Taxonomy of limnic Ostracoda (Crustacea) from the Alagamar Formation, middle–upper Aptian, Potiguar Basin, northeastern Brazil

Abstract

Fifteen limnic ostracodes species have been recorded in the Alagamar Formation, Potiguar Basin: Cypridea araripensis Silva, 1978a; Cypridea? sp., Harbinia sinuata (Krömmelbein and Weber, 1971); Harbinia crepata n. sp., Harbinia dimorphica n. sp., Harbinia alta Antonietto et al., 2012; Paracypria? elongata n. sp., Ilyocyprimorpha berthoui (Colin and Dépêche, 1997); Ilyocypris? sp., Brasacypris subovatum n. sp., Candona? sp., Theriosynoecum colini n. sp., T. guzzoi n. sp., T. silvai (Silva, 1978b) diagnosis emended by Do Carmo et al. (2004b); and Darwinula martinsi Silva, 1978c diagnosis emended by Do Carmo et al. (2004b). Nine of these species have also been recorded outside of the Potiguar Basin, either in other Cretaceous basins in Brazil or coeval strata in western Africa. Despite the controversy about dating the local Alagoas Stage and the relatively large range of the Zone Harbinia spp. 201–218, the material studied in this paper belongs to the interval corresponding to the well-defined palynological zone coded as P-270, which is mid-upper Aptian in age.

New marine data and age accuracy of the Romualdo Formation, Araripe Basin, Brazil

“…kugleri, Pseudoguembelitria blakenosensis and Microhedbergella miniglobularis, which allows a chronostratigraphic position in the upper Aptian, correlated with international foraminiferal zonal schemes 50,51,[55][56][57] . In addition, the co-occurrence of Pattersoncypris crepata, whose record is very characteristic of the middle-upper Aptian from Brazilian deposits, in the Araripe Basin 58 , Potiguar Basin 59 and Sergipe-Alagoas Basin 60 is correlated with a palynological zone coded as P-270 59 and corroborates the foraminifera dating. These data reinforce the potential 51 , the first occurrence of Microhedbergella renilaevis marks an important bioevent that represents a major step in the evolution and diversification of the Albian planktic fauna, an event that was not identified in the studied section.…”

“…The lack of a continuous reef and the lack of shallow water-derived clasts in deeper-water sediments led to the characterization of the Sítio Sobradinho section as having been deposited on a ramp-type marine shelf without a steep slope at the edge (e.g., Flügel 99 ). In addition, the presence of a monospecific fauna, Pattersoncypris crepata, associated with agglutinated foraminifers indicates its tolerance to higher-salinity conditions, and thus, it is considered a holoeuryhaline species, as was interpreted from its record with the first marine incursion in the Potiguar Basin 59,[105][106][107] . Furthermore, in the Sergipe-Alagoas Basin, the species Pattersoncypris crepata occurs at the same levels as the typical marine ostracodes of the genera Cytherella, Cytherelloidea, Patellacythere and Aracajuia 60 .…”

Ostracoda (Arthropoda, Crustacea) from the Riachuelo Formation, Sergipe-Alagoas Basin, Brazil, Upper Aptian-Albian

“…The present specimens seem to be similarly, although more discretely, ornamented as other Harbinia species (Krömmelbein & Weber 1971;Hou 1984;Antonietto et al 2012;Do Carmo et al 2013). For these reasons, the current specimens are identified dubiously as Harbinia sinuata.…”

Early Cretaceous non‐marine Ostracoda from theNorthFalklandBasin,SouthAtlantic

“…or the 15 species recorded by Do Carmo et al . () from the Alagamor Formation in the Aptian of the Portiguar Basin, NE Brazil, or the 17 species recorded by Krömmelbein (, ) in his study of the Bahia Series. The maximum diversity recorded for non‐marine Cretaceous ostracods, but in this case Upper Cretaceous Maastrichtian, is given by Whatley () who counted 133 species from the Deccan Intertrappean deposits and Lameta Formation of peninsula India.…”

“…Although this is not the place for a detailed analysis of the matter, suffice to say that in a number of papers between 1998 and 2013 Do Carmo, with various co‐authors (Do Carmo et al . , ,), had sought to synonymize the Afro–Brazilian genus Pattersoncypris Bate,with the Chinese Harbinia Tsao, 1950. One of the reasons why Poropat and Colin () objected to this was that the relationship was ‘extremely problematical from a palaeobiogeographical perspective’.…”