1661-8726/07/020243-7 Swiss j. geosci. 100 (2007) 243–249 DOI 10.1007/s00015-007-1221-5 Birkhäuser Verlag, Basel, 2007 A new bourgueticrinid (Crinoidea) from the Castle Hayne Formation (Eocene) of southeastern North Carolina, USA CHARLES N. CIAMPAGLIO1,STEPHEN K. DONOVAN2* & PATRICIA G. WEAVER3 Key words: Crinoids, Eocene, North America, systematics, new species ABSTRACT Cenozoic fossil stalked crinoids are poorly known. Based on a large, new col- are at least 1.5 times the height of radials. Some columnals of mesistele and lection of disarticulated columnals and cups, a new gracile bourgueticrinid, dististele have distinctly warty latera. This is the first nominal bourgueticrinid Democrinus simmsi species nov., is described from the Eocene Castle Hayne from the Paleogene of North America, despite their moderate diversity locally Formation as exposed at the Martin Marietta Quarry, New Hanover County, in the Paleogene of Eurasia. The small size of cups and disarticulated colum- southeastern North Carolina (USA). The smooth, conical cup of D. simmsi nals of gracile bourgueticrinids are almost certainly a factor in our poor knowl- commonly is widest at the oral surface, moderately flared orally in small (juve- edge of their fossil record. nile?) specimens, but tends to be subcylindrical in larger examples. The basals Introduction Geological setting and stratigraphy The Middle Eocene Castle Hayne Formation of North Caroli- The outcrop of the Middle-Upper Eocene Castle Hayne For- na is well known for its abundant and diverse echinoderm mation is between 16 and 32 km wide, and extends from fauna (Emmons 1858; Kellum 1926; Cooke 1959; Kier 1980; Brunswick County and New Hanover County north through Carter et al. 1988; Ciampaglio & Weaver 2004). While previ- east-central Pender County, through western portions of On- ous research has focused on the echinoids (e.g. Cooke 1959; slow, Jones and Craven counties, and into southeastern Pitt Kier 1980), a systematic survey of the crinoid fauna has only County in southeastern North Carolina (Otte 1986) (Fig. 1). recently been initiated (Ciampaglio & Weaver 2004). This is Bounded by unconformities above and below, the formation is undoubtedly due, in part, to the disarticulated nature of typically overlain by Oligocene and younger rocks, and under- crinoid fossils, and the difficulty of isolating, recognizing and lain by Paleocene and Cretaceous deposits. The Castle Hayne identifying individual elements, all of which have discouraged Formation is thought to range from middle Lutetian to Pri- taxonomic studies. Although several species of comatulid abonian in age (Harris & Laws 1997). crinoids have been described from the Castle Hayne Forma- Baum et al. (1978), Ward et al. (1978), Kier (1980), Zullo & tion (Emmons 1858; Ciampaglio & Weaver 2004), its stalked Harris (1986, 1987) and Harris & Zullo (1987) have all inter- forms have been largely overlooked. Careful examination of a preted the lithostratigraphic subdivisions of the Castle Hayne prepared bryozoan-echinoid calcirudite from the Martin Mari- Formation (Fig. 2). Ward et al. (1978) named three lithosomes etta Quarry near Castle Hayne, New Hanover County (North within the limestones of the formation; in ascending order, the Carolina, USA), has yielded over 1,000 specimens, mainly cups New Hanover, Comfort and Spring Garden members. The first and columnals, of a new species of gracile bourgueticrinid. is a slightly arenitic, micritic and phosphatic lithocalcirudite; the Comfort Member (middle) is a grey- to cream-coloured, 1 Department of Geology, Wright State University, Lake Campus, 7600 SR 703, Celina, Ohio 45822-2952, USA. 2 Department of Geology, Nationaal Natuurhistorisch Museum, Postbus 9517, NL-2300 RA Leiden, The Netherlands. 3 North Carolina State Museum of Natural Sciences, 11 West Jones Street, Raleigh, North Carolina 27601-1029, USA. * Corresponding author: S.K. Donovan. E-mail: [email protected] A new Eocene bourgueticrinid (Crinoidea) 243 Fig. 2. Correlation between sequence stratigraphy (Harris & Zullo 1987), lithostratigraphy (Ward et al. 1978) and biostratigraphy (Kier 1980) of the Castle Hayne Formation (after Ciampaglio & Weaver 2004: fig. 1). The New Hanover, Comfort and Spring Garden members are time transgressive and do Fig. 1. The outcrop of the Middle-Upper Eocene Castle Hayne Formation (in not occur in all depositional sequences, essentially forming a ‘fining-upwards’ grey) in North Carolina (USA), with the location of the Martin Marietta lithology in each depositional sequence in which they occur. Quarry. bryozoan-echinoid calcirudite, grading into a fine calcarenite; the formation from one exposure to another and the isolation and the uppermost unit is a tan to grey, arenaceous, molluscan- of outcrops (Otte 1986). Nevertheless, stratigraphic analysis mould biocalcirudite. All units are typically diachronous. has produced a fairly clear picture of the history and environ- Applying a sequence-stratigraphic approach, Harris & ment in which these carbonates were deposited (Gibson 1970; Zullo (1987) divided the Castle Hayne Formation into five Jones 1983; Otte 1986; Zullo & Harris 1986; Harris & Laws depositional sequences (numbered 0–4). These sequences, sep- 1997). Sea level rise during the Middle Eocene, coupled with a arated by regional unconformities, reflect changes in sea-level productive, relatively warm-water environment, allowed for and migrating depositional environments. A complete litho- the development of limestones of the Castle Hayne Formation logic section consists of a phosphate pebble biomicrudite base (Gibson 1970; Otte 1986; Harris & Laws 1997). The presence overlain by biosparudite, in turn overlain by biomicrudite of fossiliferous, mollusc-bearing outliers as far west as Wake grading into biosparudite. However, this complete lithostrati- County indicate that the warm Eocene sea extended at least graphic section is rarely seen at a single locality and sequences that far ‘inland’ (Richards 1950; Carter et al. 1988). The depo- are typically represented by different lithologies at various sitional basin was formed by differential movement of fault- exposures. bounded crustal blocks, which also controlled thicknesses and Using an echinoid-based biostratigraphic approach, Kier distributions of carbonate lithofacies of the strata assigned to (1980) divided the Castle Hayne Formation into three infor- the formation (Jones 1983). The Middle Eocene sea floor of mal biozones (early, middle, late). These temporal biozones North Carolina was composed of shoreline-parallel environ- overlap somewhat with the depositional sequences defined by ments that define the inner (0–15 m water depth), middle Harris & Zullo (1987), and provide a reasonable biostrati- (15–50 m) and outer shelves (50–100 m). Depositional envi- graphic interpretation. Correlation between sequence stratig- ronments were in an open, relatively warm-water embayment raphy (Harris & Zullo 1987), biostratigraphy (Kier 1980) and that paralleled the present-day shoreline (Jones 1983; Otte lithostratigraphy (Ward et al. 1978) is provided in Figure 2. 1986). Stratigraphic location of bourgueticrinids within the Castle Hayne Formation is not precisely known, but based on the lo- Materials and methods cation in the quarry where the specimens were collected, cou- pled with the presence of the echinoid Periarchus lyelli, it is Cream-coloured, bryozoan-rich matrix was collected from likely that the crinoids documented herein stem from se- abundant spoil piles in the Martin Marietta Quarry, Castle quences 3 or 4 of Zullo & Harris (1987). Hayne, New Hanover County, North Carolina. All matrix was Interpretation of the environment in which the Castle screened through a 6 mm mesh to remove large clasts and fos- Hayne Formation was deposited is complicated by several fac- sil fragments. The remaining matrix was then screened through tors, including the presence of formation outliers throughout a 0.8 mm mesh, to remove silt and small fragments, and then the southern coastal plain, the abruptly changing thickness of washed in tap water to remove remaining silt or clay. Once 244 C.N. Ciampaglio, S.K. Donovan & P.G. Weaver thoroughly dried, prepared matrix was examined under magni- than 6) low proximal columnals have synostosial articulations. fication in order to isolate and pick crinoid specimens. All fig- More distal columnals resemble those of other Bathy- ured specimens were mounted and sputter-coated with crinidae.”. gold/palladium using an Anatech Hummer V sputter coater. Once coated, all figured specimens were examined and pho- Discussion. – Of the other bathycrinid genera listed by Ras- tographed using a Philips XL 30 ESEM TMP scanning elec- mussen (1978), Bathycrinus WYVILLE THOMSON 1872 has low tron microscope (SEM). basals and a broadly conical cup with a broad radial cavity; Conocrinus D’ORBIGNY 1850 has high basals which may over- grow radials and proxistele, but the cup is strongly vase-like, Systematic palaeontology widest below the radial facets; Dunnicrinus MOORE 1967 and Morphological terminology of the crinoid endoskeleton used Monachocrinus CLARK 1917 have conical cups in which radials herein follows that of Moore et al. (1968, 1978) and Ubaghs and basals are about equal in height; and Rhizocrinus SARS (1978). Classification of the articulate crinoids follows Simms 1868 has basals slightly higher than radials, but sutures of the and Sevastopulo (1993), Simms et al. (1993) and Cohen et al. cup are fused. (2004). Specimens described