Cretaceous Bryozoa from the Campanian and Maastrichtian of the Atlantic and Gulf Coastal Plains, United States

Cretaceous Bryozoa from the Campanian and Maastrichtian of the Atlantic and Gulf Coastal Plains, United States Paul D. Taylor & Frank K. McKinney Taylor, P.D. & McKinney, F.K. Cretaceous Bryozoa from the Campanian and Maastrichtian of the Atlan- tic and Gulf Coastal Plains, United States. Scripta Geologica, 132: 1-346, 141 pls, 5 fi gs, 2 tables, Leiden, May 2006. Paul D. Taylor, Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD, UK ([email protected]); Frank K. McKinney, Department of Geology, Appalachian State Univer- sity, Boone, North Carolina 28608, U.S.A., and Department of Palaeontology, Natural History Museum, Cromwell Road, London SW7 5BD, UK ([email protected]). Key words – Bryozoa, Cretaceous, U.S.A., taxonomy The Late Cretaceous bryozoan fauna of North America has been severely neglected in the past. In this preliminary study based on museum material and a limited amount of fi eldwork, we describe a total of 128 Campanian-Maastrichtian bryozoan species from Delaware, New Jersey, North Carolina, South Carolina, Tennessee, Georgia, Alabama, Mississippi, Louisiana and Arkansas. Eighty-two of these species are new, as are fi ve (Basslerinella, Pseudoallantopora, Kristerina, Turnerella and Peedeesella) of the 77 genera. One new family, Peedeesellidae, is proposed. Cheilostomes, with 94 species (73 per cent of the total), outnumber cyclostomes, with 34 species (27 percent), a pattern matching that seen elsewhere in the world in coeval deposits. There appear to be very few species (4) in common with the better known bryozoan faunas of the same age from Europe. Although both local and regional diversities are moderately high, most of the Atlantic and Gulf Coastal Plain bryozoans are encrusters; erect species are uncommon and are never present in suffi cient density to form bryozoan limestones, in contrast to some Maastrichtian deposits from other regions. Contents Introduction ................................................................................................................................................................. 1 Geological setting ..................................................................................................................................................... 3 Palaeoenvironments ............................................................................................................................................... 8 Material and methods ........................................................................................................................................ 10 Localities ..................................................................................................................................................................... 12 Systematic palaeontology ................................................................................................................................ 16 Acknowledgements ........................................................................................................................................... 188 References ................................................................................................................................................................ 189 Introduction Bryozoans are colonial invertebrates with a rich Ordovician to Holocene fossil record. Fossil bryozoans are most often found in sedimentary rocks formed in well-oxygenated shelf environments provisioned with fi rm or hard substrates, including sequences where clastic sediments and carbonate sedimentary rocks are intermixed. Just such conditions prevailed over the coastal plains of the eastern U.S.A. for much of the Late Cretaceous. However, so infrequently are Upper Cretaceous bryozoans from the eastern states of the U.S.A. mentioned in the literature that it would be easy to be misled into believing 2 Taylor & McKinney. Cretaceous Bryozoa. Scripta Geol., 132 (2006) that they are rare and of low diversity. This situation contrasts strikingly with coeval deposits in Europe where the high abundance and diversity of bryozoans is well-known, and where they are sometimes present in rock-forming quantities, for example in the Tuff-Chalk of Maastricht in The Netherlands (Felder & Bosch, 2000) and the contemporaneous Maastrichtian bryozoan mounds of Denmark (Larsen & Håkansson, 2000). Knowledge of the fossil record of Cretaceous bryozoans is overwhelmingly de- pendent on European occurrences, even though diverse Cretaceous bryozoan faunas do occur in other parts of the world (e.g., South Africa – Brood, 1977; India - Guha & Nathan, 1996). Perceived evolutionary patterns during this important phase of evolutionary radiation are consequently dominated by European data. Our purpose here is to describe the diverse, yet hitherto largely neglected, latest Cretaceous bryozoan faunas from the Atlantic and Gulf Coastal Plains. The region of study extends from New Jersey in the northeast to Alabama in the south and Arkansas in the west. Only two major works have ever been published on bryozoans from the Campanian- Maastrichtian deposits of this region. Canu & Bassler (1926) described 22 species of bryozoans from the Maastrichtian sequence of Coon Creek in Tennessee, a fauna briefl y revised by McKinney & Taylor (in press). Shaw (1967) described the cheilostome bryozoans from the Upper Cretaceous of Arkansas. In addition, a handful of other papers have described, fi gured or mentioned Upper Cretaceous bryozoans from this broad geographical region (Butler & Cheetham, 1958; Frey & Larwood, 1971; Voigt, 1971; Turner, 1975, 1979; Cuffey, 1994; Taylor & Cuffey, 1996; Taylor & McKinney, 2000, 2002). Reasons for the paucity of previous research on these bryozoan faunas are several- fold, but perhaps the most obvious is that most of the species present are encrusting forms (Plate 1) which are much less conspicuous to geologists than are the erect bryozoans that occur so commonly in the Upper Cretaceous of Europe, as well as in various Palaeozoic formations of North America. Although often small and inconspicuous, encrusters typically account for a greater diversity in post-Palaeozoic bryozoan faunas than do erect species (e.g., Cheetham et al., 1999). This paper represents only a fi rst attempt to describe the bryozoan fauna of a vast region. We have revised all of the bryozoan taxa (excluding ctenostome borings) estab- lished in the few previous publications mentioned above, as well as describing the bryozoans from new collections made available to us by other collectors or obtained during our own limited fi eldwork. Our results should therefore be regarded as provi- sional - many additional species undoubtedly remain to be discovered and details of the geographical and stratigraphical distributions of species will need to be refi ned by future researchers. We know, for example, that there is much as yet unstudied material in the fi eld collections of N.F. Sohl that are now in the National Museum of Natural His- tory, Smithsonian Institution, Washington, D.C. Wherever possible we have made comparisons with contemporaneous bryozoan species from Europe (and elsewhere). However, the enormously rich European bryozoan biota is still inadequately described and illustrated, in spite of the efforts of, in particular, the late Professor Ehrhard Voigt. We have avoided applying the names used for poorly described European species to North American species. While revision of the myriad of European species created in the 19th century by such authors as d’Orbigny, Reuss, Pergens and von Hagenow, and subsequently in the early 20th century by Gre- gory, Lang and Levinsen, may eventually show that some of our new species are junior Taylor & McKinney. Cretaceous Bryozoa. Scripta Geol., 132 (2006) 3 synonyms, our conservative approach should minimize the pitfalls of spurious stratigraphical correlation and palaeobiogeography based on doubtful identifi cations. Geological setting Bryozoans occur in each of the eastern North American regions of Campanian to Maastrichtian outcrops in the Coastal Plain from its seaward termination in New Jersey to Arkansas, at the fl exure from the western Cretaceous belts northward into the Mis- sissippi Embayment (Fig. 1). The bryozoan-bearing units encompass a broad diversity of lithologies, generally siliciclastic and glauconitic sands along the Atlantic Coast and along the eastern margin of the Mississippi Embayment, where rivers draining the Ap- palachian Mountains were delivering abundant siliciclastic sediments. Farther away from such direct Appalachian infl uence, such as across the southern terminus of the mountains in Mississippi and Alabama and farther away in Arkansas, marls and chalks predominate. New Jersey and Delaware – Bryozoans have been noticed for decades in two units in the central Atlantic states, the Mount Laurel Formation and the Navesink Formation (e.g., Richards & Shapiro, 1963; Owens et al., 1970), and cribrimorph bryozoans have been described from the Navesink Formation in New Jersey (Turner, 1975, 1979). Di- rectly underlying the Navesink Formation (Fig. 2), the Mount Laurel Formation consists predominantly of a massive, moderately well-sorted, glauconitic, feldspar-rich quartz sand, with local regions of interbedded sands and clays and a ubiquitous pebbly quartz sand at the top of the unit (Owens & Sohl, 1969; Owens et al., 1970; Olsson et al., 1988). It outcrops at the surface in both Delaware and New Jersey. The overlying Navesink Formation consists

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