APPENDIX A
The systematic paleontology section includes taxonomic discussion of key taxa and the description of seven new species (Ahmuellerella alboradiata, Ceratolithoides perangustus, Ceratolithoides sagittatus, Tegumentum lucidum, Micula clypeata, Micula premolisilvae, and Uniplanarius clarkei) and two new combinations (Loxolithus thiersteinii and Rotelapillus biarcus). The taxonomy follows the classification and organization of Bown and Young (1997) and Burnett (1998). Only bibliographic references not included in Perch-Nielsen (1985) and Bown (1998) are included in the reference list. A full taxonomic list of species cited in this paper follows below (see
"Appendix B"). Descriptive terminology follows the guidelines of Young et al. (1997), and the following abbreviations are used in taxonomic descriptions: LM = light microscope, XPL = cross-polarized light, and PC = phase-contrast illumination. Holotype dimensions are given in parentheses. The taxa are illustrated in Plates P1–P10. The scale bar on the first figure of each plate applies to all figures on that plate.
Family Chiastozygaceae Rood et al., 1973, emend. Varol and Girgis, 1994
Ahmuellerella alboradiata sp. nov.
Derivation of name: From albus, meaning white, and radiatus, meaning with rays, referring to the distinctive XPL image of the central area plate of this coccolith.
Diagnosis: Medium-sized murolith coccolith with a narrow, unicyclic rim and a wide central area filled with a variably birefringent plate. The rim is dark under XPL. The central area plate is characterized by eight radial segments of alternating bright and dark birefringence, divided by axial and diagonal sutures. The center portion of the central plate appears to show narrow, near-axial cross bars that bear a short, broad spine (Pl. P1, fig. 3). The bars do not appear to extend to the rim.
Differentiation: The LM image is similar to Ahmuellerella regularis but is distinguished by the alternating birefringence of the central area plate (see Pl. P1, figs. 13–19).
Dimensions: length = 6.5–7.2 (6.6) µm; width = 4.7–5.5 (5.0) µm.
Holotype: Pl. P1, fig. 1 (figs. 1–6 are the same specimen).
Paratype: Pl. P1, fig. 11 (figs. 10–12 are the same specimen).
Type locality: Hole 1209C, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Maastrichtian, Sample 198-1209C-16H-6, 50 cm (Subzone UC20bTP).
Range: upper Maastrichtian (Subzones UC20bTP–?UC20cTP); Sites 1209, ?1210.
Chiastozygus sp. with indistinct subaxial bars
Remarks: Small loxolith with a broad rim and narrow central area; diagonal cross bars are occasionally visible in the central area.
Chiastozygus cf. C. trabalis (Górka, 1957) Burnett, 1997a
Remarks: Similar to Chiastozygus trabalis but has brighter, more robust central area cross bars.
Loxolithus thiersteinii (Roth, 1973) comb. nov.
Basionym: Crepidolithus thiersteinii Roth, 1973, p. 725, pl. 22, fig. 6.
Remarks: Although both Crepidolithus and Loxolithus have elliptical, loxolith rims, the central area in Loxolithus is wide and open, whereas Crepidolithus typically has a narrow to closed central area. Crepidolithus is restricted to the Jurassic.
Zeugrhabdotus embergeri (Noël, 1958) Perch-Nielsen, 1984
Zeugrhabdotus cf. Z. embergeri (Noël, 1958) Perch-Nielsen, 1984
Remarks: Large, bicyclic loxolith coccoliths with an open central area spanned by a broad transverse bar. Specimens often display distinctive orange birefringence under XPL and were rather ragged in appearance, and thus distinguishable from more typical Zeugrhabdotus embergeri specimens. These specimens are noted as Zeugrhabdotus cf. Z. embergeri on the range charts but may conform to the species concept of Zeugrhabdotus pseudanthophorus. Alternatively, these specimens may simply be preservational morphotypes of Zeugrhabdotus embergeri.
Family Eiffellithaceae Reinhardt, 1965
Tegumentum lucidum sp. nov.
Derivation of name: From lucidus, meaning bright, referring to the distinctive bright XPL image of this coccolith.
Diagnosis: Medium-sized, murolith coccolith with a broad, bicyclic rim, dominated by the thick, bright inner-cycle and a narrow central area almost filled by short, broad, bright diagonal cross bars.
Remarks: The rim of this coccolith is highly distinctive, having a broad, bright (white) inner cycle and a very narrow, dark outer cycle. The LM appearance is most reminiscent of Tegumentum but is also similar to Eiffellithus. The broad, rounded, diagonal cross bars almost fill the narrow central area and are of similar birefringence to the inner rim cycle.
Differentiation: Differentiated from other species of Tegumentum by its narrower central area and broad rounded cross bars. Somewhat similar to the Early Cretaceous Eiffellithus windii, but the cross bar morphology is distinct and outer rim cycle narrower.
Dimensions: length = 5.0–6.5 (6.0) µm; width = 3.5–5.0 (4.3) µm.
Holotype: Pl. P2, fig. 29 (figs. 29–30 are the same specimen).
Paratype: Pl. P2, fig. 25 (figs. 25–27 are the same specimen).
Type locality: Hole 1207B, Shatsky Rise, northwest Pacific Ocean.
Type level: lower Campanian, Sample 198-1207B-6R-CC (Subzones UC14dTP–UC15aTP).
Range: lower Campanian–upper Maastrichtian (Subzones UC14dTP–UC15aTP to UC20dTP); Sites 1207, 1210, and 1212.
Family Stephanolithiaceae Black, 1968
Rotelapillus biarcus (Bukry, 1969) comb. nov.
Basionym: Cylindralithus biarcus Bukry, 1969, p. 42, pl. 20, fig. 2.
Remarks: This species has comparable rim structure to other Rotelapillus coccoliths, but differs in having only two, rather than four, central area cross bars. Cylindralithus coccoliths have distinctly different rim structure, modified from the placolith Watznaueria group, and no central area bars. Stoverius has a low rim, whereas that of Rotelapillus is high.
Family Watznaueriaceae Rood et al., 1971
Perchnielsenella stradneri (Perch-Nielsen, 1973) Watkins
in Watkins and Bowdler, 1984
Remarks: A large, distinctive, highly birefringent coccolith, seen in both side and plan view. Observed commonly and consistently through the Campanian and Maastrichtian sediments from Shatsky Rise. The rim morphology most closely resembles Cylindralithus, to which it is most likely closely related.
Dimensions: length = 6.5–10.0 µm; height = 6.0–10.0 µm.
Heterococcoliths of uncertain affinity
Cribrocorona gallica (Stradner, 1963) Perch-Nielsen, 1973
Remarks: Distinctive circular to subcircular coccoliths seen in both side and plan view. Comparable in LM appearance to Cylindralithus but less birefringent in plan view and the two "shields" are clearly visible at different focal depths (see Pl. P4, figs. 44, 45). Additionally, the central area grille is very distinctive in Cribrocorona. In side view the two genera are clearly distinguishable.
Cribrocorona echinus (Bukry, 1975) comb. nov.
Synonym: Petrobrasiella? bownii Burnett, 1997a (Pl. P4, figs. 31–41).
Basionym: Cylindralithus echinus Bukry, 1975, p. 689, pl. 3, figs. 4, 5.
Remarks: Distinctive, stratigraphically short-ranging coccolith seen in both side and plan view. Originally described from Shatsky Rise, it is commonly present in the lower Maastrichtian Zone UC17 Sites 1210 and 1212.
Dimensions: length = 6.5–7.0 µm; height = ~6.0 µm.
Assipetra terebrodentarius (Applegate et al. in Covington and Wise, 1987) Rutledge and Bergen in Bergen, 1994
Description: Blocky globular nannoliths formed from six or more complexly intergrown calcite blocks that are joined along broadly radial sutures; roughly circular in plan and rectangular in side view.
Remarks: Assipetra terebrodentarius has rarely been reported from Upper Cretaceous sediments, but it is consistently present in the Aptian–Campanian of the Shatsky Rise sites, with a probable last occurrence in the upper Campanian. The forms observed are usually the larger morphotype, A. terebrodentarius youngii (Tremolada and Erba, 2002; >8.0 µm; see
Bown, this volume). Tremolada and Erba (2002) considered this subspecies to be restricted in stratigraphic range to the Aptian and possibly associated with unusual paleoceanographic conditions related to OAE1a and its immediate aftermath. We are uncertain of its paleoecology, but its presence in Upper Cretaceous sediments is without doubt, having also been observed in Upper Cretaceous sediments from the Indian Ocean (P.R. Bown, pers. observ.).
Genus Ceratolithoides Bramlette and Martini, 1964
Remarks: Arrowhead-shaped nannoliths constructed from two basal rectangular to rhombic elements and a narrow, apical, conical structure (Burnett, 1997). Morphological terminology employed below after Burnett (1997).
Ceratolithoides perangustus sp. nov.
Derivation of name: From perangustus, meaning very narrow, referring to the shape of this nannolith.
Diagnosis: Small Ceratolithoides with tall, narrow base and narrow apical cone that does not protrude far above the base. The interhorn angle is usually between 90° and 180°, and there is no distinct shoulder.
Differentiation: Narrower morphology than other Ceratolithoides species.
Dimensions: length = (4.8) µm; width = (2.0) µm.
Holotype: Pl. P6, fig. 22 (figs. 22 and 23 are the same specimen).
Paratype: Pl. P6, fig. 21.
Type locality: Hole 1210B, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Campanian, Sample 198-1210B-36H-7, 60 cm (Zone UC16).
Range: lower/upper to upper Campanian (Subzone UC15cTP–Zone UC16); Sites 1207 and 1210.
Ceratolithoides sagittatus sp. nov.
Derivation of name: From sagitta, meaning arrow-shaped, referring to the shape of this nannolith.
Diagnosis: Small Ceratolithoides with rhombic basal elements and distinct, two-part apical cone. The cone protrudes significantly above the basal elements. The interhorn angle is usually just >90°.
Differentiation: The apical cone structure is highly distinctive, formed from two large elements, protruding significantly above the base, and not enclosed within the base.
Dimensions: length = 3.5–5.5 µm; width = 3.0–5.0 µm.
Holotype: Pl. P6, fig. 26.
Paratype: Pl. P6, fig. 27.
Type locality: Hole 1210B, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Campanian, Sample 198-1210B-38H-CC (Subzones UC15dTP–UC15eTP).
Range: lower Campanian to upper Maastrichtian (Subzones UC15bTP–UC20bTP); Sites 1207, 1208, 1209, 1210, and 1212.
Family Polycyclolithaceae Forchheimer, 1972, emend. Varol, 1992
Genus Micula Vekshina, 1959
Remarks: Typically cubiform nannoliths usually formed from two superimposed and complexly intergrown cycles of four pyramidal/blocky elements each; one of the cycles may be reduced (M. murus), relict (M. prinsii), or lost (M. clypeata, M. premolisilvae, and M. praemurus). The elements are usually broadly triangular in shape and point/twist consistently in one direction on each surface; the elements may protrude slightly away from the edges of the cube. When focusing through the structure in LM, the two cycles twist in opposite directions and, at mid-focus, the bright, diagonal, barlike structures typical of Micula are seen. All elements are bright under XPL when the sides of the cube/square are parallel with the polarizing directions, but the whole structure goes into extinction when rotated 45° from this position.
The morphology of Micula may be quite altered by overgrowth, and species often show intraspecific variation, exacerbated by their complex three-dimensional structure. The dominant Micula in the Campanian and Maastrichtian sediments at Shatsky Rise is M. swastica, although M. murus and M. prinsii become common in the uppermost Maastrichtian.
Derivation of name: From clypeus, meaning "like a round shield," referring to the shape of this nannolith.
Diagnosis: Square, flat Micula that appears to be composed of a single cycle of four elements joined along uneven sutures that bend sharply at the their ends. A distinctive raised circular area, equal in diameter to the width of the nannolith, lies above the level of the main structure. A narrow zone of darker birefringence lies along each of the suture lines and broadens toward the corners.
Differentiation: Much flatter than most other Micula species but with the same crystallographic orientation (i.e., the entire structure is in extinction when the sutures are near-parallel with the polarizing directions). Similar to M. praemurus, particularly at high focus, but differs in having a square "base" and more complex suture appearance.
Dimensions: length/width = 5.5–6.5 (5.5) µm.
Holotype: Pl. P8, fig. 31 (figs. 31–34 are the same specimen).
Paratype: Pl. P8, fig. 37 (figs. 37–42 are the same specimen).
Type locality: Hole 1209C, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Maastrichtian, Sample 198-1209C-18H-7, 50 cm (Subzone UC20bTP).
Range: lower Campanian?–upper Maastrichtian (Subzones UC15bTP–UC20dTP); Sites 1208, 1209, 1210, 1211, and 1212.
Micula murus (Martini, 1961) Bukry, 1973
Remarks: Micula composed of two superimposed and complexly intergrown cycles, one much reduced in size, and each cycle twisting in opposite directions. In "normal view" the elements are broadly triangular in shape and point/twist consistently in one direction; the elements protrude significantly away from the edges of the cube. Side views of M. murus are thinner than the normal view and clearly show the two superimposed, differently sized cycles.
Micula premolisilvae sp. nov.
Derivation of name: Named for Isabella Premoli Silva, micropaleontologist and ODP Leg 198 Co-Chief Scientist.
Diagnosis: A near-square to cruciform, flat Micula, composed of a single cycle of four elements joined along distinct straight, or gently curving, sutures.
Differentiation: Similar in morphology to M. praemurus but the outline is square or cruciform rather than circular. The orientation of the sutures is variable in the specimens observed, ranging from axial (Pl. P8, figs. 25–28) to near-diagonal (Pl. P8, figs. 22–24, 29, 30). Much flatter than other Miculas, M. premolisilvae is most similar to M. praemurus and M. clypeata, to which it may be more closely related. The entire nannolith goes into extinction when the sides of the square are rotated to 45° from the polarizing directions (Pl. P8, fig. 26).
Dimensions: length/width = 5.0–6.5 µm.
Holotype: Pl. P8, fig. 25 (figs. 25 and 26 are the same specimen).
Paratype: Pl. P8, fig. 27 (figs. 27 and 28 are the same specimen).
Type locality: Hole 1210B, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Campanian, Sample 198-1210B-32H-CC (Zone UC16).
Range: upper Campanian–lower/upper Maastrichtian (Zones UC16 to UC1–UC19); Sites 1209, 1210, and 1212.
Micula swastica Stradner and Steinmetz, 1984
Remarks: Micula composed of two equidimensional, superimposed, and complexly intergrown cycles. In "normal view" the elements are broadly triangular in shape and point/twist consistently in one direction on each surface; the elements may protrude slightly beyond the cube. When focusing through the structure in LM, the two cycles twist in opposite directions and, at mid-focus, the bright diagonal image that typifies Micula is seen (Pl. P7, fig. 26). Side views of M. swastica are thinner than the normal view and clearly show the two superimposed cycles (Pl. P7, figs. 40–42).
Most likely, M. swastica gave rise to M. murus through reduction of one of the cycles, and intermediate morphologies render the FO of M. murus difficult to precisely identify. However, in this study, we were very careful in our application of the concept of M. murus, and, since the datum ties in well with the planktonic
foraminifer biostratigraphy, we have high confidence in that datum.
Micula praemurus (Bukry, 1973) Stradner and Steinmetz, 1984
Remarks: A highly distinctive, circular, disklike Micula, originally described from Shatsky Rise (Bukry, 1973), composed of a single cycle of four elements joined along curving, S-shaped sutures. Much flatter than other Miculas but with comparable crystallographic orientation.
Micula clypeata and Micula premolisilvae share a number of morphological features that distinguish them from other Micula species and likely represent closely related forms. Despite the name, Micula praemurus does not appear a likely candidate for the direct ancestor of Micula murus (see Micula swastica).
Uniplanarius Hattner and Wise, 1980
Remarks: Genus erected by Hattner and Wise (1980) for planar, radial nannoliths composed of three or four elements. We follow this concept and include the species Uniplanarius gothicus, Uniplanarius trifidus, Uniplanarius sissinghii, and a new species, Uniplanarius clarkei. We have not observed the two superimposed cycles or median diaphragm that Varol (1992) used to distinguish this genus from Quadrum. However, unlike Hattner and Wise (1980), we have retained use of the genus Quadrum for cubiform nannoliths typically formed from two superimposed cycles of four elements, each joined along straight, axial sutures (Quadrum gartneri). The transitional species, Quadrum intermedium, has additional, small elements inserted between the four major ones in one or both cycles. Using this definition, Quadrum is restricted to the upper Cenomanian–upper Coniacian. We believe the additional species Quadrum eptabrachium, Quadrum octobrachium, Quadrum eneabrachium, and Quadrum giganteum, described by Varol (1992), are Eprolithus specimens that have been modified by preservation.
Uniplanarius gothicus (Deflandre, 1959) Hattner and Wise, 1980
Uniplanarius cf. U. gothicus (Deflandre, 1959) Hattner and Wise, 1980 (small form)
Remarks: Small, square, simply constructed Uniplanarius. The elements are bright under XPL when the sutures and sides of the square nannolith are parallel to the polarizing directions and all in extinction when rotated to 45°. Similar in appearance to Quadrum gartneri, but the latter is blocky, cubiform, and constructed from two superimposed cycles of elements.
Uniplanarius cf. U. sissinghii (Deflandre, 1959) Hattner and Wise, 1980
Remarks: Uniplanarius nannoliths that have longer free rays than typical specimens of U. gothicus, but not as long as those seen in Uniplanarius sissinghii.
Uniplanarius clarkei sp. nov.
Derivation of name: Named for Leon Clarke, paleoceanographer and ODP Leg 198 Shipboard Scientist.
Diagnosis: Small, square Uniplanarius with rounded corners, formed from four blocks joined along axial sutures that are marked under XPL by relatively broad zones of darker birefringence, together resembling the blades of a propeller. The outer edges of the nannolith may show slightly higher birefringence.
Dimensions: length/width = 3.3–4.0 (3.3) µm.
Holotype: Pl. P9, fig. 1 (figs. 1–4 are the same specimen).
Paratype: Pl. P9, fig. 10 (figs. 10–12 are the same specimen).
Type locality: Hole 1210B, Shatsky Rise, northwest Pacific Ocean.
Type level: upper Campanian, Sample 198-1210B-34H-5, 45 cm (Zone UC16).
Range: lower Campanian–uppermost Maastrichtian (Subzones UC14dTP–UC15aTP to UC20dTP); Sites 1207, 1208, 1209, 1210, 1211, and 1212.
