DOI: 10.5061/dryad.tqjq2bw72
title: Supplementary data for: Another worm bites the dust

description: Based on a dataset of most mid-Paleozoic scolecodonts photographed in the
 literature, the Carnegie Museum of Natural History, and newly presented
 data from the Appalachian Basin, we find that scolecodonts (polychaete jaw
 elements) decrease in size across the Late Devonian boundary, then
 increase again to baseline in the Carboniferous. The majority of the data
 representing small scolecodonts during the extinction event are newly
 presented data in this study. These individuals were sampled from black
 shales in a small geographic range at high stratigraphic resolution. Even
 when excluding these new data, scolecodonts after the Frasnian-Famennian
 boundary are smaller than scolecodonts before the boundary. Lithology or
 water depth has a relationship with scolecodont size, but those factors
 alone cannot explain the size reduction observed across the extinction
 (i.e., we also find big scolecodonts in black shales). This represents a
 novel, previously-unreported pattern in scolecodont size occurring across
 the Late Devonian mass extinction. We interpret this as an oxygen
 stress-driven occurrence of the Lilliput Effect. The biological mechanism
 driving the change appears to be adaptation within taxa–either
 evolutionary or epigenetic–not a dying off of large clades. Although
 oxygen stress is known to reduce biomass of modern communities of
 polychaetes, this is new evidence of size reduction due to oxygen stress.
description: To increase our sample size of Appalachian Basin Lower Paleozoic
 scolecodonts, we also measured the scolecodonts from the extensive
 collections in the Carnegie Museum of Natural History (CMNH). These
 scolecodonts were collected, prepared, and described by former curator of
 the Museum E.R. Eller in the mid-1900s, and have also been described by M.
 Eriksson and C. Bergman. Some of these were photomicrographed under 40x
 magnification at Williams College, while most were photographed at the
 Museum using a ProScope EDU 300 Portable Standalone Digital
 Microscope.  Literature review
 We conducted an extensive literature review to collect data on as
 many published images of Devonian and Carboniferous age scolecodonts as
 possible, as well as a large sampling of Silurian scolecodonts. This
 search was conducted primarily using Google Scholar. We excluded from the
 dataset some images that were unusable because the scolecodonts were
 obscured or images were too low-quality; stratigraphic resolution was too
 poor; scale bars were absent and magnification could not be reliably
 determined; images were sketches rather than photomicrographs; or
 scolecodont affinity was uncertain. We also searched the literature for
 redox proxy data (i.e., molybdenum and total organic carbon) from the same
 strata that scolecodonts were sampled from, but availability of these data
 were limited. Scolecodonts in our literature search represent 73
 localities where no one locality makes up more than 9.7% of individuals
 from the literature (Figure 8). We examined 711 scolecodonts from the
 literature and 77 scolecodonts from our own samples, thus our scolecodonts
 made up 10.8% of the study.  Measurement
 The magnification of photomicrographs taken at Williams College
 varied but was recorded and calibrated to a scale in ImageJ to enable
 precise measurements. Photomicrographs taken at the Carnegie Museum were
 calibrated to a scale bar and directly measured using the ProScope
 software. Photomicrographs obtained from the literature were uploaded into
 ImageJ, calibrated using the scale bar provided in the publication, and
 measured in ImageJ (Figure 9). Sizes recorded by authors in the literature
 were ignored to ensure consistency of measuring methodology.
 The length of a scolecodont is the greatest dimension of a jaw
 approximately parallel to the dentary, while the width is the greatest
 dimension of a jaw roughly perpendicular to the length (Jansonius and
 Craig 1971).  Statistical
 analysis Statistical analyses were performed in
 RStudio using the tidyverse, maps, mapdata, rstatix, ggpubr, dplyr, RCurl,
 cowplot, reshape2, scales, plyr, and RColorBrewer packages. Initial plots
 detected some extreme outliers: scolecodonts from Szaniawski and Wrona
 (1973) were extremely large compared with the rest of the dataset. These
 individuals were excluded from all other analyses because the images in
 this paper are sketches, not photomicrographs, and therefore scale can not
 be reliably determined. Likewise, the individual pictured in Eller (1936)
 was excluded because it is a sketch. Scolecodonts from other Eller papers
 were excluded because the exact same individuals were measured in-person
 at the CMNH, or because they were sketches and therefore deemed
 unreliable. A few CMNH scolecodonts whose age could not be determined were
 also excluded from all further analyses. When a scolecodont was partially
 obscured in one dimension, the obscured dimension was not measured. Rows
 without a value assigned for the variable of interest were excluded for
 that analysis but included in other analyses.  To
 ensure replicability of results, we recorded the figure number and DOI of
 every image retrieved through literature review. Where possible, every
 individual was assigned to a lithostratigraphic age and epoch as well as
 basin, unit, and locality, based on information provided in the text and
 cross-referenced with other publications and shapefiles. For individuals
 from the Late Devonian, a separate variable specified whether they were
 dated to before, during, or after the Frasnian-Famennian boundary. Decimal
 degree latitude and longitude were sourced directly from the text or
 estimated using Google Maps. Taxonomic and morphologic (component)
 information were sourced from the text when possible and aggregated to the
 family level using the World Register of Marine Species. Though Late
 Devonian paleogeography is a work in progress, we loosely grouped
 individuals by province and paleocontinent based on basin and information
 provided in the text. We also recorded lithologic information, redox
 proxies where available, and depth of core samples. We also attempted to
 identify the species and component of the scolecodonts from the samples we
 collected, though we acknowledge that we lack expertise in polychaete jaw
 taxonomy.
description: # Supplementary data for: Another worm bites the dust Chilcoat, G., Cohen,
 P. Another worm bites the dust: The Lilliput Effect in scolecodonts from
 the Late Devonian Biodiversity Crisis.
 Paleobiology. [https://doi.org/10.5061/dryad.tqjq2bw72](https://doi.org/10.5061/dryad.tqjq2bw72) Authors:  Gwyneth Chilcoat University of California Davis Department of Earth and Planetary Sciences [gachilcoat@ucdavis.edu](mailto:gachilcoat@ucdavis.edu) Phoebe Cohen Williams College Department of Geoscience This dataset includes all measurable Devonian and Carboniferous scolecodont photomicrographs in the literature at the time of production, as well as many Silurian scolecodonts, newly-introduced Devonian Appalachian Basin data, and many of Eller's collections from the Carnegie Museum of Natural History. All measurements are in micrometers. Code files here can be opened, viewed, and edited in R. ## Description of the data and file structure * ***12172025WormCode.R*** Code for figures in the main text *Age_Fam_Separated* refers to ICS ages, including the Famennian, with the Frasnian separated into before, during, and after the Kellwasser Events. NA row refers to occurrences that could not be binned and were excluded from this analysis. *Internal bootstraps* resample the values in the specified timebin, whereas *Overall bootstraps* sample all data. In both cases, the number of values randomly drawn is equal to *freq,* where freq is the number of occurrences in the specified timebin. The *boot mean, boot5, and boot95* are the mean and 90% confidence intervals of the resampled dataset with 1000 iterations, while the *true mean* is the mean of the  * ***Family_stacked_100_bar_data.csv*** This supplementary table dataframe is used to compare the community composition before and after the extinction. All data are taken directly from scolecodont_measurements. number is arbitrary, freq is the number of occurrences of that family in that time bin, percent is freq divided by total in time bin. FF (As in Relation.to.FF" is the Frasnian/Famennian Boundary). Rows 25-27 describe the total number of individuals (identified to the family level) before, during, and after the extinction event. * ***Lithology_vs_abundance.csv*** This supplementary table dataframe is used to compare the number of horizons where scolecodonts are reported to be present or absent, sorted by lithology. Empty cells indicate missing/not applicable data. * ***lithology_vs_presence.csv*** n is the number of scolecodonts meeting the criteria for Primary.lithology and present. perc is the ratio of this subset compared with all scolecodonts where this information is known. Total n present and absent with known lithologies are calculated in columns F & G. * ***Oct25_worm_boot_backup.R*** Code for bootstrap figures (Fig 3a, Supplementary Figures 3-6) * ***Scolecodont_measurements_-_Sheet1_(29).csv*** This supplementary table is the Middle Paleozoic scolecodont database. Empty cells are unknown. *Variables* Figure number: Corresponds directly with figure number in plates for newly-presented data. For lit review individuals, the first number is the plate number and the second number or letter is the individual image reference. Source: Corresponds with locality for newly-presented data. Corresponds with first author of paper. When multiple papers are used with the same first author, some distinguishing factor is used in this column, such as a second author or year. Comment in Google Sheets format links to DOI. Age: Lithostratigraphic. When multiple are listed, the unit is somewhat unconstrained. Epoch: Early/Middle/Late refer to the Devonian. Late_Before refers to before the Lower Kellwasser Event, LKE refers to during the LKE, Late_Afterrefers to after the LKE. Relation to FF: Relation to Frasnian-Famennian mass extinction (LKE).  Age_Fam_Separated: Age, with higher resolution at the Frasnian and Famennian. Similar to Age, but the more likely age is chosen when multiple were available, and the Late Devonian is further broken up into Frasnian_Before, During (LKE), After, Early_Famennian, and Late_Famennian. Length, Width: The length of a scolecodont is the greatest dimension of a jaw approximately parallel to the dentary, while the width is the greatest dimension of a jaw roughly perpendicular to the length (Jansonius and Craig 1971). When a scolecodont was partially obscured in one dimension, the obscured dimension was not measured and the cell is empty. Measured in micrometers. Species: For new data, as much taxonomic information as I could discern; for lit review, as much taxonomic information as available in the source paper. Empty cells for newly introduced data (i.e., information not available because it could not be discerned by these authors); "Unknown" for literature review data where species was not determined in the source publication. Family: Based on Species; information usually sourced from the World Registry of Marine Species (WoRMS). Component: Refers to the morphological structure of the scolecodont apparatus. For new data, MIs were identified when obvious; for lit review, information came from the source paper. Ours: Y/N variable to delineate new data. Paleocontinent: Approximate grouping provinces onto paleocontinents using paleogeographic reconstructions. Note that Devonian paleogeography isn't well understood and these paleocontinents follow most common common groupings from the literature. Province: A term used in many papers; broader than basin, narrower than paleocontinent. Sometimes derived from the paper, sometimes estimated from paleogeographic reconstructions.  These geographic variables are intended for the purpose of grouping localities together more than delineating strong site-specific trends. At the level of the basin and more specific, we expect to see stronger locality-driven trends. Basin: Depositional basin per the paper and/or proximity to other sites in this study. Depositional basin has a strong effect on expression of the Kellwasser Events. Unit: The lithostratigraphic unit that samples were collected from. Locality: The name of the site where samples were collected from (a single unit might be expressed at multiple localities, and a locality might express multiple units).  Lat, Long: Latitude and longitude in decimal degrees. Taken directly from the paper when available, or estimated from Google Maps when necessary. Lithology: As much information as possible about the lithology of the source material. Taken from the paper when available, or from other papers based on the source unit when necessary. Empty if not available. Siliciclastic or carbonate: Limestones are carbonates. Calcareous shales were considered siliciclastic because "calcareous" modifies "shale," implying the primary lithology is still a shale. Empty if not available. Color: Color of source rock when available. Empty if not available. General lithology: Lithology, binned into limestone, shale, silt(stone), clay(stone), and sandstone. Empty if not available. TOC percent, Mo ppm: Total organic carbon and molybdenum; Taken from source paper when available, but often taken from another paper about the same unit. Empty if not available. Depth: meter markings on cores, roadcuts, etc. when available to enable plotting by stratigraphy to scale. Empty if not available or not applicable. Bad data: Scolecodonts from Szaniawski and Wrona (1973) were extremely large compared with the rest of the dataset. These individuals were excluded from all other analyses because the images in this paper are sketches, not photomicrographs, and therefore scale can not be reliably determined. Likewise, the individual pictured in Eller (1936) was excluded because it is a sketch. Scolecodonts from other Eller papers were excluded because the exact same individuals were measured in-person at the CMNH, or because they were sketches and therefore deemed unreliable. A few CMNH scolecodonts whose age could not be determined were also excluded from all further analyses. Empty if not flagged as bad data. TOC_binned: Assigning the exact TOC of the source meter marking often wasn't possible, and plotting such a wide range of TOC values wasn't very useful, so we used generalized bins: low under .5%, medium under 1%, high above 1%.  Empty if not available. ###### Table Bibliography Data in Scolecodont_measurements was derived from the following sources. When a separate publication was used to fill in geochemical data for the publication containing scolecodont images, it is listed beneath the associated publication with the demarcation "Geochemistry." Bek, J., Štorch, P., Tonarova, P., & Libertin, M. (2022). Early Silurian (mid-Sheinwoodian) palynomorphs from the Loděnice-Špičatý vrch, Prague Basin, Czech Republic. Bulletin *of Geosciences*, 97(3).  Bennett, C. E., Howard, A. S., Davies, S. J., Kearsey, T. I., Millward, D., Brand, P. J., Browne, M. A. E., Reeves, E. J., & Marshall, J. E. A. (2017). Ichnofauna record cryptic marine incursions onto a coastal floodplain at a key Lower Mississippian tetrapod site. *Palaeogeography, Palaeoclimatology, Palaeoecology*, 468, 287-300. [https://doi.org/10.1016/j.palaeo.2016.12.018](https://doi.org/10.1016/j.palaeo.2016.12.018)  *Geochemistry:* Kearsey, T. I., Bennett, C. E., Millward, D., Davies, S. J., Gowing, C. J. B., Kemp, S. J., Leng, M. J., Marshall, J. E. A., & Browne, M. A. E. (2016). The terrestrial landscapes of tetrapod evolution in earliest Carboniferous seasonal wetlands of SE Scotland. Palaeogeography, Palaeoclimatology, Palaeoecology, 457, 52-69. [https://doi.org/https://doi.org/10.1016/j.palaeo.2016.05.033](https://doi.org/https://doi.org/10.1016/j.palaeo.2016.05.033)  Eller, E. (1941). *Scolecodonts from the Windom, Middle Devonian, of western New York*. Carnegie Museum. Eller, E. R. (1942). Scolecodonts from the Erindale, Upper Ordovician, At Streetsville, Ontario. *Annals of the Carnegie Museum*, 241-262. [https://doi.org/https://www.biodiversitylibrary.org/page/52415251](https://doi.org/https://www.biodiversitylibrary.org/page/52415251)  Eller, E. (1944). Scolecodonts of the Silurian Manitoulin Dolomite of New York and Ontario. *The American Midland Naturalist*, 32(3), 732-755.  Eller, E. (1945). Scolecodonts from the Trenton Series (Ordovician) of Ontario, Quebec, and New York. Carnegie Museum.  Eller, E. (1946). New scolecodonts from the Kagawong (Ordovician) of Manitoulin Island, Ontario. Proceedings of the Pennsylvania Academy of Science. Eller, E. (1955). Additional scolecodonts from the Potter Farm Formation of the Devonian of *Michigan. Annals of the Carnegie Museum*, 33, 347-386.  Eller, E. R. (1961). *Scolecodonts from well samples of the Dundee, Devonian of Michigan*. Carnegie Museum. Eller, E. (1963). Scolecodonts from the Dundee, Devonian of Michigan. Annals of the Carnegie *Museum*, 36, 173-180.  –––. Scolecodonts from the Sheffield Shale, Upper Devonian of Iowa. Annals of the Carnegie  *Museum*, 36(14), 159-172.  Eller, E. R. (1964). *Scolecodonts of the Delaware limestone, Devonian of Ohio and Ontario*. Carnegie Museum.  *Note: Scolecodonts were measured from the CMNH collections, not from any Eller papers. Listed here are Eller papers that include some of the scolecodonts measured at the CMNH.* Filipiak, P., & Krawczyński, W. (2018). Palynological and microfacies analysis of the Famennian part of the Russkiy Brod Quarry section, Central Devonian Field, Russia. Review of *palaeobotany and palynology*, 249, 50-60. [https://doi.org/10.1016/j.revpalbo.2017.11.004](https://doi.org/10.1016/j.revpalbo.2017.11.004)  Ghavidel-syooki, M., & Owens, B. (2007). Palynostratigraphy and palaeogeography of the Padeha, Khoshyeilagh, and Mobarak formations in the eastern Alborz Range *(Kopet-Dagh region), northeastern Iran. Revue de Micropaléontologie*, 50(1), 129-144.  Hogancamp, N. (2017). Frasnian scolecodonts from the Grassy Creek Shale, eastern Iowa, *United States [Article]. Micropaleontology*, 63(1), 43-58.  *Geochemistry:* Frost, J., Koszykowski, R., & Klemm, R. (1982). Chemical characterization of gas-and oil-bearing shales by instrumental neutron activation analysis. Journal of *Radioanalytical and Nuclear Chemistry*, 71(1-2), 199-214.  Jarochowska, E., Tonarová, P., Munnecke, A., Ferrová, L., Sklenář, J., & Vodrážková, S. (2013). An acid-free method of microfossil extraction from clay-rich lithologies using the surfactant Rewoquat. *Palaeontologia Electronica*. [https://doi.org/10.26879/382](https://doi.org/10.26879/382) *Geochemistry:* Biebesheimer, E. J., Cramer, B. D., Calner, M., Barnett, B. A., Oborny, S. C., & Bancroft, A. M. (2021). Asynchronous δ13Ccarb and δ13Corg records during the onset of the Mulde (Silurian) positive carbon isotope excursion from the Altajme core, Gotland, Sweden. Chemical geology, 576, 120256.  Kondas, M., & Filipiak, P. (2022). Middle Devonian (Givetian) palynology of the northern Holy Cross-Mountains (Miłoszów, south-central Poland). Review of *palaeobotany and palynology*, 301, 104629. [https://doi.org/https://doi.org/10.1016/j.revpalbo.2022.104629](https://doi.org/https://doi.org/10.1016/j.revpalbo.2022.104629)  Lécuyer, C., & Paris, F. (1997). Variability in the δ13C of lower Palaeozoic palynomorphs: *implications for the interpretation of ancient marine sediments. Chemical geology*, *138* (3-4), 161-170. [https://doi.org/10.1016/S0009-2541(97)00009-0](https://doi.org/10.1016/S0009-2541\(97\)00009-0) *Geochemistry:* Rose, C. V., Fischer, W. W., Finnegan, S., & Fike, D. A. (2019). Records of carbon and sulfur cycling during the Silurian Ireviken Event in Gotland, Sweden. Geochimica et Cosmochimica Acta, 246, 299-316. [https://doi.org/https://doi.org/10.1016/j.gca.2018.11.030](https://doi.org/https://doi.org/10.1016/j.gca.2018.11.030)  Löw, M., Söte, T., Becker, T. R., Stichling, S., May, A., Aboussalam, S. Z., & Zoppe, F. S. (2022). The initial phase of the Hönne Valley Reef at Binolen (northern Rhenish Massif, *Middle Devonian). Palaeobiodiversity and Palaeoenvironments*, 102(3), 573-612. [https://doi.org/10.1007/s12549-022-00540-4](https://doi.org/10.1007/s12549-022-00540-4)  Makled, W. A., Gentzis, T., Hosny, A. M., Mousa, D. A., Lotfy, M. M., Abd El Ghany, A. A., El Sawy, M. Z., Orabi, A. A., Abdelrazak, H. A., & Shahat, W. I. (2021). Depositional dynamics of the Devonian rocks and their influence on the distribution patterns of liptinite in the Sifa-1X well, Western Desert, Egypt: Implications for hydrocarbon *generation. Marine and petroleum geology*, 126, 104935. [https://doi.org/https://doi.org/10.1016/j.marpetgeo.2021.104935](https://doi.org/https://doi.org/10.1016/j.marpetgeo.2021.104935)  Makled, W. A., Hints, O., Hosny, A. M., Shahat, W. I., & Gentzis, T. (2021). Exotic Devonian *palynomorphs from the Sifa-1X well in the Western Desert, Egypt. Palynology*, 45(2), 363-380. [https://doi.org/10.1080/01916122.2020.1829726](https://doi.org/10.1080/01916122.2020.1829726)  Marynowski, L., Filipiak, P., & Zatoń, M. (2010). Geochemical and palynological study of the Upper Famennian Dasberg event horizon from the Holy Cross Mountains (central *Poland). Geological Magazine*, 147(4), 527-550. [https://doi.org/10.1017/S0016756809990835](https://doi.org/10.1017/S0016756809990835)  Marynowski, L., Zatoń, M., Rakociński, M., Filipiak, P., Kurkiewicz, S., & Pearce, J. T. (2012). Deciphering the upper Famennian Hangenberg Black Shale depositional environments *based on multi-proxy record. Palaeogeography, Palaeoclimatology, Palaeoecology*, *346-347*, 66-86. [https://doi.org/10.1016/j.palaeo.2012.05.020](https://doi.org/10.1016/j.palaeo.2012.05.020)  Mendes, M., Pereira, Z., Vaz, N., Díez-Montes, A., Matos, J. X., Albardeiro, L., Fernandes, P., Jorge, R., & Chew, D. (2022). A new approach to palynostratigraphy of the middle–late Famennian Gafo Formation, southern sector of the Pulo do Lobo Domain, SW Iberia *(Portugal and Spain). Geological Magazine*, 159(8), 1454-1470. * Nazarova, V., Kononova, L., Kulashova, T., & Zaytseva, E. (2019). Biostratigraphic Characteristic of the Frasnian Age (Upper Devonian) Reference Section in the Central Voronezh Anteclise (Shchigry-16 Borehole, Nizhnekrasnoe Village, Kursk Oblast) *[Article]. Stratigraphy and Geological Correlation*, 27(2), 207-233. [https://doi.org/10.1134/S0869593819020060](https://doi.org/10.1134/S0869593819020060)  Racki, G., Mazur, S., Narkiewicz, K., Pisarzowska, A., Bardziński, W., Kołtonik, K., Szymanowski, D., Filipiak, P., & Kremer, B. (2022). A waning Saxothuringian Ocean evidenced in the Famennian tephra-bearing siliceous succession of the Bardo Unit *(Central Sudetes, SW Poland). GSA Bulletin*, 134(9-10), 2373-2398. [https://doi.org/10.1130/b35971.1](https://doi.org/10.1130/b35971.1)  Russell, E. Middle Devonian chitinozoans and scolecodonts from the Naranco Formation, northern Spain.  *Geochemistry:* Álvarez, R., Ordóñez, A., Canteli, P., & De Miguel, E. (2019). Unconventional gas resources in the Cantabrian Zone (NW Spain): A comprehensive preliminary assessment. Geological Journal, 54(4), 2608-2620. Suttner, T., & Hints, O. (2010). Devonian scolecodonts from the Tyrnaueralm, Graz Paleozoic, Austria. *Memoirs of the Association of Australasian Paleontologists*. [https://doi.org/doi.org/10.3316/informit.091893109669329](https://doi.org/doi.org/10.3316/informit.091893109669329)  *Geochemistry:* Hubmann, B., Pohler, S., Schönlaub, H.-P., & Messner, F. (2003). Paleozoic coral-sponge *bearing successions in Austria. Berichte der Geologischen Bundesanstalt*, 61, 1-91.  Sylvester, R. K. (1959). Scolecodonts from central Missouri. *Journal of Paleontology*, 33-49.  Szaniawski, H., & Drygant, D. (2013). Lochkovian, early Devonian scolecodonts from Podolia, Ukraine. *Acta Palaeontologica Polonica*. [https://doi.org/10.4202/app.2012.0120](https://doi.org/10.4202/app.2012.0120)  Szaniawski, H., & Wrona, R. M. (1973). Polychaete jaw apparatuses and scolecodonts from the *Upper Devonian of Poland. Acta Palaeontologica Polonica*, 18(3).  Thomas, N. (2004). The taphonomy of a carboniferous lagerstatte: the invertebrates of the bear *gulch limestone member* University of Leicester (United Kingdom)].  Tonarova, P., Eriksson, M. E., & Hints, O. (2012). A jawed polychaete fauna from the late Ludlow Kozlowskii event interval in the Prague Basin (Czech Republic). Bulletin of *Geosciences*, 87(4), 713-732.  *Geochemistry:* Suchý, V., Sýkorová, I., Stejskal, M., Šafanda, J., Machovič, V. r., & Novotná, M. (2002). Dispersed organic matter from Silurian shales of the Barrandian Basin, Czech Republic: optical properties, chemical composition and thermal maturity. International Journal of Coal Geology, 53(1), 1-25. Tonarová, P., Hints, O., Königshof, P., Suttner, T. J., Kido, E., Da Silva, A. C., & Pas, D. (2016). Middle Devonian jawed polychaete fauna from the type Eifel area, western Germany, and its biogeographical and evolutionary affinities. *Papers in Palaeontology*, 2(2), 295-310.  Tonarová, P., Vodrážková, S., Ferrová, L., de la Puente, G. S., Hints, O., Frýda, J., & Kubajko, M. (2017). Palynology, microfacies and biostratigraphy across the Daleje Event (Lower Devonian, lower to upper Emsian): new insights from the offshore facies of the Prague Basin, Czech Republic. *Palaeobiodiversity and Palaeoenvironments*, 97(3), 419-438. [https://doi.org/10.1007/s12549-017-0274-3](https://doi.org/10.1007/s12549-017-0274-3)  *Geochemistry (2 records):* Bábek, O., Faměra, M., Hladil, J., Kapusta, J., Weinerová, H., Šimíček, D., Slavík, L., & Ďurišová, J. (2018). Origin of red pelagic carbonates as an interplay of global climate and local basin factors: Insight from the Lower Devonian of the Prague Basin, Czech Republic. Sedimentary Geology, 364, 71-88. [https://doi.org/https://doi.org/10.1016/j.sedgeo.2017.12.007](https://doi.org/https://doi.org/10.1016/j.sedgeo.2017.12.007)  Bábek, O., Vodrážková, S., Kumpan, T., Kalvoda, J., Holá, M., & Ackerman, L. (2021). Geochemical record of the subsurface redox gradient in marine red beds: A case study from the Devonian Prague Basin, Czechia. Sedimentology, 68(7), 3523-3548.  Vandenbroucke, A. R. T., Hints, O., Williams, M., Wallis, S., Velleman, J., Kurihara, T., Tanaka, G., Komatsu, T., Männik, P., Siveter, J. D., & Backer, D. T. (2019). Chitinozoans and *scolecodonts from the Silurian and Devonian of Japan. Island Arc*, 28(3), e12294. [https://doi.org/10.1111/iar.12294](https://doi.org/10.1111/iar.12294)  Zatoń, M., & Rakociński, M. (2014). Coprolite evidence for carnivorous predation in a Late Devonian pelagic environment of southern Laurussia. Palaeogeography, *Palaeoclimatology, Palaeoecology*, 394, 1-11. [https://doi.org/https://doi.org/10.1016/j.palaeo.2013.11.019](https://doi.org/https://doi.org/10.1016/j.palaeo.2013.11.019)  Zatoń, M., Zhuravlev, A. V., Rakociński, M., Filipiak, P., Borszcz, T., Krawczyński, W., Wilson, M. A., & Sokiran, E. V. (2014). Microconchid-dominated cobbles from the Upper Devonian of Russia: Opportunism and dominance in a restricted environment following the Frasnian–Famennian biotic crisis. *Palaeogeography, Palaeoclimatology, *Palaeoecology*, 401, 142-153. [https://doi.org/https://doi.org/10.1016/j.palaeo.2014.02.029](https://doi.org/https://doi.org/10.1016/j.palaeo.2014.02.029)  ***TOCBoot.csv*** Supplementary table showing tabular data of bootstrapped total organic carbon values (percent). These values are not explored in this manuscript. freq=frequency; boot mean= mean of bootstrapping with 1000 iterations; boot5 and boot95= 5th and 95th percentile of confidence interval for bootstrapped results; true mean = true mean of data (not bootstrapped).  ***WidthBoot.csv*** Supplementary table showing tabular data of bootstrapped width values (rather than length). These values are not explored in this manuscript. freq=frequency; boot mean= mean of bootstrapping with 1000 iterations; boot5 and boot95= 5th and 95th percentile of confidence interval for bootstrapped results; true mean = true mean of data (not bootstrapped).  ***Supplemental Tables*** NA row refers to occurrences that could not be binned and were excluded from this analysis. Na refers to groupings where n = 0 and statistics could not be calculated. ***ST1_lengthanova.csv***  Summary results of analysis of variance (ANOVA) of scolecodont length across time bins. *p* &lt; 0.05, meaning that a significant difference exists between at least one pair of time bin lengths. Not all statistics can be calculated for Residuals, hence empty cells. df= degrees of freedom; sumsq= sum of squares; meansq= mean square. ***ST2_lengthtukey.csv*** Results of a Tukey’s Honest Significant Distances test using data from ST1. conf.low = low end of confidence interval; conf.high = high end of confidence interval; adj.p.value = adjusted p value; significant = binary (y/n p &lt; 0.05). ***ST3_HighResBoot.csv*** Results of bootstrapping data from Figure 3 with 1000 iterations. freq=frequency; boot mean= mean of bootstrapping with 1000 iterations; boot5 and boot95= 5th and 95th percentile of confidence interval for bootstrapped results; true mean = true mean of data (not bootstrapped).  ***ST4_ComponentBoot.csv*** Results of bootstrapping data from Figure 4 with 1000 iterations. Variables same as ST3. ***ST5_WidthBoot.csv*** Results of bootstrapping data from Figure 5 with 1000 iterations. Variables same as ST3. ***ST6_BasinBoot.csv*** Results of bootstrapping data from Figure 6 with 1000 iterations. Variables same as ST3. Na indicates that no occurrences satisfy both basin and timebin. ***ST7_FamilyBoot.csv*** Results of bootstrapping data from Figure 7 with 1000 iterations. Variables same as ST3. ***ST8_LithBoot.csv*** Results of bootstrapping data from Figure 8 with 1000 iterations. Variables same as ST3. ***SUPPLEMENTAL_FIG_1.png*** Supplementary Figure 1. * *Global map of modern geography with all sample sites plotted. Color represents the average size of scolecodonts from each locality ***FIG_S2.png*** Supplementary Figure 2.** Histogram of length distributions of all scolecodonts in the data set (bins = 40, n = 800). ***S3_OCT25.png*** Supplementary Figure 3. Bootstrap mean length (open circle) and 90% confidence intervals of only MI scolecodont element components, calculated with 1000 sampling trials across time bins (µm). Actual mean length represented by triangles. ***S4_OCT25.png*** Supplementary Figure 4. Bootstrap mean *width* (open circle) and 90% confidence intervals, calculated with 1000 sampling trials across time bins (µm). Actual mean width represented by triangles. ***S5_OCT25.png*** Supplementary Figure 5. Bootstrap mean length (open circle) and 90% confidence intervals of scolecodonts from the Appalachian, Iowa, and Michigan Basins, calculated with 1000 sampling trials across time bins (µm). Actual mean length represented by triangles. ***S6_OCT25.png*** Supplementary Figure 6. Bootstrap mean length (open circle) and 90% confidence intervals of scolecodonts identified to the families Mochtyellidae and Paulinitidae, calculated with 1000 sampling trials across time bins (µm). Actual mean length represented by triangles. ***S7.png*** Supplementary Figure 7. Community composition at the family level of scolecodonts before, during, and after the LKE. Incertae sedis individuals have a species name that is not assigned to a family, while Unknown individuals could not be assigned to any level of taxonomy. Before, n = 667; after, n = 99 ***S8_OCT25.png*** Supplementary Figure 8. Bootstrap mean length (open circle) and 90% confidence intervals of scolecodonts sourced from limestone, mudstone, and shale facies, calculated with 1000 sampling trials across time bins (µm). Actual mean length represented by triangles. **PLATE1.png** *Photomicrographs of scolecodont specimens presented in this study. Scale bar represents 100 μm. Taxonomic affinity and apparatus component not determined in most cases, but when available, published in Supplementary Materials. General format: Identifier, LOCALITYyear_horizon_imagedate_magnification_imagenumber_otherinfo. A, BCP15_5.0_12022022_8x_014_stacked; B, BCP15-3.0_8x_09012023_08_STACK; C, BCP15_5.0_12022022_8x_010_stack; D, BCP15-5.0_8x_09042023_05_STACK; E, BCP15-5.0_8x_09042023_00_STACK; F, BCP15-3.0_8x_09012023_00_STACK; G, BCP15_4.0_1042023_8x_005_stack; H, BCP15_5.0_12022022_8x_001; I, BCP15-5.0_8x_09072023_17_stack; J, BCP15-5.0_8x_09042023_10_STACK; K, BCP15-4.0_8x_09012023_00_STACK; L, BCP15_5.0_12022022_8x_008_stack; M, BCP15_5.0_12022022_8x_016; N, CAM15_-0.1_12052022_8x_001; O, CAM15-(-0.1)_8x_08252023_05_STACK; P, BCP15_5.3_1042023_8x_007; Q, BCP15-5.8_8x_09112023_00_stack; R, CAM15-(-.1)_8x_08282023_00_STACK; S, CAM15-1.0_8x_08292023_00_STACK; T, CAM15-(-.1)_8x_08282023_05_STACK; U, CAM15-(-0.1)_8x_08252023_00_STACK; CAM15_2_12092022_8x_003; W, CAM15_2_12092022_8x_001; X, CAM15_2_12092022_8x_000; Y, Copy of CAM15-2.5_8x_scolecodont_06_STACK; Z, CAM15-2.5_8x_dry_08182023_33_STACK; AA, CAM15_2.5_12092022_8x_004. **PLATE_2.png** Scalebar represents 100 μm. A, CAM15-2.75_8x_08182023_23_STACK; B, CAM15-2.75_8x_08182023_21_STACK; C, CAM15-2.75_8x_08182023_16; D, CAM15-3.0_8x_08282023_09_STACK; E, CAM15-3.9_8x_08292023_00_STACK; F, CAM15-2.75_8x_08182023_20; G, CAM15-2.75_8x_08182023_19; H, CAM15-2.75_8x_08182023_15; I, CAM15_2.75_1032023_8x_001; J, CAM15-H_8x_08292023_10_STACK; K, CAM15-H_8x_08292023_00_STACK; L, TGB18_655_8x_01182023_07_stack; M, TGB18_1510_01102023_8x_001; N, CAM15-H_8x_08292023_04_STACK; O, TGB18_1760_8x_01202023_01_STACK; P, TGB18_655_8x_01182023_09_stack; Q, TGB18_655_8x_01182023_06; R, CAM15-2.75_8x_08182023_17_STACK; S, CAM15-2.75_8x_08182023_13_STACK; T, CAM15-3.0_8x_08282023_14_STACK; U, CAM15-3.0_8x_08282023_03_STACK; V, TGB18_160_8x_01172023_01; W, TGB18_655_8x_01182023_11; X, TGB18_655_8x_01182023_04_stack; Y, Copy of TGB18_755_8x_100421_000; Z, TGB18_1510_01102023_8x_000; AA, TGB18_1760_8x_01182023_03_stack; BB, CAM15_-0.1_12052022_8x_001 (1). **PLATE_3.png** Scalebar represents 100 μm. A, BCP15_4.3_20x_081222_012; B, BCP15_5.0A_20x_1.7.23_002.JPG; C, CAM15_3.9_10x_arthH49_4_STACK; D, CAM15_0_10x_arth2_STACK; E, Copy of TGB18_160_A_20x__305.JPG; F, CAM15_.01_20x_082222_000. **PLATE_4.png** Scalebar represents 100 μm. A, BCP15_4.3_40x_02142022_023; B, CAM15_4.7_40x_arthR43_3_STACK; C, CAM15_H_40x_02162022_043.JPG; D, CAM15_-0.1_40x_arthQ42_1_STACK; E, CAM15_H_40x__033.JPG; F, PC18_223_40x_072.CR2; G, Copy of TGB18_1060A_40x_9.27.21_032; H, Copy of TGB18_350_beadcount40x_7.21.21_099; I, Copy of TGB18_985_40x_8.26.21_009; J, Copy of TGB18_655A_40x_10.2.21_002.JPG. **PLATE_5.png** Scalebar represents 100 μm (Specimens A, F), 40 μm (Specimen B), 120 μm (Specimen C, E), 65 μm (Specimen D). Various magnifications; scanning electron and light photomicrography. A, cam15_-0.1_scolec; B, CAM15_4.7_01062023_000; C, Copy of tgb18_655_110121_1; D, Copy of TGB360_63x_stacked_B; E, arthropod_cuticle_071221; F, tgb1260_081622_scolecodont.