The distribution of the Mesozoic ostracod genus Procytherura Whatley: palaeogeographical implications with special reference to Argentina

A review is undertaken of the nine species of Procytherura known to occur in Argentina and a new species, Procytherura serangodes sp. nov. is described. The global distribution of the genus indicates that it was more or less equally diverse and widely distributed in both hemispheres during most of the Lower and Middle Jurassic, but that in the Upper Jurassic and in the Lower Cretaceous, it became progressively restricted to the Southern Hemisphere. The widespread distribution of several Jurassic species of Procytherura, which occur in both Great Britain and Northwest Europe and in Argentina, is shown to be related to the availability of important migration routes, including the Tethys and the Hispanic Corridor. In the Lower Cretaceous, the very widespread distribution of Procytherura in the Southern Hemisphere, is used to support the existence of important routes along the eastern and western seaboards of Africa, the latter associated with the opening of the South Atlantic.     

Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America

Camilleri, T.A., Warne, M.T., Holloway, D.J. & Weldon, E.A., 10 May 2019. Revision of the ostracod genus Velibeyrichia Henningsmoen, 1954 from the Silurian and Lower Devonian of North America. Alcheringa XXX, X–X. ISSN 0311-5518.

Known occurrences of the ostracod genus Velibeyrichia are restricted to a number of Silurian to Lower Devonian geological strata in North America: the McKenzie Member of the Mifflintown Formation of Maryland and West Virginia; the Tonoloway Limestone of Maryland, West Virginia, Virginia and Pennsylvania; the Bloomsburg Formation of Maryland, Virginia and Pennsylvania; the Manlius Limestone of New York; and the Decker Limestone of New Jersey and New York. The genus includes six species: V. moodeyi (type species), V. mesleri, V. paucigranulosa, V. reticulosaccula, V. tonolowayensis and V. tricornia. The diagnostic combination of characters for this genus are: distinct deflection of the velum where it crosses the crumina in heteromorphs (adult female specimens), dorsal nodes on lobes L1 and L3, sexual dimorphism of the velum, and in tecnomorph specimens, either a shallow sulcus on lobe L3 or a zygal ridge (in adult tecnomorph specimens) extending from lobe L2 to lobe L3. The presence of one or the other of the latter two characters defines two distinct species groups.

Tamara T.A. Camilleri* [tamara.camilleri@deakin.edu.au], Mark T. Warne* [mark.warne@deakin.edu.au] and Elizabeth A. Weldon [l.weldon@deakin.edu.au], Deakin University, Geelong, School of Life and Environmental Sciences & Centre for Integrative Ecology (Melbourne Campus), 221 Burwood Highway, Burwood, Victoria 3125, Australia; David J. Holloway [dhollow@museum.vic.gov.au], Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia. *Also affiliated with: Museums Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.     

Mid-Cenozoic ostracod biostratigraphic range extensions and taxonomic notes on selected species from a new Oligocene (Duntroonian–Waitakian) fauna from southern New Zealand

AYRESS, M., ROBINSON, J.H. & LEE, D.E., March 2017. Mid-Cenozoic ostracod biostratigraphic range extensions and taxonomic notes on selected species from a new Oligocene (Duntroonian–Waitakian) fauna from southern New Zealand. Alcheringa 41, 487–498.

This paper discusses a highly diverse assemblage of Ostracoda, particularly biostratigraphically useful species, from a richly fossiliferous shallow-marine deposit of late Oligocene age on Cosy Dell farm, near Waimumu, Southland, New Zealand. The ostracod fauna, consisting of 126 species, is yet to be fully analysed, although it is clear that this new window into the nearshore fauna of the mid-Cenozoic provides the earliest records of many characteristic extant New Zealand genera and species, including several species hitherto only known as far back as the early Miocene (Otaian–Altonian New Zealand local Stages). Finding these younger species in an Oligocene deposit was unexpected and indicates that our current knowledge of mid-Cenozoic ostracod age ranges, particularly for nearshore species, is incomplete. Using nannofossils and molluscs, the Cosy Dell deposit is dated as late Oligocene (Duntroonian or lower Waitakian local Stages) in age; therefore, the new ostracod species occurrences described here are considered valid range extensions. Although the biostratigraphic application of the benthonic ostracod species discussed is limited owing to the effects of sedimentary facies and other palaeoenvironmental factors, the ostracod fossil record does include significant extinction and inception events that offer correlative potential for mid-Cenozoic stratigraphical studies. This study identified a need for modern illustration of many species, and we provide scanning electron microscope illustrations of those Cosy Dell taxa previously considered biostratigraphically useful, as support for species identification and associated biostratigraphic conclusions.

Michael Ayress [mike.ayress@rpsgroup.com], RPS ichron Group, Gadbrook Business Centre, Northwich CW9 7TN, UK; Jeffrey Robinson [jeffreyhrobinson@yahoo.co.nz] and Daphne Lee [daphne.lee@otago.ac.nz], Geology Department, University of Otago, Dunedin, New Zealand     

Variation in surface morphology of a Miocene hemicytherid ostracode

The development of the shell and patterns of reticulation in the middle Miocene ostracodes Hermanites glyphica and Quasibradleya are explored in relation to the development of macro-reticulation (primary) and micro-reticulation (secondary), and the effects of aggradation and degradation on surface morphology. Microreticulation is shown to be genetically controlled, not polymorphic or environmentally controlled, whereas aggradation and degradation are shown to vary continuously. Some relationships between ostracode morphology and intraspecific variation, environmentally-cued polymorphism and the phenomena of aggradation and degradation are discussed.     

Record of the deep marine Clinocythereis australis Ayress and Swanson, 1991 (Ostracoda) from the upper Miocene Tambo River Formation,Gippsland Basin,Australia: Palaeo-oceanographic and biostratigraphic implications

A new species of Tertiary lungfish, Neoceratodus djelleh, is based on two well-preserved upper tooth plates, from Duaringa, Queensland. Both specimens are elongate and have curved mediolingual faces and poorly defined ridges, with little trace of crests or clefts on the flat occlusal surface. Each ridge is supported by a bony base which extends into a peak. Enameloid is present, showing growth lines without associated cusps on the labial surface. Another specimen from Billeroo Creek, South Australia, is referred to Neoceratodus cf. N. djelleh.