Sharma, P. P. & Gavish-Regev, E. The evolutionary biology of Chelicerata. Annu. Rev. Entomol. 70, 143–163 (2025).
Dunlop, J. A. & Arango, C. P. Pycnogonid affinities: a review. J. Zool. Syst. Evol. Res. 43, 8–21 (2005).
Waloszek, D. & Dunlop, J. A. A larval sea spider (Arthropoda: Pycnogonida) from the Upper Cambrian ‘Orsten’ of Sweden, and the phylogenetic position of pycnogonids. Palaeontology 45, 421–446 (2002).
Cotton, T. J. & Braddy, S. J. The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Trans. R. Soc. Edinb. Earth Sci. 94, 169–193 (2004).
Edgecombe, G. D., García-Bellido, D. C. & Paterson, J. R. A new leanchoiliid megacheiran arthropod from the lower Cambrian Emu Bay Shale, South Australia. Acta Palaeontol. Pol. 56, 385–400 (2011).
Legg, D. A., Sutton, M. D. & Edgecombe, G. D. Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nat. Commun. 4, 2485 (2013).
Chen, J., Waloszek, D. & Maas, A. A new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia 37, 3–20 (2004).
Haug, J. T., Waloszek, D., Maas, A., Liu, Y. & Haug, C. Functional morphology, ontogeny and evolution of mantis shrimp-like predators in the Cambrian. Palaeontology 55, 369–399 (2012).
Tanaka, G., Hou, X., Ma, X., Edgecombe, G. D. & Strausfeld, N. J. Chelicerate neural ground pattern in a Cambrian great appendage arthropod. Nature 502, 364–367 (2013).
Briggs, D. E. G. & Collins, D. A Middle Cambrian chelicerate from Mount Stephen, British Columbia. Palaeontology 31, 779–798 (1988).
Legg, D. A. Sanctacaris uncata: the oldest chelicerate (Arthropoda). Naturwissenschaften 101, 1065–1073 (2014).
Jago, J. B., García-Bellido, D. C. & Gehling, J. G. An early Cambrian chelicerate from the Emu Bay Shale, South Australia. Palaeontology 59, 549–562 (2016).
Aria, C. & Caron, J.-B. Mandibulate convergence in an armoured Cambrian stem chelicerate. BMC Evol. Biol. 17, 261 (2017).
Aria, C. & Caron, J.-B. A middle Cambrian arthropod with chelicerae and proto-book gills. Nature 573, 586–589 (2019).
Budd, G. E. The origin and evolution of the euarthropod labrum. Arthropod Struct. Dev. 62, 101048 (2021).
Beccaloni, J. Arachnids (CSIRO, 2009).
Brusca, R. C., Giribet, G. & Moore, W. Invertebrates (Oxford Univ. Press, 2023).
Garwood, R. J. & Edgecombe, G. D. Early terrestrial animals, evolution, and uncertainty. Evol. Educat. Outreach 4, 489–501 (2011).
Van Roy, P. et al. Ordovician faunas of Burgess Shale type. Nature 465, 215–218 (2010).
Lustri, L., Gueriau, P. & Daley, A. C. Lower Ordovician synziphosurine reveals early euchelicerate diversity and evolution. Nat. Commun. 15, 3808 (2024).
Ortega-Hernández, J., Lerosey-Aubril, R., Losso, S. R. & Weaver, J. C. Neuroanatomy in a middle Cambrian mollisoniid and the ancestral nervous system organization of chelicerates. Nat. Commun. 13, 410 (2022).
Göpel, T. & Wirkner, C. S. An ‘ancient’ complexity? Evolutionary morphology of the circulatory system in Xiphosura. Zoology 118, 221–238 (2015).
Legg, D. A. & Pates, S. A restudy of Utahcaris orion (Euarthropoda) from the Spence Shale (Middle Cambrian, Utah, USA). Geol. Mag. 154, 181–186 (2017).
Sutton, M. D., Briggs, D. E. G., Siveter, D. J., Siveter, D. J. & Orr, P. J. The arthropod Offacolus kingi (Chelicerata) from the Silurian of Herefordshire, England: computer based morphological reconstructions and phylogenetic affinities. Proc. R. Soc. B 269, 1195–1203 (2002).
Briggs, D. E. G. et al. Silurian horseshoe crab illuminates the evolution of arthropod limbs. Proc. Natl Acad. Sci. USA 109, 15702–15705 (2012).
Sharma, P. P., Schwager, E. E., Extavour, C. G. & Giribet, G. Evolution of the chelicera: a dachshund domain is retained in the deutocerebral appendage of Opiliones (Arthropoda, Chelicerata). Evol. Dev. 14, 522–533 (2012).
Brenneis, G. & Arango, C. P. First description of epimorphic development in Antarctic Pallenopsidae (Arthropoda, Pycnogonida) with insights into the evolution of the four-articled sea spider cheliphore. Zool. Lett. 5, 4 (2019).
Sabroux, R., Garwood, R. J., Pisani, D., Donoghue, P. C. J. & Edgecombe, G. D. New insights into the Devonian sea spiders of the Hunsrück Slate (Arthropoda: Pycnogonida). PeerJ 12, e17766 (2024).
Boxshall, G. in Arthropod Biology and Evolution (eds Minelli, A. et al.) 241–267 (Springer, 2013).
Zeng, H., Zhao, F., Niu, K., Zhu, M. & Huang, D. An early Cambrian euarthropod with radiodont-like raptorial appendages. Nature 588, 101–105 (2020).
Izquierdo-López, A. & Caron, J. B. The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. R. Soc. Open Sci. 9, 220933 (2022).
O’Flynn, R. J. et al. The early Cambrian Kylinxia zhangi and evolution of the arthropod head. Curr. Biol. 33, 4006–4013 (2023).
Bousfield, E. L. A contribution to the natural classification of Lower and Middle Cambrian arthropods: food-gathering and feeding mechanism. Amphipacifica 2, 3–34 (1995).
Liu, Y., Ortega-Hernández, J., Zhai, D. & Hou, X. A reduced labrum in a Cambrian great-appendage euarthropod. Curr. Biol. 30, 3057–3061 (2020).
Parry, L. A. et al. A pyritized Ordovician leanchoiliid arthropod. Curr. Biol. 34, 5578–5586 (2024).
Schmidt, M. et al. Unveiling the ventral morphology of a rare early Cambrian great appendage arthropod from the Chengjiang biota of China. BMC Biol. 22, 96 (2024).
Sharma, P. P. Chelicerates. Curr. Biol. 28, R774–R778 (2018).
Dunlop, J. A. & Lamsdell, J. C. Segmentation and tagmosis in Chelicerata. Arthropod Struct. Dev. 46, 395–418 (2017).
Moore, R. A., Briggs, D. E. G. & Bartels, C. A new specimen of Weinbergina opitzi (Chelicerata: Xiphosura) from the Lower Devonian Hunsrück Slate, Germany. Paläontol. Z. 79, 399–408 (2005).
Aria, C. The origin and early evolution of arthropods. Biol. Rev. 97, 1786–1809 (2022).
Zhang, X. et al. Ventral organization of Jianfengia multisegmentalis Hou, and its implications for the head segmentation of megacheirans. Palaeontology 65, e12624 (2022).
Lamsdell, J. C. Revised systematics of Palaeozoic ‘horseshoe crabs’ and the myth of monophyletic Xiphosura. Zool. J. Linn. Soc. 167, 1–27 (2013).
Boxshall, G. A. The evolution of arthropod limbs. Biol. Rev. 79, 253–300 (2004).
Bicknell, R. D. C., Klinkhamer, A. J., Flavel, R. J., Wroe, S. & Paterson, J. R. A 3D anatomical atlas of appendage musculature in the chelicerate arthropod Limulus polyphemus. PLoS ONE 13, e0191400 (2018).
Shultz, J. W. Muscular anatomy of a whipspider, Phrynus longipes (Pocock) (Arachnida: Amblypygi), and its evolutionary significance. Zool. J. 126, 81–116 (1999).
Farley, R. D. Abdominal plates, spiracles and sternites in the ventral mesosoma of embryos of the desert scorpion Paruroctonus mesaensis (Scorpiones, Vaejovidae). Invertebr. Reprod. Dev. 40, 193–208 (2001).
Farley, R. D. Ultrastructure of book gill development in embryos and first instars of the horseshoe crab Limulus polyphemus (Chelicerata, Xiphosura). Front. Zool. 9, 4 (2012).
Liu, Y. et al. Exites in Cambrian arthropods and homology of arthropod limb branches. Nat. Commun. 12, 4619 (2021).
Whalen, C. D. & Briggs, D. E. G. The Palaeozoic colonization of the water column and the rise of global nekton. Proc. R. Soc. B 285, 20180883 (2018).
Lee, M. S. Y., Soubrier, J. & Edgecombe, G. D. Rates of phenotypic and genomic evolution during the Cambrian Explosion. Curr. Biol. 23, 1889–1895 (2013).
Paterson, J. R., Edgecombe, G. D. & Lee, M. S. Y. Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proc. Natl Acad. Sci. USA 116, 4394–4399 (2019).
Lozano-Fernandez, J. et al. A Cambrian–Ordovician terrestrialization of arachnids. Front. Genet. 11, 182 (2020).
Erwin, D. H. Novelty and innovation in the history of life. Curr. Biol. 25, R930–R940 (2015).
Simões, T. R., Vernygora, O., Caldwell, M. W. & Pierce, S. E. Megaevolutionary dynamics and the timing of evolutionary innovation in reptiles. Nat. Commun. 11, 3322 (2020).
Lerosey-Aubril, R. & Ortega-Hernández, J. Phylogenetic data files from ‘A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates’. figshare https://doi.org/10.6084/m9.figshare.30924617 (2026).
Lewis, P. O. Phylogenetic systematics turns over a new leaf. Trends Ecol. Evol. 16, 30–37 (2001).
Ronquist, F. et al. MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Syst. Biol. 61, 539–542 (2012).
Rambaut, A., Drummond, A. J., Xie, D., Baele, G. & Suchard, M. A. Posterior summarization in Bayesian phylogenetics using Tracer 1.7. Syst. Biol. 67, 901–904 (2018).
Goloboff, P. A., Farris, J. S. & Nixon, K. C. TNT, a free program for phylogenetic analysis. Cladistics 24, 774–786 (2008).
Goloboff, P. A. Analyzing large data sets in reasonable times: solutions for composite optima. Cladistics 15, 415–428 (1999).
Nixon, K. C. The parsimony ratchet, a new method for rapid parsimony analysis. Cladistics 15, 407–414 (1999).
Taylor, C. K. Notes on Phalangiidae (Arachnida: Opiliones) of southern Africa with description of new species and comments on within-species variation. Zootaxa 4272, 236–250 (2017).
Červená, M., Gardini, G., Jablonski, D. & Christophoryová, J. Checklist of pseudoscorpions (Arachnida, Pseudoscorpiones) of Albania. Zool. Stud. 60, e17 (2021).
de Miranda, G. S. & Reboleira, A. S. P. S. Amblypygids of Timor-Leste: first records of the order from the country with the description of a remarkable new species of Sarax (Arachnida, Amblypygi, Charinidae). Zookeys 820, 1–12 (2019).
Cabra-García, J. & Brescovit, A. D. Revision and phylogenetic analysis of the orb-weaving spider genus Glenognatha Simon, 1887 (Araneae, Tetragnathidae). Zootaxa 4069, 1–183 (2016).
Hu, S. et al. Exceptional appendage and soft-tissue preservation in a Middle Triassic horseshoe crab from SW China. Sci. Rep. 7, 14112 (2017).
