Hostname: page-component-848d4c4894-p2v8j Total loading time: 0.001 Render date: 2024-06-02T00:01:41.931Z Has data issue: false hasContentIssue false
  • English
  • Français

The trouble with trilobites: classification, phylogeny and the cryptogenesis problem

Published online by Cambridge University Press:  20 June 2019

John R. Paterson Open the ORCID record for John R. Paterson [Opens in a new window]
John R. Paterson*
Affiliation:
Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale NSW 2351, Australia
*
Author for correspondence: John R. Paterson, Email: jpater20@une.edu.au
Get access Rights & Permissions [Opens in a new window]

Abstract

Trilobites are an iconic group of extinct arthropods that lived in Palaeozoic oceans for c. 270 Ma, before their demise at the end of the Permian Period. Despite their considerable diversity (> 22 000 species) and abundance, particularly in Cambrian and Ordovician rocks, as well as intensive study for well over 200 years, trilobite systematics remains in a state of flux. In this contribution, the complex history of trilobite classification over the last century is briefly reviewed, including the seminal scheme published by Henry Swinnerton in 1915. The cryptogenesis problem, which relates to the supposedly obscure phylogenetic links between major post-Cambrian trilobite clades and their Cambrian sister taxa, is also discussed. Previous studies have suggested that the cryptogenesis problem is largely a taxonomic artefact, but the Cambrian origins of some post-Cambrian groups, such as the orders Proetida and Odontopleurida, are still unclear. Future directions for research on trilobite systematics are outlined, from taxonomic studies involving comprehensive documentation and extensive illustration of morphology at the species level, through to broad-scale phylogenetic analyses that initiate or test hypotheses about relationships across the major groups. Other ongoing issues to be addressed include identifying the sister group of Trilobita, and determining whether certain taxa, such as the suborder Agnostina and Cambrian family Burlingiidae, represent trilobites.

Keywords

ArthropodaTrilobitasystematicstaxonomyevolution
Type
Original Article
Information
Geological Magazine , Volume 157 , Special Issue 1: SPECIAL ISSUE: Commemorating the 155th anniversary of Geological Magazine , January 2020 , pp. 35 - 46
Copyright
© Cambridge University Press 2019 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adrain, JM (2008) A global species database of Trilobita: progress, results, and revision of the Treatise . In Advances in Trilobite Research (eds Rábano, I, Gozalo, R and García-Bellido, DC), pp. 27–8. Cuadernos del Museo Geominero 9, Madrid: Instituto Geológico y Minero de España.Google Scholar
Adrain, JM (2011) Class Trilobita Walch, 1771. In Animal Biodiversity: An Outline of Higher-Level Classification and Survey of Taxonomic Richness (ed. Zhang, Z-Q). Zootaxa 3148, 104–9.Google Scholar
Adrain, JM (2013) A synopsis of Ordovician trilobite distribution and diversity. In Early Palaeozoic Biogeography and Palaeogeography (eds Harper, DAT and Servais, T), pp. 297–336. Geological Society of London, Memoir no. 38.Google Scholar
Adrain, JM, Edgecombe, GD, Fortey, RA, Hammer, Ø, Laurie, JR, McCormick, T, Owen, AW, Waisfeld, BG, Webby, BD, Westrop, SR and Zhou, Z-Y (2004) Trilobites. In The Great Ordovician Biodiversification Event (eds Webby, BD, Droser, ML and Paris, F), pp. 231–54. New York: Columbia University Press.Google Scholar
Adrain, JM, Fortey, RA and Westrop, SR (1998) Post-Cambrian trilobite diversity and evolutionary faunas. Science 280, 1922–5.CrossRefGoogle ScholarPubMed
Adrain, JM, Karim, TS and Westrop, SR (2014) The Early Ordovician (Floian) bathyurid trilobite genera Jeffersonia, Cullisonia and Bathyurina . Memoirs of the Association of Australasian Palaeontologists 45, 305–47.Google Scholar
Adrain, JM and McAdams, NEB (2012) The Lower Ordovician (upper Floian) bathyurid trilobite Aponileus Hu, with species from Utah, Texas, and Greenland. Zootaxa 3293, 1–67.CrossRefGoogle Scholar
Adrain, JM, McAdams, NEB and Karim, TS (2012) The Middle Ordovician bathyurid trilobite Pseudoolenoides, with a revised trilobite biostratigraphy of the Dapingian and lower Darriwilian of western Laurentia. Zootaxa 3467, 1–97.CrossRefGoogle Scholar
Adrain, JM, McAdams, NEB and Westrop, SR (2011a) Affinities of the Lower Ordovician (Tulean; lower Floian) trilobite Gladiatoria, with species from the Great Basin, western United States. Memoirs of the Association of Australasian Palaeontologists 42, 321–67.Google Scholar
Adrain, JM, McAdams, NEB, Westrop, SR and Karim, TS (2011b) Systematics and affinity of the Lower Ordovician (Tulean; lower Floian) trilobite Psalikilopsis . Memoirs of the Association of Australasian Palaeontologists 42, 369–416.Google Scholar
Adrain, JM and Westrop, SR (2004) A late Cambrian (Sunwaptan) silicified trilobite fauna from Nevada. Bulletins of American Paleontology 365, 1–56.Google Scholar
Adrain, JM and Westrop, SR (2005) Late Cambrian ptychaspidid trilobites from western Utah: implications for trilobite systematics and biostratigraphy. Geological Magazine 142, 377–98.CrossRefGoogle Scholar
Adrain, JM and Westrop, SR (2007) Bearriverops, a new Lower Ordovician trilobite genus from the Great Basin, western USA, and classification of the family Dimeropygidae. Canadian Journal of Earth Sciences 44, 337–66.CrossRefGoogle Scholar
Ahlberg, P (1989) Cambrian stratigraphy of the När 1 deep well, Gotland. GFF 111, 137–48.Google Scholar
Álvaro, JJ, Ahlberg, P, Babcock, LE, Bordonaro, OL, Choi, DK, Cooper, RA, Ergaliev, GKH, Gapp, IW, Ghobadi Pour, M, Hughes, NC, Jago, JB, Korovnikov, I, Laurie, JR, Lieberman, BS, Paterson, JR, Pegel, TV, Popov, LE, Rushton, AWA, Sukhov, SS, Tortello, MF, Zhou, Z and Żylińska, A (2013) Global Cambrian trilobite palaeobiogeography assessed using parsimony analysis of endemicity. In Early Palaeozoic Biogeography and Palaeogeography (eds Harper, DAT and Servais, T), pp. 273–96. Geological Society of London, Memoir no. 38.Google Scholar
Aria, C and Caron, J-B (2017) Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature 545, 89–92.CrossRefGoogle ScholarPubMed
Beecher, CE (1897) Outline of a natural classification of the trilobites. American Journal of Science 3, 89–106, 181–207.CrossRefGoogle Scholar
Bergström, J (1973) Organization, life, and systematics of trilobites. Fossils and Strata 2, 1–69.Google Scholar
Bergström, J (1977) Proetida – a disorderly order of trilobites. Lethaia 10, 95–105.CrossRefGoogle Scholar
Bergström, J and Hou, X-G (2005) Early Palaeozoic non-lamellipedian arthropods. In Crustacea and Arthropod Relationships (eds Koenemann, S and Jenner, RA), pp. 73–93. Boca Raton: Taylor & Francis.CrossRefGoogle Scholar
Budd, GE (1995) Kleptothule rasmusseni gen. et sp. nov.: an ?olenellinid-like trilobite from the Sirius Passet fauna (Buen Formation, Lower Cambrian, North Greenland). Transactions of the Royal Society of Edinburgh: Earth Sciences 86, 1–12.CrossRefGoogle Scholar
Budd, GE (2011) Campanamuta mantonae gen. et sp. nov., an exceptionally preserved arthropod from the Sirius Passet fauna (Buen Formation, lower Cambrian, North Greenland). Journal of Systematic Palaeontology 9, 217–60.CrossRefGoogle Scholar
Calver, MA (1981) Palaeozoic studies in honour of Sir James Stubblefield. Geological Magazine 118, 581–9.Google Scholar
Caron, J-B, Rudkin, DM and Milliken, S (2004) A new late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada—delayed fallout from the Cambrian explosion. Journal of Paleontology 78, 1138–45.CrossRefGoogle Scholar
Chatterton, BDE and Ludvigsen, R (2004) Early Silurian trilobites of Anticosti Island, Québec, Canada. Palaeontographica Canadiana 22, 1–264.Google Scholar
Chatterton, BDE, Siveter, DJ, Edgecombe, GD and Hunt, AS (1990) Larvae and relationships of the Calymenina (Trilobita). Journal of Paleontology 64, 255–77.CrossRefGoogle Scholar
Chatterton, BDE and Speyer, SE (1997) Ontogeny. In Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, Trilobita (Revised) (ed. Kaesler, RL), pp. 173–247. Geological Society of America, Boulder and University of Kansas Press, Lawrence.Google Scholar
Cotton, TJ (2001) The phylogeny and systematics of blind Cambrian ptychoparioid trilobites. Palaeontology 44, 167–207.CrossRefGoogle Scholar
Cotton, TJ and Braddy, S (2004) The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh: Earth Sciences 94, 169–93.CrossRefGoogle Scholar
Cotton, TJ and Fortey, RA (2005) Comparative morphology and relationships of the Agnostida. In Crustacea and Arthropod Relationships (eds Koenemann, S and Jenner, RA), pp. 95–136. Boca Raton: Taylor & Francis.CrossRefGoogle Scholar
Crônier, C, Abbache, A, Khaldi, AY, Oudot, M, Maillet, S and Ouali Mehadji, A (2018) Middle Devonian trilobites of the Saoura Valley, Algeria: insights into their biodiversity and Moroccan affinities. Geological Magazine 155, 811–40.CrossRefGoogle Scholar
Du, K-S, Ortega-Hernández, J, Yang, J and Zhang, X-G (2018) A soft-bodied euarthropod from the early Cambrian Xiaoshiba Lagerstätte of China supports a new clade of basal artiopodans with dorsal ecdysial sutures. Cladistics, published online 2 July 2018, doi: 10.1111/cla.12344.Google Scholar
Ebbestad, JOR and Budd, GE (2003) Burlingiid trilobites from Norway, with a discussion of their affinities and relationships. Palaeontology 45, 1171–95.CrossRefGoogle Scholar
Ebbestad, JOR and Weidner, T (2017) Extreme protomeric development in a burlingiid trilobite from Cambrian glacial erratics of Denmark. Palaeontology 60, 233–53.CrossRefGoogle Scholar
Edgecombe, GD (1992) Trilobite phylogeny and the Cambrian–Ordovician “Event”: cladistic reappraisal. In Extinction and Phylogeny (eds Novacek, MJ and Wheeler, QD), pp. 144–77. New York: Columbia University Press.Google Scholar
Edgecombe, GD, Paterson, JR and García-Bellido, DC (2017) A new aglaspidid-like euarthropod from the early Cambrian Emu Bay Shale of South Australia. Geological Magazine 154, 87–95.CrossRefGoogle Scholar
Edgecombe, GD and Ramsköld, L (1999) Relationships of Cambrian Arachnata and the systematic position of Trilobita. Journal of Paleontology 73, 263–87.CrossRefGoogle Scholar
Edgecombe, GD, Vaccari, NE and Waisfeld, BG (1994) Lower Devonian calmoniid trilobites from the Argentine Precordillera: new taxa of the Bouleia Group, and remarks on the tempo of calmoniid radiation. Geological Magazine 131, 449–64. CrossRefGoogle Scholar
Eldredge, N (1977) Trilobites and evolutionary patterns. In Patterns of Evolution as Illustrated by the Fossil Record (ed. Hallam, A), pp. 305–32. Amsterdam: Elsevier.CrossRefGoogle Scholar
Evitt, WR (1961) Early ontogeny in the trilobite family Asaphidae. Journal of Paleontology 35, 986–95.Google Scholar
Feist, R and McNamara, KJ (2007) Biodiversity, distribution and patterns of extinction of the last odontopleuroid trilobites during the Devonian (Givetian, Frasnian). Geological Magazine 144, 777–96.CrossRefGoogle Scholar
Feist, R, McNamara, KJ, Crônier, C and Lerosey-Aubril, R (2009) Patterns of extinction and recovery of phacopid trilobites during the Frasnian–Famennian (Late Devonian) mass extinction event, Canning Basin, Western Australia. Geological Magazine 146, 12–33.CrossRefGoogle Scholar
Fortey, RA (1981) Prospectatrix genatenta (Stubblefield) and the trilobite superfamily Cyclopygacea. Geological Magazine 118, 603–14.CrossRefGoogle Scholar
Fortey, RA (1983) Cambrian–Ordovician trilobites from the boundary beds in western Newfoundland and their phylogenetic significance. Special Papers in Palaeontology 30, 179–211.Google Scholar
Fortey, RA (1989) There are extinctions and extinctions: examples from the Lower Palaeozoic. Philosophical Transactions of the Royal Society of London B 325, 327–55.CrossRefGoogle Scholar
Fortey, RA (1990) Ontogeny, hypostome attachment and trilobite classification. Palaeontology 33, 529–76.Google Scholar
Fortey, RA (1997) Classification. In Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, Trilobita (Revised) (ed. Kaesler, RL), pp. 289–302. Geological Society of America, Boulder and University of Kansas Press, Lawrence.Google Scholar
Fortey, RA (2001) Trilobite systematics: the last 75 years. Journal of Paleontology 75, 1141–51.CrossRefGoogle Scholar
Fortey, RA and Chatterton, BDE (1988) Classification of the trilobite suborder Asaphina. Palaeontology 31, 165–222.Google Scholar
Fortey, RA and Owens, RM (1975) Proetida – a new order of trilobites. Fossils and Strata 4, 227–39.Google Scholar
Fortey, RA and Owens, RM (1979) Enrollment in the classification of trilobites. Lethaia 12, 219–26.CrossRefGoogle Scholar
Fortey, RA and Owens, RM (1991) A trilobite fauna from the highest Shineton Shales in Shropshire, and the correlation of the latest Tremadoc. Geological Magazine 128, 437–64.CrossRefGoogle Scholar
Fortey, RA and Theron, JN (1994) A new Ordovician arthropod, Soomaspis, and the agnostid problem. Palaeontology 37, 841–61.Google Scholar
Fortey, RA and Whittington, HB (1989) The Trilobita as a natural group. Historical Biology 2, 125–38.CrossRefGoogle Scholar
García-Bellido, DC and Collins, DH (2006) A new study of Marrella splendens (Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada. Canadian Journal of Earth Sciences 43, 721–42.CrossRefGoogle Scholar
Geyer, G and Corbacho, J (2015) The Burlingiidae (Trilobita): revised generic composition, stratigraphy, and the first species from the early Middle Cambrian of West Gondwana. GFF 137, 212–25.CrossRefGoogle Scholar
Gutiérrez-Marco, JC, García-Bellido, DC, Rábano, I and Sá, AA (2017) Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstätte, Morocco. Scientific Reports 7, 39728. doi: 10.1038/srep39728.CrossRefGoogle Scholar
Hahn, G (1989) Reconstruction of the phylogenetic relationships among the higher taxa of trilobites. Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg 28, 187–99.Google Scholar
Hahn, G and Hahn, R (1975) Forschungsbericht über Trilobitomorpha. Paläontologische Zeitschrift 49, 432–60.Google Scholar
Harrington, HJ, Henningsmoen, G, Howell, BF, Jaanusson, V, Lochman-Balk, C, Moore, RC, Poulsen, C, Rasetti, F, Richter, E, Richter, R, Schmidt, H, Sdzuy, K, Struve, W, Størmer, L, Stubblefield, CJ, Tripp, R, Weller, JM and Whittington, HB (1959) Treatise on Invertebrate Paleontology, Part O, Arthropoda 1. Geological Society of America, New York and University of Kansas Press, Lawrence, 560 p.CrossRefGoogle Scholar
Haug, JT, Maas, A and Waloszek, D (2010) †Henningsmoenicaris scutula, †Sandtorpia vestrogothiensis gen. et sp. nov. and heterochronic events in early crustacean evolution. Earth and Environmental Science Transactions of the Royal Society of Edinburgh 100, 311–50.CrossRefGoogle Scholar
Hendricks, JR and Lieberman, BS (2008) New phylogenetic insights into the Cambrian radiation of arachnomorph arthropods. Journal of Paleontology 82, 585–94.CrossRefGoogle Scholar
Henningsmoen, G (1951) Remarks on the classification of trilobites. Norsk Geologisk Tidsskrift 29, 174–217.Google Scholar
Henry, J-L (1980) Evolution and classification of some Ordovician Calymenina (Trilobita). Geological Magazine 117, 351–62.CrossRefGoogle Scholar
Hopkins, MJ, Chen, F, Hu, S and Zhang, Z (2017) The oldest known digestive system consisting of both paired digestive glands and a crop from exceptionally preserved trilobites of the Guanshan Biota (early Cambrian, China). PLoS ONE 12, e0184982. doi: 10.1371/journal.pone.0184982.CrossRefGoogle Scholar
Hou, X, Williams, M, Gabbott, S, Siveter, DJ, Siveter, DJ, Cong, P, Ma, X and Sansom, R (2017) A new species of the artiopodan arthropod Acanthomeridion from the lower Cambrian Chengjiang Lagerstätte, China, and the phylogenetic significance of the genus. Journal of Systematic Palaeontology 15, 733–40.CrossRefGoogle Scholar
Hou, X, Williams, M, Sansom, R, Siveter, DJ, Siveter, DJ, Gabbott, S, Harvey, THP, Cong, P and Liu, Y (2018) A new xandarellid euarthropod from the Cambrian Chengjiang biota, Yunnan Province, China. Geological Magazine, published online 3 December 2018, doi: 10.1017/S0016756818000730.Google Scholar
Hughes, NC (2007) The evolution of trilobite body patterning. Annual Review of Earth and Planetary Sciences 35, 401–34.CrossRefGoogle Scholar
Hughes, NC, Minelli, A and Fusco, G (2006) The ontogeny of trilobite segmentation: a comparative approach. Paleobiology 32, 602–27.CrossRefGoogle Scholar
Hupé, P (1953a) Classification des Trilobites. Annales de Paléontologie 39, 61–168.Google Scholar
Hupé, P (1953b) Classe des Trilobites. In Traité de Paléontologie. Tome 3. Les Formes Ultimes d’Invertébrés. Morphologie et Évolution. Onycophores. Arthropodes. Échinoderms. Stomocordés (ed. Piveteau, J), pp. 44–246. Paris: Masson et Cie.Google Scholar
Hupé, P (1955) Classification des Trilobites. Annales de Paléontologie 41, 91–325.Google Scholar
Jago, JB (1972) Two new Cambrian trilobites from Tasmania. Palaeontology 15, 226–37.Google Scholar
Jell, PA (1997) Introduction to suborder Eodiscina. In Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, Trilobita (Revised) (ed. Kaesler, RL), pp. 384–6. Geological Society of America, Boulder and University of Kansas Press, Lawrence.Google Scholar
Jell, PA (2003) Phylogeny of early Cambrian trilobites. Special Papers in Palaeontology 70, 45–57.Google Scholar
Jell, PA and Adrain, JM (2003) Available generic names for trilobites. Memoirs of the Queensland Museum 48, 331–553.Google Scholar
Jell, PA and Hughes, NC (1997) Himalayan Cambrian trilobites. Special Papers in Palaeontology 58, 1–113.Google Scholar
Kihm, R and St. John, J (2007) Walch’s trilobite research – a translation of his 1771 trilobite chapter. In Fabulous Fossils, 300 Years of Worldwide Research on Trilobites (eds Mikulic, DG, Landing, E and Kluessendorf, J), pp. 115–40. New York State Museum Bulletin 507.Google Scholar
Lamsdell, JC and Selden, PA (2015) Phylogenetic support for the monophyly of proetide trilobites. Lethaia 48, 375–86.CrossRefGoogle Scholar
Lane, PD and Thomas, AT (1978) Silurian trilobites from NE Queensland and the classification of effaced trilobites. Geological Magazine 115, 351–8.CrossRefGoogle Scholar
Lauterbach, K-E (1980) Schlüsselereignisse in der Évolution. des Grundplans der Arachnata (Arthropoda). Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg 23, 163–327.Google Scholar
Lauterbach, K-E (1983) Synapomorphien zwischen Trilobiten- und Cheliceratenzweig der Arachnata. Zoologischer Anzeiger 210, 213–18.Google Scholar
Lauterbach, K-E (1989) Trilobites and phylogenetic systematics: A reply to G. Hahn. Abhandlungen des Naturwissenschaftlichen Vereins in Hamburg 28, 201–11.Google Scholar
Lee, D-C and Chatterton, BDE (2003) Protaspides of Leiostegium and their implications for membership of the order Corynexochida. Palaeontology 46, 431–45.CrossRefGoogle Scholar
Legg, DA, Sutton, MD and Edgecombe, GD (2013) Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature Communications 4, 2485. doi: 10.1038/ncomms3485.CrossRefGoogle ScholarPubMed
Lerosey-Aubril, R (2012) The late Palaeozoic trilobites of Iran and Armenia and their palaeogeographical significance. Geological Magazine 149, 1023–45.CrossRefGoogle Scholar
Lerosey-Aubril, R, Hegna, TA, Kier, C, Bonino, E, Habersetzer, J and Carré, M (2012) Controls on gut phosphatisation: the trilobites from the Weeks Formation Lagerstätte (Cambrian; Utah). PLoS ONE 7, e32934. doi: 10.1371/journal.pone.0032934.CrossRefGoogle Scholar
Lerosey-Aubril, R, Paterson, JR, Gibb, S and Chatterton, BDE (2017a) Exceptionally-preserved late Cambrian fossils from the McKay Group (British Columbia, Canada) and the evolution of tagmosis in aglaspidid arthropods. Gondwana Research 42, 264–79.CrossRefGoogle Scholar
Lerosey-Aubril, R, Zhu, X and Ortega-Hernández, J (2017b) The Vicissicaudata revisited – insights from a new aglaspidid arthropod with caudal appendages from the Furongian of China. Scientific Reports 7, 11117. doi: 10.1038/s41598-017-11610-5.CrossRefGoogle ScholarPubMed
Lieberman, BS and Karim, TS (2010) Tracing the trilobite tree from the root to the tips: A model marriage of fossils and phylogeny. Arthropod Structure & Development 39, 111–23.CrossRefGoogle Scholar
Ludvigsen, R and Chatterton, BDE (1980) The ontogeny of Failleana and the origin of the Bumastinae (Trilobita). Geological Magazine 117, 471–8.CrossRefGoogle Scholar
Mayers, B, Aria, C and Caron, J-B (2019) Three new naraoiid species from the Burgess Shale, with a morphometric and phylogenetic reinvestigation of Naraoiidae. Palaeontology 62, 19–50.CrossRefGoogle Scholar
McAdams, NEB and Adrain, JM (2009) Heckethornia, a new genus of dimeropygid trilobites from the Lower Ordovician (Ibexian; Tulean and Blackhillsian) of the Great Basin, western Utah. Canadian Journal of Earth Sciences 46, 875–914.Google Scholar
McAdams, NEB and Adrain, JM (2010) A new species of the Lower Ordovician pliomerid trilobite Pseudocybele and its biostratigraphic significance. Zootaxa 2550, 21–38.CrossRefGoogle Scholar
McAdams, NEB and Adrain, JM (2011a) Systematics of the Lower Ordovician pliomerid trilobite Hintzeia, with species from the Great Basin, western USA. Zootaxa 2910, 1–45.Google Scholar
McAdams, NEB and Adrain, JM (2011b) Panisaspis, a new genus of pliomerid trilobites from the Lower Ordovician (Ibexian; Tulean and Blackhillsian) of the Great Basin, western USA. Zootaxa 2969, 1–68.CrossRefGoogle Scholar
McAdams, NEB and Adrain, JM (2011c) Revision of the Lower Ordovician (lower Floian; Tulean) pliomerid trilobite Protopliomerella, with new species from the Great Basin, western USA. Zootaxa 3144, 1–113.CrossRefGoogle Scholar
McNamara, KJ (1980) Taxonomy and distribution of chasmopine trilobites. Geological Magazine 117, 65–80.CrossRefGoogle Scholar
Mickleborough, J (1884) Locomotory appendages of trilobites. Geological Magazine (new series, decade III) 1, 80–4.CrossRefGoogle Scholar
Moysiuk, J and Caron, J-B (2019) Burgess Shale fossils shed light on the agnostid problem. Proceedings of the Royal Society B 286, 20182314. doi: 10.1098/rspb.2018.2314.CrossRefGoogle ScholarPubMed
Müller, KJ and Walossek, D (1987) Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden. Fossils and Strata 19, 1–124.Google Scholar
Ortega-Hernández, J and Brena, C (2012) Ancestral patterning of tergite formation in a centipede suggests derived mode of trunk segmentation in trilobites. PLoS ONE 7, e52623. doi: 10.1371/journal.pone.0052623.CrossRefGoogle Scholar
Ortega-Hernández, J, Legg, DA and Braddy, SJ (2013) The phylogeny of aglaspidid arthropods and the internal relationships within Artiopoda. Cladistics 29, 15–45.CrossRefGoogle Scholar
Park, T-Y (2018) Ontogeny of the two co-occurring middle Furongian (late Cambrian) shumardiid trilobites and the protaspid morphology of shumardiids. Geological Magazine 155, 1247–62.CrossRefGoogle Scholar
Park, T-Y and Choi, DK (2009) Post-embryonic development of the Furongian (late Cambrian) trilobite Tsinania canens: implications for life mode and phylogeny. Evolution & Development 11, 441–55.CrossRefGoogle ScholarPubMed
Park, T-Y and Choi, DK (2010) Ontogeny and ventral median suture of the ptychaspidid trilobite Asioptychaspis subglobosa (Sun, 1924) from the Furongian (Upper Cambrian) Hwajeol Formation, Korea. Journal of Paleontology 84, 309–20.CrossRefGoogle Scholar
Park, T-Y and Choi, DK (2011a) Ontogeny of the Furongian (late Cambrian) remopleuridioid trilobite Haniwa quadrata Kobayashi, 1933 from Korea: implications for trilobite taxonomy. Geological Magazine 148, 288–303.CrossRefGoogle Scholar
Park, T-Y and Choi, DK (2011b) Constraints on using ontogenetic data for trilobite phylogeny. Lethaia 44, 250–4.CrossRefGoogle Scholar
Park, T-Y and Kihm, J-H (2015) Post-embryonic development of the Early Ordovician (ca. 480 Ma) trilobite Apatokephalus latilimbatus Peng, 1990 and the evolution of metamorphosis. Evolution & Development 17, 289–301.CrossRefGoogle ScholarPubMed
Park, T-Y and Kihm, J-H (2017) Head segmentation of trilobites. Lethaia 50, 1–6.CrossRefGoogle Scholar
Park, T, Kihm, JH, Kang, I and Choi, DK (2014) Ontogeny of a new species of the Cambrian Series 3 (middle Cambrian) trilobite genus Liostracina Monke, 1903 from North China and the taxonomic position of the superfamily Trinucleoidea. Journal of Paleontology 88, 395–402.CrossRefGoogle Scholar
Park, T-Y, Kihm, J-H, Woo, J, Kim, Y-H and Lee, JI (2016) Ontogeny of the Furongian (late Cambrian) trilobite Proceratopyge cf. P. lata Whitehouse from Northern Victoria Land, Antarctica, and the evolution of metamorphosis in trilobites. Palaeontology 59, 657–70.CrossRefGoogle Scholar
Paterson, JR and Edgecombe, GD (2006) The Early Cambrian trilobite family Emuellidae Pocock, 1970: systematic position and revision of Australian species. Journal of Paleontology 80, 496–513.CrossRefGoogle Scholar
Paterson, JR, Edgecombe, GD, García-Bellido, DC, Jago, JB and Gehling, JG (2010) Nektaspid arthropods from the lower Cambrian Emu Bay Shale Lagerstätte, South Australia, with a reassessment of lamellipedian relationships. Palaeontology 53, 377–402.CrossRefGoogle Scholar
Paterson, JR, Edgecombe, GD and Lee, MSY (2019) Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proceedings of the National Academy of Sciences (USA) 116, 4394–9.CrossRefGoogle ScholarPubMed
Paterson, JR, García-Bellido, DC and Edgecombe, GD (2012) New artiopodan arthropods from the early Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia. Journal of Paleontology 86, 340–57.CrossRefGoogle Scholar
Peng, S-C, Babcock, LE and Lin, H-L (2004) Polymerid Trilobites from the Cambrian of Northwestern Hunan, China - Volume 2: Ptychopariida, Eodiscida, and Undetermined Forms. Beijing: Science Press, 355 p.Google Scholar
Pollitt, JR, Fortey, RA and Wills, MA (2005) Systematics of the trilobite families Lichidae Hawle & Corda, 1847 and Lichakephalidae Tripp, 1957: the application of Bayesian inference to morphological data. Journal of Systematic Palaeontology 3, 225–41.CrossRefGoogle Scholar
Ramsköld, L and Edgecombe, GD (1991) Trilobite monophyly revisited. Historical Biology 4, 267–83.CrossRefGoogle Scholar
Reed, FRC (1898) Blind trilobites. Geological Magazine (new series, decade IV) 5, 439–47, 493–506, 552–9.CrossRefGoogle Scholar
Reed, FRC (1905) The classification of the Phacopidae. Geological Magazine (new series, decade V) 2, 172–8, 224-8.CrossRefGoogle Scholar
Reed, FRC (1927) Recent work on the Phacopidae. Geological Magazine 64, 308–22, 337–53.CrossRefGoogle Scholar
Reed, FRC (1928) Notes on the family Encrinuridae. Geological Magazine 65, 51–77.CrossRefGoogle Scholar
Robison, RA and Babcock, LE (2011) Systematics, paleobiology, and taphonomy of some exceptionally preserved trilobites from Cambrian Lagerstätten of Utah. Paleontological Contributions 5, 1–47.Google Scholar
Rushton, AWA (1978) Fossils from the Middle-Upper Cambrian transition in the Nuneaton district. Palaeontology 21, 245–83.Google Scholar
Rushton, AWA and Hughes, CP (1981) The Ordovician trilobite fauna of the Great Paxton Borehole, Cambridgeshire. Geological Magazine 118, 623–46.CrossRefGoogle Scholar
Salter, JW (1864) On some points in ancient physical geography, illustrated by fossils from a pebble-bed at Budleigh Salterton, Devonshire. Geological Magazine 1, 5–12.CrossRefGoogle Scholar
Scholtz, G and Edgecombe, GD (2005) Heads, hox and the phylogenetic position of trilobites. In Crustacea and Arthropod Relationships (eds Koenemann, S and Jenner, RA), pp. 139–65. Boca Raton: Taylor & Francis.CrossRefGoogle Scholar
Scholtz, G and Edgecombe, GD (2006) The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution 216, 395–415.CrossRefGoogle ScholarPubMed
Servais, T and Harper, DAT (2018) The Great Ordovician Biodiversification Event (GOBE): definition, concept and duration. Lethaia 51, 151–64.CrossRefGoogle Scholar
Servais, T, Owen, AW, Harper, DAT, Kröger, B and Munnecke, A (2010) The Great Ordovician Biodiversification Event (GOBE): The palaeoecological dimension. Palaeogeography, Palaeoclimatology, Palaeoecology 294, 99–119.CrossRefGoogle Scholar
Shergold, JH (1991) Protaspid and early meraspid growth stages of the eodiscoid trilobite Pagetia ocellata Jell, and their implications for classification. Alcheringa 15, 65–86.CrossRefGoogle Scholar
Stein, M, Budd, GE, Peel, JS and Harper, DAT (2013) Arthroaspis n. gen., a common element of the Sirius Passet Lagerstätte (Cambrian, North Greenland), sheds light on trilobite ancestry. BMC Evolutionary Biology 13, 99. doi: 10.1186/1471-2148-13-99.CrossRefGoogle Scholar
Stein, M and Selden, PA (2012) A restudy of the Burgess Shale (Cambrian) arthropod Emeraldella brocki and reassessment of its affinities. Journal of Systematic Palaeontology 10, 361–83.CrossRefGoogle Scholar
Stubblefield, CJ (1936) Cephalic sutures and their bearing on current classifications of trilobites. Biological Reviews 11, 407–40.CrossRefGoogle Scholar
Stubblefield, CJ (1959) Evolution in trilobites. Quarterly Journal of the Geological Society of London 115, 145–62.CrossRefGoogle Scholar
Swinnerton, HH (1915) Suggestions for a revised classification of trilobites. Geological Magazine (new series, decade VI) 2, 487–96, 538–45.CrossRefGoogle Scholar
Swinnerton, HH (1919) The facial suture of trilobites. Geological Magazine (new series, decade VI) 4, 103–10.CrossRefGoogle Scholar
Tarver, JE, Braddy, SJ and Benton, MJ (2007) The effects of sampling bias on Palaeozoic faunas and implications for macroevolutionary studies. Palaeontology 50, 177–84.CrossRefGoogle Scholar
Temple, JT (1956) Notes on the Cheiruracea and Phacopacea. Geological Magazine 93, 418–30.CrossRefGoogle Scholar
Thomas, AT and Holloway, DJ (1988) Classification and phylogeny of the trilobite order Lichida. Philosophical Transactions of the Royal Society of London B 321, 179–262.CrossRefGoogle Scholar
Thomas, AT and Narbonne, GM (1979) Silurian trilobites from arctic Canada. Geological Magazine 116, 1–19.CrossRefGoogle Scholar
Tripp, RP and Evitt, WR (1981) Silicified Lichidae (Trilobita) from the Middle Ordovician of Virginia. Geological Magazine 118, 665–77.CrossRefGoogle Scholar
Vannier, J, Aria, C, Taylor, RS and Caron, J-B (2018) Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale. Royal Society Open Science 5, 172206. doi: 10.1098/rsos.172206.CrossRefGoogle ScholarPubMed
Walch, JEI (1771) Die Naturgeschichte der Versteinerungen zur Erläuterung der Knorrischen Sammlung von Merkwürdigkeiten der Natur. Nürnberg: Paul Jonathan Felstecker, 235 p.Google Scholar
Walcott, CD (1894) Note on some appendages of the trilobites. Geological Magazine (new series, decade IV) 1, 246–51.CrossRefGoogle Scholar
Walcott, CD (1908) Cambrian trilobites. Smithsonian Miscellaneous Collections 53, 13–52.Google Scholar
Walossek, D and Müller, KJ (1990) Upper Cambrian stem-lineage crustaceans and their bearing upon the monophyletic origin of Crustacea and the position of Agnostus . Lethaia 23, 409–27.CrossRefGoogle Scholar
Wang, P, Fatka, O, Sun, Z, Budil, P and Gao, J (2018) Fossilized gut of the trilobite Lioparia bassleri and the distribution of exceptional preservation in the Cambrian Stage 4–Drumian Manto Formation of North China. Bulletin of Geosciences 93, 491–8.CrossRefGoogle Scholar
Webster, M (2015) Ontogeny and intraspecific variation of the early Cambrian trilobite Olenellus gilberti, with implications for olenelline phylogeny and macroevolutionary trends in phenotypic canalization. Journal of Systematic Palaeontology 13, 1–74.CrossRefGoogle Scholar
Westrop, SR and Adrain, JM (2016) Revision of Irvingella tropica Öpik 1963 from Australia and related species from North America: implications for correlation of the base of the Jiangshanian Stage (Cambrian, Furongian). Australasian Palaeontological Memoirs 49, 395–432.Google Scholar
Whittington, HB (1980) Exoskeleton, moult stage, appendage morphology, and habits of the middle Cambrian trilobite Olenoides serratus . Palaeontology 23, 171–204.Google Scholar
Whittington, HB (1981) Paedomorphosis and cryptogenesis in trilobites. Geological Magazine 118, 591–602.CrossRefGoogle Scholar
Whittington, HB (1994) Burlingiids: small proparian Cambrian trilobites of enigmatic origin. Palaeontology 37, 1–16.Google Scholar
Whittington, HB (2003) The upper Cambrian trilobites Plethopeltis and Leiocoryphe: morphology, paedomorphism, classification. Journal of Paleontology 77, 698–705.CrossRefGoogle Scholar
Whittington, HB (2007) Reflections on the classification of the Trilobita. In Fabulous Fossils, 300 Years of Worldwide Research on Trilobites (eds Mikulic, DG, Landing, E and Kluessendorf, J), 225–30. New York State Museum Bulletin 507.Google Scholar
Whittington, HB, Chatterton, BDE, Speyer, SE, Fortey, RA, Owens, RM, Chang, WT, Dean, WT, Fortey, RA, Jell, PA, Laurie, JR, Palmer, AR, Repina, LN, Rushton, AWA, Shergold, JH, Clarkson, ENK, Wilmot, NV and Kelly, SRA (1997) Treatise on Invertebrate Paleontology, Part O, Revised. Arthropoda 1, Trilobita 1 (Introduction, Order Agnostida, Order Redlichiida), 530 p. The Geological Society of America, Boulder and The University of Kansas, Lawrence.Google Scholar
Woodward, H (1871) On the structure of trilobites. Geological Magazine 8, 289–94.CrossRefGoogle Scholar
Woodward, H (1883) Synopsis of the genera and species of Carboniferous limestone trilobites. Geological Magazine (new series, decade II) 10, 445–54, 481–7, 534–42.CrossRefGoogle Scholar
Woodward, H (1884a) On the structure of trilobites. Geological Magazine (new series, decade III) 1, 78–9.CrossRefGoogle Scholar
Woodward, H (1884b) Synopsis of the genera and species of Carboniferous limestone trilobites. Geological Magazine (new series, decade III) 1, 484–9.CrossRefGoogle Scholar
Yuan, J-L and Esteve, J (2015) The earliest species of Burlingia Walcott, 1908 (Trilobita) from South China: biostratigraphical and palaeogeographical significance. Geological Magazine 152, 358–66.CrossRefGoogle Scholar
Yuan, J-L, Zhao, Y-L, Li, Y and Huang, Y-Z (2002) Trilobite Fauna of the Kaili Formation (uppermost Lower Cambrian–lower Middle Cambrian) from southeastern Guizhou, South China. Shanghai: Shanghai Science and Technology Publishing House, 423 p.Google Scholar
Zeng, H, Zhao, F, Yin, Z and Zhu, M (2017) Appendages of an early Cambrian metadoxidid trilobite from Yunnan, SW China support mandibulate affinities of trilobites and artiopods. Geological Magazine 154, 1306–28.CrossRefGoogle Scholar
Zhang, X-L, Shu, D-G and Erwin, DH (2007) Cambrian naraoiids (Arthropoda): morphology, ontogeny, systematics, and evolutionary relationships. Paleontological Society Memoir 68, 1–52.Google Scholar
Zhu, X, Hughes, NC and Peng, S (2007) On a new species of Shergoldia Zhang & Jell, 1987 (Trilobita), the family Tsinaniidae and the order Asaphida. Memoirs of the Association of Australasian Palaeontologists 34, 243–53.Google Scholar
Zhu, X, Hughes, NC and Peng, S (2010) Ventral structure and ontogeny of the late Furongian (Cambrian) trilobite Guangxiaspis guangxiensis Zhou, 1977 and the diphyletic origin of the median suture. Journal of Paleontology 84, 493–504.CrossRefGoogle Scholar
Żylińska, A and Masiak, M (2007) Cambrian trilobites from Brzechów, Holy Cross Mountains (Poland) and their significance in stratigraphic correlation and biogeographic reconstructions. Geological Magazine 144, 661–86.CrossRefGoogle Scholar