Enrolled agnostids from Cambrian of Spain provide new insights about the mode of life in these forms


Authors: Esteve J, Zamora S

Published in: Bulletin of Geosciences, volume 89, issue 2; pages: 283 - 291; Received 5 February 2013; Accepted in revised form 6 August 2013; Online 11 March 2014

Keywords: middle Cambrian, Gondwana, arthropods, behavior, Spain,

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Enrolled agnostids have been known since the beginning of the nineteenth century but assemblages with high number of enrolled specimens are rare. There are different hypotheses about the life habits of this arthropod group and why they enrolled. These include: a planktic or epiplanktic habit, with the rolled-up posture resulting from clapping cephalon and pygidium together, ectoparasitic habit or a sessile lifestyle, either attached to seaweeds or on the sea floor. Herein we describe two new assemblages from the middle Cambrian of Purujosa (Iberian Chains, North Spain) where agnostids are minor components of the fossil assemblages but occasionally appear enrolled. The taphonomic and sedimentological data suggest that these agnostids were suddenly buried and rolled up as a response to adverse palaeoenvironmental conditions. Their presence with typical benthic components supports a benthic mode of life for at least some species of agnostids.


Álvaro, J.J., Bauluz, B., Subías, I., Pierre, C. & Vizcaino, D. 2008. Carbon chemostratigraphy of the Cambrian-Ordovician transition in a midlatitude mixed platform, Montagne Noire, France. Geological Society of America, Bulletin 120, 962-975.View article

Álvaro, J.J., Elicki, O., Geyer, G., Rushton, A.W.A. & Shergold, J.H. 2003. Palaeogeographical controls on the Cambrian trilobite immigration and evolutionary patterns reported in the western Gondwana margin. Palaeogeography, Palaeoclimatology, Palaeoecology 195, 5-35.View article

Álvaro, J.J. & Vizcaino, D. 1998. Révision biostratigraphique du Cambrien moyen du versant méridional de la Montagne Noire (Languedoc, France). Bulletin de la Société géologique de France 169, 233-242.

Álvaro, J.J., Zamora, S., Vizcaino, D. & Ahlberg, P. 2013. Guzhangian (mid Cambrian) trilobites from silica concretions of the Valtorres Formation, Iberian Chains, NE Spain. Geological Magazine 150, 123-142.View article

Babcock, L.E., Peng, S.C., Shergold, J.H. & Geyer, G. 2005. Changing perspectives on Cambrian chronostratigraphy and progress toward subdivision of the Cambrian System. Geosciences Journal 9, 101-106.View article

Bergström, J. 1973. Organization, life and systematic of trilobites. Fossils and Strata 2, 1-69.

Bruton, D.L. & Nakrem, H.A. 2005. Enrolment in a Middle Ordovician agnostoid trilobite. Acta Palaeontologica Polonica 50, 441-448.

Courtessole, R. 1973. Le Cambrien Moyen de la Montagne Noire: biostratigraphie. 248 pp. Imprim. d’Oc, Toulouse.

Clarkson, E.N.K. & Henry, J.L. 1973. Structures coaptatives et enroulement chez quelques Trilobites ordoviciens et siluriens. Lethaia 6, 105-132.View article

Dies, M.E., Gozalo, R. & Linán, E. 2004. Agnostida de la Formación Valdemiedes (Leoniense: Cámbrico Medio basal) de las Cadenas Ibéricas (NE de Espana). Boletín IGME 115(4), 683-698.

Esteve, J. 2009. Enrollamiento en Conocoryphe heberti Munier-Chalmas & Bergeron, 1889 (Cámbrico medio, Cadenas Ibéricas, NE Espana) y estructuras coaptativas en la familia Conocoryphidae. Estudios Geológicos 65, 167-182.View article

Esteve, J. 2014. Intraspecific variability in paradoxidid trilobites from the Purujosa trilobite assemblage (middle Cambrian, northeast Spain). Acta Palaeontologica Polonica 59(2), 215-250.View article

Esteve, J., Hughes, N.C. & Zamora, S. 2011. The Purujosa trilobite assemblage and the evolution of trilobite enrollment. Geology 39, 575-578.View article

Esteve, J., Hughes, N.C. & Zamora, S. 2013. Thoracic structure and enrolment style in middle Cambrian Eccaparadoxides pradoanus presages caudalization of the derived trilobites trunk. Palaeontology 56, 589-601.View article

Esteve, J., Sundberg, F., Zamora, S. & Gozalo, R. 2012. A new Alokistocaridae Resser, 1939 (Trilobita) from the middle Cambrian of Spain. Geobios 45, 275-283.View article

Esteve, J., Zamora, S., Gozalo, R. & Linán, E. 2010. Sphaeroidal enrolment in middle Cambrian solenopleoropsine trilobites. Lethaia 43, 478-493.View article

Fatka, O. & Szabad, M. 2011. Agnostid entombed under exoskeletons of paradoxidid trilobites. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 259, 207-215.View article

Fatka, O., Vokáč, V., Moravec, J., Šinágl, M. & Valent, M. 2009. Agnostids entombed in hyolith conchs. Memoirs of the Association of Australasian Palaeontologists 37, 481-489.

Fortey, R.A. & Owens, R.M. 1999a. Feeding habits in trilobites. Palaeontology 42, 429-465.View article

Fortey, R.A. & Owens, R.M. 1999b. The trilobite exoskeleton, 537-562. In Savazzi, E. (ed.) Functional morphology of the invertebrate exoskeleton. Wiley, New York.

Geyer, G. 1988. Agnostida aus dem höheren Unterkambrium und dem Mittelkambrium von Marokko, Teil 1: Agnostina. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1988, 141-152.

Gozalo, R., Chirivella Martorell, J.B., Esteve, J. & Linán, E. 2011. Correlation between the base of Drumian Stage and the base of middle Caesaraugustan Stage in the Iberian Chains (NE Spain). Bulletin of Geosciences 86, 545-554.View article

Hoyberget, M. & Bruton, D.L. 2008. Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway. Palaeontographica, Abteilung A 286, 1-87.

Hughes, N.C. 2007. The evolution of trilobite body patterning. Annual Review of Earth and Planetary Sciences 35, 401-434.View article

Hunda, B.R., Hughes, N.C. & Flessa, K.W. 2006. Trilobite taphonomy and temporal resolution in the Mt Orab Shale Bed (Upper Ordovician, Ohio, USA). Palaios 21, 26-45.View article

Jago, J.B. 1973. Cambrian agnostid communities in Tasmania. Lethaia 6, 405-421.View article

Jaekel, O. 1909. Über die Agnostiden. Zeitschrift der Deutschen Geologischen Gesellschaft 61, 380-400.

Linán, E. & Gozalo, R. 1986. Trilobites del Cámbrico inferior y medio de Murero (Cordillera Ibérica). Memorias del Museo Paleontológico de la Universidad de Zaragoza 2, 1-104.

Mergl, M. & Zamora, S. 2012. New and revised occurrences of rhynchonelliformean brachiopods from the middle Cambrian of the Iberian Chains, NE Spain. Bulletin of Geosciences 87(3), 571-586.View article

Müller, K.J. & Walossek, D. 1985. Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden. Fossils and Strata 19, 1-124.

Öpik, A.A. 1979. Middle Cambrian agnostids: systematics and biostratigraphy. Bureau of Mineral Resources, Geology and Geophysics, Bulletin 172, 1-188.

Peng, S., Hughes, N.C., Heim, N.A., Sell, B., Zhu, X., Myrow, P.M. & Parcha, S.K. 2009. Cambrian trilobites from the Parahio and Zanskar Valleys, Indian Himalaya. Journal of Paleontology 86 (Supplement 6), 1-95.View article

Peng, S. & Robison, R.R. 2000. Agnostoid biostratigraphy across the Middle-Upper Cambrian boundary in Hunan, China. Paleontological Society Memoir 53, Journal of Paleontology 74, 1-104.View article

Pek, I. 1972. Articulation in Condylopyge rex (Barrande, 1846) (Trilobita). Acta Universitatis Palackianae Olomucensis 38, 139-141.

Pek, I. 1977. Agnostid trilobites of the central Bohemian Ordovician. Sborník geologických věd 19, 7-44.

Robison, R.A. 1964. Late Middle Cambrian faunas from western Utah. Journal of Paleontology 38, 510-566.

Robison, R.A. 1972. Mode of life of agnostid trilobites. 24th International Geological Congress, Montreal, Canada, Section 7 (Paleontology), 33-40.

Robison, R.A. 1975. Species diversity among agnostid trilobites. Fossils and Strata 4, 219-226.

Robison, R.A. 1988. Trilobites of the Holm Dal Formation (late Middle Cambrian), central North Greenland. Meddelelser om Gronland, Geoscience 20, 23-103.

Robison, R.A. 1994. Agnostids trilobites from the Henson Gletcher and Kap Stanton formations (Middle Cambrian), North Greenland. Gronlands Geologiske Undersogelse, Bulletin 169, 25-77.

Slavíčková, J. & Kraft, P. 2001. Remarks to the palaeoecology of agnostid trilobites. Journal of the Czech Geological Society 46, 215-218.

Speyer, S.E. 1988. Biostratinomy and functional morphology of enrolment in two Middle Devonian trilobites. Lethaia 51, 121-138.View article

Stitt, J.H. 1983. Enrolled Late Cambrian trilobites from the Davis Formation, southeast Missouri. Journal of Paleontology 57, 93-105.

Tortello, M.F., Vizcaino, D. & Álvaro, J.J. 2006. Early Ordovician agnostid trilobites from the southern Montagne Noire, France. Journal of Paleontology 80, 477-495.View article

Tullberg, S.A. 1880. Om-Agnostus-arterna i de kambriska aflagringarna vid Andrarum. Sveriges Geologiska Undersöking (series C) 42, 1-38.

Vermeij, G.J. 1987. Evolution and Escalation. 527 pp. Princeton University Press, Princeton.

Wallerius, I.D. 1895. Undersökningar öfver zonen med Agnostus laevigatus i Vestergötland, jämte en inledande öfversikt af Vestergötlands samtliga Paradoxideslager. 72 pp. Gleerupska Universitetsbokhandeln, Lund.

WestergArd, A.H. 1946. Agnostidea of the Middle Cambrian of Sweden. Sveriges Geologiska Undersökning Series C 40, 1-141.

Westrop, S., Adrain, J.M. & Landing, E. 2011. The Cambrian (Sunwaptan, Furongian) agnostoid arthropod Lotagnostus Whitehouse, 1936, in Laurentia and Avalonian North America: systematics and biostratigraphy significance. Bulletin of Geosciences 86, 569-594.View article

Whittington, H.B. 1963. Middle Ordovician trilobites from Lower Head, western Newfoundland. Bulletin of the Museum of Comparative Zoology 129, 1-118.

Zamora, S. 2010. Middle Cambrian echinoderms from North Spain show echinoderms diversified earlier in Gondwana. Geology 38, 507-510.View article

Zamora, S. & Smith, A.B. 2012. Cambrian stalked echinoderms show unexpected plasticity of arm construction. Proceedings of the Royal Society B 279, 293-298.View article