New Dinoflagellate Cyst and Acritarch Taxa from the Pliocene and Pleistocene of the Eastern North Atlantic (DSDP Site 610)

Home , Acritarch, Gelasian

Journal of Systematic Palaeontology 6 (1): 101–117 Issued 22 February 2008 doi:10.1017/S1477201907002167 Printed in the United Kingdom C The Natural History Museum New dinoﬂagellate cyst and acritarch taxa from the Pliocene and Pleistocene of the eastern North Atlantic (DSDP Site 610)

Stijn De Schepper∗ Cambridge Quaternary, Department of Geography, University of Cambridge, Downing Place, Cambridge CB2 3EN, United Kingdom

Martin J. Head† Department of Earth Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario L2S 3A1, Canada

SYNOPSIS A palynological study of Pliocene and Pleistocene deposits from DSDP Hole 610A in the eastern North Atlantic has revealed the presence of several new organic-walled dinoflagellate cyst taxa. Impagidinium cantabrigiense sp. nov. first appeared in the latest Pliocene, within an interval characterised by a paucity of new dinoflagellate cyst species. Operculodinium? eirikianum var. crebrum var. nov. is mostly restricted to a narrow interval near the Mammoth Subchron within the Plio- cene (Piacenzian Stage) and may be a morphological adaptation to the changing climate at that time. An unusual morphotype of Melitasphaeridium choanophorum (Deflandre & Cookson, 1955) Harland & Hill, 1979 characterised by a perforated cyst wall is also documented. In addition, the stratigraphic utility of small acritarchs in the late Cenozoic of the northern North Atlantic region is emphasised and three stratigraphically restricted acritarchs Cymatiosphaera latisepta sp. nov., Lavradosphaera crista gen. et sp. nov. and Lavradosphaera lucifer gen. et sp. nov. are formally described.

KEY WORDS taxonomy, palynology, marine, Quaternary, Neogene

Contents Introduction 102 DSDP Hole 610A 102 Materials and methods 103 Samples 103 Methods 103 Repository 103 Systematic palaeontology 103 Dinoﬂagellate cysts 103 Division Dinoﬂagellata (Butschli,¨ 1885) Fensome et al., 1993 103 Subdivision Dinokaryota Fensome et al., 1993 103 Class Dinophyceae Pascher, 1914 103 Subclass Peridiniphycidae Fensome et al., 1993 103 Order Gonyaulacales Taylor, 1980 103 Suborder Gonyaulacineae (Autonym) 103 Family Gonyaulacaceae Lindemann, 1928 103 Subfamily Cribroperidinioideae Fensome et al., 1993 103 Genus Operculodinium Wall, 1967 emend. Matsuoka et al., 1997 103 Operculodinium? eirikianum Head et al., 1989b emend. Head, 1997 103 Operculodinium? eirikianum var. crebrum varietas nov. 103

∗ Present address: Fachbereich-5, Geowissenschaften, Universitat¨ Bremen, Postfach 330 440, D-28334, Germany. E-mail: sdeschepper@uni-bremen. † de. E-mail: [email protected] 102 S. De Schepper and M. J. Head

Subfamily Gonyaulacoideae (Autonym) 106 Genus Impagidinium Stover & Evitt, 1978 106 Impagidinium cantabrigiense sp. nov. 106 Subfamily uncertain 107 Genus Melitasphaeridium Harland & Hill, 1979 107 Melitasphaeridium choanophorum (Deﬂandre & Cookson, 1955) Harland & Hill, 1979 var. A 107 Acritarchs 109 Genus Cymatiosphaera Wetzel, 1933 ex Deﬂandre, 1954 109 Cymatiosphaera latisepta sp. nov. 109 Genus Lavradosphaera gen. nov. 111 Lavradosphaera crista gen. et sp. nov. 111 Lavradosphaera lucifer gen. et sp. nov. 113 Discussion 113 Acknowledgements 115 References 115

Introduction The lithology is fundamentally pelagic, comprising calcareous nannofossil ooze, calcareous mud and calcareous The taxonomy of dinoflagellate cysts for the Pliocene and nannofossil ooze containing biogenic silica. Two litholo- Pleistocene has undergone progressive refinement in recent gical units have been recognised at Site 610. Unit I (0– years (e.g. Versteegh & Zevenboom 1995; Head 1996, 1997, 135 mbsf, 0–2.7 Ma) consists of interbedded calcareous 2003a; Head & Westphal 1999; Head & Norris 2003; De mud and foraminiferal–nannofossil ooze of Quaternary and Schepper et al. 2004; Head et al. 2004). Acritarch tax- Middle Pliocene (Piacenzian) age. Unit II is represen- onomy is less well developed for the Cenozoic, although the ted by two subunits in Hole 610A. Subunit IIA (135– biostratigraphical value of small acritarchs in the Pliocene 165 mbsf; 2.7–3.5 Ma) consists of white siliceous nanno- and Pleistocene is becoming increasingly recognised, espe- fossil ooze of Middle Pliocene age. Only the upper part cially for the higher latitudes of the North Atlantic (e.g. de of Subunit IIB (165–201 mbsf; 3.5–4.0 Ma) is represen- Vernal & Mudie 1989a,b; Head 2003b; Head & Norris 2003). ted in Hole 610A and consists of white to very light grey The present study describes three new dinoflagellate cyst taxa and three new acritarch species from Deep Sea Drilling Project (DSDP) Hole 610A, drilled in the sub- 80˚ polar eastern North Atlantic. It highlights, in particular, the Latitude Longitude DSDP 610A 53˚13’ N 18˚53’ W biostratigraphical value of small acritarchs in the higher lat- DSDP 603C 35˚30’ N 70˚2’ W itudes of the North Atlantic and adjacent seas. The study is ODP 642 67˚13’ N 2˚56’ E part of a larger investigation into the palynology of DSDP ODP 643 67˚43’ N 1˚2’ E ODP 644 66˚41’ N 4˚35’ E Hole 610A (De Schepper 2006). This hole was chosen for ODP 645 70˚27’ N 64˚39’ W ODP 646 58˚13’ N 48˚22’ W the completeness of its sedimentary record, relatively high ODP 963 37˚2’ N 13˚11’ E Baffin Bay sedimentation rates and independent age control (Shipboard Norwegian- Scientific Party 1987; Kleiven et al. 2002). 645 Greenland Sea 643 642 644 DSDP Hole 610A 60˚ Labrador Sea ◦ ◦ DSDP Hole 610A (53 13.297 N, 18 53.213 W; water depth, 646 2417 m) is located approximately 700 km due west of Ireland on the Feni Drift at the south-western edge of the Rockall 610A Trough (Fig. 1). The hole was drilled in 1983 on the crest of North Atlantic Ocean a sediment wave on the Feni Drift, as part of DSDP Leg 94. This major sediment drift is nearly 600 km in length, up to 40˚ 603C 700–1000 m thick and is characterised by rapid sedimenta- 963 tion controlled by bottom currents. It has been accumulating since Oligocene or Miocene time (Shipboard Scientific Party -60˚ -30˚ 0˚ 1987) or possibly as early as the Eocene (Kidd & Hill 1987). DSDP Hole 610A was drilled to a total depth of 201 m Figure 1 Location of Deep Sea Drilling Project (DSDP) Hole 610A in below sea floor (mbsf) and terminated in the Lower Plio- the eastern North Atlantic Ocean and location of other DSDP and cene at about 4.0 Ma (De Schepper 2006; unpublished data). Ocean Drilling Program (ODP) sites mentioned in the text. New Pliocene and Pleistocene dinoflagellates and acritarchs 103 nannofossil ooze of Middle Pliocene and Early Pliocene scope slides were scanned along non-overlapping traverses (Zanclean) age (Shipboard Scientific Party 1987, based on under a 40× objective and acritarchs and dinoflagellate cysts our new time scale). were counted until at least 300 dinoflagellate cysts had been This hole was chosen specifically for its excellent core enumerated (Fig. 2). After reaching this number, the re- recovery (95%), absence of hiatuses and high sedimentation mainder of the slide was searched for rare species using rates (Shipboard Scientific Party 1987). The accumulation a20× objective. Detailed morphological analysis of dino- rate during the Pliocene and Quaternary is high and fairly flagellate cysts and small acritarch species was undertaken constant, with rates approximating 5 cm/kyr (Shipboard Sci- using a 100× objective. entific Party 1987). Moreover, Hole 610A has detailed and Most photomicrographs were taken on a Leica DMR independent age control based on magnetostratigraphy for microscope with a Leica DC300 or DFC490 digital camera. the entire section (Clement & Robinson 1987) and marine Selected photomicrographs were taken on a Zeiss Axioplan isotope stratigraphy for the time interval between 3.6 and 2 microscope with a digital MRc5 Zeiss camera at the Pa- 2.4 Ma (Kleiven et al. 2002). Baldauf et al. (1987) combined laeontology Research Unit of Ghent University, Belgium. the available palaeontological data (nannofossils, planktonic Scanning electron microscopy was also performed there on foraminifera and diatoms) with the magnetostratigraphy for selected samples to elucidate the taxonomy of several small the core. This interpretation has largely been followed, except acritarchs and dinoflagellate cysts. Residue was mounted on for the lower part of the core, where evidence from calcareous a circular glass slide, which was attached to a metal stub nannofossils, dinoflagellate cysts and a reappraisal of the using carbon stickers. Stubs were coated with gold using a magnetostratigraphical datums has led to the construction of Bal-Tec MED 010 Planar-magnetron Sputtering Device. The a new age model (De Schepper 2006; unpublished data). This distance between the stub surface and the gold sputtering age model is adopted in the present study, where it provides head was set at 5.2 cm. A gold coating of about 15 nm was an interpolated age for every biostratigraphical datum. applied. The scanning electron microscope (SEM) used was a JEOL 6400. Pictures were acquired digitally using Noran Vantage software. The ATNTS2004 timescale of Lourens et al. (2004) is Materials and methods used throughout.

Samples Repository A total of 102 samples were analysed for biostratigraphy All microscope slides containing holotypes and other ﬁgured from the Lower Pliocene through lowermost Middle Pleis- specimens are housed in the Invertebrate Section of the De- tocene of DSDP Hole 610A, covering ca. 170 m (199.11– partment of Palaeobiology, Royal Ontario Museum, Toronto, 28.71 mbsf). One sample from each section of core was taken Ontario, under the catalogue numbers ROMP 57983–57996. between sections 610A-21-6 and 610A-4-1, providing an average sampling interval of ca. 1.5 m. Additional samples were taken for taxonomic purposes at selected intervals in the lower part of the hole. Systematic palaeontology

Methods Dinoflagellate cysts Samples of ca. 25–30 cm3 volume were cleaned with a knife Division DINOFLAGELLATA (Butschli,¨ 1885) to remove any modern microbial growth and other contam- Fensome et al., 1993 ination and oven dried at ca. 50◦C. The sediment was then Subdivision DINOKARYOTA Fensome et al., 1993 weighed and one or more Lycopodium clavatum tablets were Class DINOPHYCEAE Pascher, 1914 added to each sample to determine palynomorph concentra- tions. Standard chemical treatment was followed: cold 20 Subclass PERIDINIPHYCIDAE Fensome et al., 1993 vol% HCl, cold 48–52% HF, a second 20 vol% HCl treat- Order GONYAULACALES Taylor, 1980 ment to remove any fluosilicates and intermediate and fi- TM Suborder GONYAULACINEAE (Autonym) nal washes in deionised H2O prior to sieving on a Nitex nylon screen at 10 µm. No oxidation or alkali treatments Family GONYAULACACEAE Lindemann, 1928 were used. Samples from sections 610A-21-6 to 610A-8-1 Subfamily CRIBROPERIDINIOIDEAE Fensome et al. were prepared by M.J.H. at the University of Toronto. They 1993 received 30–45 s of ultrasonic treatment to break up flocs of amorphogen and were mounted on microscope slides using Genus OPERCULODINIUM Wall, 1967 emend. cellosize and elvacite. This mounting medium has the ad- Matsuoka et al., 1997 vantage of being permanent, but the interface between the Operculodinium? eirikianum Head et al., 1989b cellosize and elvacite was occasionally found to obscure the emend. Head, 1997 palynomorphs. Samples from sections 610A-7-6 to 610A- 4-1 were prepared by S.D.S. at the University of Cambridge Operculodinium? eirikianum var. crebrum varietas (England). The resulting residues received no ultrasound and nov. (Plate 1) were mounted using glycerine jelly. TYPE. Holotype, sample DSDP 610A-17-5, 109–114 cm A Leica DMLB microscope equipped with differential (160.12 mbsf), slide 1, England Finder reference O21/4; interference contrast optics was used for analyses. Micro- ROMP 57991; Pl. 1, figs 1–4. Age: ca. 3.27 Ma, Mammoth 104 S. De Schepper and M. J. Head

Dinoflagellate Acritarchs cysts Subchron (C2An.2r), early Piacenzian (early Middle Plio- cene).

var. A var. DIAGNOSIS. AnewvarietyofOperculodinium? eirikianum sp. nov. sp.

sp. nov. nov. sp. in which the central body wall comprises a thin (<0.3 µm) gen. et sp. nov. et sp. gen. gen. et sp. nov. et sp. gen. pedium and thicker (ca.2.0µm or more) luxuria, consisting (Ma) eirikianum crebrum

? of radiating, non-tabular septa that form a microreticulum. (Ma) (g)

(core, section, interval in cm) (core, OCCURRENCE. Recorded only from the Piacenzian (Middle (mbsf) Pliocene) of Hole 610A (Fig. 2), mostly between samples counted var. nov. var. Cymatiosphaera latisepta Cymatiosphaera crista Lavradosphaera lucifer Lavradosphaera dinoflagellate cysts Total counted acritarchs Total Series Stage Chron Subchron chron Polarity Boundary age zones Calcareous nannofossil zones Planktonic foraminiferal Depth Dry weight Calibrated ages Sample Impagidinium cantabrigiense Melitasphaeridium choanophorum Operculodinium 4-1 51–53 28.71 16.000.528 9 377 0 610A-18-1, 81–86 cm (ca. 3.33 Ma) and 610A-17-2, 108– 4-5 42–44 34.62 23.4 0.637 1 376 0

C1n 5-2 48–50 39.78 17.1 0.732 + 355 0 104 cm (ca. 3.15 Ma) near and within the Mammoth Sub-

M.PLEIST 4 319 48 BRUHNES 5-3 52–54 41.32 18.1 0.760 0.78 5-4 109–111 43.39 20.0 0.798 20 387 0 chron (C2An.2r), in calcareous nannofossil zone NN16, and 5-5 52–54 44.32 15.9 0.816 41 326 0

C1r.1r 6-4 52–54 52.42 20.0 0.967 9 335 0 0.99 planktonic foraminifer zone PL3–6. A highest abundance of 6-5 109–111 54.49 19.0 1.011 1 428 0 JAR 6-6 51–53 55.41 16.5 1.034 6 348 0 1.07 13% is reached within this interval. However, specimens do 7-1 120–122 58.20 18.5 1.097 11 340 1 C1r.1n 7-4 69–71 62.19 15.8 1.174 4 345 0 occur higher in the hole and are considered in place, with a 7-6 71–73 65.21 17.6 1.232 + 720 0 8-1 81–86 67.44 33.8 1.275 353 53 highest occurrence in sample 610A-15-4, 111–117 cm (ca. 8-2 79–85 68.92 32.5 1.304 2 421 1 8-3 113–119 70.76 27.0 1.339 385 0 2.82 Ma). 8-4 8–13 71.21 33.2 1.348 3 334 0 8-5 32–37 72.95 29.4 1.381 395 0 N22 8-6 19–25 74.32 34.0 1.408 1 360 38 8-7 19–24 75.82 35.1 1.437 + 331 1 ESCRIPTION

NN19 D . Central body wall comprises thin solid pe- 9-1 108–113 77.31 34.0 1.466 360 6 9-2 79–84 78.52 31.6 1.489 + 318 39 dium (less than 0.3 µm, only visible as dark line) and much 9-3 2–7 79.25 34.9 1.503 398 38

C1r.2r – C1r.3r C1r.2r 9-4 124–129 81.97 35.9 1.556 359 3 thicker luxuria forming microreticulum of erect, sinuous, un- 9-5 77–83 83.00 39.2 1.576 + 387 9 9-6 18–23 83.95 35.1 1.594 363 59 dulating, non-tabular muri of ca. 0.2–0.3 µm wide. Luxuria 9-7 6–11 85.29 31.4 1.620 + 381 50 E A R L Y P L E I S T O C E N Y P L E I S E A R L 10-1 18–23 86.01 32.7 1.634 437 68 at least 2.0 µm thick, with walls up to 3.0 µm thick often

P L E I S T O C E N P L E I S 10-2 77–83 88.10 31.9 1.674 389 16 10-3 63–68 89.46 26.7 1.700 325 1 observed. Muri enclose polygonal lumina of up to 0.7 µmin 10-4 23–28 90.56 32.8 1.722 384 0 10-5 110–115 92.93 35.0 1.767 327 5 diameter. Microreticulum appears radially striate in optical ? ? M A T U Y A M T U M A 1.78 10-6 18–23 93.51 35.1 1.779 + 313 0 10-7 5–8 94.87 26.7 1.823 333 269 section. Solid, granule-bearing processes arise directly from OLD ? 11-1 49–54 95.92 37.4 1.857 + 329 125 C2n 11-2 66–71 97.59 37.7 1.911 331 2

1.95 ? 11-3 65–70 99.08 37.7 1.955 322 44 surface of microreticulate layer, with little if any structural 11-4 65–70 100.58 36.1 1.989 335 3 11-5 7–12 101.50 34.4 2.010 348 0 modiﬁcation of microreticulation beneath process bases. Pro- 11-6 65–70 103.58 35.7 2.057 359 26

C2r.1r 11-7 2–5 104.44 28.0 2.076 365 5 cesses arise mostly from circular bases. Precingular archeo- 12-1 63–68 105.66 39.6 2.104 342 1 2.13 12-2 123–128 107.76 30.8 2.141 329 78 REU pyle (by loss of plate 3 ) is large, with well-deﬁned angles. 2.15 12-3 83–88 108.86 39.6 2.159 344 3 12-4 63–68 110.16 30.8 2.190 350 15 C2r.1n 12-5 110–115 112.13 37.9 2.236 363 3 DIMENSIONS. Holotype: central body length, 32 µm; cent- 12-6 18–24 112.71 38.8 2.250 354 17 NN18 13-1 6–12 114.69 36.7 2.297 361 4 ral body width, 29 µm; wall thickness, 3.0 µm; archeopyle G E L A S I N 13-2 34–39 116.47 38.2 2.339 342 1 13-3 67–72 118.30 32.4 2.382 372 2 length, 20 µm; archeopyle maximum width, 14 µm; max- C2r.2r 13-4 82–87 119.95 37.8 2.421 359 0 13-5 82–88 121.45 35.4 2.455 335 25 13-6 64–69 122.77 37.0 2.485 346 1 imum process length, 10 µm. Range (minimum, average and 13-7 4–10 123.67 37.2 2.505 487 0 14-1 78–83 125.01 40.6 2.535 332 31 maximum measurements are given): central body maximum 14-2 64–69 126.37 42.1 2.565 403 163 2.58

? 14-3 124–129 128.47 37.3 2.617 6 352 201 diameter, 28 (35.9) 42 µm; wall thickness, 2.0 (2.4) 3.0 µm; 14-4 36–41 129.09 39.4 2.631 5 352 40 14-5 78–83 131.01 41.6 2.667 + 9 326 80 average process length, 9 (10.3) 12. Nine specimens meas- 1 362 23 NN17 14-6 37–42 132.10 37.4 2.688

? 15-1 123–128 135.06 39.0 2.742 3 335 550 ured. 15-2 35–41 135.68 38.7 2.754 1 391 154 15-3 108–113 137.91 40.1 2.793 3 383 52 15-4 111–117 139.44 37.4 2.821 2 3 336 250 TYMOLOGY 15-5 63–68 140.46 40.4 2.839 9 2 1 309 496 E . Latin crebrum, thick, pressed together; with 81–86 5 337 143 C2An.1n 15-6 142.14 42.2 2.870 15-7 1–4 142.83 22.8 2.883 5 1 332 1190 reference to the thick wall of this variety. 16-1 33–38 143.76 38.7 2.900 1 2 360 210 16-2 35–38 145.26 28.5 2.928 1 380 49 16-3 83–88 147.26 41.0 2.965 2 343 18 REMARKS. The greater thickness of the central body wall 1 90 329 412 PL3 – PL6 16-4 112–117 149.05 36.9 2.998 G A U S 3.03 16-5 126–131 150.69 38.5 3.028 27 346 201 alone distinguishes this variety from Operculodinium? ei- KAE 16-6 20–26 151.13 42.4 3.037 + 358 101 3.12 P L I O C E N 1 78 385 948 C2An.1r 17-1 51–56 153.54 36.3 3.091 rikianum var. eirikianum (autonym): the luxuria on Opercu-

P I A C E N Z 17-2 108–114 155.61 34.9 3.149 + 1 85 317 1419 C2An.2n 17-3 81–87 156.84 43.7 3.198 76 + 28 369 120 lodinium? eirikianum var. eirikianum is between about 0.5 3.21 17-4 65–70 158.18 40.1 3.229 +45 3 105 1 355 647 MAM C2An.2r 17-5 109–114 160.12 39.7 3.266 16 1 32 375 734 and 1.0 µm (Head 1997), although thicknesses up to 1.5 µm

NN16 17-6 111–117 161.64 35.4 3.295 1 170 353 1159 3.33 18-1 81–86 163.44 40.1 3.330 + + 344 6 18-2 109–114 165.22 38.2 3.421 70 382 278 have also been recorded (Head et al. 1989b; this study). In ad- 18-3 108–113 166.71 34.4 3.504 152 366 987 14 366 113 dition, the average process length (9–12 µm) appears slightly C2An.3n 18-4 19–24 167.32 43.6 3.534

? 3.60 18-5 80–86 169.43 42.5 3.604 41325 80 18-6 3–8 170.17 42.1 3.614 75364 104 longer than for Operculodinium? eirikianum var. eirikianum 19-1 78–83 173.01 45.2 3.651 +2374 39 19-2 79–84 174.52 41.8 3.671 + 356 4 (5–10 µm in Head et al. 1989b; 4–9.5 µm in Head 1997). 19-3 111–116 176.34 43.4 3.695 362 30 19-4 62–67 177.35 43.4 3.708 1 341 44 ? Operculodinium? eirikianum var. crebrum differs from Fili- 19-5 111–116 179.34 41.1 3.735 16 20 352 166 19-6 21–26 179.94 41.8 3.743 18376 60 sphaera ﬁlifera Bujak, 1984 emend. Head, 1994 in possess- 20-1 31–36 182.14 42.4 3.772 83346 55 20-2 32–38 183.65 45.4 3.792 1 349 29 ing processes.

C2Ar 20-3 31–36 185.65 43.3 3.818 1 413 61

? 20-4 16–22 186.49 39.0 3.829 11 1 337 45 20-5 32–38 188.15 45.7 3.851 + 343 10 20-6 35–40 189.68 42.9 3.871 331 13 Z A N C L E

G I L B E R T (p a r s) G I L B E R 21-1 24–30 191.67 43.1 3.897 ++345 31 21-2 35–40 193.28 46.3 3.919 353 1 ?

NN15 21-3 39–44 194.82 46.5 3.939 1 330 18 and higher) and to calcareous nannofossil (Takayama & Sato 21-4 35–41 196.28 47.9 3.958 + 361 31 21-5 33–39 197.76 42.3 3.978 23 + 339 306 1987) and planktonic foraminiferal biostratigraphy (Weaver & Clement

? ? 21-6 18–24 199.11 43.7 3.996 336 16 1987). The magnetostratigraphy below the Piacenzian is considered questionable (De Schepper 2006). The time scale (including boundary Figure 2 Stratigraphic distribution of new dinoﬂagellate cyst and ages) follows Lourens et al. (2004) and calibrated ages are updated acritarch taxa from DSDP Hole 610A and calibration of their ranges to from De Schepper (2006). The raw counts of each taxon are given, and magnetostratigraphy (Clement & Robinson 1987, for the Piacenzian a cross (+) indicates the presence of a taxon outside the regular counts. New Pliocene and Pleistocene dinoﬂagellates and acritarchs 105

Plate 1 Operculodinium? eirikianum var. crebrum var. nov. All images in bright ﬁeld, except where indicated. Figs 1–4, Holotype, sample DSDP 610A-17-5, 109–114 cm, slide 1, O21/4; ROMP 57991. Dorsal view of (1,2) high and slightly lower foci on dorsal surface, (3) mid-focus showing thick luxuria on central body and (4) lower focus on ventral surface. Central body maximum length, 32 µm. Figs 5–7, Sample DSDP 610A-17-5, 109–114 cm, slide 1, U28/2; ROMP 57991. Uncertain view at (5)highfocus,(6) mid-focus showing thick luxuria on central body and (7) lower focus. Maximum diameter, 29 µm. Fig. 8, Sample DSDP 610A-17-4, 65–70 cm, slide 1, C29/1; ROMP 57992. Dorsal view of dorsal surface and large archeopyle. Central body maximum length, 32 µm, central body maximum width, 30 µm, archeopyle maximum length, 21 µm. Figs 9–12, Sample DSDP 610A-17-4, 65–70 cm, slide 1, U34/0; ROMP 57992. Ventral view of (9) ventral surface, (10)midfocusand(11) dorsal surface. 106 S. De Schepper and M. J. Head

AUTECOLOGY. Operculodinium? eirikianum is generally wall layers that are closely adpressed except at bases of su- considered a cold-intolerant species found in middle to tural crests. Pedium solid, smooth. Tegillum thin (<0.3 µm), high latitudes (Head 1993, 1997). Operculodinium? eiriki- solid; has shagreenate to finely granulate outer surface; forms anum var. crebrum may represent a morphological adapt- suturocavate crests that may be hollow along entire height ation to relatively warm and stable climates, as revealed (e.g. Pl. 2, figs 10, 16) or hollow only at their base (e.g. by the low amplitude of oscillations in the oxygen isotope Pl. 2, figs 3, 14). Both types may be present on same cyst. record, following the well-expressed Marine Isotope Stage Some crests may be entirely solid (e.g. Pl. 2, figs 2, 6) but M2 (Lisiecki & Raymo 2005) around the Mammoth Sub- suturocavate crests always present. Crests are entire, locally chron in the eastern North Atlantic. Multivariate analysis on of even height, but highest on hypocyst, reaching maximum a detailed dataset from a glacial–interglacial cycle around height at antapex. Epicyst bears lower crests; at apex they 3.30 Ma (Marine Isotope Stage M2) in Hole 610A sug- are invariably low and almost half the height of crests at ant- gests that this variety has an affinity for warmer waters (De apex. A funnel-like structure may occur at antapex, formed Schepper 2006), although confirmation from other datasets is by convergence of cavate crests surrounding antapical plate needed. (Pl. 2, figs 2, 7). Crests incompletely express tabulation, especially in dorsal and ventral areas. On dorsal surface, anterior Subfamily GONYAULACOIDEAE (Autonym) cingular margin expressed by a crest, whereas posterior cingular margin is not. A crest demarcates boundary between Genus IMPAGIDINIUM Stover & Evitt, 1978 two cingular plates (possibly 3c and 4c) immediately below archeopyle. On some specimens both anterior and posterior Impagidinium cantabrigiense sp. nov. (Plate 2) cingular margins are vaguely recognisable on ventral surface, TYPE. Holotype, sample DSDP 610A-5-5, 52–54 cm (44.32 where cingulum meets sulcus. Outline of sulcus expressed mbsf), slide 2, England Finder reference H44/0; ROMP by crests. No crests present within sulcus, but tabulation oc- 57995; Pl. 2, Figs 1–3. Age: ca. 0.82 Ma, Subchron C1r.1r, casionally traced by faint lineation, including along anterior just below the Bruhnes/Matuyama boundary, Early Pleisto- margin of posterior sulcal plate. Archeopyle 1P (plate 3), cene. with sharp angles and operculum free. Archeopyle approximately congruent with plate boundaries. DIAGNOSIS. A small suturocavate Impagidinium species with smooth inner wall, spherical to subspherical central DIMENSIONS. Holotype: cyst length (including crests), body and incomplete tabulation. Shagreenate to finely gran- 43 µm; cyst width (including crests), 40 µm; central body ulate tegillum forms crests locally of even height, but lower length (excluding crests), 27 µm; central body width (ex- towards apex and higher towards antapex. Crests absent or cluding crests), 25 µm; minimum apical crest height, 4 µm; weakly expressed on dorsal surface along posterior cingular maximum antapical crest height, 12 µm. Range (minimum, margin; no crests within sulcus. average and maximum measurements are given): central body maximum diameter, 25 (29.0) 36 µm; maximum dia- OCCURRENCE. Latest Pliocene through Middle Pleistocene meter including crests, 38 (46.8) 54 µm; maximum apical of Hole 610A (Fig. 2), with a lowest occurrence in sample crest height, 4 (5.8) 8 µm; maximum antapical crest height, 610A-11-1, 49–54 cm, in the Olduvai Subchron (C2n), cal- 9 (11.7) 15 µm. Nineteen specimens measured. careous nannofossil zone NN19, planktonic foraminifer zone PL6–N22, at ca. 1.86 Ma. It occurs infrequently and in COMPARISON. Impagidinium japonicum Matsuoka, 1983 low abundance (<3% of total assemblage) until just before has crests of equal height in apical and antapical areas. Im- the Jaramillo Subchron (0.99–1.07 Ma) and from then on- pagidinium velorum Bujak, 1984 has smooth to shagreenate, wards becomes more common (3–10%) and peaks (13% in membranous sutural crests, that are also higher (19–25 µm) sample 610A-5-5, 52–54 cm) at ca. 0.82 Ma just before the and of equal height over the entire cyst. Bruhnes/Matuyama boundary. It has a highest occurrence in the highest sample processed from Hole 610A, which is of ETYMOLOGY. Named after the city of Cambridge (Latin, Middle Pleistocene age and dated at 0.53 Ma. Cantabrigium), where this species was first identified. Also recorded from the Early and Middle Pleistocene of Zakynthos Island, Greece and from the Early (post-Jaramillo) AUTECOLOGY. An oceanic cyst, reported from the oceanic and Middle Pleistocene of ODP Site 963, offshore Sicily (M. realm in the present study (DSDP Hole 610A) and from Papanikolaou, pers. comm.). the deep shelf of the Mediterranean (ODP Site 963 and Zakynthos, Greece; M. Papanikolaou, pers. comm.). DESCRIPTION. Central body small and spherical to subspher- The transition from a warm to cold interval at ca. ical, sometimes bearing small, faintly discernible apical pro- 0.82 Ma (MIS 20) in Hole 610A is marked by high numbers of tuberance of about 0.5 µm high. Sutural crests partially de- Impagidinium pallidum Bujak, 1984 and Nematosphaerop- limit gonyaulacoid tabulation. Central body comprises two sis labyrinthus (Ostenfeld, 1903) Reid, 1974, the latter

Detail of wall structure (12). Maximum diameter, 33 µm. Figs 13–16, Sample DSDP 610A-17-4, 65–70 cm, slide 1, H33/1; ROMP 57992. Ventral view of (13) ventral surface, (14)midfocusand(15,16) slightly lower foci of dorsal surface. Figs 17, 18, Sample DSDP 610A-17-4, 66–68 cm. Scanning electron microscope (SEM) image. Diameter, 34 µm. Dorsal view (17) of dorsal surface and large archeopyle, with sharp angles. Same view (18), detail of wall surface and processes bearing granules (height of photomicrograph, 21.5 µm). Fig. 19, Sample DSDP 610A-17-4, 66–68 cm. SEM image. Maximum diameter, 37 µm. Dorsal view of dorsal surface showing large archeopyle. Fig. 20, Sample DSDP 610A-17-3, 81–87 cm. SEM image. Detail of processes and wall structure. Height of photomicrograph, 17 µm. New Pliocene and Pleistocene dinoﬂagellates and acritarchs 107

Plate 2 Impagidinium cantabrigiense sp. nov. All images in bright ﬁeld. Figs 1–3, Holotype, sample DSDP 610A-5-5, 52–54 cm, slide 2, H44/0; ROMP 57995. Dorsal view of (1) dorsal surface showing 1P archeopyle (plate 3) and immediately below, a crest demarcating boundary between two cingular plates (possibly 3c and 4c), (2) mid-focus, and (3) ventral surface showing absence of crests in sulcal area. Central body length (excluding crests), 27 µm. Figs 4–8, Sample DSDP 610A-5-5, 52–54 cm, slide 1, L34/4; ROMP 57996. Left latero-ventral view of (4,5) ventral surface with sulcus and cingulum, (6,7) higher and slightly lower mid foci, with view of antapical funnel-shaped structure and (8)right latero-dorsal surface with archeopyle on the right and view of cingular plate, probably 4c. Figs 9–12, Sample DSDP 610A-5-5, 52–54 cm, slide 1, O27/2; ROMP 57996. Ventral view of (9) ventral surface, (10,11) successively lower mid foci and (12) dorsal surface. Central body maximum diameter, 25 µm. Figs 13–16, Sample DSDP 610A-5–5, 52–54 cm, slide 2, O27/2; ROMP 57995. Uncertain view of (13) high focus, revealing the suturocavate crests, (14,15) successively lower mid foci and (16) low focus. Central body maximum diameter, 29 µm. becoming the dominant species in the assemblage. Also Subfamily uncertain at this time, Impagidinium cantabrigiense sp. nov. has its Genus MELITASPHAERIDIUM Harland & Hill, 1979 highest recorded abundance for Hole 610A and remains abundant during the cold phase. Therefore, Impagidinium Melitasphaeridium choanophorum (Deﬂandre & cantabrigiense sp. nov. seems related to transitional phases Cookson, 1955) Harland & Hill, 1979 var. A (Plate 3) from warm to cold surface waters in open-marine settings, OCCURRENCE. Recorded from two adjacent samples in suggesting a preference for cooler conditions. DSDP Hole 610A, at Subchron C2An.2r? (3.23 Ma) and 108 S. De Schepper and M. J. Head

Plate 3 Melitasphaeridium choanophorum var. A. All images in bright ﬁeld, except where indicated. Figs 1–5, Sample DSDP 610A-17-3, 65–70 cm, slide 1, K10/3; ROMP 57993. Dorsal view of (1) dorsal surface and archeopyle, (2) slightly lower focus, (3) mid-focus showing the relatively thick wall and (4,5) slightly lower foci of ventral surface, showing the perforated wall structure. Central body length, 32 µm. Figs 6–11, Sample DSDP 610A-17-3, 65–70 cm, slide 1, M36/0; ROMP 57993. Ventral view of (6–8) successively lower foci on ventral surface, (9)midfocus and (10,11) dorsal surface, revealing the perforated wall structure. Central body length, 27 µm. Fig. 12, Sample DSDP 610A-17-3, 65–70 cm. New Pliocene and Pleistocene dinoﬂagellates and acritarchs 109

Subchron C2An.2n (3.20 Ma), both within the Piacenzian Acritarchs (Middle Pliocene) and within calcareous nannofossil zone NN16 and planktonic foraminifer zone PL3–6 (Fig. 2). This Genus CYMATIOSPHAERA Wetzel, 1933 ex morphotype has not been reported previously. Deflandre, 1954 Cymatiosphaera latisepta sp.nov.(Plate4) DESCRIPTION. A morphotype of Melitasphaeridium choanophorum characterised by a thick (>1.0 µm), perforate cent- 1989b Nematosphaeropsis sp. I. de Vernal & Mudie: 414; ral body wall. Central body spheroidal, with wall consist- pl. 2, figs 9–11. ing of thin (<0.3 µm), perforated pedium and thick (1.0– 1997 Nematosphaeropsis sp. I. Versteegh: 335; pl. II, figs 2.0 µm), perforated luxuria that almost form coarse retic- 5, 6. ulum. Perforations approximately circular in outline, with ETYMOLOGY. From the Latin latus, broad and the Latin diameters ca. 1.0–2.0 µm, separated from one another by septum, wall, partition; with reference to the distally expan- as much as ca.1.0µm. Distribution of perforations slightly ded crests. irregular; adjacent perforations sometimes adjoined. Circu- lar perforations of pedium appear contiguous with those of TYPE. Holotype, sample DSDP 610A-15-3, 108–113 cm luxuria. Perforations of pedium were observed under SEM (137.91 mbsf), slide 1, England Finder reference D11/1; (Pl. 3, fig. 12) and using light microscopy (Pl. 3, fig. 3). Per- ROMP 57994; Pl. 4, figs 1–5. Age: ca. 2.79 Ma, Subchron forations occasionally interrupt principal archeopyle suture. C2An.1n, Piacenzian (Middle Pliocene). Processes generally long, slender, hollow, distally open; process terminations typically aculeate but variable, may include DIAGNOSIS. Small acritarch with smooth thin-walled spher- reduced aculeae and may even taper to simple acuminate tips oidal central body whose surface bears crests of even height (Pl. 3, figs 17–20). Some specimens have smaller processes that delimit polygonal fields of approximately equal size. with acuminate endings in addition to normal aculeate pro- Crests thickened at intersections and expanded distally to cesses (Pl. 3, figs 3, 9, 12). No specimens found bearing form flat or slightly invaginated tops, are extremely thin else- processes with wide, circular distal platforms and serrated where and may have occasional perforations. Crests other- edges. wise solid except for thicker distal parts where small vacuoles are usually present.

DIMENSIONS. Range (minimum, average and maximum OCCURRENCE. Always present in low abundance and re- measurements are given): central body length, 27 (30.3) stricted to the Piacenzian of DSDP Hole 610A (Fig. 2). 33 µm; central body width, 24 (28.0) 31 µm; process length, It has its lowest occurrence in sample 610A-18-1, 81– 7 (9.9) 12 µm; wall thickness, 1.0 (1.7) 2.0 µm. Seven spe- 86 cm, Subchron C2An.3n?, calcareous nannofossil zone cimens measured. NN16, planktonic foraminifer zone PL3–6 and Marine Iso- tope Stage MG2, at ca. 3.33 Ma. The highest occurrence is REMARKS. Process terminations compare favourably with in sample 610A-14-3, 124–129 cm, Subchron C2An.1n, cal- the wide range of development illustrated for Melit- careous nannofossil zone NN17/18, planktonic foraminifer asphaeridium choanophorum by Strauss & Lund (1992). The zone PL3–6 and Marine Isotope Stage 104, at ca. 2.62 Ma. wall of Melitasphaeridium choanophorum var. A seems un- In DSDP Hole 607, central North Atlantic, it has a usually thick for this species. The presence of a perforated sporadic occurrence from Marine Isotope Stage 113, at pedium on a chorate dinoﬂagellate cyst is unknown to us 2.80 Ma (the lowest sample examined) to Marine Isotope and would seem to compromise any protective function the Stage 98, at 2.48 Ma (Versteegh 1997). cyst wall might confer upon its contents. Perhaps the per- In DSDP Hole 646B, Labrador Sea, it has an isol- forations of the wall are caused by microbial degradation. ated lowest occurrence in calcareous nannofossil zone NN16 However, no specimens transitional between Melit- (Piacenzian), it becomes persistently present in the upper part asphaeridium choanophorum var. A and the normal morpho- of zone NN16 and has a highest occurrence just above the logy of this species were found, even though both morpho- Gauss/Matuyama boundary at 2.58 Ma (Clement et al. 1989; types were recorded in the same samples. In addition, no de Vernal & Mudie 1989b;Knuttel¨ et al. 1989). specimens belonging to other species in the two samples In the western North Atlantic DSDP Hole 603C, it has containing Melitasphaeridium choanophorum var. A were a persistent occurrence within the Piacenzian from near the found to have suffered microbial degradation. Hence, prima base of the Gauss Chron (within Subchron C2An.3n) to near facie evidence suggests that the thick wall and perforated the top of the Gauss Chron (within Subchron C2An.1n). pedium are primary features. However, because microbial In summary, this species is presently known only from degradation cannot be excluded, these specimens are placed the North Atlantic where it is recorded from near the base of in open nomenclature pending further information regarding the Piacenzian into the lower Gelasian. Rare and questionable this unusual morphological feature. occurrences in the Zanclean may require veriﬁcation.

Scanning electron microscope (SEM) image. Dorsal view of dorsal surface showing archeopyle. Maximum diameter, 28 µm. Figs 13–16, Sample DSDP 610A-17-3, 65–70 cm, slide 1, F21/0; ROMP 57993. Uncertain view of (13,14) high and slightly lower foci on processes and upper wall surface, (15)midfocusand(16) lower surface. Central body maximum diameter, 29 µm. Figs 17–20, Sample DSDP 610A-17-3, 65–70 cm, slide 1, U48/3; ROMP 57993. Ventral view of (17) ventral surface, (18,19) slightly lower mid foci and (20) dorsal surface with archeopyle. Central body length, 31 µm. 110 S. De Schepper and M. J. Head

Plate 4 Cymatiosphaera latisepta sp. nov. All images in bright ﬁeld, except where indicated. Figs 1–5, Holotype, sample DSDP 610A-15-3, 108–113 cm, slide 1, D11/1; ROMP 57994. Uncertain view at (1) upper focus, (2) slightly lower focus, (3)midfocus,(4)lowerfocusand(5) lowermost focus. Central body maximum diameter, 18 µm. Figs 6–8, Sample DSDP 610A-17-4, 65–70 cm, slide 1, V34/1; ROMP 57992. Uncertain view at (6) upper focus, (7) mid focus and (8) lower focus. Vacuoles and perforations visible within expanded crest tops (indicated with arrow on ﬁgs 6, 7) on membranous crests at and between gonal junctions. Central body maximum diameter, 20 µm. Figs 9–11, Sample DSDP 610A-17-4, 65–70 cm, slide 1, V37/0; ROMP 57992. Uncertain view at (9) upper focus, (10)midfocusand(11) lower focus. Central body maximum diameter, 20 µm. Fig. 12, Sample DSDP 610A-15-4, 111–117 cm. Scanning electron microscope (SEM) image, maximum diameter (including crests), 24 µm. Figs 13–15, Sample DSDP 610A-17-6, 9–11 cm, slide 1, D31/2; ROMP 57990. Uncertain view at (13) upper focus showing vacuoles (indicated with arrow) within tops of crest intersections, (14)midfocusand(15) slightly lower focus. Central body maximum diameter, 23 µm. Fig. 16, Sample DSDP 610A-15-1, 123–128 cm. SEM image, maximum diameter, 22 µm. Note distally expanded crests and pitted surface at top of some crest intersections.

DESCRIPTION. Small acritarch with thin-walled (<0.3 µm) invaginated (Y-shaped) tops up to 3.0 µm wide. Crests solid spheroidal central body, surface subdivided by crests into except that thicker distal parts of crests, especially at distal about 22–26 polygonal fields of approximately equal size. parts of intersections, commonly have small (ca.1.0µmor Crests of even height, thickened where they intersect one an- less) vacuoles and perforations visible under light micro- other and distally expanded to form flat (T-shaped) or slightly scope. Between intersections and below distal margins, crests New Pliocene and Pleistocene dinoflagellates and acritarchs 111 are extremely thin and may have occasional perforations. DIAGNOSIS. A species of Lavradosphaera with spherical to Central body surface smooth, crest surfaces also smooth, al- spheroidal central body bearing relatively straight intersect- though under SEM the tops of crests may show pitting and ing crests that subdivide the acritarch into about nine poly- perforations (Pl. 4, figs 12, 16). gonal fields of unequal size and shape. Pylome always occurs on a large field. Crests are widest at base and narrow DIMENSIONS. Holotype: maximum diameter (including distally to irregular or even spinulose margins. Surface of crests), 23 µm; central body diameter, 18 µm; crest height, central body scabrate to granulate and crests have radially 2.5 µm. Range (minimum, average and maximum measure- striate surface. Pylome approximately pentagonal with well- ments are given): maximum diameter (including processes), defined angles and thin margin; operculum monoplacate, 23 (24.1) 26 µm; central body diameter, 18 (18.5) 20 µm; free. crest height, 2.5 (2.8) 3.0 µm. Eight specimens measured. De Vernal & Mudie (1989a,b) recorded a maximum dia- OCCURRENCE. In DSDP Hole 610A, the lowest occurrence meter of 25–30 µm, a central body diameter of 15–20 µm is in sample 610A-21-5, 33–39 cm near the base of the hole and crest height of 4–6 µm. and dated at 3.98 Ma (late Zanclean, Fig. 2). The highest common occurrence is in sample 610A-16-4, 112–117 cm REMARKS. This species differs from all others of the genus (3.00 Ma; mid-Piacenzian), in the lower part of Subchron Cymatiosphaera in the presence of distally expanded crests C2An.1n, calcareous nannofossil zone NN16, planktonic fo- and the typical development of small vacuoles and perfora- raminifer zone PL3–6 and the Nitzschia jouseae diatom zone. tions within the crests, especially at the tops of crest intersec- There are four isolated records higher in the hole (Fig. 2), tions. De Vernal & Mudie (1989b) assigned this species to which probably represent reworking. Even if these occur- the dinoflagellate cyst genus Nematosphaeropsis Deflandre rences are in place, the highest occurrence (sample 610A-14- & Cookson, 1955 emend. Wrenn, 1988 (as Nematosphaerop- 5, 78–83 cm, 2.67 Ma; late Piacenzian, where nine specimens sis sp. I) in the belief that the wall contained processes linked were counted) would still fall within Subchron C2An.1n, in distally by single trabeculae. It now appears that the ‘pro- calcareous nannofossil zone NN17, planktonic foraminifer cesses’ interpreted by de Vernal & Mudie (1989b) are thick- zone PL3–6 and the Nitzschia marina diatom zone. The enings of the crests where they intersect and that the single range of Lavradosphaera crista extends from the mid- or ‘trabeculae’ are the expanded distal margins of the crests. late Zanclean to the mid- or late Piacenzian in Hole 610A. These intersections impart a rounded appearance to the lu- In Baffin Bay, ODP Site 645, recorded rarely and men of the reticulation, so adding to the distinctiveness of sporadically from both the Upper Pliocene (de Vernal & this species. This species also shows no evidence of dinofla- Mudie 1989a) and middle Upper Miocene through Up- gellate tabulation. per Pliocene or Lower Pleistocene (Anstey 1992). Labrador Sea, ODP Site 646, occurring rarely in the Lower Pliocene Genus LAVRADOSPHAERA gen. nov. but abundantly in the Middle Pliocene and with a well- defined top about 20 m below the Gauss/Matuyama boundary TYPE. The holotype of Lavradosphaera crista gen. et sp. (Clement et al. 1989; de Vernal & Mudie 1989b). Norwegian nov. (Pl. 5, figs 1–4) Sea, ODP Leg 104, from the Upper Miocene through Middle Pliocene with a range top near the top of the Gauss Chron DIAGNOSIS. Small spheroidal to subspheroidal acritarchs (as Platycystidia sp. 1 in Mudie 1989). Western North At- whose vesicle wall comprises a thin, smooth inner layer, lantic, DSDP Hole 603C, from the Upper Miocene (Messin- a continuous or discontinuous spongy to cancellous middle ian) through Middle Pliocene (Piacenzian) with a highest layer and a thin, continuous outer layer. All layers closely common occurrence in the Kaena Subchron, although with adpressed. Middle and outer layers form crests, ridges or rare specimens persisting into the Upper Pliocene or Lower cones or combinations thereof that are spongy to cancellous Pleistocene that may represent reworking (M.J.H., unpub- internally. Pylome polygonal to rounded–polygonal in shape. lished data). Lavradosphaera crista has a total known range of Upper ETYMOLOGY. Named with reference to the Labrador Sea Miocene through Upper Pliocene or Lower Pleistocene, with where the stratigraphical utility of this genus was first estab- a conspicuous range top in the northern North Atlantic within lished (de Vernal & Mudie 1989b). The origin of the name Subchron C2An.1n (3.03–2.58 Ma). Labrador is widely assigned to Joao˜ Fernandes Lavrador, = a Portuguese explorer and landholder ( lavrador in Por- DESCRIPTION. Small acritarch whose wall comprises a thin tuguese) in the Azores. (<0.3 µm) smooth inner layer of spherical to spheroidal shape, a discontinuous coarsely spongy to cancellous middle Lavradosphaera crista gen. et sp. nov. (Plate 5) layer (3–5 µm) and a thin (<0.3 µm) finely ornamented outer 1989 Platycystidia sp. 1. Mudie: pl. 3, figs 9–12. layer. All layers closely adpressed. Outer layer is raised to 1989a Incertae sedis I. de Vernal & Mudie: 396; pl. 2, figs form intersecting crests, in which middle layer is developed. 8, 9. Vacuoles within spongy middle layer are variable in dia- 1989b Incertae sedis I. de Vernal & Mudie: 415; pl. 5, figs meter within an individual specimen and may reach 3.5 µm. 20, 23. Crests run in relatively straight lines over entire vesicle, sep- arating about nine polygonal fields whose size and shape TYPE. Holotype, sample DSDP 610A-17-6, 105–107 cm varies within an individual specimen. Crests widest at base (161.6 mbsf), slide 17.6h (1), England Finder reference and narrow distally. Distal margins of crests irregular and A32/1; ROMP 57988; Pl. 5, figs 1–4. Age: ca.3.30Ma, undulations are often drawn into points. Surface of cent- Subchron C2An.2r?, Piacenzian (Middle Pliocene). ral body is scabrate to granulate, crests have radially striate 112 S. De Schepper and M. J. Head

Plate 5 Lavradosphaera crista gen. et sp. nov. All images in bright field, except where indicated. Figs 1–4, Holotype, sample DSDP 610A-17-6, 132–134 cm, slide 17.6j(1), A32/1; ROMP 57987. Oblique apical view at (1) high focus on apical field with polygonal pylome, (2,3) successively lower mid foci revealing the cancellous, spongy crests and (4) lower focus. Maximum diameter (including crests), 23 µm. Figs 5–8, Sample DSDP 610A-21-1, 24–30 cm, slide 1, F21/1; ROMP 57983. Apical view at (5) high focus on apical field with polygonal pylome, (6) slightly lower focus, (7)midfocusand(8) lower focus. Maximum diameter (including crests), 18 µm. Figs 9–12, Sample DSDP 610A-17-6, 105–107 cm, slide 17.6h(1), N24/0; ROMP 57988. Oblique apical view of (9) upper focus on apical field, showing upper margin of pylome, (10) mid focus on cancellous, spongy crests and (11,12) lower foci. Maximum diameter (including crests), 19 µm. Figs 13–15, Sample DSDP 610A-17-6, 9–11 cm, slide 17.6a(1), U33/1; ROMP 57989. Antapical view of (13) antapical surface, (14)midfocusand(15) lower focus showing detached operculum within vesicle. Maximum diameter (including crests), 24 µm. Fig. 16, Sample DSDP 610A-17-4, 66–68 cm. Scanning electron microscope (SEM) image, maximum diameter, 20 µm. View of large apical field showing polygonal pylome and radial striations on crests. surface. Pylome always occurs on a large field, is approx- DIMENSIONS. Holotype: maximum diameter (including imately pentagonal with well-defined angles, has thin mar- crests), 23 µm; central body diameter, 18 µm; crest height, gins comprising only inner and outer wall layers. Operculum 3.0 µm. Range (minimum, average and maximum meas- monoplacate and free, occasionally found detached within urements are given): maximum diameter (including crests), vesicle (Pl. 5, fig. 15). Crest present on operculum. 18 (22.1) 26 µm; central body diameter, 12 (15.6) 19 µm; New Pliocene and Pleistocene dinoflagellates and acritarchs 113 maximum crest height, 3 (3.4) 5 µm. Eighteen specimens the Upper Miocene (Messinian) through Middle Pliocene measured from Hole 610A. (Piacenzian) with a highest occurrence in Subchron C2An.3n A range in maximum diameter of 12–25 µm has been (M.J.H., unpublished data). recorded for specimens from the Labrador Sea and Baffin Accepted range is from the Upper Miocene (mid- Bay (de Vernal & Mudie 1989a,b; and 16 (21) 25 µm with a Tortonian) calcareous nannofossil zone NN10 (Head et al. maximum crest height of 4–5 µm for specimens from Baffin 1989a) to lower Piacenzian (Subchron C2An.3n) in DSDP Bay (Anstey 1992). Hole 603C (M.J.H., unpublished data), with higher occurrences possibly representing reworking. ETYMOLOGY. From the Latin Crista, crest, which refers to crests on the central body. DESCRIPTION. Small acritarch having three closely- adpressed concentric wall layers. Innermost layer is thin REMARKS. The name ‘Poculumoides pyxidatum’ was not (<0.3 µm), smooth and spherical to spheroidal in shape. validly described in Anstey (1992) as it was avowedly not in- Middle layer (2.5–5 µm) has loosely spongy to cancellous tended for effective publication, appearing in an unpublished structure containing vacuoles of variable size up to ca. dissertation. 4.0 µm. Middle layer much thicker than inner or outer wall COMPARISON. Lavradosphaera crista differs from Lav- layers and varies in thickness over vesicle. Outer layer thin radosphaera lucifer in having a middle wall layer that is (<0.3 µm) and follows relief of middle layer. Outer surface discontinuous and a relatively thin vesicle wall bearing in- finely ornamented with submicron-size bumps and undula- tersecting crests that subdivide the acritarch into discrete tions and may have smooth areas and scattered small perfora- polygonal fields. tions. It forms irregular relief of low, broad-based ridges and cones. Ridges typically rise into cones where they intersect. Lavradosphaera lucifer gen. et sp. nov. (Plate 6) Relatively large circular to subpolygonal pylome is usually visible. Thick margins of pylome are covered by outer wall 1987 Hystrichokolpoma sp. 1. Mudie: 803; pl. 4, figs 10a, layer, which fuses with inner wall layer. Operculum mono- b, 11. placate and free, sometimes found detached within vesicle 1989a Incertae sedis II of de Vernal & Mudie: 396; pl. 2, (Pl. 6, fig. 18). figs4,5. 1989b Incertae sedis II of de Vernal & Mudie: 415; pl. 5, DIMENSIONS. Holotype: maximum diameter (including figs 18, 19. crests), 26 µm; maximum diameter central body, 16 µm; 1989a Acritarch sp. 1 of Head et al.: 441; pl. 7, figs 4, 8, 9, maximum crest height, 5 µm; pylome length, 9 µm; pylome 12, 13. width, 7 µm. Range (minimum, average and maximum measurements are given): maximum diameter (including crests), TYPE. Holotype, sample DSDP 610A-19-5, 111–116 cm (179.34 mbsf), slide 1, England Finder reference C18/0; 19 (23.2) 26 µm; maximum diameter central body, 12 (14.7) ROMP 57985; Pl. 6, figs 1–5. Age: ca. 3.74 Ma, Subchron 17 µm; maximum crest height, 2.5 (4.3) 5 µm. Twenty-three C2Ar, Zanclean (Lower Pliocene). specimens measured. Pylome length, 7 (8.0) 9 µm; pylome width, 4 (5.5) 7 µm; pylome measurements on two specimens DIAGNOSIS. A species of Lavradosphaera with spherical to only. spheroidal central body consisting of a thin, smooth, inner Head et al. (1989a) recorded a maximum diameter of wall layer; a thick, continuous, spongy to cancellous middle 19 (23.1) 30 µm; Anstey (1992) recorded a maximum dia- layer of irregular thickness; and a thin outer layer. Outer sur- meter of 18 (23) 27 µm; and de Vernal & Mudie (1989a,b) face forms an irregular relief of low, broad-based ridges and recorded a size of 15–25 µm. cones. Pylome circular to subpolygonal; operculum monoplacate and free. ETYMOLOGY. Named after the Latin Lucifer, the planet Venus in its appearance as the morning star. The species OCCURRENCE. Possibly restricted to the Zanclean of Hole recalls the small spiked ball, also called a ‘morning star’, 610A, but no clearly defined range top (Fig. 2). The highest that forms the head of a mediaeval weapon. occurrence is accepted as being in sample 610A-18-5, 80– 86 cm (at 3.60 Ma) near the Gilbert/Gauss boundary, with two REMARKS. Thename‘Poculumoides multifastigatum’was higher occurrences in the Gauss Chron possibly reworked. not validly described in Anstey (1992) as it was avowedly The highest accepted occurrence is within calcareous nan- not intended for effective publication, appearing in an un- nofossil zone NN16, planktonic foraminifer zone PL3–6 and published dissertation. the Nitzschia jouseae diatom zone. COMPARISON. Lavradosphaera lucifer differs from Lav- In the Labrador Sea, ODP Site 646, this species ranges radosphaera crista in having a continuously thick wall from Upper Miocene (mid-Tortonian) (Head et al. 1989a)to whose surface bears a combination of low ridges and Middle Pliocene where it has a highest occurrence about 15 m cones. below the Gauss/Matuyama boundary (Clement et al. 1989; de Vernal & Mudie 1989b). In Baffin Bay, ODP Site 645, it is reported from the Upper Pliocene (de Vernal & Mudie 1989a) and from the Upper Miocene or Lower Pliocene through Discussion upper Pliocene or Lower Pleistocene (Anstey 1992). In the northern North Atlantic, DSDP Hole 611, it is recorded from This study formally describes new taxa of dinoflagellate cysts the Upper Miocene through lowermost Middle Pliocene and and acritarchs from DSDP Hole 610A and establishes their with an isolated higher record in the Upper Pliocene (Mudie stratigraphical ranges in this hole and from additional sites 1987). In the western North Atlantic, DSDP Hole 603C, from in the North Atlantic and adjacent seas. 114 S. De Schepper and M. J. Head

Plate 6 Lavradosphaera lucifer gen. et sp. nov. All images in bright ﬁeld, except where indicated. Figs 1–5, Holotype, sample DSDP 610A-19-5, 111–116 cm, slide 1, C18/0; ROMP 57985. Apical view of (1) apical surface showing rounded pylome, (2,3) slightly lower and mid foci, (4,5) antapical surface. Maximum diameter (including crests), 26 µm. Figs 6–8, Sample DSDP 610A-19-5, 111–116 cm, slide 1, D48/0; ROMP 57985. Antapical view of (6) antapical surface, (7) mid focus and (8) apical surface showing pylome margin. Maximum diameter (including crests), 22 µm. Figs 9–11, Sample DSDP 610A-19-5, 111–116 cm, slide 1, C13/4; ROMP 57985. Lateral view at (6)highfocus,(7) mid focus and (8) lower focus showing pylome margin. Maximum diameter (including crests), 25 µm. Fig. 12, Sample DSDP 610A-17-4, 66–68 cm. Scanning electron microscope (SEM) image showing apical view of rounded pylome. Maximum diameter (including crests), 24 µm. Figs 13–17, Sample DSDP 610A-18-5, 80–86 cm, slide 1, D4/0; ROMP 57986. Antapical view of (13) antapical surface, (14) slightly lower focus, (15) mid focus and (16,17) low foci on pylome margin. Maximum diameter (including crests), 24 µm. Fig. 18, Sample DSDP 610A-19-5, 111–116 cm, slide 1, D42/4; ROMP 57985. Uncertain view at mid focus, with detached operculum inside vesicle. Maximum diameter (including crests), 24 µm. Figs 19–20, Sample DSDP 610A-19-6, 21–26 cm, slide 1, D39/4; ROMP 57984. Apical view of (19) apical surface showing pylome and (20) antapical surface. Maximum diameter (including crests), 20 µm. New Pliocene and Pleistocene dinoﬂagellates and acritarchs 115

Operculodinium? eirikianum var. crebrum var. nov. is a known range of Upper Miocene through Upper Pliocene. restricted to the Piacenzian (Middle Pliocene) of Hole 610A It has a well-defined range top in the northern North Atlantic and it has not been reported from elsewhere. In contrast, within the mid- to upper Piacenzian (upper Middle Pliocene). Operculodinium? eirikianum var. eirikianum (autonym) is Lavradosphaera lucifer gen. et sp. nov. (= incertae sedis frequently present in the Upper Miocene and Pliocene of the II of de Vernal & Mudie 1989a) is possibly restricted to the North Atlantic (Head 1997). The thicker wall that character- Zanclean of Hole 610A but does not have a well-defined ises Operculodinium? eirikianum var. crebrum may represent highest occurrence. Elsewhere in the North Atlantic, it ranges a morphological adaptation in response to changing environ- from the Upper Miocene at least to lower Piacenzian (lower mental conditions in the eastern North Atlantic, but there is Middle Pliocene). presently no information from other sites to test this interpretation and no culturing studies on living cysts have yet elucid- ated the environmental controls on wall thickness in chorate dinoflagellate cysts. Whether this taxon is an ecophenotype Acknowledgements or represents an incipient evolutionary branch remains to be determined, but the wall thickness seems sufficiently dis- This contribution is based partly on the doctoral research tinctive and stratigraphically restricted to warrant treatment of S.D.S. who is grateful to the Gates Cambridge Trust for as a new variety. the award of a Gates Cambridge Scholarship (University of The dinoflagellate cyst record of the Late Pliocene Cambridge) and additional funding from the Dudley Stamp (Gelasian) and Pleistocene is marked mostly by the disap- Memorial Trust (Royal Society) and Philip Lake Fund (De- pearance of taxa and few species have their first appearances partment of Geography, University of Cambridge). M.J.H. in this interval (Williams et al. 2004). Impagidinium cantab- acknowledges support from a Natural Sciences and Engineer- rigiense sp. nov. is an exception at DSDP Hole 610A. This ing Research Council of Canada discovery grant. Colleagues species has a lowest occurrence in the Olduvai Subchron at at the Palaeontology Research Unit, University of Ghent, around 1.86 Ma, occurs sporadically to 1.23 Ma, after which are kindly thanked for the use of the SEM and transmitted it occurs persistently and becomes an important part of the light microscopes. S. Louwye and an anonymous reviewer assemblage shortly before the Bruhnes/Matuyama boundary. are thanked for their constructive comments. Its range top in DSDP Hole 610A has not been established because it is present in the highest sample at 0.53 Ma. How- ever, records from the Early and Middle Pleistocene of the Mediterranean (M. Papanikolaou, pers. comm.) corroborate References a latest Pliocene through Middle Pleistocene range. Anstey, C. A. 1992. Biostratigraphic and paleoenvironmental interpreta- Melitasphaeridium choanophorum var. A is restricted to tion of upper middle Miocene through lower Pleistocene dinoflagellate two adjacent samples near the top of the Mammoth Subchron cyst, acritarch, and other algal palynomorph assemblages from Ocean (within the Piacenzian, Middle Pliocene) in Hole 610A. This Drilling Program Leg 105, Site 645, Baffin Bay. Unpublished MSc cyst is apparently unique in having a perforated pedium as thesis: University of Toronto, Toronto, 210 pp. well as perforations and depressions in the luxuria of the Baldauf, J. G., Thomas, E., Clement, B. M., Takayama, T., Weaver, central body surface. Although these features might represent P. P. E., Backman, J., Jenkins, G., Mudie, P. J. & Westberg-Smith, preservational artefacts (borings made by marine microbes), M. J. 1987. Magnetostratigraphic and biostratigraphic synthesis, Deep Sea Drilling Project Leg 94. Pp. 1159–1205 in W. F. Ruddiman, there is no direct evidence from Hole 610A to suggest such R. B. Kidd, J. G. Baldauf, B. M. Clement, J. F. Dolan, M. R. Eggers, an origin. P. R. Hill, L. D. Keigwin Jr., M. Mitchell, I. Phillips, F. Robinson, Small acritarchs are often abundant throughout Miocene S. A. Salehipour, T. Takayama, E. Thomas, G. Unsold, P. P. E. and Pliocene deep-ocean sediments of the North Atlantic and Weaver & S. Orlofsky (eds) Deep Sea Drilling Project, Initial Re- adjacent seas and many appear to be in situ representatives of ports 94. US Government Printing Office, Washington, DC. the oceanic flora. Their taxonomic treatment nevertheless re- Bujak, J. P. 1984. Cenozoic dinoflagellate cysts and acritarchs from the mains a significant challenge because of their small size and Bering Sea and northern North Pacific, DSDP Leg 19. Micropaleon- unknown biological affinities. Small acritarchs have, con- tology 30: 180–212. sequently, been neglected until recently in spite of their evid- Butschli,¨ O. 1885. Erster Band. Protozoa. Pp. 865–1088 in D. H. G. ent stratigraphical potential (e.g. de Vernal & Mudie 1989a,b; Bronn (ed.) Klassen und Ordnungen des Thier-Reiches, wissenschaft- lich dargestellt in Wort und Bild. C. F. Winter’sche Verlagshandlung, Head 2003b; Head & Norris 2003). Three species are newly Leipzig and Heidelberg. described and have stratigraphically restricted distributions Clement, B. M. & Robinson, F. 1987. The magnetostratigraphy of Leg 94 in Hole 610A and elsewhere. sediments. Pp. 635–650 in W. F. Ruddiman, R. B. Kidd, J. G. Baldauf, Cymatiosphaera latisepta sp. nov. (= Nematosphaerop- B. M. Clement, J. F. Dolan, M. R. Eggers, P. R. Hill, L. D. Keigwin Jr., sis sp. I of de Vernal & Mudie 1989b) is one of the few M. Mitchell, I. Phillips, F. Robinson, S. A. Salehipour, T. Takayama, species restricted to the Piacenzian in Hole 610A, east- E. Thomas, G. Unsold, P. P. E. Weaver & S. Orlofsky (eds) Deep Sea ern North Atlantic. It occurs relatively abundantly near the Drilling Project, Initial Reports 94. US Government Printing Office, Gauss/Matuyama boundary in the Labrador Sea ODP, Site Washington, DC. 646 (Clement et al. 1989; de Vernal & Mudie 1989b). This —, Hall, F. & Jarrard, R. 1989. The magnetostratigraphy of Leg 105 species ranges into the lowermost Gelasian of Hole 607, cent- sediments. Pp. 583–595 in S.P.Srivastava,M.A.Arthur,B.M. Clement, A. Aksu, J. Baldauf, G. Bohrman, W. Busch, T. Cederberg, ral North Atlantic (as Nematosphaeropsis sp. I in Versteegh M. Cremer, K. Dadey, A. de Vernal, J. Firth, F. Hall, M. Head, R. 1997). Hiscott, R. Jarrard, M. Kaminski, D. Lazarus, A.-L. Monjanel, O. B. Lavradosphaera crista gen. et sp. nov. (= incertae sedis Nielsen, R. Stein, F. Thiebault, J. Zachos, H. Zimmerman & S. K. I of de Vernal & Mudie 1989a,b) extends from the upper Zan- Stewart (eds) Proceedings of the Ocean Drilling Program, Scientific clean to the Piacenzian of Hole 610A and, elsewhere, it has Results 105. Texas A&M University, College Station, TX. 116 S. De Schepper and M. J. Head

De Schepper, S. 2006. Plio–Pleistocene dinoflagellate cyst biostrati- M. Head, R. Hiscott, R. Jarrard, M. Kaminski, D. Lazarus, A.-L. graphy and palaeoecology from the eastern North Atlantic and Monjanel, O. B. Nielsen, R. Stein, F. Thiebault, J. Zachos, H. southern North Sea Basin. Unpublished PhD thesis: University of Zimmerman & S. K. Stewart (eds) Proceedings of the Ocean Drilling Cambridge, Cambridge, 327 pp, 6 app. & 23 pls. Program, Scientific Results 105. Texas A&M University, College Sta- —, Head, M. J. & Louwye, S. 2004. New dinoflagellate cyst and incertae tion, TX. sedis taxa from the Pliocene of northern Belgium, southern North Sea —, — & — 1989b. New species of dinocysts and a new species of acritarch Basin. Journal of Paleontology 78: 625–644. from the upper Miocene and lowermost Pliocene, ODP Leg 105, Site deVernal,A.&Mudie,P.J.1989a. Late Pliocene to Holocene pa- 646, Labrador Sea. Pp. 453–466 in S. P. Srivastava, M. A. Arthur, lynostratigraphy at ODP Site 645, Baffin Bay. Pp. 387–399 in S. P. B. M. Clement, A. Aksu, J. Baldauf, G. Bohrman, W. Busch, T. Srivastava, M. A. Arthur, B. M. Clement, A. Aksu, J. Baldauf, G. Cederberg, M. Cremer, K. Dadey, A. de Vernal, J. Firth, F. Hall, Bohrman, W. Busch, T. Cederberg, M. Cremer, K. Dadey, A. de M. Head, R. Hiscott, R. Jarrard, M. Kaminski, D. Lazarus, A.-L. Vernal, J. Firth, F. Hall, M. Head, R. Hiscott, R. Jarrard, M. Kaminski, Monjanel, O. B. Nielsen, R. Stein, F. Thiebault, J. Zachos, H. D. Lazarus, A.-L. Monjanel, O. B. Nielsen, R. Stein, F. Thiebault, Zimmerman & S. K. Stewart (eds) Proceedings of the Ocean Drilling J. Zachos, H. Zimmerman & S. K. Stewart (eds) Proceedings of the Program, Scientific Results 105. Texas A&M University, College Ocean Drilling Program, Scientific Results 105.TexasA&MUniver- Station, TX. sity, College Station, TX. —, Riding, J. B., Eidvin, T. & Chadwick, R. A. 2004. Palynological — & — 1989b. Pliocene and Pleistocene palynostratigraphy at ODP and foraminiferal biostratigraphy of (Upper Pliocene) Nordland Group sites 646 and 647, eastern and southern Labrador Sea. Pp. 401–422 in mudstones at Sleipner, northern North Sea. Marine and Petroleum S. P. Srivastava, M. A. Arthur, B. M. Clement, A. Aksu, J. Baldauf, Geology 21: 277–297. G. Bohrman, W. Busch, T. Cederberg, M. Cremer, K. Dadey, A. de Kidd, R. B. & Hill, P. R. 1987. Sedimentation on Feni and Gardar sed- Vernal, J. Firth, F. Hall, M. Head, R. Hiscott, R. Jarrard, M. Kaminski, iment drifts. Pp. 1217–1244 in W. F. Ruddiman, R. B. Kidd, J. G. D. Lazarus, A.-L. Monjanel, O. B. Nielsen, R. Stein, F. Thiebault, Baldauf, B. M. Clement, J. F. Dolan, M. R. Eggers, P. R. Hill, L. D. J. Zachos, H. Zimmerman & S. K. Stewart (eds) Proceedings of the Keigwin Jr., M. Mitchell, I. Phillips, F. Robinson, S. A. Salehipour, Ocean Drilling Program, Scientific Results 105.TexasA&MUniver- T. Takayama, E. Thomas, G. Unsold, P. P. E. Weaver & S. Orlofsky sity, College Station, TX. (eds) Deep Sea Drilling Project, Initial Reports 94. US Government Deflandre, G. 1954. Systematique´ des hystrichosphaerides:´ sur Printing Office, Washington, DC. l’acception du genre Cymatiosphaera O.Wetzel. Compte Rendu Som- Kleiven, H. F., Jansen, E., Fronval, T. & Smith, T. M. 2002. Intens- maire et Bulletin de la Societ´ eG´ eologique´ de France 4: 257– ification of Northern Hemisphere glaciations in the circum Atlantic 258. region (3.5–2.4 Ma); ice-rafted detritus evidence. Palaeogeography, — & Cookson, I. C. 1955. Fossil microplankton from Australian Late Palaeoclimatology, Palaeoecology 184: 213–223. Mesozoic and Tertiary sediments. Australian Journal of Marine and Knuttel,¨ S., Russell, M. D., Jr. & Firth, J. V. 1989. Neogene calcareous Freshwater Research 6: 242–313. nannofossils from ODP Leg 105: implications for Pleistocene pa- Fensome, R. A., Taylor, J. R., Norris, G., Sarjeant, W. A. S., leoceanographic trends. Pp. 245–262 in S. P. Srivastava, M. A. Arthur, Wharton, D. I. & Williams, G. L. 1993. A classification of living B. M. Clement, A. Aksu, J. Baldauf, G. Bohrman, W. Busch, T. and fossil dinoflagellates. Micropaleontology, Special Publication 7: Cederberg, M. Cremer, K. Dadey, A. de Vernal, J. Firth, F. Hall, 1–351. M. Head, R. Hiscott, R. Jarrard, M. Kaminski, D. Lazarus, A.-L., Harland, R. & Hill, J. 1979. A reappraisal of the Cainozoic dinoflagellate Monjanel, O. B. Nielsen, R. Stein, F. Thiebault, J. Zachos, H. cyst “Hystrichosphaeridium” choanophorum Deflandre et Cookson Zimmerman & S. K. Stewart (eds) Proceedings of the Ocean Drilling 1955. Review of Palaeobotany and Palynology 28: 37–45. Program, Scientific Results, 105. Texas A & M University, College Head,M.J.1993. Dinoflagellates, sporomorphs and other palynomorphs Station, TX. from the Upper Pliocene St. Erth Beds of Cornwall, southwestern Lindemann, E. 1928. Abteilung Peridineae (Dinoflagellatae). Pp. 3–104 England. Journal of Paleontology Memoir 31: 1–62. in A. Engler & K. Prantl (eds) Die Naturlichen¨ Pflanzenfamilien nebst — 1994. A forum on Neogene and Quaternary dinoflagellate cysts. The ihren Gattungen und wichtigeren Arten insbesondere den Nutzpflanzen. edited transcript of a round table discussion held at the Third Workshop Zweite stark vermehrte und verbesserte Auflage herausgegeben von A. on Neogene and Quaternary dinoflagellates, with taxonomic appendix. Engler. 2 Band. Wilhelm Engelmann, Leipzig. Palynology 17: 201–239. Lisiecki, L. E. & Raymo, M. E. 2005. A Pliocene–Pleistocene stack — 1996. Late Cenozoic dinoflagellates from the Royal Society borehole of 57 globally distributed benthic δ18O records. Paleoceanography at Ludham, Norfolk, eastern England. Journal of Paleontology 70: 20(PA1003): 1–17. 543–570. Lourens, L., Hilgen, F., Shackleton, N. J., Laskar, J. & Wilson, J. — 1997. Thermophilic dinoflagellate assemblages from the mid Pliocene 2004. The Neogene. Pp. 409–430 in F. M. Gradstein, J. G. Ogg & of eastern England. Journal of Paleontology 71: 165–193. A. G. Smith (eds) A Geological Time Scale 2004. Cambridge Univer- — 2003a. Echinidinium zonneveldiae sp. nov., a dinoflagellate cyst from sity Press, Cambridge. the Late Pleistocene of the Baltic Sea, northern Europe. Journal of Matsuoka, K. 1983. Late Cenozoic dinoflagellates and acritarchs in the Micropalaeontology 21: 169–173. (Imprinted, 2002). Niigata district, central Japan. Palaeontographica Abteilung B 187: — 2003b. Neogene occurrences of the marine acritarch genus Nanno- 89–154. barbophora Habib and Knapp, 1982 emend., and the new species N. —, McMinn, A. & Wrenn, J. H. 1997. Restudy of the holotype of Oper- gedlii. Journal of Paleontology 77: 382–285. culodinium centrocarpum (Deflandre & Cookson) Wall (Dinophyceae) — & Norris, G. 2003. New species of dinoflagellate cysts and other from the Miocene of Australia, and the taxonomy of related species. palynomorphs from the latest Miocene and Pliocene of DSDP Palynology 21: 19–33. Hole 603C, western North Atlantic. Journal of Paleontology 77: Mudie, P. J. 1987. Palynology and dinoflagellate biostratigraphy of Deep 1–15. Sea Drilling Project Leg 94, sites 607 and 611, North Atlantic Ocean. — & Westphal, H. 1999. Palynology and paleoenvironments of a Pliocene Pp. 785–812 in W. F. Ruddiman, R. B. Kidd, J. G. Baldauf, B. M. carbonate platform: the Clino core, Bahamas. Journal of Paleontology Clement, J. F. Dolan, M. R. Eggers, P. R. Hill, L. D. Keigwin Jr., M. 73: 1–25. Mitchell, I. Phillips, F. Robinson, S. A. Salehipour, T. Takayama, E. —, Norris, G. & Mudie, P. J. 1989a. Palynology and dinocyst strati- Thomas, G. Unsold, P. P. E. Weaver & S. Orlofsky (eds) Deep Sea graphy of the Upper Miocene and lowermost Pliocene, ODP Leg 105, Drilling Project, Initial Reports 94. US Government Printing Office, Site 646, Labrador Sea. Pp. 423–451 in S. P. Srivastava, M. A. Arthur, Washington, DC. B. M. Clement, A. Aksu, J. Baldauf, G. Bohrman, W. Busch, T. — 1989. Palynology and dinocyst biostratigraphy of the late Miocene Cederberg, M. Cremer, K. Dadey, A. de Vernal, J. Firth, F. Hall, to Pleistocene, Norwegian Sea; ODP Leg 104, Sites 642 and 644. New Pliocene and Pleistocene dinoflagellates and acritarchs 117

Pp. 587–610 in O. Eldholm, J. Thiede, E. Taylor, C. Barton, K. P. P. E. Weaver & S. Orlofsky (eds) Deep Sea Drilling Project, Initial Bjørklund, U. Bleil, P. Ciesielski, A. Desprairies, D. Donnally, C. Reports 94. US Government Printing Office, Washington, DC. Froget, R. Goll, R. Henrich, E. Jansen, L. Krissek, K. Kvenvolden, A. Taylor, F. J. R. 1980. On dinoflagellate evolution. BioSystems 13: 65–108. LeHuray, D. Love, P. Lysne, T. McDonald, P. Mudie, L. Osterman, Versteegh, G. J. M. 1997. The onset of major Northern Hemisphere L. Parson, J. D. Phillips, A. Pittenger, G. Qvale, G. Schonharting,¨ L. glaciations and their impact on dinoflagellate cysts and acritarchs from Viereck & W. R. Winkler (eds) Proceedings of the Ocean Drilling Pro- the Singa section, Calabria (southern Italy) and DSDP Holes 607/607A gram, Scientific Results 104. Texas A&M University, College Station, (North Atlantic). Marine Micropaleontology 30: 319–343. TX. —, & Zevenboom, D. 1995. New genera and species of dinoflagellate Ostenfeld, C. H. 1903. Phytoplankton from the sea around the Faeroes.¨ cysts from the Mediterranean Neogene. Review of Palaeobotany and Botany of the Faeroes¨ based upon Danish investigations Part II: 558– Palynology 85: 213–229. 612. Wall, D. 1967. Fossil microplankton in deep-sea cores from the Caribbean Pascher, A. 1914. Uber¨ Flagellaten und Algen. Deutsche Botanische Sea. Palaeontology 10(1): 95–123. Gesellschaft, Berichte 32: 136–160. Weaver, T. T. E. & Clement, B. M. 1987. Magnetobiostratigraphy of Reid, P. C. 1974. Gonyaulacacean dinoflagellate cysts from the British planktonic foraminiferal datums; Deep Sea Drilling Project Leg 94, Isles. Nova Hedwigia 25: 579–637. North Atlantic. Pp. 815–829 in W. F. Ruddiman, R. B. Kidd, J. G. Shipboard Scientific Party 1987. Site 610. Pp. 351–470 in W. F. Baldauf, B. M. Clement, J. F. Dolan, M. R. Eggers, P. R. Hill, L. D. Ruddiman, R. B. Kidd, J. G. Baldauf, B. M. Clement, J. F. Dolan, Keigwin Jr., M. Mitchell, I. Phillips, F. Robinson, S. A. Salehipour, M. R. Eggers, P. R. Hill, L. D. Keigwin Jr., M. Mitchell, I. Phillips, T. Takayama, E. Thomas, G. Unsold, P. P. E. Weaver & S. Orlofsky F. Robinson, S. A. Salehipour, T. Takayama, E. Thomas, G. Unsold, (eds) Deep Sea Drilling Project, Initial Reports 94.USGovernment P. P. E. Weaver & S. Orlofsky (eds) Deep Sea Drilling Project, Initial Printing Office, Washington, DC. Reports 94. US Government Printing Office, Washington, DC. Wetzel, O. 1933. Die in organischer Substanz erhaltenen Mik- Stover, L. E. & Evitt, W. R. 1978. Analyses of pre-Pleistocene organic- rofossilien des baltischen Kreide–Feuersteins mit einem sediment- walled dinoflagellates. Stanford University Publications, Geological petrographischen und stratigraphischen Anhang. Palaeontographica Sciences, Stanford, CA, 300 pp. Abteilung A 78: 1–110, pl. 1–7. Strauss, C. & Lund, J. J. 1992. A Middle Miocene dinoflagellate cyst Williams, G. L., Brinkhuis, H., Pearce, M. A., Fensome, R. A. & microflora from Papendorf near Hamburg, Germany. Mitteillungen Weegink, J. W. 2004. Southern Ocean and global dinoflagellate cyst Geologisch–Palaontologischen¨ Institut der Universitat¨ Hamburg 73: events compared: index events for the Late Cretaceous–Neogene. 159–189. Pp. 1–98 in N. F. Exon, J. P. Kennett & M. J. Malone (eds) Pro- Takayama, T. & Sato, T. 1987. Coccolith biostratigraphy of the North ceedings of the Ocean Drilling Program, Scientific Results, 189. Texas Atlantic Ocean, Deep Sea Drilling Project Leg 94. Pp. 651–702 in W. A&M University, College Station, TX. F. Ruddiman, R. B. Kidd, J. G. Baldauf, B. M. Clement, J. F. Dolan, Wrenn, J. H. 1988. Differentiating species of the dinoflagellate cyst M. R. Eggers, P. R. Hill, L. D. Keigwin Jr., M. Mitchell, I. Phillips, genus Nematosphaeropsis Deflandre and Cookson 1955. Palynology F. Robinson, S. A. Salehipour, T. Takayama, E. Thomas, G. Unsold, 12: 129–150.