Current
research
The following subjects are currently under
investigation. General topics and preliminary results are mentioned as well as
the state of progress
1. Holoplanktonic Mollusca
(Heteropoda, Janthinidae, Thecosomata, and
Gymnosomata) from the Pliocene of Pangasinan (Luzon, Philippines).
Fifteen
samples taken from interbedded sandstone, siltstone and claystone of Pliocene
age, underlying the Bolinao Limestone, at the localities Anda, Roxas and Tiep
(Pangasinan, Luzon, Philippines), were analysed for holoplanktonic gastropods;
they have yielded 50 species (16 Heteropoda, one Janthinidae, and 33 Pteropoda,
the latter consisting of 30 Euthecosomata, two Pseudothecosomata and one
Gymnosomata). Faunal diversity between the localities sampled is restricted and
explained by differences in sample size and/or preservation. The time interval
represented by all samples taken together is postulated to have been brief.
Fifteen new taxa (= 30% of the total number of encountered holoplanktonic
molluscan species) are erected; Atlanta lingayanensis sp. nov., A. richteri sp. nov., A.
seapyi sp. nov., Heliconoides sondaari sp. nov., Striolimacina
andaensis sp. nov., Hyalocylis marginata sp. nov., Cavolinia
baniensis sp. nov., C. perparvula sp. nov., C. shibatai sp.
nov., Diacavolinia pristina sp. nov., Diacria italica Grecchi, 1982 f. fissicostata f. nov., D. microstriata sp.
nov., D. paeninsula sp. nov., D. philippinensis sp. nov. and Sphaerocina convolvula
sp. nov.
Calibration with vertical ranges
of holoplanktonic molluscan species as now known enables an age assignment for
the Pangasinan assemblages of Pliocene (Piacenzian). A number of species, in
particular Atlantidae (Heteropoda), were so far known only from Quaternary or
extant assemblages. Comparisons with published data for Japan allow the
conclusion that the Philippine assemblages are coeval with the Takanabe Member
(Miyazaki Group) in Miyazaki Prefecture (southwest Japan), a unit which
incidentally has yielded far fewer species. The absence of bathypelagic
holoplanktonics, as well as littoral benthic species indicate an epi- to upper
mesopelagic setting, with depth ranges extending to a maximal depth of c. 200 to 300 m.
Submitted
for Scripta Geologica 135, to be published end 2007.
2. Heliconoides
linneensis sp. nov., a new holoplanktonic gastropod (Mollusca, Thecosomata)
from the Late Oligocene of the Aquitaine Basin (France, Landes)
The gastropod Heliconoides linneensis sp. nov.
(Mollusca, Thecosomata) is described from Late Oligocene (Chattian) deposits of
several localities in the southwestern Aquitaine Basin (France, Landes).
Submitted for Zoologische
Mededelingen, 2008
3. Holoplanktonic Mollusca
from the Aquitaine Basin (SW France)
Systematical
revision of material housed in the collections of the Musée nationale
d'Histoire naturelle (Paris, France) , the Musée d'Histoire naturelle and the
Faculté des Sciences (both Bordeaux, France), the National Museum of Natural
History (Leiden, The Netherlands), as well as various private collections.
Re-interpretation of less well-known species, lecto- and neotype designations,
descriptions of new taxa. Biostratigraphical application.
Dr. Bruno
Cahuzac agreed to be a co-author on this paper, predominantly concerning
himself with localities and stratigraphy !
Publication
expected 2008.
4. Early Pliocene heteropods and pteropods (Mollusca, Gastropoda) from
Santa Maria Island (Azores, Portugal): systematics and biostratigraphic
implications (together with Andreas Kroh and Sérgi Ávila).
A
holoplanktonic mollusc assemblage from Neogene sediments of the Azorean island
Santa Maria is described and analysed with regard to the age of the sediments.
Sixteen taxa are documented (three Heteropoda, thirteen Pteropoda), fourteen of
which are new records for the fossil f
The
pteropod Cavolinia marginata (Bronn, 1862) is re-described based on
abundant topotypic material and a neotype is designated. The species Cavolinia vendryesiana (Guppy, 1873) is considered a junior
subjective synonym of C. marginata. The temporal range of the
pteropod Limacina trochiformis (d’Orbigny, 1836) is extended to the
Zanclean.
Submitted
October 2007 Acta Geologica Polonica.
5. Holoplanktonic Gastropoda from the Miocene of
Cyprus) (together with Crispin Little)
Some
30 species of Heteropoda and Pteropoda were collected from Miocene deposits
(Langhian and Tortonian) in Cyprus.
Manucript
ready early 2008, Palaeontology ?
6. Miocene holoplanktonic
molluscs from the Maltese archipelago
Long term
project, with sampling of many localities of the Globigerina Limestone
(phosphoritic levels), the Blue Clay and the Green Sand formations in Malta and
Gozo, with comparisons of similar deposits in Gargano, Salentino, and Sicily
(Italy). Many new species, interesting correlation possibilities. First
observation of Cainozoic Gymnosomata. Biostratigraphical zonation. For this
subject a large series of SEM-images could be made in the Leiden Museum
(December 2004), thanks to a grant of SYNTHESYS. One of the new Maltese
pteropod species was described recently in Basteria (see chapter Notes).
Publication
hopefully possible around 2008-9.
7. Further holoplanktonic
molluscs from the Fiji Islands
Additional
to the material from the Fiji Islands discussed in a recent paper (Janssen, 1999b) on the Buton fauna (Indonesia) a
collection of heteropods and pteropods was made available by Mr A. Grebneff
(Dunedin, New Zealand). This material contains interesting new information on
the Cenozoic Pacific assemblages.
Publication
expected 2008.
8. Pliocene holoplanktonic
Mollusca from the Mediterranean area
A
considerable material is available from various localitities in Italy, France
and Spain. Long term project ! Publication will take several years. Material
recently made available from the Estepona area (Málaga, Spain) was published separately (see above nr. 1)..
Publication
?
9. Cainozoic pteropoda from
the North Sea Basin
A
substantial material, both from outcrops and boreholes, housed in many public
and private collections is studied gradually. Manuscript (2001) comprising over
50 pages already, but only part of the material is sufficiently investigated
yet. Numerous species of pteropods, biostratigraphical results, long distance
correlations ...
Publication
.... ????