Oriocrassatella, IN

Anelli, Luiz E., Simões, Marcello G., González, Carlos Roberto & Souza, Paulo A., 2012, A new Pennsylvanian Oriocrassatellinae from Brazil and the distribution of the genus Oriocrassatella in space and time, Geodiversitas 34 (3), pp. 489-504 : 491-495

ORIOCRASSATELLA IN SPACE AND TIME

According to the available data, around 42 occurrences of Oriocrassatella are known at the present time. The genus was recorded in nearly 24 localities throughout the Pangea in Carboniferous and Permian strata (see Figs 1 ; 2).

Figure 2 displays the distribution of Oriocrassatella in space and time together with the Permo-Carboniferous glacial events. A simplified correlation of the Late Palaeozoic brachiopod zones from Argentina and eastern Australia is also shown. In this context we discuss the issues related to time and region of origin of the genus, and possible pathways that lead Oriocrassatella to reach and widespread in warm water environments throughout the Late Paleozoic.

THE CARBONIFEROUS FOSSIL RECORD

OF ORIOCRASSATELLA IN THE GONDWANA

Nine occurrences are restricted to the Carboniferous, eight from Gondwanaland and one from Early Pennsylvanian Carboniferous in northern Laurussia ( Muromtzeva 1974 in Biakov 2005). This record is puzzling, since all other Carboniferous occurrences are invariably recorded in Gondwana terrains ( Figs 1 ; 2).

Australia

Two occurrences were described from Carboniferous strata in Australia. Records of Oriocrassatella compressa Maxwell, 1964 , from Rands (Carboniferous) and Burnet formations (Lower Permian) were long considered to be the oldest for the genus in Gondwana (see Boyd & Newell 1968; Archbold et al. 1996). The Burnett Formation is probably Permian – it has Eurydesma burnettensis Waterhouse, 1986 that looks moderately close to E. cordatum Morris, 1845 , and both are considered to be Early Asselian in age (Waterhouse pers. comm.). Overlying beds with Bandoproductus macrospina Waterhouse, 1986 are either latest Asselian (as generally favored for South Asian occurrences) or Early Tastubian (Sakmarian) (Waterhouse pers. comm.). In the Rands Formation O. compressa occurs below Auriculispina levis , and above Levipustula levis zones. Auriculispina levis appears to be the youngest known Carboniferous occurrence in eastern Australia, but the precise age of this record is open to conjecture. It could be Gzhelian or probably post-Moscovian, and certainly not as old as Namurian (Waterhouse pers. comm.). Hence, these data confine O. compressa to Upper Early to Middle Pennsylvanian beds. However, if O. compressa occurs within the post-Moscovian Rands Formation as well as in the upper part of the Marginirugus barringtonensis zone in the Faulkland Formation (Namurian after Peou & Engel 1979), the range of the species may be limited from Bashkirian to Moscovian, respectively Early to Middle Pennsylvanian.

Based on data above, the small Oriocrassatella sp. of Peou & Engel (1979) probably is the oldest known occurrence of this genus. This is because Oriocrassatella sp. occurs within the upper part of the Marginirugus barringtonensis zone of Faulkland Formation in the Rawdon Valley region (Australian Gondwana; Peou & Angel 1979; see Figs 1A , 2), being considered by Roberts et al. (1976) Upper Visean to Lower Early Serpukhovian in age.

South America

Coeval marine deposits in South America are found in western Argentina referred to the Rugosochonetes- Bulahdelia zone ( Taboada 1997; see also Fig. 2), but Oriocrassatella was not found in these rocks, perhaps due to incomplete sampling or poor preservation. In western Argentina (San Eduardo Formation) the Rugosochonetes -Bulahdelia fauna occurs in beds immediately above the glacial phase El Paso II, and underlay the Levipustula levis zone ( González 1990). In fact, Sterren (2005) identified as Oriocrassatella ? sp. a specimen from the upper portion of the Rugosochonetes -Bulahdelia fauna (see Figs 1 , 2), but it shows an incomplete hinge and an unusual profile for the genus.

The earliest known record of the genus in South America could be Oriocrassatella andina González, 2002 , described from Serpukhovian-Bashkirian deposits of Western Argentina (see Figs 1A , 2; González 2002). Oriocrassatella andina is the only Oriocrassatellinae species known from the Levipustula levis zone (Serpukhovian-Bashkirian).

Oriocrassatella sp. ( González 1997) from the Río del Peñón Formation belongs to the Kochiproductus - Heteralosia assemblage, the youngest faunal assemblage of the informal Aguanegran faunal stage. The same is also true for Oriocrassatella sp. ( Manceñido et al. 1976). Both species are restricted to the Gzhelian (see Fig. 2 [7; 8]).

Oriocrassatella sanjuanina? ( González 1982) from the Agua del Jaguel Formation (southern Uspallata- Iglesia Basin) is probably a new species. It is much younger than O. sanjuanina ( González 1976) from the Cerro Agua Negra Formation and belongs to the Costatumulus amosi fauna, restricted to the Upper Asselian-Lower Sakmarian, subsequent to the Early Permian glacial sequence, that should be restricted to early Asselian in western Argentina.

In Brazil, Oriocrassatella piauiensis n. sp., which is described below, was found in the Piauí Formation (Upper Carboniferous), Parnaíba Basin, Northeastern Brazil. The Piauí Formation crops out in a large area at the northeastern part of the Parnaíba Basin ( Fig. 3A ), Piauí State, Brazil. Several fossiliferous dolostones beds occur near the José de Freitas village, and are associated with sandstones, siltstones, and mudstones deposited in a shallow- marine carbonatic shelf ( Lima Filho 1991, 1999). One of the dolostones, informally named Mucambo ( Fig. 3 A-C), together with other three beds located in the region (see Anelli et al. 2006), contains the most diverse bivalve fossil record known from the Upper Paleozoic rocks of South America ( Anelli 1999; Anelli et al. 2002, 2006, 2009). The Mucambo dolostone bed is Lower to Middle Pennsylvanian in age (Bashkirian to Lower Moscovian; Campanha & Rocha-Campos 1979). The fauna also includes commonly many gastropods, cephalopods, brachiopods and bryozoans. Trilobites are less common ( Anelli 1999). The associated fauna shows clear affinities to other Upper Pennsylvanian South and North American warm water faunas.ABashkirian to Lower Moscovian age attributed to the Piauí Formation is also supported by palynomorphs, from subsurface material ( Dino & Playford 2002; Souza et al. 2010). An age younger than Middle Moscovian to this unit is discarded, taking into account the glacial event in Paraná Basin (Itararé Subgroup), that occurred after these times. Then, a significant gap separates the Piauí Formation and the overlying Pedra de Fogo Formation, comprising the Late Moscovian to Carboniferous/Permian boundary (Melo J.H.G. pers. comm.).

THE PERMIAN FOSSIL RECORD

OF ORIOCRASSATELLA IN GONDWANA

The early portion of Early Permian was marked by an intense period of glaciation both in Argentina (Asselian to Early Sakmarian, González 2002) and Brazil (Asselian-Sakmarian; Holz et al. 2008; see Fig. 2) that may have restricted the occurrences of Oriocrassatella in southern South America. During the Early Permian (Cisuralian) there are only two scattered occurrences of the genus, being one in the post- glacial interval in western Argentina (Upper Asselian-Lower Sakmarian) and a second one in Brazil in post-glaciation rocks (Upper Sakmarian-Lower Artinskian, see both occurrences in Figures 1B and 2 [5, 15]).

During the Early Permian, Oriocrassatella is well recorded in deposits of central Gondwana fringe ( Oman, Afghanistan and India; Figs 1B , 2 [11, 13a-c, 14a-c]) with seven species assigned. Species described in Oman and Afghanistan occur out of glacial areas of perigondwanan regions during the Asselian and Sakmarian ( Angiolini et al. 2007, 2009). Larghi (2005) described a dubious Oriocrassatella (see Figs 1B , 2 [14c]) in the Dickinsartella fauna of the Saiwan Formation, Oman. According to this author, this fauna is indicative of climatic amelioration in North-Eastern Gondwanan fringe after the end of the Early Permian glacial events. Angiolini et al. (2006) stated that the progressive increase of carbonate deposits (Haushi Formation) where Oriocrassatella was recorded by Dickins & Shah (1979; see Figs 1B , 2 [14b]) is correlative to this time of climatic warming during the Upper Sakmarian. Indeed, based on oxygen isotope composition of brachiopod shells Angiolini et al. (2009) suggested that low-latitude Early Permian ocean waters did not undergo significant cooling during the final episode of Gondwanan glaciations (Glacial III).

The Carboniferous and Permian glacial interval in India is just roughly understood from the contributions of Sen (1991), Sen & Banerji (1991) and Maejima et al. (2001). It seems that all occurrences known from India are present in rocks deposited after the glacial interval ( Figs 1B , 2 [13a-c, 14a]).

Three occurrences of Oriocrassatella are scattered throughout Permian in Eastern Australia in both glacial and interglacial intervals. However, this should be viewed with caution since the dating of some occurrences is not precise, lacking resolution to attribute them to worldwide accepted Permian stages ( Figs 1B, C , 2 [12, 16, 33]). In Western Australia and peripheral regions the genus is known only from post-glaciated deposits ( Figs 1B, C , 2 [17, 31, 34-36]), except by the Early Permian occurrence from Timor ( Figs 1 , 2 [18]) an area apparently free from glaciers during this time ( Angiolini et al. 2009).

THE PERMIAN FOSSIL RECORD OF ORIOCRASSATELLA IN LAURUSSIA

The oldest known record of the genus in the Laurussia refers to an isolated Middle Carboniferous occurrence in Kazakhstan ( Muromtzeva 1974; Figs 1A , 2 [10]), followed by an extensive hiatus throughout the entire Pennsylvanian. During the Early Permian (Asselian to Sakmarian) Oriocrassatella is present in only two localities in Laurussia (see

Figs 1B , 2 [19, 20a, b]). After that, another gap in the stratigraphical distribution of the genus occurs during the entire Artinskian to Early Kungurian.

During the Upper Kungurian and Roadian the genus reached its maximum paleobiogeographic distribution in Laurussia ( Figs 1B , 2 [21-29]). Only one species was recorded in deposits of Early Lopingian age ( Figs 1C , 2 [30]) in the end of the Middle Permian and beginning of the Upper Permian. Indeed, the genus is declined significantly in the Upper Permian rocks of Laurussia.

Figures

FIG. 1. — Paleogeographic distribution ofOriocrassatella Etheridge Jr.,1907 in the:A, Carboniferous;B, Lower Permian;C, Upper/Middle Permian. Paleogeography according to Scotese’s Climate Story at www.scotese.com. Numbers according to references in Figure 2.

FIG. 3. — A, map showing the area of occurrence of the Upper Carboniferous Piauí Formation (in black) in the Parnaíba Basin, northeastern Brazil; B, localization of the outcrop of Mucambo dolostone; C, stratigraphic section showing the Mucambo dolostone.