A New Fossil Provannid Gastropod from Miocene Hydrocarbon Seep Deposits, East Coast Basin, North Island, New Zealand

Abstract

Provanna marshalli sp. nov. is described from Early to Middle Miocene−age fossil hydrocarbon seep localities in the East Coast Basin, North Island, New Zealand, adding to 18 modern and three fossil species of the genus described. Modern species are well represented at hydrothermal vent sites as well as at hydrocarbon seeps and on other organic substrates in the deep sea, including sunken wood and whale falls. Described fossil Provanna species have been almost exclusively reported from hydrocarbon seep deposits, with a few reports of suspected fossil specimens of the genus from other chemosynthetic environments such as sunken wood and large vertebrate (whale and plesiosaurid) carcasses, and the oldest occurrences are dated to the Middle Cenomanian (early Late Cretaceous). The New Zealand fossil species is the most variable species of the genus described to date, and its shell microstructure is reported and found to be comparable to the fossil species Provanna antiqua and some modern species of the genus.

Miocene abyssochrysoid gastropod Provanna from Japanese seep and whale-fall sites

“…Kiel (2006) identified three microstructural layers in the shell of the fossil species P. antiqua Squires, 1995: an outer prismatic layer, a central complex crossed lamellar layer and an inner homogeneous layer. Given what we have seen in P. alexi this inner layer of P. antiqua might not be a primary structure, but could rather represent an innermost layer of dissolution and recrystallization, as suggested for P. marshalli by Saether et al (2010).…”

“…There is no inner prismatic layer in P. alexi, which is also the case for P. marshalli. Saether et al (2010) suggested that the lack of this layer in P. marshalli might have been due to differential taphonomic and diagenetic processes affecting the shells, either on the seafloor or during early burial, where the outer shell microstructural layers were protected for longer from these processes by the periostracum in relation to the innermost shell layers. An alternative explanation is that an inner layer of simple prismatic microstructure was not present in P. alexi and P. marshalli.…”

“…Both the outer simple prismatic and crossed lamellar layers are present in the shells of the fossil species P. alexi sp. nov. and P. marshalli Saether, Little, and Campbell, 2010 (Table 1). In P. alexi these two layers are very clear towards the exterior of the shell (Fig.…”

“…However, two of these (P. admetoides Ponder, 1991 andP. marshalli Saether, Little, andCampbell, 2010) have distinct tabulated shoulders, lacking in the Rekifune species, and one (P. nassariaeformis Okutani, 1990) has a wider body whorl than seen in either of the Rekifune specimens.…”

An unusual new gastropod from an Eocene hydrocarbon seep in Washington State

“…Kiel (2006) also re− ported a healed shell injury in a single specimen of Pro− vanna antiqua Squires, 1995 from the Oligocene Lincoln Creek Formation, north−western USA, that may have re− sulted from a predatory crab attack. Species of Provanna are often reported as endemic to vent−seep environments (e.g., Hessler and Lonsdale 1991;Warén and Bouchet 1993;Carney 1994;Yamamoto et al 1999;Fujikura et al 2002;Cordes et al 2009), but some species have been re− ported from other organic substrates such as sunken drift− wood Bouchet 2001, 2009) and whale falls (Smith et al 2002;Smith and Baco 2003). These more 508 ACTA PALAEONTOLOGICA POLONICA 55 (3), 2010 …”