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Journal of Foraminiferal Research, v. 41, no. 4, p. 371–383, October 2011

TAXONOMIC OVERVIEW AND EVOLUTIONARY HISTORY OF GLOBOTRUNCANITA INSIGNIS (GANDOLFI, 1955) FRANCESCA FALZONI*

AND

MARIA ROSE PETRIZZO

Dipartimento di Scienze della Terra ‘‘A. Desio’’, Universita` degli Studi di Milano, via Mangiagalli 34, 20133 Milano, Italy ABSTRACT

Pessagno, 1967; Robaszynski and others, 1984; Longoria and VonFeldt, 1991). Moreover, the loss of the holotype together with the inaccessibility of the paratype and of the topotypes (Caron 1983a) hindered resolution of the taxonomic ambiguities related to this species, and the designation of a neotype by Caron (1983a) was intensively discussed and rejected by Longoria (1983) and Longoria and Pessagno (1984). More recently, Longoria and VonFeldt (1991) ascribed G. insignis to Globotruncanita and suggested that G. insignis derived from Globotruncanita elevata (Brotzen, 1934). Nevertheless, many subsequent studies have following Robaszynski and others (1984) by referring G. insignis to Globotruncana (Zepeda, 1998; Premoli Silva and others, 1998; Luciani, 2002; Howe and others, 2003; Sari, 2006; Huber and others, 2008; Robaszynski and Mzoughi, 2010). The differences between the primary morphological features of G. elevata and G. insignis may argue against an evolutionary link between the two species. This paper presents the results of our detailed biostratigraphic and taxonomic analysis on well-preserved midCampanian planktonic foraminiferal assemblages from Tanzanian Drilling Project sites 23 and 35 in southeastern Tanzania (Fig. 1). The primary focus of the study is G. insignis and our goal was to 1) recognize its distinctive morphological features, 2) emend its description, 3) clarify its taxonomic position, and 4) reconstruct its phylogenetic history. Moreover, we anticipated that our conclusions would illuminate the phyletic relationship between its holotype and neotype. After a brief summary of the principal biostratigraphic events recognized in the examined assemblages, and in order to avoid any bias in the reconstruction of the evolutionary history of G. insignis, we also discuss the species concepts of Globotruncana rosetta (Carsey, 1927) and Globotruncanita elevata (Brotzen, 1934).

Globotruncanita insignis (Gandolfi, 1955) is a planktonic species commonly recognized in Late Cretaceous foraminiferal assemblages, but uncertainty about its morphologic variability and phyletic relationships have led to different interpretations of it. The taxon was considered to be morphologically and evolutionary related to Globotruncana rosetta (Carsey, 1926), phyletically linked to Globotruncanita elevata (Brotzen, 1934), or a junior synonym of the latter species. In addition, the neotype that replaced the lost holotype caused a taxonomic debate and compromised the identification of G. insignis, which has been assigned to both Globotruncanita and Globotruncana. This study resolves the taxonomic problems and reconstructs the phyletic lineage of this species on the basis of a continuous sequence of exceptionally well preserved and highly diversified planktonic foraminiferal assemblages in the Contusotruncana plummerae and Radotruncana calcarata zones, recently recovered from southeastern Tanzania drillholes. In addition to common G. insignis that characteristically have a strongly convex umbilical side, we recognized succession of morphotypes intermediate between Globotruncanita stuartiformis and G. insignis that demonstrates an ancestor–descendant relationship between the two taxa and further validates the assignment of G. insignis to Globotruncanita. Moreover, our results confirm that the neotype falls in the same phyletic lineage, but it represents a primitive form of G. insignis. INTRODUCTION Globotruncanita insignis (Gandolfi, 1955) was first described as a subspecies of Globotruncana rosetta (Carsey, 1926) from the Maastrichtian of the Colon Formation (Colombia). However, some of the most important distinguishing features, such as the number of keels and the umbilical structure covering the primary aperture are not mentioned in its type description, even if they were shown in the type-figure drawing. As a consequence, the original species concept and the determination of its phyletic relationships are still not clear despite its common occurrence in middle Campanian–upper Maastrichtian planktonic foraminiferal assemblages from several localities (i.e., Australia [Zepeda, 1998; Howe and others, 2003]; Gulf of Mexico [Longoria and VonFeldt, 1991]; North Atlantic [Huber and others, 2008]; Algeria and North Atlantic [Robaszynski and others, 1984]; eastern Mediterranean [Premoli Silva and others, 1998]; Turkey [Sari, 2006]; and Tunisia [Solakius and others, 1984; Luciani, 2002; Robaszynski and Mzoughi, 2010]). This species has been variably interpreted in the literature, including its attribution at genus level (Gandolfi, 1955; Bro¨nnimann and Brown, 1956; *

MATERIALS AND METHODS Tanzania Drilling Project Site 23 (Fig. 1) was drilled in 2007, 0.10 km E off the main road to Lindi and 5.10 km to the W of Lindi (UTM 37L 573638, 8893108). The principal lithologies from the bottom of the hole (90.70 m) to 64.10 m consist of greenish-gray, weakly bedded, massive siltstones and sandy siltstones. The 64.10–57.10 m section comprises light-gray, medium- to fine-grained, massive sandstones, whereas from 57.10 m to the surface grayish blue-green, massive, calcareous claystones (Jimenez Berrocoso and others, 2010). Site 35 was drilled in 2008, 60 m E off the main road to Lindi, 6.8 km W of Lindi (UTM 37L 571341, 8893754). There was good to moderate recovery of microfossils from surface to bottom (92 m). The principal lithology from the bottom to 14 m is greenish-gray and greenish-black, massive

Correspondence author. E-mail: [email protected]

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FIGURE 1. Paleogeographic reconstruction for the Late Cretaceous (84.0 Ma) with the location of TDP Sites 23 and 35 (coastal Tanzania, western Indian Ocean) and the other sites cited in the paper (Colombia, Texas, western Atlantic Ocean; Shatsky Rise, northwestern Pacific Ocean and Bottaccione section, Tethys). After Hay and others, 1999.

to slightly laminated siltstones, whereas the overlying section is yellowish-brown and greenish-gray, massive to slightly laminated claystones and silty claystones. Samples were processed for foraminifera by standard procedure, and 84 washed residues from Site 23 and 80 washed residues from Site 35, then were examined under a stereomicroscope. Scanning electron microscopy enabled more detailed observations on the shell morphology and wall structure of planktonic foraminifera. Samples were also processed following standard procedure for calcareous nannofossils (Jimenez Berrocoso and others, 2010). A detailed biostratigraphic analysis was carried out on the planktonic foraminiferal assemblages to determine their composition and to identify the main bioevents. Relative abundances of planktonic and benthic foraminiferal were calculated as: very abundant (VA) 5 .50%; abundant (A) 5 25–50%; common (C) 5 16–25%; few (F) 5 6–15%; rare (R) 5 2–5%; very rare (VR) 5 , 2%. The preservation was estimated as excellent (E) for specimens with pristine and ‘‘glassy’’ shells, good (G) for specimens showing little diagenetic alteration and little fragmentation, moderate (M) for specimens with diagenetic alteration, little fragmentation and totally or partially infilled tests, and poor (P) for specimens showing strong diagenetic alteration, high fragmentation and completely infilled tests. The relative abundance of planktonic foraminifera, their preservation and the distribution of selected species for Sites 23 and 35 are indicated in the tables of Appendices 1 and 2. For genera and species identification, we follow the taxonomic concepts that are presented in the CHRONOS online Mesozoic Planktonic Foraminiferal Taxonomic Dictionary (http://portal.chronos.org). Comments included for each discussed species clarify its taxonomic concept followed in this study and note significant morphological features. The description of one species is emended. Synonymies are limited to the original descriptions, and additional references are included when needed to support our species concepts. BIOSTRATIGRAPHY Planktonic foraminifera are generally common to very abundant and show moderate to excellent preservation in the samples collected from sites 23 and 35. Nevertheless, glassy

foraminifera are rare and confined to limited stratigraphic intervals. The planktonic assemblages from both sites are similar and usually quite diverse, represented by genera that are large and double- or single-keeled (Contusotruncana, Globotruncana, Globotruncanita, Radotruncana, and Globotruncanella), and smaller globigeriniform (Muricohedbergella Huber and Leckie, 2011 and Archaeoglobigerina), planispiral (Globigerinelloides) or biserial (Heterohelix, Hendersonites, Pseudoguembelina, and Pseudotextularia), suggesting the presence of a well-stratified water column. However, the abundance of calcareous perforate benthic foraminifera in most samples indicates relatively shallow waters and a possible deposition on the slope. Petrizzo and others (2011) assigned the bottom sediments (88.53–17.10 m) of Site 23 to the mid-Campanian Contusotruncana plummerae Zone, which they named to replace the Globotruncana ventricosa Zone because of the uncertain identification and diachronous lowest occurrence (Petrizzo, 2000, 2001, 2003) of its nominate marker species. The stratigraphic interval of the Contusotruncana plummerae Zone is characterized by the co-occurrence of C. plummerae and G. elevata and by the absence of Radotruncana calcarata (Cushman, 1927). The upper 17.00 m of the hole (from sample TDP23/1/1, 16–30 cm to sample TDP23/10/1, 18–40 cm) belong to the late Campanian R. calcarata Zone. The biostratigraphic analysis revealed additional bioevents, here listed in stratigraphic order: 1) the extinction of Hendersonites carinatus (Cushman, 1938) in sample TDP23/ 38/1, 3–21 cm; 2) the lowest occurrence (LO) of Globotruncanella havanensis (Voorwijk, 1936) in sample TDP23/ 22/1, 12–30 cm; 3) the LO of Radotruncana subspinosa (Pessagno, 1960) in sample TDP23/17/1, 33–43 cm; 4) the highest occurrence (HO) of Globotruncanita atlantica (Caron, 1972) in sample TDP23/9/2, 10–30 cm, and 5) the HO of G. elevata in sample TDP23/9/1, 0–20 cm. Petrizzo and others (2011) elaborate on the reliability of these bioevents in global correlation. Well-preserved calcareous nannofossils from Site 23 reveal two other datums—the LO of Uniplanarius sissinghii (Perch-Nielsen) at 78.51 m and the LO of Uniplanarius trifidus (Stradner) at 21.25 m (Jimenez Berrocoso and others, 2010) (Fig. 2). All cores from Site 35 are assigned to the mid-Campanian C. plummerae Zone based on the co-occurrence of the

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FIGURE 2. Summary of lithology, cores and bioevents identified in this study from sediment recovered at TDP Site 23. Lithology, cores, and calcareous nannofossil bioevents according to Jimenez Berrocoso and others (2010); planktonic foraminifera bioevents as identified in this study.

FIGURE 3. Summary of lithology, cores and bioevents identified in this study from sediment recovered at TDP Site 35. Calcareous nannofossil bioevents (Lees, written communication, 2009); planktonic foraminifera bioevents as identified in this study.

nominate species with G. elevata in the absence of R. calcarata. The extinction of H. carinatus was identified in sample TDP35/13/1, 7–28 cm and the LO of R. subspinosa in sample TDP35/7/1, 25–45 cm, whereas Globotruncanella havanensis was not found. Calcareous nannofossils are well preserved and allow the recognition of the LO of U. sissinghii at 39.10 m (Lees, written communication, 2009; Fig. 3). Based on the HO of H. carinatus and the LO of U. sissinghii, the estimated sedimentation rates of the two holes are significantly different. This suggests faulting between the two drillhole sites.

Globotruncana Cushman, emended in Reiss, 1957, p. 136 Globotruncana Cushman in Robaszynski and others, 1984, p. 176–177. Globotruncana Cushman in Loeblich and Tappan, 1987, p. 468

SYSTEMATIC TAXONOMY Supergroup RHIZARIA Cavalier-Smith, 2002 Class FORAMINIFERA d’Orbigny, 1826 Order GLOBIGERININA Delage and He´rouard, 1896 Superfamily GLOBOTRUNCANACEA Brotzen, 1942 Family GLOBOTRUNCANIDAE Brotzen, 1942 Genus Globotruncana Cushman, 1927 Type species: Pulvulina arca Cushman, 1926 Globotruncana Cushman, in Cushman, 1927, p. 39. Globotruncana Cushman, emended in Bro¨nnimann and Brown, 1956, p. 538

Remarks. Cushman (1927) erected the new genus Globotruncana for ‘‘trochoid tests’’ displaying a ‘‘truncate periphery, usually with a double keel on the dorsal and ventral sides’’. He did not differentiate genera by as singlevs. double-keeled. Cushman (1928) added that in wellpreserved specimens the ventral side often has ‘‘a thin plate like structure over the umbilical area’’. The genus Globotruncana was first emended by Bro¨nnimann and Brown (1956), who described it as characterized by having an ‘‘imperforate peripheral band, either single or double keeled’’. The principal aperture is interiomarginal and opens into a small to large umbilicus. Long apertural flaps extend into the umbilicus, and in later chambers form a protruded, imperforate, umbilical cover-plate structure with accessory apertures. A year later, Reiss (1957) erected Globotruncanita to accommodate single-keeled species with trumpet-shaped lips (portici of Banner and Blow, 1959; see also Longoria and Gamper, 1975), and emended Globotruncana by restricting it to taxa possessing a double-keeled profile at least in the early ontogenetic stages, and apertural features ranging from fairly large lips to trumpet-shaped to

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an umbilical cover-plate partly or entirely covering the large umbilicus, but he did not mention accessory apertures. However, Reiss’ (1957) concept of Globotruncana emphasizes the presence of a double-keel but does not take into account the different apertural structures, and that resulted in a relatively wide concept of the genus relative to its present-day classification. Contemporaneously, Bolli and others (1957) redescribed the genus Globotruncana including both single- and double-keeled taxa and introduced the term tegillum for Bro¨nnimann and Brown’s cover-plate formed by the coalescence of large umbilical flaps ‘‘perforated by accessory infralaminal and intralaminal apertures’’. However, Bolli and others (1957) did not differentiate tegilla from portici (Banner and Blow, 1959), which resulted in the rejections of Rugotruncana Bro¨nnimann and Brown 1956 and Marginotruncana Hofker 1956. Bolli and others’ (1957) concept of Globotruncana, reiterated in Loeblich and Tappan’s (1964) classification, has been followed by many, even after its new classification by Longoria and Gamper (1975). Globotruncana rosetta (Carsey, 1926) Figs. 4.1–4.2, 4.5–4.6 Globigerina rosetta Carsey in Carsey, 1926, p. 44, pl. 5, figs. 3a–b (Cretaceous, Texas, United States). Globotruncana rosetta (Carsey) rosetta Gandolfi in Gandolfi, 1955, p. 117, pl. 6, figs. 1a–c (Coniacian–Maastrichtian, Colon Shale, Colombia). Globotruncana rosetta (Carsey) in Bro¨nnimann and Brown, 1956, pl. 21, figs. 11–13 (Campanian–Maastrichtian, upper Taylor Marl, Texas). Not Globotruncana rosetta (Carsey) in Pessagno, 1967, pl. 70, figs. 9– 12, pl. 73, figs. 5–8, pl. 97. figs. 19–23, pl. 98, fig. 14, (lower Campanian–lower Maastrichtian, Taylor Marl, Texas and Mendez Shale, Mexico). Globotruncana rosetta (Carsey) in Esker, 1968, p. 170–171, figs. 1–3 (Upper Taylor Marl, Texas).

Original description. ‘‘Test coiled, flattened to slightly convex with surface of chambers flattened seldom inflated, but occasionally resting at an angle to the dorsal plane causing the anterior margin of each to be slightly raised; sutures sweep from the centre and roundly curved on the periphery giving a subpetaloid appearance, are distinctly marked, slightly broadened and frequently ornamented by tubercles which are coarser toward the center. Their periphery, formed by the extremity of the sutures, is scalloped or lobed, subcarinate and ornamented by fine excrescences. The ventral side is convex to protruded with usually only one whorl visible, and the chambers on this side are somewhat inflated with sutures marked by line of depression sometimes curving and extending from the periphery to the broad umbilicus. Umbilical margin of the chambers is marked on each by an extended lip; apertures open from the chambers in the final whorl into the receding umbilical vestibule; shell very finely perforate. The width of the shell varies from 0.3 mm to 0.7 mm, but the size is usually intermediate. Variations noted in the structure of this shell lead to the belief that if this one type were given extensive study several varieties of the species might be determined to good advantages.’’ Remarks. Following the original description, this species is basically characterized by spirally subpetaloid chambers, a convex to protruding umbilical side, and an extended lip

covering the primary aperture. Neither the number of chambers, the rate of chamber size increase, or the presence and the number of keels are directly mentioned, and the description is inadequate to unequivocally identify this species. The drawings of the spiral and umbilical views of the holotype (Fig. 4.1) show six subpetaloid chambers moderately increasing in size on the spiral side and kidneyshaped chambers on the umbilical side. The umbilical sutures seem raised, especially in the earlier chambers, suggesting a double-keeled periphery at least at the beginning of the last whorl. Unfortunately, there is no lateral view in the type figure and the drawings of the umbilical and spiral sides are too poor to help clarify the main distinguishing features of the species. As a consequence, the identification of G. rosetta has always been subjective, as demonstrated below. Gandolfi (1955), in his revision of the genus Globotruncana, identified a G. rosetta morphological and evolutionary branch within the Late Cretaceous globotruncanids. He split the species G. rosetta rosetta; (Fig. 4.2), G. rosetta insignis Gandolfi (Fig. 4.3) and G. rosetta pettersi Gandolfi (Fig. 4.4), based on specimens from the Pullenia cretacea Zone in the Colon Shale, which also yielded the planktonic foraminifera Contusotruncana contusa (Cushman, 1926) and Abathomphalus mayaroensis (Bolli, 1951), which are of Maastrichtian age (Gradstein and others, 2004). All figured specimens that Gandolfi (1955) assigned to the rosetta branch have a single keel. A year later, Bro¨nnimann and Brown (1956) re-examined the holotype of G. rosetta and noted that it possesses a narrow double keel on the earliest chambers of the last whorl, merging to form a single keel in the last ones. The same authors figured a topotype of G. rosetta (Fig. 4.5) that resembles the holotype (Fig. 4.1). Without a lateral view in the type figure, the two type specimens in the original drawing prevents to completely compare the two type specimens. In 1967, Bandy re-examined the type material selected by Carsey and noted high morphological variability among its Globotruncana specimens, among which he also recognized Globotruncana ventricosa (White, 1928). Moreover, Bandy (1967) observed that the holotype of G. rosetta rosetta was entirely single-keeled. Because of the general confusion regarding the identification of G. rosetta, and its missing holotype, Esker (1968) examined the three cotypes designated by Carsey, and chose for the neotype the one that matched Bro¨nnimann and Brown’s (1956) description of the holotype as having two keels merging in the final chambers; the other two specimens were double-keeled along the entire last whorl and believed to fall within the range of variability of Globotruncana aegyptiaca Nakkady, 1950. Esker’s neotype (Fig. 4.6) differs from the type figure (Fig. 4.1) as well as Bro¨nnimann and Brown’s (1956) topotype (Fig. 4.5) by being almost symmetrically and markedly biconvex instead of almost planoconvex, possessing five instead of six chambers in the outer whorl, increasing in size at a faster rate, and in having a less compact peripheral outline and a smaller umbilicus surrounded by less reniform chambers. The lack of clarity in the distinction between G. rosetta, G. ventricosa, and G. aegyptiaca (Bro¨nnimann and Brown,


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FIGURE 4. Type figures of species currently assigned to Globotruncana and Globotruncanita. 1, 2, 5, 6 Globotruncana rosetta (Casey, 1926): 1, holotype; 2, hypotype of Gandolfi (1955); 5, topotype by Bro¨nnimann and Brown, 1956; 6, neotype of Esker (1968). 3, 10, 11 Globotruncanita insignis (Gandolfi, 1955): 3, holotype; 10, paratype; 11, neotype of Caron (1983a). 4 Globotruncanita pettersi (Gandolfi, 1955), holotype. 7–9 Globotruncanita elevata (Brotzen, 1934): 7, holotype; 8, lectotype of Kuhry (1970); 9, specimen from sample TDP23-13-1, 8–23 cm. 12 Globotruncana lamellosa (Sigal, 1952), holotype; considered by Robaszynski and others (1984) a junior synonym of G. rosetta and to represent an intermediate morphotype between Globotruncana rosetta and G. insignis. Scale bar 5 100 mm.

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1956; Bandy, 1967; Esker, 1968) was confirmed by Pessagno (1967), who highlighted that G. rosetta could be easily confused with the other two species and considered G. rosetta as a senior synonym of Globotruncana mariei Banner and Blow, 1960. Robaszynski and others (1984) illustrated under the name of G. rosetta some specimens, including one indicated as topotype, that are rather different from each another and, more importantly, are quite different from Bro¨nnimann and Brown’s topotype and poorly match Esker’s neotype. It is worth mentioning that the specimen figured by Gandolfi (1955) as G. rosetta (Fig. 4.2) clearly differs from the neotype (Fig. 4.6) by its less convex umbilical and spiral sides, different chamber size increasing rate, and different chamber shape on the spiral side, and in being entirely single-keeled. Thus, the species concept adopted by Gandolfi (1955) for G. rosetta does not correspond to the original concept as interpreted by Bro¨nnimann and Brown (1956) nor to Esker’s neotype (1968). For these reasons, the ancestor–descendant relationship between G. rosetta and G. insignis proposed by Gandolfi (1955) is not only questionable, but must be rejected (see below) and we can conclude that so far Globotruncana rosetta (Carsey) must be considered as a dubious taxon. Stratigraphic range. The stratigraphic distribution of G. rosetta was poorly documented in the original description, in which no type level was designated. Carsey (1926) mentioned that it is common in the Navarro and Taylor Formations and ‘‘sparingly represented’’ in the Austin Formation (Gulf Series) and very rare in Del Rio Formation (Comanchean Series), that can be translated as being a Campanian–Maastrichtian taxon. Gandolfi (1955) identified this species in Maastrichtian planktonic foraminiferal assemblages that included C. contusa and A. mayaroensis. Bro¨nnimann and Brown (1956), Pessagno (1967), and Bandy (1967) observed G. rosetta in Campanian–Maastrichtian sediments. Robaszynski and others (1984) reported G. rosetta occurring in the interval from the G. ventricosa Zone to the A. mayaroensis Zone. Even if Premoli Silva and Sliter (1995) identified G. rosetta in thin section in the mid-Campanian–upper Maastrichtian planktonic foraminiferal assemblages from the Bottaccione section of Gubbio, Italy (Fig. 1), this species was not identified upon re-examining of the washed residues (Petrizzo and others, 2011). Moreover, specimens strictly resembling G. rosetta’s type illustrations (Figs. 4.1, 4.2, 4.5, 4.6) were not recognized in the examined middle Campanian assemblages from Tanzania or from other coeval stratigraphic intervals located in the equatorial Pacific, Atlantic, and Indian oceans (Petrizzo and others, 2011). Genus Globotruncanita Reiss, 1957 Type species: Rosalina stuarti de Lapparent, 1918 Globotruncanita Reiss, in Reiss, 1957, p. 136. Globotruncanita Reiss, in Longoria and Gamper, 1975, p. 91. Globotruncanita Reiss, emend. Robaszynski and others, 1984, p. 218– 219. Globotruncanita Reiss, in Loeblich and Tappan, 1987, p. 469. ? Globotruncanitella Ion and Odin, in Ion and Odin, 2001, p. 375.

Remarks. According to its original description by Reiss (1957), Globotruncanita is characterized by a single periph-

eral keel around the entire test, an umbilical structure composed of trumpet-shaped lips forming a ‘‘cover-plate covering entirely the umbilical cavity’’. He also included in this genus morphotypes with spine-shaped extensions of the chambers, which were later accommodated in the subgenus Radotruncana El-Naggar, 1971. Globotruncanita has been accepted as a valid genus by some (e.g., Maslakova, 1963; Longoria and Gamper 1975), but several workers considered it a junior synonym of Globotruncana (e.g., Loeblich and Tappan, 1964; Pessagno, 1967; Longoria, 1968). Moreover, Longoria and Gamper (1975) assigned all single-keeled Globotruncaninae, whose ‘‘members represent a separate phyletic group’’ to Globotruncanita, including G. stuarti (de Lapparent, 1918), G. stuartiformis (Dalbiez, 1955), G. elevata (Brotzen, 1934), G. calcarata (Cushman, 1927), G. subspinosa (Pessagno, 1960), and G. conica (White, 1928). Examination of isolated specimens with the SEM, combined with thin-section study of Late Cretaceous globotruncanids from outcrops and deep-sea sediments (Linares, 1977; Premoli Silva and Boersma, 1977; Premoli Silva and Sliter, 1995) revealed the presence of numerous morphotypes identical to G. elevata and G. stuartiformis in association with the last of the Dicarinella concavata group in the late Santonian (Petrizzo, 2000; Gale and others, 2008). These morphotypes consistently show a second umbilical row of pustules close to the peripheral keel in the inner whorls, extending to the first one or two chambers of the last whorl. On the basis of these observations, Robaszynski and others (1984) emended the original description to include morphotypes occasionally showing two close rows of pustules on the first chambers of the last whorl. They also specified that 1) the primary aperture is umbilical; 2) the ‘‘umbilical system’’ in Globotruncanita is ‘‘composed of portici bordering the successive primary apertures, either free or coalescing in the umbilicus and, if so, leaving proximal, never distal accessory apertures’’; and 3) on the umbilical side ‘‘adumbilical ridges are well developed’’ and sutures are either depressed or raised. Accordingly, Robaszynski and others (1984) stated that the Gansserina could not be included in Globotruncanita. In addition, these authors summarized the evolution within Globotruncanita as follows: towards the end of the Santonian, ‘‘the primary aperture of one of the species of the Marginotruncana sigali group becomes umbilical in position, although the umbilical system remains composed of portici (in contrast with that of Globotruncana).’’ Robaszynski and others’ (1984) emendation was rejected by Longoria and VonFeldt (1991), who excluded from Globotruncanita ‘‘all forms having two keels at any stage of their ontogeny, considering the single-keeled periphery the most reliable character to discriminate the genus Globotruncanita from the genus Globotruncana.’’ Moreover, they considered that ‘‘an occasional row of pustules are peripheral extensions of the curved umbilical sutures’’ and cannot be regarded as a remnant of a second keel (‘‘vestige of the marginotruncanid ancestors’’). In fact, Longoria and Gamper (1975) previously stated that Globotruncanita is ‘‘a separate phyletic group, which originate directly from an archaeoglobigerinid ancestor during the early Campanian.’’


Based on previous and present observations, we confirm that primitive and ancestral forms, juvenile specimens, and intermediate morphotypes of G. elevata, G. stuartiformis (Petrizzo, 2000), and G. atlantica (Petrizzo and others, 2011) may possess an umbilical row of pustules in the earliest chambers of the last whorl. Consequently, we follow the genus concept proposed by Robaszynski and others (1984), except for the attribution of the species subspinosa and calcarata to Radotruncana El-Naggar 1971, which was erected as subgenus of Plummerita Bro¨nnimann, 1952 and later elevated to genus (see Premoli Silva and Sliter, 1995). Ion and Odin (2001) described Globotruncanitella (type species Globotruncanitella tercensis, n. sp.), a new late Campanian–late Maastrichtian genus, to accommodate specimens showing intermediate features between Globotruncana (ancestor) and Globotruncanita (descendant) and possessing a single peripheral keel and an umbilical system ‘‘composed first by portici and then by tegilla’’. They assigned G. insignis to the new genus, but their illustrated specimen is very poorly preserved and it does not display the apertural diagnostic features of their new genus. However, the holotype of G. insignis (Fig. 4.3) clearly shows portici covering the primary aperture throughout the last whorl. Moreover, a direct phyletic relationship between Globotruncanitella and Globotruncanita is difficult to demonstrate because the first specimens of G. stuartiformis and G. elevata appear in the late Santonian (Robaszynski and others, 1984; Robaszynski and Caron, 1995; Petrizzo 2000, 2002; Gradstein and others, 2004; Premoli Silva and Verga, 2004; Gale and others, 2008), well below the stratigraphic level at which G. insignis and G. tercensis are first recorded (Ion and Odin, 2001). Pending related studies and new observations, we consider Globotruncanitella a junior synonym of Globotruncanita. Globotruncanita elevata (Brotzen, 1934) Figs. 4.7–4.9 Rotalia elevata Brotzen in Brotzen, 1934, p. 66, pl.3, fig. c (Santonian– Campanian, Israel). Globotruncana andori Klasz, 1953 in Klasz 1953, p. 223–225, pl. 6, figs. a–c (upper Santonian, Germany). Not Globotruncana elevata (Brotzen), in Pessagno, 1967, pl. 78, figs. 12–14, pl. 81, figs. 10–14 (late Campanian–Maastrichtian, upper Taylor Marl, Texas and and Mendez Shale, Mexico). Globotruncana elevata (Brotzen) in Kuhry, 1970, p. 295, pl. 1, figs. 1–3 (upper Santonian, Israel). Globotruncana dentata Hooper in Hooper, 1977, p. 362, fig. 3 (Santonian–Campanian, Australia). Globotruncanita elevata (Brotzen) ‘‘formas primitivas’’ in Linares, 1977, pl. 34, figs. 1, 2 (lower Campanian, Spain). Globotruncanita elevata (Brotzen) in Robaszynski and others, 1984, p. 229, pl. 27, figs. 1–3, p. 331, pl. 28, figs., 1–3 (upper Santonian– lower Campanian, Israel, Germany, Tunisia, Spain). Globotruncanita elevata (Brotzen) in Premoli Silva and Sliter, 1995, p. 69, pl. 18, figs. 5 and 7 (upper Santonian–mid Campanian, Bottaccione section, Gubbio, Italy). Globotruncanita elevata (Brotzen) in Petrizzo, 2000, p. 503, pl. 18, figs. 5, 6 (lower Campanian, Exmouth Plateau).

Original description (translated from German). ‘‘Test nearly circular with spiral side slightly elevated towards the central part; border sharp, umbilicus deep and wide. Last chambers are indistinct on spiral side, but a small disk in

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the middle. Last whorl presents six to nine chambers, which are bordered on the spiral side by small, curved ledges. The chambers are strongly inflated sidewise on the umbilical side and slope towards the umbilical side. Border formed by a sharp ledge. The surface is rough.’’ Remarks. According to the original description and to holotype (Fig. 4.7) and lectotype (Fig. 4.8) images, this species is mainly characterized by having initially crescentic and later petaloid chambers on the spiral side, a typical central cone formed by the earliest whorl, a single peripheral keel, and a markedly asymmetrical profile with a strongly convex umbilical side. The features of the umbilical area are not directly mentioned in the original description, nor are they apparent in the type figure (Fig. 4.7) or visible in the lectoype (Fig. 4.8). However, probably on the basis of the type description and drawings, Reiss (1957) ascribed this species to Globotruncanita because of the single keeled and the apertural features, both of which were distinctly different from the other Globotruncana species. The central cone and the umbilically highly developed last chamber that forms a right angle with the equatorial plane are both very stable morphological characters within the range of variability of G. elevata, and thus can be considered distinctive of this species. In agreement with Robaszynski and others (1984), we also included in this taxon, morphotypes showing triangular to crescentic chambers on the spiral side and two close rows of beads on the first chambers of the last whorl (Fig. 4.9). Longoria and VonFeldt (1991) proposed an ancestor– descendant relationship between G. elevata (Figs. 4.7–4.9) and G. insignis Gandolfi (Fig. 4.3) based on their observation of transitional morphotypes characterized in spiral view by the crescentic chambers of G. elevata in the earliest whorls and the petaloid chambers of G. insignis in the ultimate whorl, and on the presence of a strongly convex umbilical side in both species. However, G. elevata clearly differs from G. insignis by having a pronounced central cone on the spiral side and a much highly developed last chamber on the ventral side (Robaszynski and others, 1984). Moreover, we did not detect an intermediate morphotype between the two species in the examined assemblages. For these reasons, we are reluctant to accept the phyletic reconstruction proposed by Longoria and VonFeldt (1991). Stratigraphic range. Brotzen (1934) observed G. elevata in Santonian–Campanian strata from Israel. The LO of G. elevata is in the Dicarinella asymetrica Zone (Spain: Linares, 1977; Bottaccione section: Premoli Silva and Sliter, 1995; Mediterranean area: Robaszynski and Caron, 1995; Tunisia: Robaszynski and others, 2000; Exmouth Plateau: Petrizzo, 2000; Austria: Wagreich, 2010). The HO of G. elevata falls in the R. calcarata Zone at TDP Site 23 at the Shatsky Rise (Petrizzo and others, 2011) and generally in the Mediterranean area (Robaszynski and Caron, 1995; Turkey: Sari, 2006), but it was recorded from the upper C. plummerae Zone at the Bottaccione section (Premoli Silva and Sliter, 1995; Petrizzo and others, 2011) and in Tunisia (Robaszynski and others, 2000). Ion and Odin (2001) reported the HO of this species in the lower C. contusa Zone at Tercis les Bains, France.

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Globotruncanita insignis (Gandolfi, 1955) Figs. 4.3, 4.10–4.11, 5.2–5.3, 5.7–5.8 Globotruncana rosetta insignis Gandolfi in Gandolfi, 1955, p. 67, pl. 6, figs. 2a–c (upper Senonian, Colon Formation, Colombia). Globotruncanita insignis (Gandolfi) in Caron, 1983a, p. 184, fig. 2a–c (upper Campanian, upper Taylor Clay, Texas). Globotruncana insignis Gandolfi in Robaszynski and others, 1984, p. 199, pl. 12, figs. 1–3 ( Campanian–Maastrichtian, North Atlantic and Algeria). Globotruncanita insignis (Gandolfi) in Longoria and VonFeldt, 1991, p. 229, pl. 5, fig. 6 (Maastrichtian, Meńdez Shale, Mexico). Not Globotruncanita insignis (Gandolfi) in Longoria and VonFeldt, 1991, p. 229, pl. 5, figs. 1–5, 7, 8 (late Campanian, Mendez Shale, Mexico and Marlbrook Marl, Texas).

Original description. ‘‘Usually seven to eight fairly lobate (especially the last one) chambers, which become shorter in the adult stages. They are strongly protruding and slightly inflated on the ventral side, where the sutural elevations disappear here and there in the sutural depressions, however, with the ‘bourrelet umbilical’ generally present. The sutures are more conspicuously beaded than in Globotruncana rosetta rosetta (Carsey). Fairly arched lips are present in the umbilical cavity.’’ Emended description. Trochospire extremely low and profile strongly asymmetrical; spiral side flat, umbilical side strongly convex. Outline circular, slightly lobate. Six to seven chambers in last whorl increasing slowly in size as added. Final chambers inflated on umbilical side. Spiral chambers triangular in inner whorl, petaloid in the outer whorl. Spiral sutures straight to curved, raised and beaded. Umbilical chambers trapezoidal, umbilical sutures straight, beaded in early chambers as in holotype, then becoming depressed between last chambers. Single peripheral keel, but two close rows of pustules in earliest chambers of last whorl commonly observed in ancestral forms. Umbilical area circular and small, from M to J of the maximum diameter, surrounded by well-developed adumbilical ridges. Primary aperture umbilical and covered by portici. Remarks. When Pessagno (1967) re-examined the holotype of G. insignis, he described the specimen as ‘‘planoconvex, single-keeled and with petaloid chambers spirally throughout its last whorl.’’ He regarded this species as a junior synonym of G. elevata (Figs. 4.7–4.9), and G. insignis was ignored for several years afterwards by planktonic foraminiferal specialists. In 1981, during the preparation of the Atlas of Late Cretaceous Globotruncanids (Robaszynski and others, 1984), the holotype was lost by the European Working Group in Rouen, France. Museum of Bogota´ authorities refused to provide their paratype for illustration and eventual transfer to the Paleontological Research Institute (Ithaca, New York State) where the other primary types of Gandolfi reside. Instead, the Museum of Bogota´ provided micrographs of their paratype (Fig. 4.10), but the quality was deemed unacceptable for designating a neotype, and the conspecificity of holotype and paratype could not be confirmed (Caron, 1983b). Because no other material from the type locality in Colombia could be obtained and it was impossible to reliably locate the original type level (Caron, 1983b), a neotype (Fig. 4.11) was designated by Caron (1983a,), who selected it from a Taylor Marl (Texas) assemblage that also included late Campanian R. calcarata (Fig. 1). She described the neotype as follows: ‘‘Test low

trochospiral, umbilical side strongly convex. Equatorial periphery lobate, axial periphery acute with single keel. On spiral side, chambers increasing slowly in size as added, last whorl having six chambers with flat surface, first ones elongate and last three typically petaloid; sutures oblique, curved and distinctly raised. On the umbilical side, six chambers of last whorl, inflated and trapezoidal; umbilicus narrow, less than one third of test diameter; sutures radial, outlined by prolongation of keel, raised between earlier chambers and depressed between last ones. Primary aperture umbilical, shielded by system of portici.’’ The designation of the neotype caused a strong taxonomic debate (Longoria, 1983; Caron, 1983b; Longoria and Pessagno, 1984), mainly in regards to International Code of Zoological Nomenclature (ICZN, 1964) Article 75d, which lists six qualifying conditions for a neotype to be valid. Those that were not adequately addressed or met involve 1) the necessity to erect a neotype; 2) the selection of the neotype from existing type material, or from the same stratigraphic level and geographic area from which the type specimens were obtained; and 3) the need to establish the conspecificity of the holotype and neotype. Longoria and Pessagno (1984) noted that the holotype and the neotype were obtained from different stratigraphic levels and from a different geographic area. They also pointed out that the type description of G. insignis indicates that it is characterized by an inflated umbilical side with straight radial sutures, without any trace of raised sutures, whereas the neotype was described as having umbilical sutures radial ‘‘outlined by prolongation of keel, raised between earliest chambers and depressed between the last ones’’, which suggests the presence of an umbilical keel in the early part of the ultimate whorl. This was a major reason why Longoria and Pessagno (1984) rejected the neotype selected by Caron, as it was proof that the holotype and neotype did not belong to the same species. Although Gandolfi (1955) observed that both G. insignis and G. elevata have a strongly protruding umbilical side, as well as many chambers in the last whorl, he pointed out that the holotype of G. elevata figured by Brotzen (1934; Fig. 4.7) shows ‘‘radial depressed sutures, without any trace of raised sutures’’ on the umbilical side, while describing G. insignis as having ‘‘sutural elevations that disappear here and there in the sutural depressions’’. This was one of the main reasons why he considered them different species. Robaszynski and others (1984) regarded G. insignis as a valid species and tentatively assigned it to Globotruncana, although the presence of a single keel and the unambiguous presence of portici covering the primary aperture suggested a possible link with the single-keeled Globotruncanita group. Globotruncanita insignis was considered by these authors as a direct descendant of Globotruncana rosetta (Carsey, 1926) based on the presence of an intermediate species, Globotruncana lamellosa Sigal, 1952 (Fig. 4.12) characterized by the periphery of ultimate whorl bearing a double keel on the earliest chambers and a single keel thereafter. Longoria and VonFeldt (1991), in revising the taxonomy and the phylogeny of the single-keeled globotruncanids, recognized G. insignis as a valid species, assigned it to


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FIGURE 5. Type illustrations of species in the Globotruncanita stuartiformis–Globotruncana insignis phyletic lineage from TDP Sites 23 and 35. 1 Globotruncanita stuartiformis (Dalbiez, 1955), holotype. 2 Globotruncana bollii Gandolfi, 1955, holotype. 3, 4 Globotruncanita insignis: 3, sample TDP23-9-2, 10–30 cm; 4, sample TDP23-19-2, 49–63 cm. 5 Globotruncanita stuartiformis, sample TDP23-36-1, 40–60 cm. 6, 7 Morphotype A: 7, sample TDP23-18-2, 2–18 cm; 8, sample TDP23-34-1, 50–70 cm. 8 Morphotype B, sample TDP23-28-1, 0–12. 9, 10 Morphotype C: 9, sample TDP2327-2, 14–34 cm; 10, sample TDP35-7-1, 25–45 cm. Scale bar 5 100 mm.

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Globotruncanita, and rejected any phyletic link between it and G. rosetta. They figured eight specimens (p. 229, pl. 5, n. 1–8) that, with one exception (n. 6) do not show an ‘‘axial periphery strongly umbilico-convex’’ and spiral petaloid chambers in the last whorl, nor do they fall within the variability range of G. insignis. Instead, they are characterized by a moderately convex umbilical side (when compared to the holotype of G. insignis, Fig. 4.3) with curved and raised sutures throughout the last whorl, and they lack the typical umbilical inflation of the outer chambers, most of which appear triangular on a slightly convex spiral side. We consider the specimens shown by Longoria and VonFeldt (1991) to be within the morphological variability of G. stuartiformis, based on their variably convex umbilical and spiral sides, single peripheral keel sometimes with a close umbilical row of pustules on the first chambers of the last whorl, and spiral subtriangular to triangular chambers in the last whorl. These morphological characteristics are consistent with the type descriptions and holotype images of G. stuartiformis (Fig. 5.1) and Globotruncana bollii Gandolfi, 1955 (Fig. 5.2), the latter regarded as a junior synonym of the former in the Atlas of Late Cretaceous Globotruncanids by Robaszynski and others (1984). The exception (n. 6) among Longoria and VonFeldt’s images shows a strongly convex umbilical side with inflated umbilical chambers, and final petaloid chambers on the spiral side; therefore it effectively falls within the range of variability of G. insignis. Longoria and VonFeldt selected this specimen from the late Maastrichtian Abathomphalus mayaroensis Zone in agreement with the established stratigraphic distribution of G. insignis that was initially recognized by Gandolfi (1955). Repositories. Holotype and neotype (catalogue no 30047) are in the collections of the Paleontological Research Institution, Ithaca, New York. Topotypes are in the collections of the Museo Geolo´gico, Bogota`, Colombia. Size. Holotype: width 0.99 mm; thickness 0.33 mm. Neotype: width 0.70 mm; thickness 0.30 mm. Average dimensions of specimens assigned to G. insignis in the studied assemblages: width 0.60 mm; thickness 0.30 mm. Stratigraphic range. Globotruncanita insignis was first described by Gandolfi (1955) from the Colon Formation (Colombia) in sediments assigned to the middle part of the Pullenia cretacea Zone, and it was in association with C. contusa and A. mayaroensis, marker species for the lower and upper Maastrichtian, respectively (Gradstein and others, 2004). According to our study, the LO of G. insignis falls in the upper Contusotruncana plummerae Zone extending its stratigraphic distribution down in the mid Campanian. Geographic distribution. Texas, Mexico, Colombia, Tanzania. Evolutionary history and phyletic lineage. The planktonic foraminiferal assemblage from Tanzania shows higher morphological variability and higher species diversity than other tropical and subtropical populations (e.g., Shatsky Rise, northwestern Pacific Ocean; Bottaccione section; Fig. 1). That assemblage shed light on the taxonomic problems related to G. insignis and it was useful in reconstructing the evolutionary history of this species.

Specimens closely matching the type figure of G. insignis are relatively common in the upper part of the sections studied, where they are easily recognized because of their consistent shell morphology. In addition to G. insignis (Figs. 5.3 and 5.4), we recognized three stratigraphically ordered morphotypes (A–C) that grade between G. stuartiformis (Fig. 5.5) and G. insignis. Whereas morphotypes A and B appear to be within the range of variability of G. stuartiformis, we consider morphotype C a primitive form of G. insignis, from which the typical G. insignis evolved its completely planoconvex lateral profile and progressively more petaloid chambers. Morphotype A (Figs. 5.6 and 5.7) resembles G. stuartiformis, but differs from it in having a slightly more convex umbilical side with weakly inflated chambers, a very faint umbilical keel on the first chambers of the last whorl, and a petaloid instead of a triangular ultimate chamber on the spiral side. Morphotype B (Fig. 5.8) shows a more convex umbilical side with a more strongly inflated last chamber. Spirally, the chambers also appear triangular, except for the last two that are typically petaloid, as in morphotype A. Morphotype C (Figs. 5.9 and 5.10) differs from morphotype B in having triangular-shaped to more numerous petaloid chambers on the spiral side and a strongly asymmetrical profile, with a spiral side from slightly convex to flat and an umbilical side markedly convex; it differs from typical G. insignis in possessing a less robust appearance, less inflated chambers on the umbilical side and in still presenting slightly raised umbilical sutures on the first chambers of the last whorl. Despite the discrete range of morphologic variability shown by the three morphotypes (thus considered intermediate forms instead of true species), all specimens in this phyletic lineage present a stuartiformis-like inner whorl with triangular chambers, confirming the existence of an ancestor–descendant relationship between the two taxa. As shown in the reconstruction of the phyletic lineage presented in Figure 6, the neotype selected by Caron is morphologically comparable to morphotype C, and we therefore ascribe the specimen to the G. stuartiformis–G. insignis phyletic lineage and consider it a primitive form of G. insignis. The reconstruction of this ancestor–descendant relationship through clear and gradual evolutionary steps excludes the existence of any phyletic link between G. insignis and G. rosetta (Gandolfi, 1955; Robaszynski and others, 1984) or G. elevata (Longoria and VonFeldt, 1991). Moreover, based on its phyletic relation with G. stuartiformis, single keel, and portici covering the primary aperture, G. insignis can be unequivocally included in the genus Globotruncanita, in agreement with Longoria and VonFeldt (1991). CONCLUSIONS Mid-Campanian planktonic foraminiferal assemblages from Tanzania are more diverse than expected and globotruncanids showing a strongly convex umbilical side are very common in the population. Examination of stratigraphically ordered samples ascribed to the C. plummerae–R. calcarata zones allowed reconstruction of the ancestor–descendant relationship between G. stuartiformis and G. insignis through the recognition of three

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FIGURE 6. Reconstruction of the phyletic lineage of Globotruncana insignis through the three intermediate morphotypes identified in this study. Biozonation after Premoli Silva and Sliter (1995), Robaszynski and Caron (1995), and Petrizzo and others (2011). Age according to Gradstein and others (2004).

intermediate morphotypes. The main taxonomic ambiguities, related to the identification of G. insignis and its neotype, have been solved with interpretation of the latter as a primitive form of this species. On the other hand, we demonstrate that the phyletic link between G. rosetta and G. insignis proposed by Gandolfi (1955) is unlikely, since the species concept of G. rosetta adopted by this author does not match with the morphological characters shown by the holotype and by the neotype. We also excluded a possible phyletic relationship between G. insignis and G. elevata, as these species clearly show different morphological features. In conclusion, the temporal (stratigraphic) cline of intermediate morphotypes confirms that G. insignis is a direct descendant of G. stuartiformis. Moreover, if recognized in other localities, the lowest occurrence of G. insignis could be a good marker for approximating the boundary between the middle and upper Campanian (Gradstein and others, 2004). ACKNOWLEDGMENTS We are indebted to Isabella Premoli Silva for her fruitful comments on earlier versions of the manuscript. We also thank Brian Huber and Dan Georgescu for their thorough and thoughtful reviews, and the Editor Ken Finger for numerous helpful editorial suggestions. The Tanzanian Drilling Project coordinated by B.T. Huber and K.G. MacLeod is thanked for inviting us to the field seasons and

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APPENDIX 1 TDP Site 23. Planktonic and benthic foraminifera relative abundances. Preservation and stratigraphic distribution of selected planktonic foraminifera species and morphotypes A, B, and C discussed in this study. See text for further explanation. This table can be found on the Cushman Foundation website in the JFR Article Data Repository (http://www.cushmanfoundation.org/jfr/index.html) as item number JFR-DR2011011. APPENDIX 2 TDP Site 35. Planktonic and benthic foraminifera relative abundances. Preservation and stratigraphic distribution of selected planktonic foraminifera species and morphotypes A, B, and C discussed in this study. See text for further explanations. This table can be found on the Cushman Foundation website in the JFR Article Data Repository (http://www.cushmanfoundation.org/jfr/index.html) as item number JFR-DR2011011.