Rev. bras. paleontol. 18(3):xxx-xxx, Setembro/Dezembro 2015
© 2015 by the Sociedade Brasileira de Paleontologia
doi: 10.4072/rbp.2015.2.01
BIOSTRATIGRAPHIC AND PALEOZOOGEOGRAPHIC REVIEW OF THE UPPER 
APTIAN-ALBIAN OSTRACODS OF RIACHUELO FORMATION, SERGIPE-
ALAGOAS BASIN, NORTHEASTERN BRAZIL
LUCAS SILVEIRA ANTONIETTO, DERMEVAL APARECIDO DO CARMO
Laboratory of Micropaleontology, Institute of Geosciences, University of Brasilia, Darcy Ribeiro Campus, 70919-970, 
Brasilia, DF, Brazil. antoniettols@gmail.com
MARTA CLAUDIA VIVIERS
PETROBRAS-CENPES/DIVEX, Cidade Universitária, Quadra 7, Ilha do Fundão, 21949-900, Rio de Janeiro, RJ, Brazil. 
mcviviers@petrobras.com.br
RODRIGO RODRIGUES ADÔRNO
Serviço Geológico do Brasil, DEGEO/DIPALE-CPRM/REPO, Avenida Lauro Sodré, 2561, CEP. 76801-58, Porto Velho, 
Rondônia, Brazil. rodrigo.adorno@cprm.gov.br
ABSTRACT – A biostratigraphic and paleozoogeographic revision of upper Aptian-Albian ostracods of the Riachuelo 
Formation, in the Sergipe-Alagoas Basin, Brazil, was conducted. The studied material comprised 336 samples from 
several outcrops, along with well cores drilled by Petróleo Brasileiro S.A. (PETROBRAS). After taxonomic analysis, 
including the description of Reticulocosta edrianae n. sp., a new biozonation scheme was obtained for the Albian interval 
of that formation, and the paleozoogeographic affi nities of the Brazil-Central West Africa province were reviewed 
through comparison with results published in the current literature. Several changes were made to the previously 
established ostracod zones. A new code for the Aracajuia benderi Zone (OSE-1), MSA-0, was created, with impact in 
all of its subzones. The names of the Pattersoncypris ex. gr. angulata (OSE-1.1), ‘Patellacythere’ sp. GA E 27 (OSE-
1.3) and Veenia guianensis (OSE-1.4) subzones were changed to Harbinia sinuata? (MSA-0.1), Praebythoceratina 
amsittenensis (MSA-0.3) and Reticulocosta edrianae (MSA-0.4), respectively. The Sergipella viviersae Subzone (OSE-
1.2) had its code changed for MSA-0.2; also, a stratotype was stablished for it, and its lower limit repositioned in time 
(from early Albian to upper Aptian). The Metacytheropteon aff. Metacytheropteron sp. GA C 24 Subzone (OSE-1.5) 
was renamed MSA-0.5. The uppermost Albian Aracajuia antiqua Latest Occurrence Interval Zone (MSA-1) is herein 
proposed, following the reclassifi cation of specimens of the Subzone Aracajuia benderi (OSE-1.6) from this species to 
Aracajuia antiqua. Paleozoogeographic analyses showed some faunal interchange with Tethyan provinces, beginning 
in the early Albian, at both specifi c and generic levels. Limited northward marine infl uxes across the Walvis Ridge 
were also observed during this age, while larger scale southward migrations occurred in the early Cenomanian. The 
presence of Brachycytherinae species in the Brazil-Central West Africa province as early as the Aptian indicates a new 
zoogeographic origin for this subfamily, while explaining the occurrence of the group in both the Austral realm and 
part of the Tethyan realm during the Albian.
Key words: Early Cretaceous, South Proto-Atlantic Ocean, marine ostracods, MSA-1 Zone, province interchange.
RESUMO – Uma revisão bioestratigráfi ca e paleozoogeográfi ca dos ostracodes do Aptiano superior-Albiano da Formação 
Riachuelo, bacia de Sergipe-Alagoas, Brasil, foi proposto no presente trabalho. O material estudado compreendeu 
336 amostras de vários afl oramentos, juntamente com testemunhos de poços perfurados pela Petróleo Brasileiro S.A. 
(PETROBRAS). Após a análise taxonômica, incluindo a descrição de Reticulocosta edrianae sp. nov., um novo zoneamento 
bioestratigráfi co foi obtido para a formação, e as afi nidades paleozoogeográfi cas da província Brasil-África Central 
Ocidental (incluindo a bacia de Sergipe-Alagoas) foram revistas por meio da comparação com resultados publicados 
na literatura existente. Várias mudanças foram feitas nas biozonas previamente estabelecidas com base em ostracodes. 
O código da Zona Aracajuia benderi (OSE-1) foi alterado para MSA-0. As subzonas Pattersoncypris ex. gr. angulata, 
(OSE-1.1) ‘Patellacythere’ sp. GA E 27 (OSE-1.3) e Veenia guianensis (OSE-1.4) tiveram seus nomes e espécies guia 
alterados respectivamente para Harbinia sinuata (MSA-0.1), Praebythoceratina amsittenensis (MSA-0.3) e Reticulocosta 
edrianae (MSA-0.4), respectivamente. A subzona Sergipella viviersae (OSE-1.2) teve seu código alterado para MAS-0.2, 
e um novo estratótipo foi proposto para a mesma. A Subzona Metacytheropteron aff. Metacytheropteron sp. GA C 24 
(OSE-1.5) foi renomeada como MSA-0.5. A Zona Diferencial Superior Aracajuia antiqua (MSA-1), do Albiano terminal, 
é aqui proposta, uma vez que espécimes tidos como fósseis guia para a Subzona Aracajuia benderi (OSE-1.6) são aqui 
identifi cados como pertencendo à espécie Aracajuia antiqua. Análises paleozoogeográfi cas evidenciaram intercâmbio de 
1
2 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
faunas da Província Brasil-África Central Ocidental com províncias Tetianas a partir do Albiano, tanto em nível de espécie 
quanto de gênero. Infl uxos marinhos limitados para o norte através da Cordilheira de Walvis também foram observados 
durante esta idade, enquanto migração de maior intensidade em direção ao sul ocorreu no Eocenomaniano. A presença de 
espécies de Brachycytherinae na Província Brasil-Central África Ocidental a partir do Aptiano indica uma nova origem 
zoogeográfi ca para esta subfamília, ao mesmo tempo em que explica a ocorrência do grupo tanto em regiões austrais 
quanto tetianas durante o Albiano.
Palavras-chave: Eocretáceo, Proto-Oceano Atlântico Sul, ostracodes marinhos, Zona MSA-1, intercâmbio faunístico.
INTRODUCTION The Sergipe-Alagoas Basin is a marginal basin located 
in northeastern Brazil (9-11°30ʼS/37-35°30ʼW). Its onshore 
The present work is a biostratigraphic and paleozoo- portion is between 16 and 50 km long and 170 km wide, 
geographic revision of the upper Aptian-Albian ostracods covering a total area of approximately 11,000 km2 (Feijó, 
of the Riachuelo Formation, in the Sergipe-Alagoas Basin, 1994), bounded by the Pernambuco-Paraíba to the northeast 
northeastern Brazil. Its main objectives are to upgrade the (Maragogi high) and the Jacuípe basin to the southwest (Itapuã 
biostratigraphic framework based on ostracods for the Albian fault) (Figure 1). It has been the subject of several studies, 
of the basin and to re-evaluate the correlations between the mainly due to the amount of data acquired from efforts such as 
ostracod biozones and those based on planktic and benthic well and outcrop sampling, investigations of seismic lines and 
foraminifera and cephalopods. At the same time, we also seek gravimetric and magnetic surveys. Most of these studies have 
to determine the relationships between the “Brazil-Central focused on the oil- and gas-producing strata of the basin, i.e., 
West Africa” biological province proposed by Tambareau the Carmópolis oil fi eld (Late Jurassic-Aptian) and the Calumbi 
(1982) with its counterparts worldwide, through comparison Formation (Santonian-Cenozoic) (Marques, 1965; Souza-Lima 
with previous works addressing the same issue. et al., 2002; Campos Neto et al., 2007; Graddi et al., 2007).
A B
C
Figure 1. Location of the Sergipe-Alagoas Basin in South America (A) and Brazil (B), along with the outcrops and wells studied in the present 
work (C).
ANTONIETTO ET AL. – REVIEW OF UPPER APTIAN-ALBIAN OSTRACODS FROM NE BRAZIL 3
Since the fi rst studies on ostracods from the Sergipe- STUDY AREA
Alagoas basin conducted in the 1960s (Krömmelbein, 1962, 
1964), the Riachuelo Formation has been at the heart of The Sergipe-Alagoas basin was originally described 
important discoveries. Viviers et al. (2000) established the by Schaller (1969) as a single basin. However, a later 
fi rst ostracod-based biostratigraphy of the basin (Figure 2), stratigraphic revision by Feijó (1994) considered two 
integrating it with previous cephalopod and foraminifer separate basins, the Sergipe basin and the Alagoas Basin, 
data (Koutsoukos & Bengtson, 1993) and, in this process, separated by the Japoatã-Penedo high. Campos Neto et al. 
identifying several new species in the aforementioned (2007) recently dismissed the Japoatã-Penedo high as a 
formation. Do Carmo et al. (2008, 2012), Poropat & Colin divisor between them, as it is not observable throughout the 
(2012) and Antonietto et al. (2013) presented subsequent entire basin. It is noteworthy that the sedimentary deposits 
taxonomic updates of some species. and tectonic style in the basin vary in the states of Sergipe 
Figure 2. Biostratigraphy of the Albian and early Cenomanian sections of the Sergipe-Alagoas Basin, Brazil, based in ostracodes, foraminifers 
and cephalopods (modified from Koutsoukos & Bengtson, 1993; Viviers et al., 2000).
4 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
and Alagoas, and they are therefore still considered to be 1-US-1; however, these wells were previously illustrated in 
separate sub-basins. maps by Viviers et al. (2000).
The basin consists of 23 formations, which are correlatable Point ESTRE (713561 N, 8816808 E) in the Municipality 
to the evolutionary stages of the formation and the expansion of Rosário do Catete begins with marly mudstones that are 
of the South Atlantic Ocean: syneclise, pre-rift, rift, gulf and rich in phytofossils, followed by interbedded carbonate/clay 
drift (Ponte & Asmus, 1976; Feijó, 1994). In the beginning levels. Bioturbed creamy shales with abundant impregnations 
of the drift phase, initially restricted marine deposits and fossil-rich siliceous concretions on the top make up the 
evolved into open sea environments. The early Albian-late next strata. Immediately above it lie creamy-to-gray carbonate 
Cenomanian Riachuelo Formation was established during this mudstones that are abundant in phytofossils, especially from 
phase, due to a transgression that allowed the sedimentation angiosperms. In the same municipality, the Fazenda Santa 
of openly marine sediments. There are three members of Bárbara outcrop occurs (716635 N, 8821887 E), which is 
this formation: at the basin margins and grabens, deltaic considered to be the type section of the Taquari Member of the 
fans were formed, and the coarse sediments they carried Riachuelo Formation (Schaller, 1969). The analyzed section 
constitute the Angico Member. In lower sedimentation areas, comprises reddish calciferous mudstones, with a fossil record 
the Maruim Member dominates, with carbonate ramps and consisting of gastropod shells (Family Turritellidae Loven, 
dolomitized oolite/oncolite banks deposited under fl uctuating 1847) as well as possible brachiopods.
sea level conditions. The Taquari Member, on the other hand, The Porto dos Barcos 3 location is situated in the 
corresponds to calcareous mudstone and shale from lagoonal municipality of Riachuelo (699059 N, 8814030 E). From 
and slope environments. Two third-order sequences are the base to the top, this slightly saprolitic sequence shows 
observed in the formation, which are characterized by a highly levels of creamy calcareous siltstone, followed by alternating 
organic clay basal interval and retrogradational stacking and creamy and gray calciferous siltstones. Upward, there is 
are interpreted as transgressive systems. A third sequence, a layer of gray-to-yellowish mudstones that become very 
with predominantly calcareous deposits and a progradational fossiliferous near the top. Over this mudstone, creamy 
pattern, is interpreted as a highstand system (Campos Neto calciferous siltstones are observed, and the outcrop ends with 
et al., 2007). creamy micaceous mudstones. The fossil record of the outcrop 
includes echinoderm spines, gastropods and bivalves. Point 
Regional settings Penha (692726 N, 8812604 W), also located in Riachuelo, 
The material studied in the present work comprised 147 presents a sequence of yellow, calcareous fi ne sandstones 
samples collected from outcrops of the Riachuelo Formation, with levels of brachiopod-coquina and sparse phytofossils 
in the State of Sergipe, Brazil, plus 189 samples from cores at its base. This sequence is followed by gray calciferous 
drilled by Petróleo Brasileiro S.A. (PETROBRAS) (Figures shales, laminated calcareous siltstones and laminated fi ne 
1, 3), totaling 336 samples (Table 1). The UTM quadrant sandstones. Abundant occurrences of bivalves and echinoids 
reference for coordinates is 24L, in the SAD69 default system. are also recorded in these strata.
The majority of the outcrops (ESTRE, Fazenda Santa Bárbara, In the same municipality, the São José 1 outcrop (693824 
Porto dos Barcos 3, Penha, São José 1 and P384) is composed N, 8811279 W) presents the most complex lithology among the 
of alternate strata of the Taquari and Angico members. The sampled sites. Basal siltstones with calcareous impregnations 
Maruim Member is only present in the upper part of the are superposed with yellow silty fi ne sandstones and calciferous 
Massapê outcrop. No lithology or GPS coordinates were yellow siltstones with limestone levels. After a non-observable 
provided by PETROBRAS for wells 1-CPB-1, 7-CP-252 and interval, massive yellow sandstones are recorded, followed 
Table 1. Sampled depths analyzed by well in the present work.
Well Sampled depth (m)
1-CPB-1 198, 222, 345.5, 348, 348.5, 35, 354.5, 355.5, 356.5, 358.5, 359.5, 360.5, 364.5
0, 12, 30, 60, 90, 98.5, 99.5, 100.5, 101.1, 120, 150, 180, 210, 240, 246, 261, 270, 270.05, 276, 291, 300, 306, 321, 330, 336, 351, 
360, 366, 381, 390, 396, 399, 399.5, 400.5, 411, 420, 426, 441, 450, 456, 471, 480, 486, 501, 510, 516, 531, 540, 541, 546, 552, 
1-US-1 552.5, 553.5, 554.5, 555.5, 561, 570, 576, 591, 600, 606, 621, 630, 636, 651, 660, 666, 678, 679.55, 681, 690, 696, 711, 720, 726, 741, 750, 756, 771, 780, 786, 801, 804, 810, 816, 831, 840, 846, 861, 870, 876, 891, 900, 906, 921, 930, 936, 951, 953, 953.1, 960, 
966, 981, 990, 996, 1011, 1020, 1026, 1041, 1050, 1056, 1067, 1067.25, 1071, 1080, 1086, 1101, 1110, 1116, 1131, 1139.2, 1139, 
1140, 1146, 1161, 1170, 1200, 1230, 1260, 1290, 1320, 1350, 1380, 1395, 1410, 1425
466, 466.2, 466.7, 467.5, 467.55, 467.9, 468.7, 469.2, 469.75, 469.8, 470.15, 470.6, 470.65, 471.25, 471.8, 472.25, 472.3, 472.6, 
473.3, 473.8, 474.45, 474.5, 474.85, 475.3, 475.85, 476.25, 476.3, 476.5, 476.7, 477.1, 477.5, 477.95, 478.45, 478.85, 479.5, 480.3, 
7-CP-252 480.55, 480.95, 481.6, 481.8, 482.9, 483.5, 483.55, 484.15, 484.4, 484.75, 485.6, 486.05, 486.45, 487, 488.15, 488.4, 489.15, 489.2, 489.7, 490, 490.1, 490.35, 492.95, 493, 493.45, 493.5, 494.3, 494.75, 495.85, 495.9, 496.55, 496.6, 497.7, 498.3, 498.6, 502.4, 
503.35, 503.53, 506.3, 507.15, 508.4, 508.75, 509.3, 511.35, 511.4, 511.9, 512.7, 514, 514.05, 515, 516, 517.45, 518.3, 518.8, 521, 
521.4, 523.9, 527.1, 534.8, 535.55, 540.05, 552, 553.4, 558.9, 560.3, 564.8, 567.15, 568.15, 568.95,  581.35
ANTONIETTO ET AL. – REVIEW OF UPPER APTIAN-ALBIAN OSTRACODS FROM NE BRAZIL 5
by limestones with abundant bivalves, cephalopods and RESULTS AND DISCUSSION
bioturbations. Towards the top, marl levels with varying 
amounts of limestone occur, and above them, there are very The revision of the ostracod biostratigraphy of the 
fossiliferous solid limestones, immediately under a non- Riachuelo Formation’s Albian strata demonstrates the 
rhythmic intercalation of creamy laminated siltstone marls necessity of the present changes in range and nomenclature 
and mudstones, rich in turritelid gastropods. The section ends of the zones and subzones established by Viviers et al. (2000). 
with the deposition of creamy-to-yellowish, medium-to-thinly New information was added to the Aptian-Albian ostracod 
laminated calcareous sandstones, with many phytofossils. zones, in order to improve application and resolution of the 
Locality P384 (695625 N, 8814175 E), also in Riachuelo analyzed units. In accordance to the “Código Brasileiro de 
Formation, comprises, from the base to the top, creamy Nomenclatura Estratigráfi ca” (Murphy & Salvador, 1999), 
calciferous laminated mudstones with bioturbation levels, a new code name for these units, “MSA” (“Marinho de 
rich in brachiopods, bivalves and phytoclasts; interbedded Sergipe-Alagoas”), was established in substitution for the 
yellowish calciferous siltstones and creamy sandstones; and original “OSE”. A new interval zone was also formalized in 
creamy calciferous laminated mudstones. The whole section the uppermost Albian of the Riachuelo Formation.
is abundant in turritelid shells. Point Massapê (700764 N, Some specimens identifi ed as Veenia guianensis by Viviers 
881233 L), located at the homonymous village in Riachuelo, et al. (2000) were guide fossils to one of the subzones of the 
is the only section addressed in the present work identifi ed as Albian of the Riachuelo Formation. However, they belong in 
part of the Maruim Member. The lithology of this extensive fact to an entirely new species, Reticulocosta edrianae n. sp., 
outcrop begins with yellow-creamy laminated calciferous which is herein described. A paleozoogeographic revision is 
and micaceous siltstones. Over these siltstones, fi ne-to-very also performed in this work, expanding on the correlations 
fi ne yellowish calciferous/micaceous sandstones occur. These with paleozoogeographic provinces in the northern and 
are followed by (in this order) intercalations of yellow-to- southern regions along the Proto-Atlantic Ocean.
creamy siltstones and mudstones; gray greywacke with 
dark impregnations; and, fi nally, interposed levels of oolitic Systematic paleontology
calcarenites and yellow sandstones with smoky quartz grains, The suprafamiliar classifi cation used here follows Liebau 
sparse ooids and bioturbations. (2005), while the taxonomy of lower ranks was based on 
Gründel (1974). The morphological terminology is the same 
MATERIAL AND METHODS from Sylvester-Bradley & Benson (1971), except for the usage 
of the term “ridge”, in which Kesling (1951) is followed. 
One hundred forty-seven samples collected during Terms used to describe the curvature of anterior and posterior 
fi eldwork were listed, prepared and packaged according ends – infra-curvate, equi-curvate and supra-curvate – were 
to the methodology developed by the Laboratory of adopted from Lüttig (1962). Type materials were housed 
Micropaleontology of the University of Brasilia (LabMicro- at the research collection of the Museum of Geosciences, 
UnB), Brazil. Sixty grams of each sample was prepared, University of Brasilia (UnB), under the prefi x CP (“Coleção 
and the remainder was packed in double plastic bags with de Pesquisa”).
catalogue-record sheets. The sample contents separated for 
preparation were treated as follows: fi rst, they were treated Subclass OSTRACODA Latreille, 1802
with a solution containing 30% hydrogen peroxide (H2O2), Superorder PODOCOPOMORPHA Kozur, 1972
with the aim of fragmenting rock particles. Ethanol at 92 GL Order PODOCOPIDA Sars, 1866
was added to interrupt this reaction, after which separation of Suborder CYTHEROCOPINA Gründel, 1967
grains by size was performed, using mesh sieves of 630, 250, Infraorder NOMOCYTHERININA Liebau, 1991
160 and 80 μm. For samples MP-1430 to MP-1434, MP-1493, Superfamily TRACHYLEBERIDOIDEA Sylvester-
MP-1494 and MP-1678, the 80 μm sieve was replaced by a Bradley, 1948
90 μm-56 μm dual set. Family CYTHERETTIDAE Triebel, 1952
The carapaces and valves of several species were studied Subfamily PALAEOCYTHERIDEINAE Ljubimova, 1955
at LabMicro-UnB and the Smithsonian National Museum of Tribe CYTHERETTINI Triebel, 1952
Natural History (NMNH), Washington D.C., United States. 
The analysis of the additional 189 previously processed Reticulocosta Gründel, 1974
samples from PETROBRAS was conducted at the “Centro de 
Pesquisas Leopoldo Américo Miguez de Mello” (CENPES), Type species. Reticulocosta ornatoreticulata Reyment, 1963, 
Rio de Janeiro, Brazil. After taxonomic analysis of the by subsequent designation of Gruendel (1974).
ostracods present in the samples, a new biozonation scheme 
for the Albian of the Sergipe-Alagoas Basin was obtained. The Reticulocosta edrianae n. sp.
ostracods were also used to revise the paleozoogeographic (Figures 4A-L)
affi nities of the Sergipe-Alagoas basin with other basins 
during the Albian-early Cenomanian through comparison 2000 Veenia guianensis Swain. Viviers, Koutsoukos, Silva-
with previous results from the current literature on this topic. Telles Jr. & Bengtson, p. 413, fi g. 22.10.
6 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
2000 Veenia sp. P1. Viviers, Koutsoukos, Silva-Telles Jr. & view, Paramphidont hinge, composed of an elliptical, 
Bengtson, p. 410, fi gs. 23.3, 23.4. four-lobed tooth in the right valve, followed by an anterior 
round socket, a smooth bar and a posterior, also four-lobed 
Etymology. Latinized form of “Edriana”, first name of tooth; elements in the left valve are complementary. Well-
Edriana Araújo de Lima. The name of this species is a tribute developed inner lamela, not visible in the oral region, where 
to her. the valve margin bends inwards expressively. Selvage is not 
Holotype. Female carapace (CP-716). visible at the postero-ventral and postero-central regions. 
Alotype. Male carapace (CP-717). Central muscle scars group consisting of a slightly concave 
Paratypes. Female carapace (CP-718), female carapace set of four adductor scars, the second from dorsum to venter 
(CP-719), female left valve (CP-720) and male right valve subdivided in two, and two elliptical frontal scars. Strong 
(CP-768). sexual dimorphism: females are shorter and more oblong 
Type locality and stage. Riachuelo Formation, Sergipe- in dorsal view than males; thicker ridges and less reticulate 
Alagoas Basin, Riachuelo Municipality, Sergipe State, Brazil, ornamentation in females than males. Interspecifi c variation 
approximate coordinates: 699059N, 8814030L (UTM 24L observed as follows: degree of reticulation in the carapace 
quadrant, SAD69 geodesic reference system), Porto dos lateral surface varying from widespread to concentrate along 
Barcos 3 outcrop, Sample MP-1461. middle Albian, Aracajuia its central region, and height/length ratios of the specimens 
benderi Zone (MSA-0), Praebythoceratina amsittenensis resulting in sturdier or more elongate forms.
Subzone (MSA-0.3). Dimensions. CP-716 (holotype), length 0.54 mm, height 
Diagnosis. A species of Reticulocosta distinguished by the 0.33 mm, width 0.27 mm; CP-717 (alotype), length 0.57 mm, 
following features: carapace ornamentation consisting of height 0.31 mm, width 0.26 mm; CP-718 (paratype), length 
three highly acuminate ridges, quite varied in thickness, at 0.52 mm, 0.32 mm, width 0.29 mm; CP-719 (paratype), length 
dorsal, central and ventral position. Secondary ornamentation 0.52 mm, height 0.31mm, width 0.28 mm; CP-720 (paratype), 
includes rounded to foveolate reticulation in several degrees length 0.55 mm, height 0.33 mm; CP-768 (paratype), length 
of extension, but always present at the centro-anterior region. 0.56 mm, height 0.28 mm.
Description. In lateral view, subtriangular to sub-rectangular Occurrence. ESTRE outcrop, samples MP-1423 and MP-
carapace, with greatest height at the antero-central and 1424; Fazenda Santa Bárbara outcrop, samples MP-1419 
greatest length at the central regions. Left valve is larger and MP-1420; P384 outcrop, samples MP-1496, MP-1497, 
than the right, overlapping it through the entire free margin, MP-1499, MP-1506 and MP-1509 to MP-1513; Porto dos 
but more intensely at the antero-dorsal, antero-ventral and Barcos 3 outcrop, samples MP-1460 to MP-1466, MP-1468 
postero-dorsal margins. Round anterior end, becoming to MP-1472, MP-1474 to MP-1477, MP-1481 and MP-1482.
slightly rectilinear close to the dorsal margin, where an Remarks. Reticulocosta edrianae n. sp. is similar to 
obtuse cardinal angle is formed. Round, supra-curvate Reticulocosta tarfayensis (Reyment, 1978), even presenting 
posterior end, becoming slightly rectilinear close to the some degree of intraspecific variation on the reticulate 
dorsal margin, where they form an obtuse cardinal angle; ornamentation, like the latter (see Reyment, 1978; Andreu-
a small caudal process is present. Rectilinear to slightly Boussut, 1991; Majoran, 1991). Even so, the aforementioned 
concave dorsal margin. Rounded ventral margin, with a mild species, plus Reticulocosta vitiliginosa (Apostolescu, 1961), 
concavity at the oral region. Ornamentation consisting of differ from the present species by its overall lesser presence 
three highly acuminate ridges, quite varied in thickness, at of reticulation and sharper ridges, when compared to them 
dorsal, central and ventral position: the generally smooth, (see Apostolescu, 1961). In addition, R. edrianae n. sp. has its 
curved dorsal one runs from the postero-dorsal to the antero- occurrence restricted to the Lower Cretaceous (Albian), while 
dorsal region, projecting behind the dorsal margin; the lightly the others are Upper Cretaceous species (upper Cenomanian-
posteriorly nodulate and undulate central one runs from the Santonian).
postero-central to the central region, where it connects to the 
reticulate centro-anterior tubercle; and the lightly posteriorly Biostratigraphy
nodulate and curved ventral one runs from the postero- According to Viviers et al. (2000), the Albian Stage in 
ventral to the antero-ventral region. Two riblets also occur, the Sergipe-Alagoas basin originally comprised one zone, 
one originating from the eye tubercle and running along the Amphycytherura benderi, or OSE-1, later renamed Aracajuia 
anterior end, right below it, and the other, irregularly shaped, benderi by Antonietto et al. (2013). This zone was subdivided 
runs along the ventro-central area, partially covering the into six subzones from bottom to top: Pattersoncypris ex. 
ventral margin. Additionally, a series of teeth radiates from gr. angulate, OSE-1.1; Sergipella transatlantica, OSE-1.2, 
the anterior and posterior ends. Secondary ornamentation renamed as Sergipella viviersae Do Carmo et al., 2012 by Do 
includes rounded to foveolate reticulation in several degrees Carmo et al. (2012); ‘Patellacythere’ sp. GA E 27, OSE-1.3; 
of extension, but always present at the centro-anterior Veenia guianensis Swain, 1976, OSE-1.4; Metacytheropteron 
region; Well-developed rounded eye tubercle. In dorsal aff. M. sp. GA C 24, OSE-1.5; and Amphycytherura benderi, 
view, elliptical, with greatest width at the centro-posterior OSE-1.6 – also Aracajuia benderi, after Antonietto et al. (2013). 
region; a fl at surface is formed between the anterior and Between subzones OSE-1.3 and OSE-1.4, there was an interval 
posterior cardinal angles and the dorsal ridges. In internal where no zonation based on ostracods could be established, 
ANTONIETTO ET AL. – REVIEW OF UPPER APTIAN-ALBIAN OSTRACODS FROM NE BRAZIL 7
although a transition is observable in the planktic (ending of Sergipella viviersae Latest Occurrence Interval Subzone 
Ticinella bejaouensis Zone, Ticinella bejaouensis Subzone) and (MSA-0.2)
benthic (ending of Epistomina carpenteri Zone, Osangularia Defi nition. Lower and upper boundaries of the subzone 
schloenbachi-Pseudogaudryinella/Spiroplectinata ex gr. defi ned by the last occurrences of Harbinia sinuata? and 
dividens Subzone) foraminiferal faunas as well as between Sergipella viviersae, respectively.
cephalopods (ending of Douvilleiceras Zone ) (Figure 2). Characterization. Other species observed in this 
At the present revision of the upper Aptian-Albian zone include Cytherella besrinensis (Bischoff, 1964), 
stratigraphy of the basin, several changes were made in Cytherelloidea btaterensis Bischoff, 1964, Bairdoppilata 
previously established ostracod zones and subzones, based on pseudoseptentrionalis Mertens, 1956, Cetacella sp. 1, 
the correlation of outcrops and wells analyzed (Figure 5). The Paracypris eniotmetos Nicolaidis & Piovesan, 2013, 
OSE-1 Zone and its subzones, OSE-1.1, OSE-1.2, OSE-1.3 and Harbinia crepata Do Carmo et al., 2013, Liasina sp. 1, 
OSE-1.4, are renamed and redescribed below, while OSE-1.5 Praebythoceratina amsittenensis, Praebythoceratina sp. 1, 
had only its name changed (MSA-0.5). An entirely new zone, Praebythoceratina reducta (Gründel, 1964), Patellacythere 
MSA-1, is created in the uppermost Albian of the Riachuelo shimonensis (Rosenfeld & Raab, 1983), Xestoleberis? sp. 
Formation, susbstituting the form OSE-1.6 Subzone. 1, Xestoleberis? sp. 2, Dico, Aracajuia antiqua (Rosenfeld 
& Raab, 1983), Aracajuia benderi, Eocytheropteron sp. 1, 
Aracajuia benderi Range Zone (MSA-0) Metacytheropteron aff. M. sp. GA C 24 and Metacytheropteron 
Defi nition. Stratigraphic interval corresponding to the local minuta? (Swain, 1976).
range of Aracajuia benderi Krömmelbein, 1967. Stratotype. 1-CPB-1 well, between depths of 348 and 354.5 
Characterization. From the base to the top, the following m, Municipality of Carmópolis, Sergipe State, Brazil.
subzones are recognized: the Harbinia sinuata? (Krömmelbein Stage. Uppermost Aptian-lowermost Albian.
& Weber, 1971) (MSA-0.1), Sergipella viviersae (MSA- Observations. A detailed discussion on the MSA-0.2 
0.2), Praebythoceratina amsittenensis Andreu-Boussut, Subzone (formerly OSE-1.2) can be found in Viviers et al. 
1991 (MSA-0.3), Reticulocosta edrianae (MSA-0.4) and (2000). The present work formalizes the taxonomic changes 
Metacytheropteron aff. M. sp. GA C 24 (MSA-0.5). made to this subzone by Do Carmo et al. (2012), while 
Stage. UpperAptian-upper Albian. proposing a stratotype for it. Originally, this subzone was 
Stratotype. 1-US-1 well, between depths of 690 and 1161m, restricted to the Taquari Member; however, present data 
Municipality of Laranjeiras, Sergipe State, Brazil. show it also occurs in the Angico Member. The occurrence 
Observations. A detailed discussion on the Zone MSA-0 of Harbinia crepata, a characteristic species of the Aptian 
(formerly OSE-1) can be found in Viviers et al. (2000). A of Brazil (Do Carmo et al., 2013), at the lowest portion of 
stratotype, established in core sections of the 1-US-1 well, MSA-0.2, associated with other Aptian species (Cytherella 
is also proposed for MSA-0 for the fi rst time. Although the besrineensis, Cytherelloidea btaterensis, Patellacythere 
zone is not entirely represented in this well (it lacks MSA-0.1, shimonensis and Aracajuia benderi) led to repositioning 
MSA-0.3 and MSA-0.4 subzones), this is is the most complete the lower limit of this subzone from the lower Albian to the 
section of MSA-0 so far analyzed. uppermost Aptian. Conchoecia? sp. Se1 was not observed 
Harbinia sinuata? Range Subzone (MSA-0.1) in the present work.
Defi nition. Stratigraphic interval corresponding to the local 
range of Harbinia sinuata?. Praebythoceratina amsittenensis Latest Occurrence 
Characterization. Interval containing a characteristic Interval Subzone (MSA-0.3)
association of Harbinia sinuata?, Aracajuia benderi, Defi nition. Lower and upper boundaries of the subzone 
Sergipella viviersae and Dicrorygma? sp. 1. defi ned by the last occurrences of Sergipella viviersae and 
Stratotype. 7-CP-252 well, between depths of 478.45 and Praebythoceratina amsittenensis, respectively.
484.4m, Municipality of Santo Amaro das Brotas, Sergipe Characterization. The ostracod assemblage of the subzone 
State, Brazil. also comprises Cytherella besrinensis, Cytherelloidea 
Stage. Upper Aptian. btaterensis, Bairdoppilata pseudoseptentrionalis, Robsoniella 
Observations. A detailed discussion on the MSA-0.1 Subzone falklandensis Dingle, 1984, Paracypris eniotmetos, 
(formerly OSE-1.1) can be found in Viviers et al. (2000). Praebythoceratina amsittenensis, Patellacythere parva? 
This subzone was established using Pattersoncypris ex. gr. Weaver, 1982, Xestoleberis? sp. 2, Apatocythere? sp. 1, 
angulata (Krömmelbein & Weber, 1971) as its fossil guide. Dicrorygma? sp. 1, Neocythere tenuis, Aracajuia benderi, 
However, Harbinia sinuata? (Krömmelbein & Weber, 1971) is Microceratina azazoulensis Andreu & Colin, 2005, 
more abundant in the studied samples (including the reviewed Microceratina? sp. 1, Reticulocosta edrianae, Algeriana? 
well material), which justifi es its preference as a marker for sp. 1 and Quasihermanites? sp. 1. Among species from 
the interval. A stratotype is also proposed for the subzone for Viviers et al. (2000) not observed in the MSA-0.3 Zone in the 
the fi rst time. Additionally, several species from Viviers et al. present revision are Cytherella sp. Se4, Liasina sp. 1, Veenia 
(2000), such as Ovocytheridea? aff. Ovocytheridea? sp. GA guianensis (Swain, 1976), Sergipella aff. S. transatlantica 
D 6, Pattersoncypris ex. gr. angulata, Conchoecia? sp. Se1 Krömmelbein, 1967, Cetacella aff. C. sp. GA D 24 and 
were not observed in the present study. Metacytheropteron aff. M. sp. GA C 24.
8 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
Figure 3. Lithology of sampled Riachuelo Formation outcrops in the Sergipe-Alagoas basin, Brazil. The samples are numbered from MP-1421 
to MP-1698. Abbreviations: MP, Micropaleontological collection of the “Museu de Geociências” of the “Universidade de Brasilia”. 
Stratotype. 1-CPB-1 well, between depths of 345.5 and 348 m, Characterization. This subzone fauna also includes 
Municipality of Carmópolis, Sergipe State, Brazil. Cytherella icknieldensis?, Paracypris eniotmetos, Neocythere 
Stage. Lower-middle Albian. tenuis, Aracajuia benderi and Aracajuia fragilis (Piovesan 
Observations. The species which originally named the & Nicolaidis, 2013).
MSA-0.3 (formerly OSE-1.3) subzone, ‘Patellacythere’ Stratotype. Porto dos Barcos 3 outcrop (699059 N, 8814030 
sp. GA E 27, was found to actually belong to a group E, 24L UTM quadrant reference, SAD69 default system), 
of species in the Family Bythocytheridae Sars, 1926. between 6.7 and 7m high from the outcrop base, Municipality 
The figured specimen in Viviers et al. (2000) was of Riachuelo, Sergipe State, Brazil.
reclassified as Patellacythere shimonensis, a species Stage. Middle Albian.
restricted to MSA-0.2 subzone, and most of the material Observations. The specimens identifi ed by Viviers et al. (2000) 
assigned to this species in fact belonged to another taxon, as Veenia guianensis, the fossil guide for MSA-0.4 (formerly 
Praebythoceratina amsittenensis. This was particularly OSE-1.4), belong to Reticulocosta edrianae leading to the 
true for specimens occurring after the end of MSA-0.2. renaming of this subzone. Nevertheless, Veenia guianensis 
Therefore, Praebythoceratina amsittenensis is considered was also found in the present material, though not associated 
to be the true MSA-0.3 marker. A detailed discussion on this with R. edrianae Between subzones MSA-0.3 and MSA-0.4, 
subzone can be found in Viviers et al. (2000). The MSA-0.3 Viviers et al. (2000) observed an absence of any clear biozone 
subzone was originally restricted to the Angico Member of marking species, and the interval between these subzones was 
the Riachuelo Formation; its occurrence is herein expanded left open for biozonation. The present work established the 
to the Taquari Member. Species not observed in the present contact between the two zones, although it was not possible 
work include Cytherella sp. Se4, Liasina sp. 1, Veenia to determine when in time it occurred. Therefore, the authors 
guianensis, Sergipella aff. S. transatlantica, Cetacella aff. chose to maintain along the top limits of MSA-0.3, Ticinella 
C. sp. G D 24 and Metacytheropteron aff. M. sp. GA C 24. bejaouaensis Zone (Al2) of planktic foraminifera and 
Douvilleiceras Zone of ammonites. A detailed discussion on 
Reticulocosta edrianae Latest Occurrence Interval this subzone can be found in Viviers et al. (2000). Originally, 
Subzone (MSA-0.4) there was no information about which members of the Riachuelo 
Defi nition. Lower and upper boundaries of the subzone Formation MSA-0.4 was present at; therefore, according to 
defined by the last occurrences of Praebythoceratina our results, it is restricted to the Angico and Taquari members. 
amsittenensis and Reticulocosta edrianae, respectively. Ovocytheridea? sp. Se1 was not observed in the present study.
ANTONIETTO ET AL. – REVIEW OF UPPER APTIAN-ALBIAN OSTRACODS FROM NE BRAZIL 9
Aracajuia antiqua Latest Occurrence Interval Zone 0 Zone (Viviers et al., 2000), were reclassifi ed as Aracajuia 
(MSA-1) antiqua, creating an entirely new zone in the latest Albian 
Defi nition. Lower boundary of the zone defi ned by the last of the Riachuelo Formation, the Aracajuia antiqua Latest 
occurrences of Aracajuia benderi and Metacytheropteron aff. Occurrence Interval Zone, after its guiding species, and coded 
M. sp. GA C 24, while the upper boundary is defi ned by the as MSA-1. Although its lower limit is established based in 
last occurrence of Aracajuia antiqua. two species, Aracajuia benderi and Metacytheropteron aff. 
Characterization. The MSA-1 Zone spans areas nearby M. sp. GA C 24, these two disappear from the fossil record 
the Massapê outcrop and the 1-US-1 well, between the within a slightly different interval between them. Viviers et 
towns of Riachuelo and Laranjeiras, Sergipe State, Brazil. al. (2000) did not discuss the distribution of this zone along 
It is observable in Massapê in all members of the Riachuelo the Riachuelo Formation; according to present results, it is 
Formation. Its thickness varies between 11 (Massapê observable at all members of that formation.
outcrop) and almost 300m (1-US-1 well). Other taxa present 
in this zone include Cytherella besrinensis, Cytherelloidea Paleozoogeography
btaterensis, Bairdoppilata comanchensis (Alexander, 1929), Original attempts to establish relationships based 
Bairdoppilata sp. 1, Bairdoppilata sp. 2, Cetacella sp. 1, on the composition of taxa between the upper Aptian-
Paracypris eniotmetos, Xestoleberis? sp. 1, Dicrorygma? Albian ostracodefaunas of the Riachuelo Formation and 
sp. 1, Neocythere pseudovanveeni (Gründel, 1966), coeval lithologic units from western Africa indicated 
Eocytheropteron? sp. 1, Microceratina azazoulensis, Veenia great similarity between the latter units and the Madiéla 
guianensis and Brachycythere sp. 1. Formation in the Gabon basin, Gabon (Krömmelbein, 
Stratotype. 1-US-1 well, between depths of 480 and 681 m, 1966, 1975; Krömmelbein & Wenger, 1966; Bertels, 
Municipality of Laranjeiras, Sergipe State, Brazil. 1977; Grosdidier, 1979; Koutsoukos & Silva-Telles Jr., 
Stage. Uppermost Albian. 1993). Tambareau (1982) even suggested the existence of 
Observations. Specimens previously considered to be a “Central Brazil-West Africa” biological province. This 
Aracajuia benderi in the OSE-1.6 Subzone, at the top of MSA- correlation was later expanded by Koutsoukos & Dias-
A G
C D H
B
I
F J
E
K L
Figure 4. Reticulocosta edrianae n. sp., Riachuelo Formation, Sergipe-Alagoas Basin, Middle Albian, Brazil. A, CP-716, holotype, female 
carapace, right lateral view. B, CP-718, paratype, female carapace, left lateral view. C, CP-719, paratype, female carapace, dorsal view. 
D, E, CP-717, alotype, male carapace; D, dorsal view; E, right lateral view. F-J, CP-720, paratype, female left valve; F, internal view; G, detail of 
the hinge line; H, interpretation of the hinge line structures; I, detail of the central and anterior muscle scars; J, interpretation of the central and 
anterior muscle scars. K, L, CP-768, paratype, male right valve; K, dorsal view; L, interpretation of the hinge line structures. Scale bars = 100 μm.
10 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
Britto (1987) and Piovesan et al. (2013), who observed Switzerland (Charollais et al., 1977), the Persian Gulf and 
the co-occurrence of ostracod species and genera of the Israel (Rosenfeld & Raab, 1983). This observation was partly 
Riachuelo Formation in other Brazilian shore units, such confi rmed by Piovesan et al. (2013), following a review by 
as the northeasternmost Potiguar and the southeastern Andreu (2002), who identifi ed some genera distributed along 
Campos and Santos basins. the Brazilian coast (including the Sergipe-Alagoas Basin) and 
Dias-Brito (2000), based on the occurrence of pithonellids lithologic units in Morocco.
(calcispheres), established the notion of the “Megatethys”, Reyment (1980) and Dingle (1999) studied the role of 
or the “Mid Cretaceous Tethyan Realm”. According to this the proto-Walvis ridge as a geographical barrier between the 
concept, the global distribution of pithonellids defi ned a central and southernmost Atlantic ostracodefaunas during 
realm occupying both hemispheres, approximately between the Berriasian-Santonian. After a taxonomic study of several 
latitudes 40ºN and 40ºS, in the Albian-Turonian time interval. Cretaceous stages of the Sergipe-Alagoas Basin, Viviers et 
This Megatethys Ocean reached its maximum extension in al. (2000) summarized the relationships of the Riachuelo 
the late Albian, when warm water reached temperate regions Formation with strata in several Early-Late Cretaceous 
and initially tropical organisms made brief incursions into realms along the Proto-Atlantic Ocean. These correlations 
high-latitude areas. The southern limit of this Tethyan arm was were made based in part on the chronologic and geographic 
coincident with the Walvis Ridge, an effective topographic distributions of the ostracod genera Conchoecia Dana, 1849, 
barrier at that time. Amphicytherura Butler & Jones, 1957 and Veenia Butler 
The first evidence of faunal similarity between the & Jones, 1957. A signifi cant faunal renewal was recorded 
Riachuelo Formation and strata outside of the central South approximately in the middle Cenomanian, with the fi rst 
Atlantic Ocean was provided by Colin & Andreu (1990), who appearance in the basin of genera such as Brachycythere 
were working with halocypridid ostracods. These authors Alexander, 1933 and Paracypris Sars, 1866.
found the formations in eastern Brazil and western Africa Present results corroborate previous assumptions 
to be strongly correlated with those from the North Atlantic herein summarized about the paleozoogeography of the 
Ocean, from areas such as the Agadir basin in Morocco, Riachuelo Formation ostracods, both at specifi c and generic 
southern England (Kaye, 1965), the Jura Mountains in levels. Although the majority of the species identifi ed are 
Figure 5. Reviewed ostracod biostratigraphy of the Sergipe-Alagoas basin, along with the temporal distribution of its late Aptian-Albian ostracod 
species. Names of species in bold indicate fossil guides to each biozone.
ANTONIETTO ET AL. – REVIEW OF UPPER APTIAN-ALBIAN OSTRACODS FROM NE BRAZIL 11
endemic to this province, some interchange is observed through their origins, greater paleozoogeographical 
with Tethyan faunas beginning in the early Albian (Figure proximity with the Tethysyan realm, such as Dicrorygma 
6). Species such as Veenia guianensis and Bairdoppilata Poag, 1962 (see also Christensen, 1965), Neocythere 
comanchensis are shared with North-Central American Mertens, 1956, Veenia Butler & Jones, 1957, Reticulocosta 
shores (Veenia guianensis is also found in Africa), while Gründel, 1974, Robsoniella Kuznetsova, 1956 (see also 
Conchoecia? sp. 1, Cytherella besrinensis, Cytherelloidea Gramm & Kuznetsova, 1970) and Microceratina Swanson, 
btaterensis, Praebythoceratina amsittenensis, Patellacythere 1980 (see also Colin et al., 2005). Sergipella Krömmelbein, 
shimonensis and Aracajuia antiqua appear in both 1967 is the only endemic genus of the region, according 
Brazil-Central West Africa and the Levantine region in to the occurrences summarized in Do Carmo et al. (2012).
the Middle East (Israel and Lebanon). Bairdoppilata The genus Aracajuia Krömmelbein, 1967 originated in 
pseudoseptentrionalis, Praebythoceratina reducta, the Austral province during the Berriasian, prior to becoming 
Neocythere pseudovanveeni and Neocythere tenuis co-occur very common in this realm during the Hauterivian. However, 
in the Riachuelo Formation and some of the southern-to- this genus showed its peak diversity and abundance at the 
western European basins in England, France and Germany. end of the Early Cretaceous (Barremian-Albian), along 
Two species shared with realms south of the Walvis Ridge, the shores of Brazil-Central West Africa and the South 
Microceratina azazoulensis and Robsoniella falklandensis, Mediterranean, extending to the Middle East (Antonietto et 
probably originated in Brazil-Central West Africa, where al., 2013). According to Dingle (1999), limited northward 
they surged in the middle Albian. These species reached the marine infl uxes across the Walvis Ridge are postulated for the 
former regions during the Cenomanian. middle Aptian age, while large-scale southward migrations 
The exchange of genera between the provinces of marine ostracods from the northern sector occurred in 
appears to follow the same pattern observed at the early Cenomanian and/or Turonian times. This observation 
specifi c level. Genera such as Cytherella Jones, 1849, is confi rmed by the occurrences of Aracajuia in the early-late 
Cytherelloidea Alexander, 1929, Bairdoppilata Coryell Albian of the Sergipe-Alagoas Basin.
et al., 1935, Paracypris, Bythoceratina Hornibrook, Brachycythere appeared to have originated during 
1952 and Patellacythere Gründel & Kozur, 1971 are both the Albian, somewhere close to the limits of the North 
geographically and chronologically cosmopolitan. However, American and African regions of the Tethysian realm (Colin 
some other genera present a more limited distribution, at & Babinot, 1996; Puckett, 2002), although occurrences in 
least during the Early Cretaceous, and seem to indicate, India (Austral realm) have also been reported for the same 
Figure 6. Paleozoogeography of species with occurrences in the Riachuelo Formation, Sergipe-Alagoas Basin, and coeval lithologies worldwide 
during the Albian and early Cenomanian. Paleomaps were adapted from ODSN (2011).
12 REVISTA BRASILEIRA DE PALEONTOLOGIA, 18(3), 2015
age (Andreu et al., 2008). The presence of Brachycythere (Project no. 401.794/2010-5). We are also grateful to UnB 
sp. 1 in the Brazil-Central West Africa province dates from for fi nancial support to the visit to PETROBRAS. Thanks 
the late Aptian (Grosdidier, 1979), much earlier than the to CENPES for technical support with core sample slides 
previous earliest record for this region, i.e., Brachycythere (J.V. Queiroz Neto and J.L.Grillo) and SEM photography 
sapucariensis Krömmelbein, 1964 from the Cenomanian of (R.S.M. Costa). Special thanks go to the “Agência Nacional 
several Brazilian and African basins (Viviers et al., 2000). do Petróleo, Gás Natural e Biocombustíveis”, PETROBRAS 
Therefore, it relocates the geographic origin of the Subfamily and the “Fundação de Empreendimentos Científicos e 
Brachycytherinae Puri, 1954 southwards, as it helps to explain Tecnológicos” (FINATEC) for fi nancial support to the fi eld 
the occurrence of the group in both the Austral realm and part work in the Sergipe-Alagoas basin, through the OSTRAKi 
of the Tethyan realm during the Albian. project (PETROBRAS/GEO-2007/03676). The fi rst author 
L.S. Antonietto wishes to thank the Coordination for the 
CONCLUSIONS Improvement of Higher Education Personnel (CAPES) for 
granting support that allowed the realization of most of the 
The present revision of the ostracod biostratigraphy and work in the Smithsonian NMNH from July 2013 to July 
paleozoogeography of the upper Aptian and Albian stages of 2014 (Process no. 3604-13-6), and the board of the Institute 
the Riachuelo Formation resulted in the description of a new of Geosciences-UnB, for all cooperation throughout the 
species, Reticulocosta edrianae. There were also changes in process. Last, but not least, the fi rst author thanks the NMNH 
one previously established zone and its fi ve subzones, along Paleobiology Department staff members, G. Hunt and C.E. 
with the proposition of an entirely new zone, MSA-1, created Sanford, for all of their help and great joyful moments during 
in detriment of OSE-1.6 and based on Aracajuia antiqua. The his stay at Washington, D.C., United States.
Zone OSE-1, following the present stratigraphic revision, 
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