Basin in Northern Minas Gerais, Brazil Preliminary

.J.S. Bittencourt et al. / Geonomos, 27(1), 1-10, 2019 1 www.igc.ufmg.br/geonomos

PRELIMINARY REPORT ON THE LACUSTRINE STRATA OF THE SANFRANCISCANA BASIN IN NORTHERN MINAS GERAIS, BRAZIL

Jonathas S. Biencourt1,2 , Pedro L. C. R. Vieira1 , Raphael M. Horta, André G. Vasconcelos1,2 , Natália C. A. Brandão2,3 , Angelo Dos Santos4 ,Luiz Guilherme Knauer1

¹Instuto de Geociências, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos 6627, 31270-901, Belo Horizonte, Minas Gerais, Brazil. jsbi[email protected] (* autor correspondente). ²Laboratório de Paleontologia e Macroevolução, Centro de Pesquisas Professor Manoel Teixeira da Costa, Instuto de Geociências, UFMG. ³Programa de Pós-graduação em Zoologia, Instuto de Ciências Biológicas, UFMG. ⁴Department of Earth and Planetary Sciences, McGill University, Montréal, Quebec H3A 0E8, Canada.

Received on March 18, 2019; accepted on October 13, 2019 Abstract: We report new data on the geology and the fossil record of the Sanfranciscana Basin in sites to the north of the tradionally explored localies within Minas Gerais. The strata in the new explored area are formed by disnct lithologies, encompassing pelic rocks with caliche levels and metric bodies of cross-bedded sandstone towards the top, similar to the fluviolacustrine beds of the Areado Group in the southern porons of the basin. Also similar to other regions of the São Francisco Craton, the deposits of the Sanfranciscana Basin studied herein lie discordantly to the rocks of the Bambuí Basin. We preliminarily report neopterygian fish scales, lile informave archosaurian bones and an associaon of the ostracods Ilyocypris- Fossocytheridea. This ostracod associaon is registered for the first me in the Cretaceous of the Sanfranciscana Basin. The ostracods have been collected from the lacustrine, vertebrate-bearing rocks cropping out in Lagoa dos Patos and Coração de Jesus. The cytherideid Fossocytheridea assigns a minimal Apan age to its bearing rocks. Its associaon with Ilyocypris was also reported in Upper Cretaceous oligohaline paleoenvironments in Brazil and Argenna, indicang similar deposional condions to the strata reported in this paper. The putave affinies of the specimens of the Sanfranciscana Basin with F. ventrotuberculata, and their associaon with Ilyocypris, raise the hypothesis of a younger age for some levels of that basin in northern Minas Gerais, perhaps ranging into the Late Cretaceous.

Keywords: Ostracoda, Archosauria, Areado Group, Cretaceous, Gondwana

INTRODUCTION corresponds to the Phanerozoic secons of the São Francisco Basin as defined by Alckmin & Marns-Neto – . The Sanfranciscana Basin corresponds to the most Lying discordantly to the rocks of the Bambuí Basin, recent, massive deposional event over the São which is represented in the studied area by the Serra de Francisco Craton . Despite its wide geographical Santa Helena, Lagoa do Jacaré and Serra da Saudade extension, the fossil record is poorly known – . Most formaons, it spans over ca. 150,000 km2 in southeast specimens have been recovered from the lacustrine and and northeast porons of Brazil –– . Yet, only the fluvial strata of the Areado Group at Planalto Mata da outcrops within Minas Gerais State have yielded fossils Corda, in the central-northwestern region of Minas unl now (Biencourt et al., 2015). Gerais State . In fact, most research conducted since The lowest strata of the Sanfranciscana Basin (Santa Fé 1950's has focused on this area. Group, Paleozoic) have glacial origins – . The Cretaceous The recent discovery of sauropod and theropod secons (Figure 1–2), which are the bulk of the strata dinosaurs in northern porons of the Sanfranciscana within that basin, are assembled into the Areado, Mata Basin within Minas Gerais has drawn aenon to its da Corda and Urucuia groups. The former encloses the importance as a window to the Cretaceous ecosystems non-fossiliferous Abaeté Formaon (alluvial fan, braided on the central-western Gondwana. These discoveries fluvial paleoenvironment) at the base, the may help to understand the paleogeography and paleobiota of the inner poron of the São Francisco Craton under influence of the opening of the Atlanc Ocean. Yet, sampled material for biostragraphic correlaon within the Sanfranciscana Basin and with other sedimentary basins worldwide is rather poor. Recent studies parally refined the age of the Areado Group, including a Valanginian–Apan range for the Quiricó Formaon – , and a possible Albian to Coniacian me span to the overlying Três Barras Formaon (Maraschin et al., 2016). The data discussed in this paper will help to improve the correlaon between south and north outcrops of the Sanfranciscana Basin.

GEOLOGICAL SETTING

The Sanfranciscana Basin sensu Campos & Dardenne – Figure 1 – Stragraphy of the Sanfranciscana Basin. Modiﬁed from several sources . doi:10.18285/geonomos.v27i1.21721

Geonomos is published by CPMTC-Professor Manoel Teixeira da Costa Research Center, Instute of Geosciences, Federal University of Minas Gerais .J.S. Bittencourt et al. / Geonomos, 27(1), 1-10, 2019 2 www.igc.ufmg.br/geonomos predominantly lacustrine Quiricó Formaon and the than the me of deposion (Hagen et al., 2001; upper Três Barras Formaon, deposited in fluvial, deltaic, Maraschin et al., 2016). and eolian environments (Campos & Dardenne, 1997; Sgarbi et al., 2001;Figure 1). In southern porons of the Sanfranciscana Basin (Figure 2), the Areado Group is capped by the volcanic rocks of the Mata da Corda Group (Figure 1). The laer is dated minimally as Turonian, based on disnct radiometric dang techniques (see Maraschin et al., 2016, for review). The Upper Cretaceous sandstones of the Urucuia Group crops out further north, and were deposited in eolian and fluvial context (Campos & Dardenne, 1997; Sgarbi et al., 2001). The Chapadão Formaon sensu Campos & Dardenne (1997) includes Cenozoic, reworked, unconsolidated sediments spread over the Sanfranciscana Basin (Campos & Dardenne, 1997). The Areado Group is especially noceable due to its fossil Figure 2 – Geological map of Minas Gerais, highlighng the Cretaceous record. The paleobiota of the Quiricó Formaon includes secons of the Sanfranciscana Basin. Modified from several sources so far charophytes, connental palynomorphs, (Chaves & Andrade, 2013; Costa et al., 2013; Knauer et al., 2013; gymnosperms and angiosperms, ostracods, Romano et al., 2013; Uhlein et al., 2013; CPRM/CODEMIG, 2014). 'conchostracans', insects, elasmobranchs, acnopterygians, the coelacanthiform Mawsonia and MATERIAL AND METHODS dinosaurs (Scorza & Silva Santos, 1955; Barbosa, 1965; Cardoso, 1971; Santos, 1971; Lima, 1979; Silva Santos, We surveyed outcrops of the Sanfranciscana Basin in the 1985; Marns-Neto, 1996; Duarte, 1997; Carvalho & region of Lagoa dos Patos and Coração de Jesus, north Kaah, 1998; do Carmo et al., 2004; Carvalho & Maisey, Minas Gerais (Figure 3), following previously published 2008; Zaher et al., 2011; Biencourt et al., 2015, 2018; geological maps of the area (Chaves & Andrade, 2013; Carvalho & Santucci, 2018; Leite et al., 2018). Fossils Knauer et al., 2013). The sedimentary data collected recovered from the Três Barras Formaon include therein were used to design a stragraphic secon of the enigmac marine microfossils, notably radiolarians, in region (Figure 4). very restricted horizons (Kaah & Koutsoukos, 1992; The ostracods were recovered aer disaggregaon of 60 Pessagno Jr. & Dias-Brito, 1996; Dias-Brito et al., 1999), g of sedimentary rock from each sampled level with and dinosaur footprints (Carvalho & Kaah, 1998). oxygen peroxide 30%; screen-washed with 90 µm, 150 The ages of the Areado and Urucuia groups are poorly µm, 250 µm and 1 mm mesh sieves and collected under constrained. The Quiricó Formaon has been considered stereomicroscope. The most relevant specimens Barremian–Apan by several authors (see Biencourt et received a carbon coat and were then visualized with a al., 2015), mainly based on the occurrence of terrestrial JEOL JSM-6510 electron scanning microscope. All the palynomorphs (Lima, 1979; Arai et al., 1995) and specimens discussed below are housed at the Instuto de ostracods (do Carmo et al., 2004). Yet, Leite et al. (2018) Geociências, Universidade Federal de Minas Gerais (IGC- found a basal range of the podocopidan Cypridea hystrix P), Belo Horizonte, Brazil. Krömmelbein, 1962 in the classical locality 'Fazenda Tereza', near João Pinheiro (Figure 2), assigning a RESULTS AND DISCUSSION Valanginian age to that level. This assignment confirmed a previous hypothesis according to which the lower levels Geology of the area of the Quiricó Formaon are pre-Barremian (Kaah, In the region studied for this paper (Figure 3), the rocks 1991; Sgarbi, 1997). here ascribed to the Areado Group crop out as The lower member of the Três Barras Formaon has been connuous deposits at 700–800 m of altude. Similar to recently dated as Albian–Coniacian based on K-Ar dang previous reports on the geology of the region (Pires- of authigenic K-feldspar (Maraschin et al., 2016). This age Domingues, 2009), we idenfied three sets of lithologies. is different from that hinted by the enigmac radiolarians The most common of them (Figure 4A–C) is formed by found within the same levels, which suggested Lower silty claystones, clayey siltstones, mudstones and Cretaceous (possibly Barremian–Apan) for the early greywacke sandstones with carbonate cement. deposion of the Três Barras Formaon (Pessagno Jr. et Occasionally, mudstones bear small calcite veins and al., 1997; Dias-Brito et al., 1999). This age incongruency is carbonate concreon grown over silty intraclasts. Most not enrely unexpected, both because of the fossils have been recovered from this lithology, including stragraphically problemac posion of the marine lile informave archosaur bones, fish scales and microfossils (Sgarbi et al., 2001), and the post-burial age ostracods (see below). of the diagenec potassic minerals, which can be younger

Figure 3 – Geological map of the studied area in north Minas Gerais. Stars indicate fossil localies discussed by (1) Zaher et al. (2011), (2) Biencourt et al. (2017), (3) Carvalho & Santucci (2018), (4–6) this paper. Fm: Formaon. Map modified from several works (Chaves & Andrade, 2013; Costa et al., 2013; Knauer et al., 2013; Uhlein et al., 2013). The second lithology encompasses repeve 30 cm to 4 lake), similar to the deposits of the Areado Group in the m intercalaon of claystone/siltstones/caliche, or Planalto Mata da Corda (Sgarbi et al., 1993; Campos & claystone/sandstones with horizontal laminaon (Figure Dardenne, 1997; Sgarbi et al., 2001; Mescolo et al., 4A). The claystone/sandstones intercalaon is composed 2015). The assignment of these beds in north Minas of spherical to subspherical quartz grains at silt and fine Gerais to the Quiricó Formaon has been hinted by some sand size, and claystone laminae. Laminaon within this authors (Zaher et al., 2011; Biencourt et al., 2017; lithology is variably thick. Each caliche lamina is no thicker Carvalho & Santucci, 2018). Yet, addional data on the than 3 cm. Siltstone, claystone and sandstone laminae stragraphic distribuon of the lacustrine deposits in are no thicker than 5 mm. that region and its fossil content are required to confirm The third lithology (Figure 4A, D–E) comprises massive, this hypothesis. poorly sorted sandstones, with frequent quartz and rare feldspar grains. The sandstone shows horizontal, tabular Fossil Ocurrences cross-bedded or trough-bedded straficaon, silty and Isolated neopterygian scales, archosaur bones and clayey matrix and carbonate cement. In upper sandy ostracods have been recovered in several localies of the levels, the matrix is scanty or absent. area. The neopterygian scales (most probably belonging The set of lithologies described above support the to lepisosteid) are similar to those reported by i nter p retaon of the paleoenvironment as Biencourt et al. (2017), from the locality 2 (Figure 3). predominantly lacustrine with episodic influx of fluvial They are abundant in the horizon V, rarer in I, III–IV, and sediments, under the influence of deserc climate (playa absent in the horizon II. None specimen has been found complete.

The archosaur bones (Figure 4F–K) were found as Albeit being found out of stragraphic context, no bone crushed and fractured pieces scaered on the ground. In was recovered from levels below the ostracod-bearing thin secon, they show dense Haversian replacement of strata. several generaons (Figure 4F). In some specimens, the The ostracods are by far the most relevant finding internal architecture was parally destroyed by the reported herein. The specimens were recovered either as infilling and crystallizaon of calcite during diagenesis complete carapaces or as isolated valves, and are very (Figure 4G). Their anatomy is not informave. The common in the strata surveyed during this invesgaon. idenficaon as archosaur is compable with more Some taxa found in the region of Lagoa dos Patos and complete and informave theropod and sauropod Coração de Jesus are disnct from those recovered in dinosaurs previously found in the area, including southern poron of the Sanfranciscana Basin. The results localies near Coração de Jesus (Zaher et al., 2011; Silva, discussed below are preliminary. A thorough study of the 2013) and Campo Azul (Figure 3) (Carvalho & Santucci, collected material is being conducted and will be 2018). reported elsewhere.

(playa

Figure 4 – A, Generalized stragraphic secon of the Sanfransciana Basin in the region of Lagoa dos Patos and Coração de Jesus. B–C, petrographic secon of the lithology 1 in normal and polarized light, respecvely, showing ostracod carapaces. D–E, petrographic secon of the lithology 3 in normal and polarized light, respecvely. F, thin secon of archosaurian bone, showing the Haversian remodeling. F, thin secon of archosaurian bone showing the destrucve diagenesis of the Haversian remodeling. H–K, isolated archosaurian bones (their exact level in the stragraphic secon is unknown). Scale bars B–G: 500 µm, H – K: 2 cm.

Among disnct taxa, two genera, namely Ilyocypris Brady Araripe have low T1–T3, with poorly delimitated margins, & Norman, 1889 and Fossocytheridea Swain & Brown, and the posterior margin of the carapace is smaller and 1964 (emend. Tibert et al., 2003), are more abundant and bear less conspicuous cardinal angle (Antonieo, 2010). more frequently recovered from different levels of the The carapaces described here are more similar to those sampled localies. Ilyocypris is more abundant in the of Upper Cretaceous strata in Argenna (Musacchio & level IV (several hundreds of specimens), and less Simeoni, 1991) and Brazil (Dias-Brito et al., 2001). The frequent in the levels V (>50 specimens) and I–III (>15 carapace size (specially the smaller ones), ornamentaon specimens). Fossocytheridea is parcularly abundant in and contour, including the straight and posteriorly the horizon V (hundreds of specimens), I–III (> 30 inclined dorsal profile, the concave ventral margin and specimens) and is absent in the level IV. the conspicuous anterior cardinal angles, of the material The carapaces of Ilyocypris recovered in this work are from northern of Minas Gerais are comparable to those subrectangular (Figure 5 A–B, E–F) to subtriangular of Ilyocypris riograndensis Musacchio & Simeoni, 1991, (Figure C – D). Their size is variable: 510–690 µm long, from the Neuquina Basin (minimally Coniacian for the 255–372 µm high, and the le valve (LV) parally overlaps ostracod-bearing levels), in Argenna (Musacchio & (dorsal and posterior porons) the right (RV) one (Figure Valla, 2007; Carignano & Varela, 2011). The main 5F, H). The carapace dorsal margin is straight and slants difference between them is the configuraon of T3, posteriorly. The anterior cardinal angle is conspicuous, which is significantly inclined in the specimens figured notably in the smaller carapaces (Figure 5C–D). The herein and mostly horizontal in I. riograndensis type anterior margin is rounded, and significantly broader material (Musacchio & Simeoni, 1991). As the than the posterior one. The posterior margin also varies morphology of T3 is diagnosc to that species, the among disnct specimens: the larger individuals have Ilyocypris from the Sanfranciscana Basin cannot be oblique posterior margin, whereas in the smaller ones it treated as conspecific. is rounded and significantly smaller than the anterior The species Ilyocypris riograndensis has also been margin. The ventral margin is slightly concave, with reported in the Araçatuba Formaon in São Paulo State, maximum concavity at the posterior half of the carapace indicang its presence in the Upper Cretaceous of Brazil length. The three tubercula typical to the genus are (Gobbo et al., 1999). Dias-Brito et al. (2001) reported conspicuous. The anterior tuberculum (T1) is the smallest several Ilyocypris species from the Adamanna one, subtriangular to rounded, located slightly dorsal to Formaon, including I. cf. wichmanni Musacchio, 1973, I. the mid-height. The middle tubercle (T2) is also cf. riograndensis and two subspecies of I. bauruensis subtriangular to rounded. The posterior tubercle (T3) is Dias-Brito et al., 2001. Some Ilyocypris described here the largest, ellipsoid, inclined 30º–40º to the (Figure 5C–D) have close affinies with I. baurensis anteroposterior axis of the carapace. T1, T2 and T3 are recdorsata Dias-Brito et al., 2001 (estampa III, fig. 2) due separated by dorsoventral sulci, which is also typical to to the shape of the carapace and the general morphology the genus. The ornamentaon is reculated. of T1–T3. The specimen assigned here to Ilyocypris show significant The cytherideid Fossocytheridea Swain & Brown, 1964 morphological variaon, especially in the size and valve (emend. Tibert et al., 2003) is reported in the contour, which may be result from accentuated sexual Sanfranciscana Basin for the first me. The carapaces dimorphism or the occurrence of more than one species here assigned to that genus (Figure 5I–T) are of that genus in the sampled material. Yet, considering subrectangular in lateral view, with variable length that the carapace ornamentaon and the configuraon (620–845 µm). RV overlaps LV for most of its extension. of T1–T3 are rather conservave in disnct valves or The dorsal margin is straight and inclined carapaces, we provisionally maintain all specimens under posteroventrally in RV, and rather convex in LV. The hinge the same generic iden fi ca o n , w i t h o p e n is anmerodont. The anterodorsal sulcus, typical for the nomenclature, unl a more detailed study is concluded. genus, is broad and vercal, bounding anteriorly the The genus Ilyocypris was reported in southern porons of conspicuous centroposterior swelling. The ocular the Sanfranciscana Basin (do Carmo et al., 2004), but the tubercle is located anterior to the anterodorsal sulcus. specimens are poorly preserved. According to the The carapace is widest at the posterior third. RV is highest aforemenoned authors, these carapaces bear pustulate at the anterior cardinal angle, and LV at midlength or ornamentaon, not reculate, as we described for the posterior to the anterodorsal sulcus. The anterior margin northern Minas Gerais specimens. A recent study based is rounded, with a compression along its anterior margin; on more complete material from several localies within and the posterior margin asymmetrically rounded the Planalto Mata da Corda did not report the presence of (ventroposteriorly projected, especially in female LV). Ilyocypris in that area (Leite et al., 2018). The ventral margin bears a posterior concavity in RV, and The Ilyocypris specimens from the Sanfranciscana Basin is straight in LV. A posteroventral rounded tubercle is also differs from previous records of that genus in the noted on the le valve. The ornamentaon is recular, Apan-Albian (?) of the Santana Formaon, Araripe Basin notably in marginal areas of the carapace. There is (Antonieo, 2010). Unlike the material described in this conspicuous sexual dimorphism: males are larger, with paper, the specimens from lower cardinal angle, and their posterior margin is more symmetrically rounded (compared with Figure 5P–Q).

The cytherideid Fossocytheridea is common in Upper Yet, as menoned by Bergue et al. (2011), there is visible Cretaceous strata within marginal basins in Brazil (Bergue variaon in the morphology of F. ventrotuberculata, and et al., 2011; Fauth et al., 2012; Piovesan et al., 2015), and future studies can test if Fossocytheridea from the its occurrence has been used as marker to lagoonal, Sanfranciscana Basin belongs to that species. brackish and marine paleoenvironments (e.g. Swain & The presence of reculaon has been recorded in other Brown, 1964; Tibert et al., 2003; Santos Filho et al., 2015). species of Fossocytheridea, including the type-species F. The specimens studied in this paper share the diagnosc lenoirensis Swain and Brown 1964, and F. kirklandi Tibert characters of Fossocytheridea ventrotuberculata, et al., 2003. Yet, these and other Fossocytheridea species including the subrectangular carapace, valve reversal and (Swain & Brown, 1964; Colin et al., 1996; Tibert et al., a tubercle in the posteroventral region of the le valve 2003), including some described from the Upper (Bergue et al., 2011). Addional characters shared by that Cretaceous marginal basins in Brazil (Bergue et al., 2011; species and the specimens described herein Fauth et al., 2012; Piovesan et al., 2014, 2015), diﬀer from encompasses sexual dimorphism, posterior 'rib' and the the material described in this paper in disnct aspects of carapace dimensions, including length-height rao the carapace morphology. The earliest Fossocytheridea (0.50). The main diﬀerence between them is the sensu Tibert et al. (2003), which includes specimens from presence of extensive reculaon in the outer surface of the Apan of Portugal (Damoe et al., 1988; Damoe et the carapace, rather than extensive punctae and minor al., 1990), is also disnct from those of the reculaon. Despite this feature was not assigned as Sanfranciscana Basin in details of the carapace shape and diagnosc to F. vetrotuberculata, we provisionally refer the absence of valve reversal, sexual dimorphism and the material of the Sanfranciscana Basin to carapace reculaon. Fossocytheridea sp., unl a more detailed study is conducted.

Figure 5 – Most abundant ostracods sampled from the horizons indicated in the Figure 4, including Ilyocypris (A–H) and Fossocytheridea (I–T). A, IGC-P 0053/11 (le); B, IGC-P 0053/10 (le); C, IGC-P 0053/06 (le valve); D, IGC-P 0053/12 (le); E, IGC-P 0053/17 (right); F, IGC-P 0052/05 (right); G, IGC-P 0053/141 (dorsal); H, IGC-P 0053/142 (ventral); I, IGC-P 0053/143 (male, le); J, IGC-P 0053/34 (male, le); K, IGC-P 0053/143 (male, le); L, IGC-P 0053/08 (male, le); M, IGC-P 0053/09 (male, right); N, IGC-P 0053/32 (male, right); O, IGC-P 0178/01 (le valve, internal); P, IGC-P 0053/144 (female, le); Q, IGC-P 0053/145 (female, right); R, IGC-P 0053/146 (dorsal, note RV overlapping LV); S, IGC-P 0052/36 (dorsal, note RV overlapping LV); T, IGC-P 0052/36 (ventral). Scale bar A–H: 200 μm; I–T: 100 μm.

Implicaons for the Sanfranciscana Basin Sanfranciscana Basin in northern Minas Gerais were deposited in brackish-water connental environment, The geological and paleontological research in the not lagoon. Interesngly, where Ilyocypris is more Sanfranciscana Basin is increasing in the last few years abundant (level IV), no carapace of Fossocytheridea has (Biencourt et al., 2015, 2017, 2018; Mescolo, 2015, been recovered, suggesng probable vercal variaon of 2017; Carvalho & Santucci, 2018; Leite et al., 2018). Yet, salinity. the outcrops in northern Minas Gerais are less studied The strata of the Quiricó Formaon in southern areas of than those in southern localies. In fact, a large amount the Sanfranciscana Basin have been dated as Valanginian of data about this area remains unpublished (Pires- to Apan with basis on ostracods and palynomorphs Domingues, 2009; Silva, 2013). This preliminary report (Lima, 1979; do Carmo et al., 2004; Leite et al., 2018). This fills parally informaon gaps on its geology and fossil indicates that this unit encloses diachronous paleobiotas. record. Previous studies in the region of Ibiaí, Lagoa dos Patos Concerning ostracods, these are known from the Quiricó and Coração de Jesus have assigned the fossiliferous Formaon since early works conducted in the Planalto lacustrine strata to the Lower Cretaceous Quiricó Mata da Corda. Barbosa et al. (1970) menoned the Formaon (Zaher et al., 2011; Biencourt et al., 2017; genera Eucyproides [sic], Heterocypris Claus, 1893, Carvalho & Santucci, 2018). Albeit the strata of northern Candonopsis Vávra, 1891 and Darwinula Brady & and southern areas of the Areado Group are geologically Robertson, 1870; Sgarbi (1997) later reported and similar, such an assignment requires further scruny. figured Paersoncypris (?), Darwinula cf. marnsi Silva, Considering that Fossocytheridea ranges from Apan to 1978 , Darwinula sp., Cypridea sp. and Ilyocypris sp.; and Maastrichan (Tibert et al., 2003), its occurrence in the Delicio et al. (1998) recorded Darwinula and Cypridaceae Sanfranciscana Basin raises disnct hypothesis for the from João Pinheiro. In these studies, no detailed chronostragraphy of the lacustrine strata of the informaon on the fossil localies and exact fossiliferous Sanfranciscana Basin. The first one is that horizons strata was provided. In a more detailed study, Do Carmo sampled here were at least parally deposited during et al. (2004) idenfied the genera Harbinia Tsao, 1959, Apan, which would correspond to the age of the upper Brasacypris Krömmelbein, 1965, Cypridea Bosquet, levels of the Quiricó Formaon (Lima, 1979; Arai et al., 1852, Bisulcocypridea (Sohn, 1969), Ilyocypris Brady & 1995; do Carmo et al., 2004; Leite et al., 2018). The Norman, 1889, several ontogenec instars of Darwinula alternave hypothesis is that the levels sampled for this and Wolburgiopsis Uliana & Musacchio, 1978 in Carmo study are younger than that implied by a possible do Paranaíba and at BR-040 road, near João Pinheiro. A correlaon with the fossil record from the Planalto Mata recent detailed paper report several species of Harbinia, da Corda. In this case, based on the associaon of Brasacypris, Cypridea, Penthesilenula Rosse & Fossocytheridea and Ilyocypris in Upper Cretaceous Martens, 1998, Alicenula Rosse & Martens, 1998, strata in Brazil and Argenna, and the Santonian age of F. Neuquenocypris Musacchio, 1973 and Timiriasevia ventrotuberculata (with possible affinies with the sanfranciscanensis Leite et al., 2018 from João Pinheiro material described here), the levels studied herein can and Presidente Olegário (Leite et al., 2018). In possibly span into the Late Cretaceous. Interesngly, the comparison with previous works, our results suggest that tanosaur Tapuiasaurus macedoi has been nested within the distribuon of ostracods within the Sanfranciscana Late Cretaceous clades in several phylogenec scenarios Basin is not uniform. Ilyocypridids, for instance, occur in (Zaher et al., 2011; Lacovara et al., 2014; Wilson et al., some outcrops near João Pinheiro, but not at Carmo do 2016). Paranaíba and Presidente Olegário (do Carmo et al., Yet, the me range of both Fossocytheridea and Ilyocypris 2004; Leite et al., 2018). In Lagoa dos Patos and Coração are long, hampering more accurate dang. Further data, de Jesus, ilyocypridids are very common. The genus including a more complete taxonomic study of the Fossocytheridea, on the other hand, is reported in the ostracods from the localies discussed here, are required Sanfranciscana Basin for the first me and is so far to elucidate the age of the Sanfranciscana Basin in restricted to northern localies. northern Minas Gerais. The associaon between Fossocytheridea (sensu Tibert et al., 2003) and Ilyocypris has also been recorded in ACKNOWLEDGEMENTS oligohaline environments of Santos Basin in Brazil (Fauth et al., 2012), and the Neuquén Group in Río Negro and We acknowledge the CPMTC-IGC-UFMG and the Center Neuquén, Argenna (Musacchio, 1973). This laer can be of Microscopy (UFMG) for assistance with sample compared to the strata of the Neuquén Group in El preparaon and SEM. Enelise K. Piovesan and Crisanini Zampal (Uliana & Musacchio, 1978), where Ilyocypris is T. Bergue are thanked for reviewing earlier dras of this abundant, and the associaon with typical brackish- manuscript, greatly improving its final version. This water ostracods is probably related to oligohaline research was funded by FAPEMIG, grants PEP-01114-15, connental environment, not necessarily with persistent APQ-01110-15, PPM-00304-18 to JSB. It also benefited marine connecon (Musacchio, 1973). So far, the lack of from the equipment acquired from Programa Petrobras unequivocal marine elements in the associaon de Formação de Recursos Humanos (PRH-PB 238). described in this paper suggests that some levels of the

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Geonomos is published by CPMTC-Professor Manoel Teixeira da Costa Research Center, Instute of Geosciences, Federal University of Minas Gerais