First record of Acesta (Bivalvia: Limidae) from the Cretaceous of Australia

The cosmopolitan, Jurassic to Recent, bivalve Acesta (Limidae) is documented from Australian Cretaceous (upper Albian) rocks in the lowermost section of the Mackunda Formation of Queensland. These specimens from Landsborough Downs, Flinders Shire, represent an endemic new species, herein named Acesta (Acesta) backae n. sp. Acesta (A.) backae n. sp. was a shallow-water suspension feeder that inhabited the Cretaceous Australian epicontinental sea of the Great Artesian Basin. Although hinge details of Acesta (A.) backae n. sp. are wanting, this new taxon is most closely allied with Acesta? sp. of the Miria Formation of Western Australia and can clearly be discriminated from other Cretaceous Austral forms.     

Pliocene Mollusca (Bivalvia,Gastropoda) from the Sørsdal Formation,Marine Plain,Vestfold Hills,East Antarctica: taxonomy and implications for Antarctic Pliocene palaeoenvironments

Quilty, P.G., Darragh, T.A., Gallagher, S.J. & Harding, L.A. July 2016. Pliocene Mollusca (Bivalvia, Gastropoda) from the Sørsdal Formation, Marine Plain, Vestfold Hills, East Antarctica: taxonomy and implications for Antarctic Pliocene palaeoenvironments. Alcheringa 40, XXX–XXX. ISSN 0311-5518.

Pliocene shallow-water marine sediments at Marine Plain (centred on 68°37.7?S; 78°07.8?E) and covering approximately 10 km² in the Vestfold Hills, East Antarctica, have yielded six species of gastropods, and 11 species of bivalves from two beds within the Sørsdal Formation. Most of the material is close to in situ but some specimens have been disturbed from their life position; there is no evidence of significant transport. The gastropods include Nacella concinna (Strebel, 1908), Falsimargarita parvispira Quilty, Darragh, Gallagher & Harding sp. nov., indeterminate species of trochids and naticids, Chlanidota (Chlanidota) sp. cf. C. signeyana Powell, 1951, and two species of Trophon/Trophonella. Bivalves include Ennucula sp. aff. E. grayi (d’Orbigny, 1846), Aequiyoldia defossata Quilty, Darragh, Gallagher & Harding, sp. nov., ‘Pectunculina’ sp., Lissarca sp., Austrochlamys anderssoni (Hennig, 1911), Ruthipecten campestris Quilty, Darragh, Gallagher & Harding sp. nov., Adamussium necopinatum Quilty, Darragh, Gallagher & Harding sp. nov., Limatula (Antarctolima) sp. cf. L. hodgsoni (Smith, 1907), Cyclocardia magna Quilty, Darragh, Gallagher & Harding sp. nov., ?Hiatella sp. cf. H. arctica (Linnaeus, 1767) and Laternula elliptica (King, 1832). Preservation varies considerably owing to recrystallization, dissolution or distortion through compaction, so several species are left in open nomenclature. Oxygen isotope data indicate that water temperature was 4–7.5°C at the time of shell growth. Many species or species groups are now extinct or have migrated away from the Antarctic to the sub-Antarctic region. An Antarctic mollusc fauna has been characteristic of the region for much of the Cenozoic.

Patrick G. Quilty [p.quilty@utas.edu.au], Discipline of Earth Sciences, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, Australia; Thomas A. Darragh [tdarragh@museum.vic.gov.au], Museum Victoria, GPO Box 666 Melbourne, Victoria 3000, Australia; Stephen J. Gallagher [sjgall@unimelb.edu.au], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Lucy A. Harding [harding.lucy.a@edumail.vic.gov.au], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia.     

A rare,late Paleocene molluscan faunule from the Kings Park Formation,Perth Basin,Western Australia

A shallow marine faunule of eight taxa from the Kings Park Formation of the Perth Basin is the first described Paleocene molluscan assemblage from Western Australia. These species are part of a depauperate suite of macroinvertebrates (molluscs, echinoids and corals) derived from deep, onshore caissons in Perth and are inferred to be late Paleocene in age, based on planktonic foraminiferal biostratigraphy and associated age ranges of the molluscan fauna. Bivalves are Sarepta austranaxa sp. nov. (Sareptidae), Solemya kingsparki sp. nov. (Solemyidae), Periploma vivarirex sp. nov. (Periplomatidae), Parvamussium sp. nov.? (Propeamussiidae), Serripecten? sp. (Pectinidae) and Venericardia (Rotundicardia) petraea Darragh (Carditidae). Gastropods are Levifusus? sp. cf. L.? quadrifunifer Darragh (Buccinidae), and Columbarium rumatoides Darragh (Turbinellidae). Bivalves dominate the fauna in dark, glauconitic siltstone and sandstone facies; gastropods are of relatively poor preservation and low diversity.     

Unusual belemnite — incoceramid bivalve association from the Albian (late Early Cretaceous) of Queensland,Australia

An unusual occurrence in the upper Albian Toolebuc Formation of Queensland, Australia, of penetration of a guard of the belemnite Dimitobelus (Dimitobelus) stimulus into the disc of an indeterminate inoceramid bivalve, is the first report of this type of shell damage in the fossil record. The belemnite punctured completely both valves of the bivalve to the maximum diameter of the belemnite guard, by inferred compaction from sediment overburden during post-mortem biostratinomic processes. Shell thickening of the inoceramid bivalve by shearing of prismatic layers at the site of puncture indicates that the bivalve shell behaved plastically during the puncture and that the great flexibility of the prismatic layers was facilitated by the relatively thin shell and presence of organic sheaths around individual prisms. This flexibility may have been advantageous during a predatory attack, by allowing the maintenance of a seal during breakage of the shell margin.     

Chlorozyga,a new caenogastropod from the Early Carboniferous of Australia

Chlorozyga, a new genus of Australian Tournaisian (Early Carboniferous) caenogastropod, is proposed and assigned to the Imoglobidae. Chlorozyga has a larval shell like Imogloba from the Early Carboniferous of North America but differs in teleoconch morphology. As in Imogloba, the initial whorl of Chlorozyga is openly coiled, a feature unknown in Mesozoic and Recent caenogastropods. However, Chlorozyga and Imogloba belong to the Caenogastropoda, given their multi-whorled orthostrophic larval shells.     

Molluscan death assemblages from uplifted Holocene terraces,Mahia Peninsula,New Zealand,interpreted from present-day intertidal ecology

Beu, A.G., August 2016. Molluscan death assemblages from uplifted Holocene terraces, Mahia Peninsula, New Zealand, interpreted from present-day intertidal ecology. Alcheringa 41, xxx–xxx. ISSN 0311-5518.

Macrofossils from cover beds of marine terraces at Table Cape, Mahia Peninsula, uplifted coseismically ca 250, 1400, 1850 and 3500 years ago are compared with the fauna living on the nearby 200-m-wide intertidal rock platform. The inner platform is dry at low tide, apart from shallow pools containing Diloma aethiops and abundant but unexpected specimens of Zeacumantus subcarinatus and Cominella glandiformis exposed to the sun; all are common fossils in the terrace cover beds. The outer platform is carpeted densely with the alga Hormosira and shelters a diverse fauna, again all common fossils in the terrace cover beds. Sand and gravel containing shell fragments and supporting Zostera sea-grass turf unexpectedly covers ca 5% of the platform in low areas along the east coast. The fossil fauna is listed from 47 samples from two trenches excavated east–west and north–south through the terrace cover beds. Death assemblages of 158 molluscs, including 24 new records as fossils, and 11 taxa in other phyla delimit sediment derived from four shell accumulation sites identified around the present cape: storm beach, high-tidal strand line, hollows in the rock platform and Zostera flats. Up to 32 of the 47 samples (68%) possibly were deposited in Zostera flats; the rest were sand beach accumulations deposited at and near the high-tidal strand line. All fossils common in the cover beds lived on the rock platform. Differences between the deposits in the two trenches result from two factors. Protection along the east coast by protruding tephra beds and an outer rampart armoured with the macroalga Durvillaea prevented erosion of Zostera-supporting sediment which, therefore, was retained after each uplift event. The exposed eastern position of Table Cape also caused sediment to be transported predominantly westwards, onshore on the east coast but away from Table Cape along the north coast.

A.G. Beu [a.beu@gns.cri.nz], Paleontology Department, GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand.     

Notocarpos garratti gen. et sp. nov., a new Silurian mitrate carpoid from Victoria

Notocarpos garratti gen. et sp. nov. is described from the middle Ludlovian Humevale Formation of the Clonbinane district, Victoria. It is compared with similar anomalocystitid carpoids and is found to resemble most closely Allanicytidium flemingi Caster & Gill 1968 from the Early Devonian Reefton Beds of New Zealand. N. garratti provides evidence that anomalocystitids rested with the flattened thecal surface against the sea floor (i.e., an orientation opposite to that proposed by Jefferies, 1968). It is further suggested that the stele was adapted to provide a rearward mode of locomotion.     

A new Ordovician rostroconch mollusc from Kazakhstan

The rostroconch mollusc Eopteria aiteneria sp. nov. is described from the Late Ordovician Angrensor Formation of north-eastern Central Kazakhstan; it is the first and only known representative of this group from the Ordovician of central Asia. By the beginning of the Late Ordovician Eopteria and the family Eopteriidae were on the verge of extinction and the new Kazakhstan species represents the youngest preserved record of the family in the Ordovician. It is likely that the group found a refuge in the diverse, but rather conservative, faunal assemblage of the Hiberno-Salairian type associated with Late Ordovician carbonate algal build-ups and mud mounds which spread widely during the late Caradoc to mid Ashgill across Kazakhstanian volcanic island arcs and microplates.     

A model of prehistoric collecting on the rocky shore

Selective resource exploitation patterns in prehistory are often explained in terms of cultural preference, but this paper argues that a non-cultural explanation based upon zoological models of consumer choice may be equally valid. A model of shell-fishing behaviour concerning the relationship of abundance and yield is developed and used to predict that rocky shore collectors should ignore all factors other than the individual size of shellfish and that, in doing so, they would become progressively selective in their collecting patterns. Data from prehistoric rocky shore shell middens in Palliser Bay, New Zealand, indicates several phases of progressively selective collecting over a period of 600 years and these patterns appear best explicable in terms of the model.