Exoskeletal architecture, hypostomal morphology and mode of life of Silurian and Lower Devonian dalmanitid trilobites

 

Authors: Budil P, Thomas AT, Hörbinger F

Published in: Bulletin of Geosciences, volume 83, issue 1; pages: 1 - 10; Received 23 August 2007; Accepted in revised form 4 December 2007;

Keywords: Dalmanitidae, trilobite, mode of life, body morphology, hypostomes,

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Abstract

The overall exoskeletal architecture and hypostomal morphology of Silurian Dalmanites and Lower Devonian Odontochile, Reussiana and Zlichovaspis are compared and discussed. All four genera were benthic. However, a gradual shift from predator-scavenger to a scavenging feeding habit is inferred from the evolution of these dalmanitids in the Upper Silurian and Lower Devonian. In the more conservative, probable predator-scavenger Dalmanites, the posterior hypostomal doublure has a group of robust denticles: these would have been effective shredding structures, enabling milling or cutting of food into smaller particles, and allowing Dalmanites to deal with mechanically relatively robust prey. Lower Devonian dalmanitids from the Prague Basin possess a comparable denticulate structure on the posterior hypostomal doublure. However, although overall exoskeletal dimensions are larger, the denticles are significantly finer and denser. The whole exoskeleton of these younger dalmanitids, with a large multi-segmented pygidium, is considered well adapted for close approximation to the sediment surface. Shallow burrowing in a soft substrate, and scavenging with opportunistic predation, is therefore considered to be their main feeding habit. Odontochile, Reussiana and Zlichovaspis characteristically occur in micritic limestone facies, where the sediment surface is likely to have been soft. The shift from a more predatory to a dominantly scavenging mode of life may have occurred independently in several unrelated dalmanitid groups, with “odontochilid” characteristics developing at different stratigraphical levels.

References

Barrande, J. 1852. Systeme Silurien du centre de la Boheme. 1ere partie. Recherches paléontologiques, vol. 1. Crustacés, Trilobites. 935 pp. Privately published, Prague & Paris.View article

Barrande, J. 1872. Systeme Silurien du centre de la Boheme. 1ere partie. Recherches paléontologiques. Supplement au vol. 1. 648 pp. Privately published, Prague & Paris.

Brünnich, M.T. 1781. Beskrivelse over Trilobiten, en Dyreslaegt og dens Arten, med en nye Arts Aftegning. Nye Samling af det Kongelige Danske Videnskabers Selskabs Skrifter 1, 384–395.

Brongniart, A. 1822. Histoire naturelle des Crustacés fossils, sous les rapports zoologigique et géologique, savoir les Trilobites. Les Crustacés proprement dits par A.-G. Desmarest. 65 pp. Paris.

Bruton, D.L. & Haas, W. 2003a. Making Phacops come alive. Special Papers in Palaeontology 70, 331–347.

Bruton, D.L. & Haas, W. 2003b. The puzzling eye of Phacops. Special Papers in Palaeontology 70, 349–361.

Budil, P., Hörbinger, F. & Menzel, R. S 2008. Lower Devonian dalmanitid trilobites of the Prague Basin (Czech Republic). Transactions of the Royal Society of Edinburgh. 99, 61-100.View article

Campbell, K.S.W. 1977. Trilobites of the Haragan, Bois d’Arc and Frisco Formations (Early Devonian), Arbuckle Mountains region, Oklahoma. Bulletin of the Oklahoma Geological Survey 123, 1–139.

Chatterton, B.D.E. & Perry, D. 1983. Silicified odontopleurid trilobites from the MacKenzie Mountains. Palaeontographica Canadiana 1, 1–55.

Cherns, L., Wheeley, J.R. & Karis, L. 2006. Tunneling trilobites: habitual infaunalism in an Ordovician carbonate seafloor. Geology 34, 657–660.View article

Clarkson, E.N.K. 1966. Schizochroal eyes and vision of some phacopid trilobites. Palaeontology 9, 464–487.

Curtis, N.J. & Lane, P.D. 1998. The Llandovery trilobites of England and Wales. Part 2. Monograph of the Palaeontographical Society, London 152, 51–101.

Dalman, J.W. 1827. Om Palaederna, eller sa kallade Trilobiterna. Kongliga Svenska Vetenskaps-Akademiens Handlingar 1826, 113–152, 226–294.

Dean, W.T. 1960. The Silurian trilobite Dalmanites myops (König.). Palaeontology 2, 280.

Delo, D.M. 1935. A revision of the phacopid trilobites. Journal of Paleontology 9, 402–420.

Destombes, J. 1963. Quelques noveaux Phacopina (trilobites) de l’Ordovicien supérieur de l’Anti-Atlas (Maroc). Notes du Service Geologique du Maroc 23(172), 47–65.

El Chair, M., Hammann, W. & Thiedig, F. 1985. Neue Trilobiten- und Graptolithenfunde aus den Tanezzuft-Schiefern (Llandovery, Silur) des Fezzan, Südwest-Libyen. Mitteilungen aus dem Geologisch-Paläontologische Institut der Universität Hamburg 59, 83–98.

Eldredge, N. 1971. Patterns of cephalic musculature in the Phacopina (Trilobita) and their phylogenetic significance. Journal of Paleontology 45, 52–67.

Fortey, R.A. & Owens, R.M. 1999a. Feeding habits in trilobites. Palaeontology 42(3), 429–465.View article

Fortey, R.A. & Owens, R.M. 1999b. The trilobite exoskeleton, 538–562. In Savazzi, E. (ed.) Functional morphology of the invertebrate skeleton. John Wiley and Sons Ltd., London.

Hawle, I. & Corda, A.J.C. 1847. Prodrom einer Monographie der böhmischen Trilobiten. 176 pp. Prague.

Holloway, D.J. 1981. Silurian dalmanitacean trilobites from North America, and the subfamilies Dalmanitinae and Synphorinae. Palaeontology 24, 695–731.

Ivantsov, A.J. 1990. Svjaz morphologii gipostomy i sposoba pitania trilobitov roda Asaphus, 128–130. In Betekhtina, O.A. & Zhuravleva, I.T. (eds) Sreda i zhizn’ v geologicheskom proshlom. Trudy Instituta Geologii i Geofiziki imenji 60-letia Sojuza SSR . Nauka, Novosibirsk.

Kaesler, R.L. Ed. 1997. Treatise on invertebrate paleontology, Part O, Arthropoda 1 Trilobita. 535 pp. Geological Society of America & University of Kansas Press, Lawrence, Boulder.

König, C.E. 1825. Icones fossilium sectiles. 4 pp. London.

Lespérance, P.J. 1975. Stratigraphy and palaeontology of the Synphoriidae (Lower and Middle Devonian dalmanitacean trilobites). Journal of Palaeontology 49, 91–137.

Lindström, G. 1885. Förteckning pa Gotlands siluriska crustacéer. Öfversigt Kongliga Svenska Vetenskaps-Akademiens Förhandlingar 6, 37–100.

Maksimova, Z.A. 1972. New Devonian trilobites of the Phacopoidea [Novye devonskie trilobity Phacopoidea]. Paleontologicheskij Zhurnal 14(1), 88–95.

Meslinger, K. 1987. Fine structure of scorpion trichobothria (Arachnida, Scorpiones). Zoomorphology 107, 49–57.View article

Morris, S.F. 1988. A review of British trilobites, including a synoptic revision of Salter’s monograph. Monograph of the Palaeontographical Society 140(574), 1–316.

Murchison, R.I. 1839. The Silurian System, founded on geological researches in the counties of Salop, Hereford, Radnor, Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester and Stafford; with descriptions of the coalfields and overlying formations. London.View article

Přibyl, A. & Vaněk, J. 1971. Phacopida Struve, 1959 (Trilobita) im böhmischen Silur und Devon. Acta Universitatis Carolinae, Geologica 1, 53–68.

Ramsköld, L. 1985. Silurian phacopid and dalmanitid trilobites from Gotland. Stockholm Contributions in Geology 40(1), 1–62.

Reed, F.R.C. 1901. Woodwardian Museum notes: Salter’s undescribed species, 3. Geological Magazine 4(8), 106–110.View article

Salter, J.W. 1864. A monograph of the British trilobites from the Cambrian, Silurian and Devonian formations, part 1. 224 pp. Monograph of the Palaeontographical Society.

Sandford, A.C. & Holloway, D.J. 2006. Early Silurian phacopide trilobites from central Victoria, Australia. Memoirs of Museum Victoria 63, 215–255.View article

Schoenemann, B. 2007. Trilobite eyes and a new type of neural superposition eye in an ancient system. Palaeontographica A, 281, 63–91.View article

Šnajdr, M. 1985. Bohemian representatives of the subfamily Odontochilinae subf. nov. Věstník Ústředního ústavu geologického 60, 165–169.

ŠNajdr, M. 1987a. Reussiana, new name replacing Reussia Maksimova, 1972 (Trilobita). Věstník Ústředního ústavu geologického 62, 104.

Šnajdr, M. 1987b. Bohemian Lower Devonian Odontochilinae (Trilobita). Sborník geologických věd, Paleontologie 28, 9–60.

Struve, W. 1959. Beitrage zur Kenntnis der Phacopina (Trilobita). 4: Volkops volki n.g., n. sp., ein Phacopinae aus dem deutschen Ordovizium. Senckenbergiana lethaea 40, 29–45.

Stürmer, W. & Bergström, J., 1973. New discoveries on trilobites by X-rays. Paläontologische Zeitschrift 47, 104–141.View article

Thomas, A.T. & Lane, P.D. 1984. Autecology of Silurian trilobites, 55–69. In Bassett, M.G. & Lawson, J.D. (eds) Autecology of Silurian organisms. Special Papers in Palaeontology 32.

Vogdes, A.W. 1890. A bibliography of Palaeozoic Crustacea from 1698 to 1899, including a list of the North American species and a systematic arrangement of genera. Bulletin of the US Geological Survey 63, 1–177.

Weller, S. 1907. The palaeontology of the Niagara Limestone in the Chicago area. The Trilobita. Bulletin of the Chicago Academy of Sciences 4, 163–281.