Bryozoans in transition: The depauperate and patchy Jurassic biota

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Abstract

Bryozoans were profoundly affected by the end Permian and probably also by the end Triassic mass extinction events. Their recovery in terms of diversity and disparity during the Jurassic was slow and geographically patchy. Critical compilation of data from the published literature reveals only 172 valid species – 160 cyclostomes, 10 ctenostomes and 2 cheilostomes – some as yet not formally named. However, the rate of description of new Jurassic bryozoan species during the last two hundred years implies that many more species remain to be discovered and described. The Jurassic is the only geological period during which cyclostomes were the dominant order and is also important in having the oldest cheilostome bryozoan, the first representative of the order that dominates the modern bryozoan biota. Species diversity peaked in the Bathonian where local assemblages may contain up to 33 species. Encrusters account for 124 (73%) of the 172 Jurassic species, among which small sheet-like forms, especially those assigned to the form-genus 'Berenicea', are the most numerous. The overwhelming predominance in the Jurassic of ‘weeds’ with runner, ribbon or sheet colony-forms is striking. Unlike the Triassic and Cretaceous, large, tree-like or frondose erect colonies are uncommon, and species with fenestrate, articulated and free-living colonies are unknown. Of 92 geographically categorized entries for Jurassic bryozoans in the Zoological Record (1937–2003), 80 (87%) are European records. Outside Europe, diversity appears to have remained low throughout the Jurassic, and non-weedy species are particularly scarce. Compared with the Cretaceous, Jurassic bryozoans show no adaptations that can be interpreted as related to the increased predation pressure associated with the Mesozoic Marine Revolution. The Jurassic bryozoan biota shares characteristics with both the stenolaemate-dominated Palaeozoic–Triassic biota and the cheilostome-dominated Cretaceous–Recent biotas.

Introduction

Bryozoans are among the best-represented macroinvertebrates in the fossil record, reflecting the presence of a calcareous skeleton in the great majority of species. The pattern of changing bryozoan diversity through the Phanerozoic closely parallels that of marine invertebrates in general, as reflected by the similarity between the bryozoan family diversity curve (e.g. Taylor and Larwood, 1990) and the iconic Sepkoski marine invertebrate family curve (e.g. Sepkoski, 1981). Particularly striking features of the bryozoan family pattern are the rapid climb in diversity during the Ordovician to a level that is maintained as a plateau through most of the Palaeozoic, followed by a dramatic decline at the end of this era and renewed diversification in the post-Palaeozoic, scarcely perturbed by the KT event, that culminates in the diversity high of the Neogene. Available data on species numbers through time show a very similar pattern (Horowitz and Pachut, 2000, Fig. 1).

Recovery from the Permian mass extinction occurred more slowly in bryozoans than in many other invertebrate groups. Indeed, it took until the Late Cretaceous for the family-level diversity of the Palaeozoic to be regained. Both the Triassic and the Jurassic contain depauperate bryozoan biotas. Triassic bryozoans are considered to be particularly scarce and there has been a tendency to describe all newly discovered examples (Nakrem and Mørk, 1991, Schäfer et al., 2003a, Schäfer et al., 2003b, Zágorsek, 1993). Most Triassic bryozoans belong to Palaeozoic ‘holdover taxa’, especially trepostomes (see Schäfer and Fois, 1987). While there exist several papers reviewing Triassic bryozoans (Bizzarini and Braga, 1982, Morozova, 1969, Sakagami, 1985, Schäfer and Fois, 1987, Schäfer, 1994), Jurassic bryozoans have been conspicuously neglected. Nonetheless, the Jurassic was an important time in bryozoan evolution, witnessing a radiation of cyclostomes as well as the first appearance of cheilostomes, the bryozoan order that dominates at the present day.

This paper reviews the bryozoan biota of the Jurassic. We have compiled data from the literature and our own unpublished research records to document genus- and species-level patterns of bryozoan diversity through the stages of the Jurassic, assemblage species richness, the geographical distribution of Jurassic bryofaunas, and aspects of bryozoan palaeoecology. One hope is that this review will increase the awareness of Jurassic bryozoans among geologists and palaeontologists. The need for this is evident from the high incidence in the literature of inexact identifications of bryozoans as well as misidentification of other groups (especially sponges) as bryozoans. First, however, we describe the history of research and review the taxonomic composition of the Jurassic bryozoan biota.

Section snippets

History of research

Lamouroux (1821) was the first scientist formally to name bryozoan species from the Jurassic. Based on collections from the Bathonian of Normandy, he described 23 new species of ‘polypiers’ that subsequently became regarded as bryozoans. However, three of these species are now known to be sponges and one is an Upper Cretaceous bryozoan (Walter, 1970, pp. 214–215). Several of Lamouroux's Jurassic taxa are the type species of genera, either introduced by Lamouroux himself (Apsendesia, Berenicea,

Taxonomic composition of the Jurassic bryozoan biota

Three orders of marine bryozoans are represented unequivocally in the Jurassic: Cyclostomata, Cheilostomata and Ctenostomata. There are also records of statoblasts produced by the freshwater class Phylactolaemata, a dubious record of the Palaeozoic order Fenestrata, a trepostome and some ‘pseudobryozoans’.

Generic and specific diversity changes through the Jurassic

Critical appraisal of the literature on Jurassic bryozoans, together with unpublished records of occurrences, has allowed the assembly of a database of species occurrences at stage-level resolution. In total, this database contains 172 species, compared with the diversity estimate of 202 species quoted for the Jurassic by Horowitz and Pachut (2000, Table 1). Most species (102; 60%) in our database are known from only a single stratigraphical stage. However, 29 species (17%) occur in two stages,

Biogeography

Anecdotal observations suggest that Jurassic bryozoans are rare outside northern Europe. Most of the formally named species have been described using material from France, England or Germany (see historical review above), with just a few taxa based on Polish (Hara and Taylor, 1996, Reuss, 1867), Spanish (Taylor and Sequeiros, 1982) or Russian (Gerasimov, 1955, Viskova, 2006) material. Additional European records of Jurassic bryozoans have been made in Spain (Higazi, 1985, López, 1987, Reolid

Colony-forms

Several different schemes exist for classifying colony-forms in bryozoans, varying in the degree of subdivision as well as the terminology employed (Hageman et al., 1998, Nelson et al., 1988, Schopf, 1969). For the purposes of the current analysis of colony-forms in Jurassic bryozoans, a coarse subdivision is here adopted, based on the generalized geometric shapes recognised in benthic colonial animals by Jackson (1979). Colonies of Jurassic species can be classified into six main shape

Palaeoecology

As epibenthic suspension feeders, bryozoans in the Jurassic were dependent on hard or firm substrates for attachment, encrustation or boring, and a phytoplanktonic food resource, like their counterparts at the present day. While the details of the trophic preferences of bryozoans in the Jurassic are unknown, some information is available on the identity of the substrates they colonized, as well as biotic interactions with living substrates and other organisms.

Many Jurassic bryozoans are

Jurassic bryozoans and the Mesozoic Marine Revolution

The Mesozoic Marine Revolution (MMR) is a hypothesis of evolutionary changes driven by escalating biotic interactions, especially predation but also competition (Vermeij, 1977, Vermeij, 1987, Vermeij, 2008). Although the MMR intensified in the Cretaceous, it can be traced back to the Late Triassic, and Aberhan et al. (2006) provided evidence that it had an impact on Jurassic benthic animals. Is there any evidence for the impact of the MMR in Jurassic bryozoans? This question can be approached

Conclusions

  • 1.

    Bryozoans were very slow to recover from the Permian and Triassic mass extinctions and the known Jurassic bryozoan fossil record comprises fewer than 200 species (172 species are included in our database). This is significantly greater than the diversity of the Triassic but an order of magnitude less than that of the Cretaceous (Horowitz and Pachut, 2000).

  • 2.

    The rate of description of new Jurassic bryozoan species has continued to climb steadily over the last two hundred years, showing no sign of

Acknowledgements

This paper arose from presentations given at the 4th Polish Jurassica Symposium held in September 2004 at Baltów, as well as the Annual Meeting of the Geological Society of America held in October 2005 at Salt Lake City. Participation of PDT in the latter was made possible by a grant from the Royal Society. Rachel Prebble assisted with data compilation. The German Research Foundation (DFG) is thanked for the financial support to AE under DFG-Projekt Scha 355/22-1 “Radiation of bryozoans in

References (210)

  • BrookfieldM.E.

    The life and death of Torquirhynchia inconstans (Brachiopoda, Upper Jurassic) in England

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (1973)
  • FürsichF.T. et al.

    Open crustacean burrows associated with hardgrounds in the Jurassic of the Cotswolds, England

    Proceedings of the Geologists' Association

    (1975)
  • HollingworthN.T.J. et al.

    The Callovian–Oxfordian boundary in Oxfordshire and Wiltshire based on two new temporary sections

    Proceedings of the Geologists' Association

    (1992)
  • AberhanM. et al.

    Testing the role of biological interactions in the evolution of mid-Mesozoic marine benthic ecosystems

    Paleobiology

    (2006)
  • Ait AddiA. et al.

    Les bioconstructions du Bajocien-Bathonien pp. du Haut-Atlas marocain (Nord d'Errachidia-Boudenib): sédimentogenèse paléogéographique

    Géologie Méditerranéenne

    (1998)
  • AngseesingJ.P.A.

    Preservation of Stroudithyris in the Middle Jurassic of the Cotswold Hills

    Proceedings of the Cotteswold Naturalists' Field Club

    (2005)
  • ArkellW.J.

    Jurassic Geology of the World

    (1956)
  • BertlingM.

    Ökologie und Taxonomie koralleninkrustierender Bryozoen des norddeutschen Malm

    Paläontologische Zeitschrift

    (1994)
  • BertlingM.

    Ropalonaria arachne (Fischer, 1866) eine Bryozoen-Bohrspur aus dem norddeutschen Malm

    Münstersche Forschungen zur Geologie und Paläontologie

    (1995)
  • BishopJ.D.D.

    Colony form and the exploitation of spatial refuges by encrusting Bryozoa

    Biological Reviews

    (1989)
  • BizzariniF. et al.

    Prima segnalazione del genere Stomatopora (Bryozoa Cyclostomata) nel Trias Superiore delle Dolomite Orientali (Italia)

    Società Veneziana di Scienze Naturali Lavori

    (1981)
  • BizzariniF. et al.

    The Triassic Bryozoa of the Western Tethyan basin

    Bollettino della Societa Paleontologica Italiana

    (1982)
  • BizzariniF. et al.

    Braiesopora voigti n. gen. n. sp. (cyclostome bryozoan) in the S. Cassiano Formation in the Eastern Alps (Italy)

  • BizzariniF. et al.

    Corynotrypoides ladina gen. et sp. nov., a questionable cyclostomatous bryozoan from the Upper Triassic of the Eastern Dolomites (NE Italy)

  • BlakeD.B.

    The Arthrostylidae and articulated growth habits in Paleozoic bryozoans

  • BoardmanR.S.

    Origin of the post-Triassic Stenolaemata (Bryozoa): a taxonomic oversight

    Journal of Paleontology

    (1984)
  • BolleM.-P. et al.

    Microfaciès, minéralogie, stratigraphie du Dogger de la région du Furcil (NE)

    Bulletin de la Société Neucháteloise des Sciences Naturelles

    (1996)
  • BromleyR.G.

    A stratigraphy of marine bioerosion

  • BroodK.

    Upper Cretaceous Bryozoa from Need's Camp, South Africa

    Palaeontologia Africana

    (1977)
  • BugeE. et al.

    Atractosoecia incrustans (d'Orbigny) (Bryozoa Cyclostomata) espèce bathonienne symbiotique d'un Pagure

    Bulletin de la Société Géologique de France

    (1970)
  • CanuF.

    Contributions à l'étude des Bryozoaires fossiles. Bryozoaires jurassiques

    Bulletin de la Société Géologique de France

    (1913)
  • CanuF.

    Les ovicelles des Bryozoaires cyclostomes. Études sur quelques familles nouvelles et anciennes

    Bulletin de la Société Géologique de France

    (1918)
  • CanuF.

    Bryozoaires. Types du Prodrome de Paléontologie d'Alcide d'Orbigny

    Annales Paléontologie

    (1931)
  • CanuF. et al.

    Studies on the cyclostomatous Bryozoa

    Proceedings of the United States National Museum

    (1922)
  • CanuF. et al.

    Études sur les ovicelles des Bryozoaires Jurassiques

    Bulletin de la Société Linnéenne de Normandie

    (1929)
  • CheethamA.H. et al.

    Morphological differentiation of avicularia and the proliferation of species in the mid-Cretaceous Wilbertopora Cheetham, 1954 (Bryozoa: Cheilostomata)

    Journal of Paleontology

    (2006)
  • ConroyJ. et al.

    Bored and encrusted carbonate cobbles and hardgrounds at the base of a regressive sequence (lower Sundance Formation, Middle Jurassic, eastern Wyoming)

    Geological Society of America Abstracts with Programs

    (2002)
  • CookP.L. et al.

    A short history of the lunulite Bryozoa

    Bulletin of Marine Science

    (1983)
  • CraginF.W.

    Paleontology of the Malone Jurassic Formation of Texas

    U.S. Geological Survey Bulletin

    (1905)
  • CuffeyR.J. et al.

    New bryozoan species from the Mid-Jurassic Twin Creek and Carmel formations of Wyoming and Utah

    Journal of Paleontology

    (1984)
  • DacquéE.

    Beiträge zur Geologie des Somalilandes. II. Teil. Oberer Jura

    Beiträge zur Paläontologie Oesterreich-Ungarns

    (1905)
  • de BlainvilleH.M.D.

    Zoophytes

    Dictionnaire des Sciences Naturelles

    (1830)
  • DoganA.U. et al.

    Classifications of hardgrounds based upon their strength properties

    Carbonates and Evaporites

    (2006)
  • DollfusS.

    Über den Helvetischen Dogger zwischen Linth und Rhein

    Eclogae Geologicae Helvetiae

    (1965)
  • d'OrbignyA.

    Prodrome de paléontologie stratigraphique universelle des animaux Mollusques et rayonnés

    (1850)
  • d'OrbignyA.

    Paléontologie Francaise

    Terrain Crétacé, 5. Bryozoaires

    (1851–4)
  • EngeserT. et al.

    Supposed Triassic bryozoans in the Klipstein collection from the Cassian formation of the Italian dolomites redescribed as calcified demosponges

    Bulletin of the British Museum (Natural History). Geology Series

    (1989)
  • EnsomP.

    Pyriporopsis portlandensis Pohowsky 1973, a bryozoan from the Scallop Member, Purbeck Limestone Formation, of Worbarrow Tout, Dorset

    Proceedings of the Dorset Natural History and Archaeological Society

    (1985)
  • ErnstA. et al.

    Palaeozoic vs. post-Palaeozoic Stenolaemata: phylogenetic relationship or morphological convergence? Courier Forschungsinstitut Senckenberg

    (2006)
  • EtallonA.

    Etudes paléontologiques sur le Haut Jura

    Mémoires de la Société d'Emulation Doubs

    (1859)
  • EtallonA.

    Etudes paléontologiques sur le Jura graylois

    Mémoires de la Société d'Emulation Doubs

    (1862)
  • FeldmanH.R. et al.

    Epi- and endobiontic organisms on Late Jurassic crinoid columns from the Negev Desert, Israel: implications for co-evolution

    Lethaia

    (1998)
  • FlügelE.

    Ein neues Vorkommen von Plassenkalk (Ober-Jura) in Steirischen Salzkammergut, Österreich

    Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen

    (1964)
  • FürsichF.T.

    Genesis, environments, and ecology of Jurassic hardgrounds

    Neues Jahrbuch für Geologie und Paläontologie. Abhandlungen

    (1979)
  • FürsichF.T.

    Preserved life positions of some Jurassic bivalves

    Paläontologische Zeitschrift

    (1980)
  • FürsichF.T. et al.

    Hardgrounds, reworked concretion levels and condensed horizons in the Jurassic of western India: their significance for basin analysis

    Journal of the Geological Society (London)

    (1992)
  • FürsichF.T. et al.

    Growth and disintegration of bivalve-dominated patch reefs in the Upper Jurassic of southern England

    Palaeontology

    (1994)
  • GerasimovP.A.

    Index Fossils (Mesozoic) of the European USSR (Central). Part 2

    (1955)
  • GardetG. et al.

    Contribution a l'étude paléontologique du Moyen-Atlas Septentrional

    Notes et Mémoires de la Division des Mines et de la Géologie Service Géologique de la Republique Francaise au Maroc

    (1946)
  • GoldfussG.A.

    Petrefacta Germaniae. Teil 1

    (1826–33)
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