07 81,430,082 17,872
Middle Jurassic Proeryon giganteus FSL 170603 9,100 90 Quadratic Flat 101 0 65,038,822 8,100 8,029
Hemispheric 159 1.13 130,077,644 16,059
UJF-ID 11547 11,000 88 Quadratic Flat 125 0 95,033,178 7,744 12,272
Hemispheric 196 0.92 190,066,356 24,544
UJF-ID 14020* 11,600 78.8 Quadratic Flat 147 0 105,683,177 6,209 17,020
Hemispheric 231 0.78 211,366,354 34,040
UPMC-248 NA 77 Quadratic Flat NA NA NA 5,929 NA
Hemispheric NA NA NA NA
Hellerocaris falloti FSL 710108 1,900 62 Quadratic Flat 31 0 2,835,287 3,844 738
Hemispheric 48 3.74 5,670,575 1,475
MNHN.F.A50709* 850 24.25 Quadratic Flat 35 0 567,450 588 965
Hemispheric 55 3.27 1,134,900 1,930
Willemoesiocaris ovalis MNHN.F.A29521* 7,000 68.83 Quadratic Flat 102 0 38,484,510 4,738 8,122
Hemispheric 160 1.13 76,969,020 16,245
Early Jurassic Gabaleryon sp. SMNS 67631 1,850 55 Quadratic Flat 34 0 2,688,025 3,025 889
Hemispheric 53 3.41 5,376,050 1,777
Coleia viallii MSNM.i3368 5600 82 Quadratic Flat 68 0 24,630,086 6,724 3,663
Hemispheric 107 1.68 49,260,173 7,326
Coleia barrovensis NHMUK.I6589 4100 66 Quadratic Flat 62 0 13,202,543 4,356 3,031
Hemispheric 98 1.84 26,405,086 6,062
  1. The size of square ommatidial facets corresponds to the measure of their side length; that of hexagonal ommatidial facets corresponds to the distance between to opposite summits of the hexagon, which is in turn equal to two times the side length. The asterisks after specimens registry numbers indicate that given values are based on multiple ommatidia length measurements, in these cases average values are given. Measured values for these specimens are indicated in Table 2. Distances in μm, surfaces in μm2