APPENDIX 1

Dataset sampling summary - taxonomic and temporal counts of the data gathered and analysed for this study.

TABLE 1A 1. Number of species sampled for seven trilobite orders (Asaphida, Corynexochida, Lichida, Phacopida, Proetida, Ptychopariida, and Redlichiida), the taxonomically problematic Agnostida, and one incerti ordinis group. Orders are then divided into Suborders, subfamilies, and families, showing the taxon sampling for each. Trinucleidae, Harpetida, Agnostida, and a burlingiid species have been removed from the data set. Total species sampled = 355.

Order # Suborder # Superfamily # Family #
Asaphida
       
61        Asaphina         61        Anomocaroidea  2 Aphelaspididae 1
Pterocephaliidae 1
Asaphoidea  37 Asaphidae 32
Ceratopygidae 5
Cyclopygoidea  14 Cyclopygidae 5
Nileidae 9
Trinucleioidea  8 Alsataspididae 1
Raphiophoridae 7
Corynexochida       44       Corynexochina     27     Corynexochoidea     27     Corynexochidae 1
Dolichometopidae 11
Dorypygidae 6
Oryctocephalidae 3
Zacanthoididae 6
Illaenina  17  Illaenoidea  17 Illaenidae 11
Styginidae 6
Lichida/
Odontopleurida
18  Lichina 4 Lichoidea 4 Lichidae 4
Odontopleurina 14 Odontopleuroidea 14 Odontopleuridae 14
Phacopida          93          Calymenina  27  Calymenoidea  27 Calymenidae 23
Homalonotidae 4
Cheirurina   23   Cheiruroidea   23 Cheiruridae 10
Encrinuridae 10
Pliomeridae 3
Phacopina     43     Acastoidea  7 Acastidae 6
Calmoniidae 1
Dalmanitoidea 12 Dalmanitidae 12
Phacopoidea  24 Phacopidae 19
Pterygometopidae 5
Proetida    22    Proetina    22    Aulacopleuroidea 5 Aulacopleuridae 5
Bathyuroidea 1 Telephinidae 1
Proetoidea  16 Proetidae 15
Tropidocoryphidae 1
Ptychopariida               71               Olenina 38 Olenoidea 38 Olenidae 38
Ptychopariina              33              Ellipsocephaloidea   9 Agraulidae 3
Ellipsocephalidae 5
Estaingiidae 1
Ptychoparioidea           24           Alokistocaridae 2
Conocoryphidae 1
Conokephalinidae 1
Dokimocephalidae 1
Elviniidae 2
Kingstoniidae 1
Marjumiidae 2
Papyriaspididae 1
Proasaphiscidae 1
Ptychopariidae 6
Solenopleuridae 6
Redlichiida          46          Olenellina   9   Fallotaspidoidea 4 Fallotaspididae 4
Olenelloidea Holmiidae 1
Olenellidae 4
Redlichiina       37       Emuelloidea 1 Emuellidae 1
Paradoxidoidea   28   Centropleuridae 2
Paradoxididae 22
Xystriduridae 4
Redlichioidea   8   Gigantopygidae 1
Menneraspidae 1
Redlichiidae 6

TABLE 1A 2. Number of species sampled for each Epoch of the Palaeozoic Era, with their upper and lower boundary dates, and resulting bin lengths (in millions of years). Epoch dates taken from the ICS (2018; Cohen et al., 2013 updated). Total species sampled = 371, as the 13 boundary species have been counted within each Epoch they occurred in.

Geological Epoch Lower boundary
(Ma)
Upper boundary
(Ma)
Bin size
(Ma)
Designation # Species
Cambrian S2 521 509 12 1 21
Miaolingian 509 497 12 2 87
Furongian 497 485.4 11.6 3 38
Early Ordovician 485.4 470 15.4 4 30
Middle Ordovician 470 458.4 11.6 5 59
Late Ordovician 458.4 443.8 14.6 6 39
early Silurian (Llandovery and Wenlock) 443.8 427.4 16.4 7 38
late Silurian (Ludlow and Pridoli) 427.4 419.2 8.2 8 16
Early Devonian 419.2 393.3 25.9 9 11
Middle Devonian 393.3 382.7 10.6 10 13
Late Devonian 382.7 358.9 23.8 11 6
Mississippian 358.9 323.2 35.7 12 9
Pennsylvanian 323.2 298.9 24.3 13 3

APPENDIX 2.

Raw trilobite moulting behaviour dataset - collected as a basis for the entire study. All results are replicable from this data. This data is supplied in two formats, an Excel spreadsheet, and a tab-delimited text file, to download.

 

APPENDIX 3.

Sampling numbers for raw trilobite moulting behaviour dataset.

TABLE 3A 1. Counts for number of specimens sampled per species in each trilobite order.

Order 1 specimen 2 specimens 3 4 5 6 7 8 9 10 11+ ? TOTAL
Asaphida 37 9 3 2 0 2 1 3 0 1 2 1 61
Corynexochida 25 14 2 1 0 0 1 0 0 0 1 0 44
Lichida / Odontopleurida 11 2 3 1 0 0 0 0 0 0 1 0 18
Phacopida 47 15 9 6 3 0 0 0 1 0 5 7 93
Proetida 17 4 1 0 0 0 0 0 0 0 0 0 22
Ptychopariida 37 13 5 2 1 1 1 1 0 0 5 5 71
Redlichiida 22 7 3 3 0 1 0 1 0 1 4 4 46
TOTAL 196 64 26 15 4 4 3 5 1 2 18 17 355

TABLE 3A 2. Percentage of trilobite species in each order that had samples comprised of 1, 2, 3-5, 6-8, 9-10, and 11+ specimens.

Order 1 2 3-5 6-8 9-10 11+ ?  
Asaphida 37 9 5 6 1 2 1  
Corynexochida 25 14 3 1 0 1 0  
Lichida / Odontopleurida 11 2 4 0 0 1 0  
Phacopida 47 15 18 0 1 5 7  
Proetida 17 4 1 0 0 0 0  
Ptychopariida 37 13 8 3 0 5 5  
Redlichiida 22 7 6 2 1 4 4  
TOTAL 196 64 45 12 3 18   338
% TOTAL 57.99 18.93 13.31 3.55 0.89 5.33    

 

TABLE 3A 3. For each trilobite species, the number of moulting characteristics it displayed (1-6) given with the number of specimens sampled for that species. Some results removed because many species analysed from the literature were not given proper counts, and so these are from at least 1 specimen (but probably more), but could not be included due to their uncertainty.

# species for each data point
# moulting characteristics
displayed by a species
# specimens sampled
for a species
Count
1 1 135
2 33
3 10
4 4
6 1
8 1
12 2
20 1
2 1 37
2 20
3 10
4 4
5 2
7 2
14 3
3 1 10
2 10
3 6
4 4
5 2
6 1
8 1
10 1
11 1
26 1
32 1
34 1
4 3 1
4 2
6 2
7 1
9 2
10 1
12 3
43 1
5 4 2
8 2
12 1
20 1
6 1 1
17 1
20 1

APPENDIX 4.

Diversity data - generated from Fossilworks and the Paleobiology database, with dataset sample diversity.

These data represent the total diversity of the dataset created for this study (i.e. using the species counts also included in Additional file 1), and the dataset generated from the online database of fossil occurrences at Fossilworks/The Paleobiology Database. Accessed 25/01/2018, and publically available at http://fossilworks.org.

TABLE 4A 1. Trilobite taxonomic diversity data. Total diversity represents all occurrences of trilobite species for each order recorded in the Paleobiology Database and Fossilworks (Kiessling et al., 2018), downloaded 25/01/18. Sample diversity represents all species recorded within this data set.

Order # species
total diversity
# species
sample diversity
Asaphida 1668 61
Corynexochida 1276 44
Lichida 639 18
Phacopida 1766 93
Proetida 1629 22
Ptychopariida 2346 71
Redlichiida 429 46
TOTAL 9753 355

TABLE 4A 2. Trilobite diversity data through the Palaeozoic. Total diversity represents all occurrences of trilobite species for each Epoch recorded in the Paleobiology Database and Fossilworks (Kiessling et al., 2018), downloaded 25/01/18. SQS diversity is the same data corrected for sampling using Shareholder Quorum Subsampling through Fossilworks. Sample diversity represents all species recorded within this data set (boundary species recorded twice). Numbers for the Cambrian are slightly offset because the epochs are delineated differently within Fossilworks (Lower Cambrian, Middle Cambrian, Furongian) compared to this data set (following the ICS, 2018; Cohen, 2013 updated; Cambrian Series 2, Miaolingian, Furongian).

Geological Epoch # species
total diversity
# species
SQS diversity
# species
sample diversity
lower Cambrian 896 563 21
middle Cambrian 1454 549 87
Furongian 1757 567 38
Early Ordovician 634 221 30
Middle Ordovician 433 194 59
Late Ordovician 917 189 39
early Silurian 564 248 38
late Silurian 245 157 16
Early Devonian 720 366 11
Middle Devonian 247 47 13
Late Devonian 75 43 6
Mississippian 279 153 9
Pennsylvanian 27 6 3
early Permian 61 36 1
TOTAL 8309 3339 371

APPENDIX 5

Statistical test results - the pertinent results are also reported within the study text. Abbreviations used: VS, open ventral sutures moulting characteristic; FS, open facial sutures moulting characteristic; Ce, disarticulated cephalon moulting characteristic; Th, disarticulated thorax moulting characteristic; Py, disarticulated pygidium moulting characteristic; Cr, disarticulated cranidium moulting characteristic; O, observed counts; E, expected counts.

TABLE 5A 1. Chi2 values with their associated p-values (at 6 degrees of freedom). Test of ordinal-level variability in numbers of species (observed versus expected) for each mode of moulting (Sutural Gape and Salter’s). Statistical significant analyses shaded.

Order Total #
species
Sutural Gape
mode (observed)
Sutural Gape
mode (expected)
Salter’s mode
(observed)
Salter’s mode
(expected)
Asaphida 61 49 48.1 25 25.9
Corynexochida 44 41 34.45 12 18.55
Lichida 18 15 13 5 7
Phacopida 93 43 68.9 63 37.1
Proetida 22 18 16.25 7 8.75
Ptychopariida 71 68 55.9 18 30.1
Redlichiida 46 39 36.4 17 19.6
TOTAL 355 273 273 147 147
Chi 2 analyses
α=0.05 (0.025 with Bonferroni correction)
14.299
p=0.027
26.556
p=0.00018

TABLE 5A 2. Chi 2 values with their associated p-values (at 6 degrees of freedom). Test of ordinal-level variability in numbers of species (observed versus expected) for each of the six moulting characteristics. Statistically significant analyses shaded.

Order Total # species VS
(O)
VS
(E)
FS
(O)
FS
(E)
Ce
(O)
Ce
(E)
Th
(O)
Th
(E)
Py
(O)
Py
(E)
Cr
(O)
Cr
(E)
Asaphida 61 5 9.33 45 46.12 15 16.29 16 15.74 16 10.43 13 12.08
Corynexochida 44 3 5.35 37 26.42 5 9.33 6 9.01 5 5.98 7 6.92
Lichida 18 3 2.38 14 11.74 3 4.15 3 4.01 3 2.66 2 3.07
Phacopida 93 4 13.07 40 64.57 56 22.81 25 22.04 19 14.61 10 16.91
Proetida 22 1 2.46 16 12.16 5 4.29 4 4.15 1 2.75 2 3.18
Ptychopariida 71 8 10.1 63 49.9 3 17.62 20 17.03 9 11.29 16 13.07
Redlichiida 46 27 8.32 37 41.09 2 14.51 12 14.02 4 9.29 16 10.76
TOTAL 355 51 51 252 252 89 89 86 86 57 57 66 66
Chi 2 analyses
α=0.05 (0.0083 with Bonferroni correction)
52.779
p=0.0000000013
19.115
p=0.004
73.782
p=0.000000000000068
2.48
p=0.87
9.09
p=0.17
6.9194
p=0.33

 

TABLE 5A 3. Chi 2 values with their associated p-values (at 6 degrees of freedom). Test of ordinal-level variability in numbers of species (observed versus expected) that ‘normally’ display (i.e. data condensed to that which they use most often) each of the six moulting characteristics. Statistically significant analyses shaded.

Order Total #
species
VS (
O)
VS
(E)
FS
(O)
FS
(E)
Ce
(O)
Ce
(E)
Th
(O)
Th
(E)
Py
(O)
Py
(E)
Cr
(O)
Cr
(E)
Asaphida 61 2 3.74 41 36.94 12 12.86 1 1.3 1 0.98 5 6.18
Corynexochida 44 1 2.72 36 26.81 4 9.33 0 0.94 0 0.71 4 4.89
Lichida 18 0 1.09 13 10.72 3 3.73 0 0.38 0 0.28 2 1.8
Phacopida 93 1 6.16 33 60.77 53 21.15 5 2.14 4 1.61 6 10.17
Proetida 22 0 1.33 16 13.11 4 4.56 0 0.46 0 0.35 2 2.19
Ptychopariida 71 4 4.59 57 45.28 2 15.76 1 1.6 0 1.2 12 7.58
Redlichiida 46 15 3.38 31 33.36 1 11.61 1 1.18 1 0.88 7 5.59
TOTAL 355 23 23 227 227 79 79 8 8 6 6 38 38
Chi 2 analyses
α=0.05 (0.0083 with Bonferroni correction)
48.643
p=0.0000000088
20.609
p=0.0022
72.991
p=0.000000000000099
5.918
p=0.43
6.1189
p=0.41
4.97
p=0.55

 

TABLE 5A 4. Chi 2 values (left-hand column in each pair) with their associated p-values (n-1 degrees of freedom, right-hand column in each pair, α=0.05, 0.0083 with Bonferroni correction). Test of familial/superfamilial-variability in numbers of species (observed versus expected) that display each of the six moulting characteristics. Statistically significant analyses shaded. Only tests indicated with * had close to sufficient numbers of expected samples for a reliable test.

Order Ventral
sutures
Facial
sutures
Cephalon Thorax Pygidium Cranidium
Asaphida 15.068 p=0.035 *7.5447 *p=0.37 *16.362 *p=0.022 4.7795 p=0.69 2.7808 p=0.9 10.318 p=0.17
Corynexochida 5.1779 p=0.52 *4.2538 *p=0.64 6.2269 p=0.4 6.1255 p=0.41 2.1792 p=0.9 5.3548 p=0.5
Phacopida 11.86 p=0.22 *24.505 *p=0.0036 *26.026 *p=0.002 1.0944 p=1 4.9277 p=0.84 9.0536 p=0.43
Ptychopariida 4.1625 p=0.12 *4.8357 *p=0.089 0.84624 p=0.66 *0.53597 *p=0.76 1.6154 p=0.45 *3.4243 *p=0.18
Redlichiida *3.5856 *p=0.46 *2.3727 *p=0.67 7.3333 p=0.12 1.1626 p=0.88 2.2473 p=0.69 *2.7019 *p=0.61

 

TABLE 5A 5. Chi 2 values with their associated p-values (at 4 degrees of freedom). Test of temporal (Geological Periods) variability in numbers of species (observed versus expected) for each of the six moulting characteristics. Statistically significant analyses shaded.

Geological Period Total #
species
VS
(O)
VS
(E)
FS
(O)
FS
(E)
Ce
(O)
Ce
(E)
Th
(O)
Th
(E)
Py
(O)
Py
(E)
Cr
(O)
Cr
(E)
Cambrian 145 35 20.16 129 108.39 7 36.13 33 36.97 19 24.37 32 28.99
Ordovician 125 9 16.69 79 89.68 39 29.89 34 30.59 23 20.16 27 23.99
Silurian 51 4 7.04 37 37.83 15 12.61 15 12.9 10 8.5 8 10.12
Devonian 29 0 2.93 4 15.73 23 5.24 4 5.36 5 3.54 1 4.21
Carboniferous 12 0 1.19 9 6.38 2 2.13 2 2.17 1 1.43 1 1.71
TOTAL 362 48 48 258 258 86 86 88 88 58 58 69 69
Chi 2 analyses
α=0.05 (0.0083 with Bonferroni correction)
19.878
p=0.00053
15.036
p=0.0046
86.873
p=6.1x10-18
1.508
p=0.83
2.5821
p=0.63
3.8704
p=0.42

 

TABLE 5A 6. Chi 2 values with their associated p-values (at 9 degrees of freedom). Test of temporal (Geological Epochs) variability in numbers of species (observed versus expected) for each of the six moulting characteristics. Statistically significant analyses shaded.

Geological Epoch Total #
species
VS
(O)
VS
(E)
FS
(O)
FS
(E)
Ce
(O)
Ce
(E)
Th
(O)
Th
(E)
Py
(O)
Py
(E)
Cr
(O)
Cr
(E)
Cambrian Series 2 21 10 3.41 12 17.62 3 5.85 7 6.13 2 4.11 8 4.88
Miaolingian 87 21 12.35 83 63.77 3 21.17 17 22.18 10 14.87 18 17.65
Furongian 38 5 5.28 35 27.27 1 9.05 10 9.49 7 6.36 7 7.55
Early Ordovician 30 2 4.23 20 21.82 6 7.24 8 7.59 8 5.09 8 6.04
Middle Ordovician 59 5 8.21 39 42.38 20 14.07 16 14.74 10 9.88 11 11.72
Late Ordovician 39 2 5.28 21 27.27 17 9.05 11 9.49 6 6.36 8 7.55
early Silurian 38 3 5.77 27 29.79 12 9.89 13 10.36 9 6.95 7 8.24
late Silurian 16 1 1.87 12 9.65 4 3.2 2 3.36 2 2.25 2 2.67
Early Devonian 11 0 1.14 0 5.87 9 1.95 2 2.04 2 1.37 1 1.63
Middle Devonian 13 0 1.46 4 7.55 9 2.51 2 2.63 3 1.76 0 2.09
TOTAL 352 49 49 253 253 84 84 88 88 59 59 70 70
Chi 2 analyses
α=0.05 (0.0083 with Bonferroni correction)
27.582
p=0.0011
20.02
p=0.018
76.78
p=7.03x10-13
3.1046
p=0.96
6.2279
p=0.72
5.445
p=0.79

TABLE 5A 7. Chi 2 values with their associated p-values (at 4 degrees of freedom). Test of temporal (Geological Periods) variability in numbers of species (observed versus expected) that ‘normally’ display (i.e. data condensed to that which they use most often) each of the six moulting characteristics. Statistically significant analyses shaded.

Geological Period Total #
species
VS
(O)
VS
(E)
FS
(O)
FS
(E)
Ce
(O)
Ce
(E)
Th
(O)
Th
(E)
Py
(O)
Py
(E)
Cr
(O)
Cr
(E)
Cambrian 145 20 9.85 117 95.18 4 32 2 3.69 1 2.87 16 16.41
Ordovician 125 4 8.25 67 79.71 36 26.8 4 3.09 4 2.41 19 13.74
Silurian 51 0 3.32 35 32.12 13 10.8 2 1.25 1 0.97 3 5.54
Devonian 29 0 1.85 4 17.85 23 6 1 0.69 1 0.54 1 3.08
Carboniferous 12 0 0.74 9 7.14 2 2.4 0 0.28 0 0.22 1 1.23
TOTAL 362 24 24 232 232 78 78 9 9 7 7 40 40
Chi 2 analyses
α=0.05 (0.0083 with Bonferroni correction)
18.565
p=0.00096
18.516
p=0.00098
76.34
p=1.03x10-15
1.9118
p=0.75
2.8896
p=0.58
4.6293
p=0.33