I am currently employed as collection manager of invertebrate palaeontology at Museum Victoria in Melbourne, Australia - how good is that!! I love fossils and I like sorting things - I'm still coming to terms with my charmed life (nerd alert! I hear you call, but I don't care :).
I am interested in anything to do with palaeontology, but because life's short I have focussed on Bryozoa, and I have gravitated to alpha taxonomy, as well as biogeography and palaeoecology using growth-forms.
My main interest at the moment is in the Cretaceous and Cainozoic Bryozoa of the southern and western Australian margins.

Publications
Conference abstracts
PhD thesis abstract
Honours thesis abstract

Rolf Schmidt & Yvonne Bone
Dept Geology & Geophysics, Adelaide University, Adelaide, South Australia

Bryozoans have been a major component of the Australian fossil fauna throughout the Tertiary. In modern times the genus Adeona is one of the most recognised bryozoans due to its characteristic fenestrate growth form, especially in Southern Australia. It is, however, not known for certain when and where from this genus first appeared in Australian waters. The discovery that colonies that had been informally identified as Adeona in hand specimens from Late Eocene limestones of the St Vincent Basin, actually belong to the quite unrelated species Macropora clarkei has several implications (NB: proper identifications of these colonies had already been published by Waters, 1885, and MacGillivray, 1895).
The oldest confirmed appearance of Adeona is from the Early Miocene of southern Australia, and there are some questionable species from the Oligocene. Because marine sedimentation did not fully start until the Eocene and Oligocene, most localities have patchy fossil records of what is likely to be the crucial time period. If the spread of this genus was not strongly diachronous across Southern Australia, it may now be possible to give a bracket on the arrival or evolution of Adeona in Australia (evolution within Australia is most likely as all known species occur around Australia, the Indian Ocean and Southern Pacific Ocean).
But absence of evidence is not necessarily evidence of absence: Because all modern Adeona species make their skeleton of aragonite which is highly unstable after the death of the organism, their absence these diagenetically altered sediments may not be a secondary feature. Because of the coarse nature of the sediment, fragments of bryozoans that have been dissolved, are unlikely to leave a recognizable imprint. The only sediment likely to preserve them is the Blanche Point Formation which contains some layers of aragonitic fossils preserved due to the fine-grained sediment. Although Macropora clarkei does occur in these, no Adeona have been found, either indicating an unsuitable environment or their actual absence.
The high similarity of the growth form of Macropora clarkei to Adeona (even the border cells around the fenestrae are similar to the 'blind cells' in Adeona) indicate convergent evolution which may be an adaptation to certain environments. Adeona are rooted into unconsolidated substrates via a stem and roots which are mostly organic and therefore disintegrate soon after death. If Macropora clarkei had a similar mode of attachments, the absence of any fossilised basal attachment structure would make sense. If this particular type of growth form is specific to such environments, such information could be used in palaeoenvironmental interpretations.
Interestingly, Macropora clarkei still occurs in the Early Oligocene of the St Vincent Basin, but only as a flat robust branching growth form, while Adeona still does not occur in these sediments.

NOTE: Some of the statements in this abstract have been superceded since the presentation of this paper due to ongoing research (this genus was a tough one to get!). The final article is published in Alcheringa in 2004. See the current abstract.

Ph.D. Thesis Abstract:

The first extensive and stratigraphically detailed taxonomic study of fossil bryozoans within the Late Eo-cene sediments of the St Vincent Basin has revealed a range of faunas from very high abundance and diversity to almost monotypic assemblages. Overall 177 species of Cheilostomes and 33 species of cy-clostomes were positively identified, with an additional 35 and 30 unclassified taxa respectively.
Biogeographic comparisons show a mixture of temporal and spacial components. Approximately two thirds of the species are new, and therefore regarded as ‘basin endemic’. The common Cellariidae are represented by 20 species, none of which can confidently be assigned to species of the equally diverse fauna of the Otway Basin Tertiary in Victoria. Seven new genera are also only known to occur in the St Vincent Basin. All the prviously described species are endemic to the Australian region. Many of the genera are equally restricted to Australia throughout the Tertiary to the Recent. This distinct endemism is typical of the isolated Australia in the Neogene. Minor links with other continents still exist as well. Shared taxa include Reticrescis (Eocene, Antarctica) and a potentially new genus of Romancheinidae (Eocene Eastern Europe and North America). Taxa considered to have originated in the Eocene, which rapidly dispersed throughout the world before the end of that Epoch, occur commonly, such as the Phi-doloporidae (13 species in 6 genera) and the Smittinidae (19 species in 3 genera). This shows strong dipersal links still existed between all continents. The fauna has a distinct Cretaceous character, char-acterised by the abundance and diversity of erect Onychocellidae, which are generally rare after the ear-liest Palaeogene. Four species are tentatively assigned to species which still exist in Recent waters of the Australian region (Rhamphosmittina lateralis, Hiantopora quadricornis, Melicerita angustiloba., Arachnopusia unicornis). The implied time range is very long for bryozoan species. Nine genera have their oldest recorded occurrence here (Antropora, Chaperiopsis, Hippoporina, Dactylostega, Foveolaria (Odontionella), Otionellina, Acerinucleus, Strophipora, Stenostomaria). Wide dispersal of genera and families was probably facilitated by interconnected continental shelves and low latitudinal temperature gradients. Species level endemism is promoted by the short range of dispersal of most larvae.
Palaeoenvironmental analysis indicates that within the small geographic area and relatively short pe-riod of deposition in the Eocene, St. Vincent Basin saw a wide range of depositional facies. The initial transgressive marine facies on all margins saw the greatest diversity and abundance of bryozoans. These basal facies also contained most of the ‘deep water’ taxa and sand-fauna growth forms. This rep-resents a well oxygenated and moderate energy environment. Higher sea levels probably flooded the Kangaroo Island basement high to allow sufficient open ocean access. The very different overlying as-semblages indicate a more restricted environment, which represents a shallowing, with the Kangaroo Island High restricting open ocean access. The embayments on the eastern margin became very silica and organic carbon rich, with a low diversity and low abundance bryozoan fauna. Occasional fossiliferous beds dominated by Celleporaria and a few other erect ascophorans represent a brief reprive allowing a few opportunists to flourish, but too short for any others. Bryozoa are essentially absent on the western margin, with only a few rooted forms occuring in the siliciclastic sediments of the Rogue Formation. This margin was dominated by rivers and the resulting high sedimentation rate and low salinity inhibited bryozoan colonisation. The shallow sediments of the Lower Kingscote Limestone on the southern margin are dominated by infaunal echinoids, and bryozoans are occasionally sub-dominant. This was probably a shallow passage through a chain of ‘Kangaroo Islands’.

Macrofaunal assemblages of the Mannum Formation were sampled and analysed for each measured bed as well as in some sedimentary features to enable a stratigraphic and palaeoenvironmental interpretation.
Seven sections were analysed in detail at Devon Downs, Ngaut Ngaut and Walker Flat. Correlation was excellent and was often achieved to meso-scale (tens of centimetres). Although an eighth section near Mannum was quite different lithologically, it could be tied to the others via several marker beds. This correlation was confirmed via the overall biofacies pattern. Changes in fossil assemblages appear to be more reliable isochronous events than lithology. The biofacies analysis furthermore enabled the location boundary between the Upper and Lower Member at the approximate level that Ludbrook (1961) defined it to be. A possible location for the TB1/TB2 sequence boundary may indicate a major erosional event within all the sections apart from the one at Mannum. This in turn can be ascribed to tectonically influenced variations in palaeotopography.
The strongly cyclic bedding of the formation indicates a fairly consistent influence causing changes in the depostional environment. Milankovitch perturbations appear to be of the correct fifth order time scale and indicate the main cause to be minor fluctuations in sea level. As the character of these cycles generally changes up-section, other causes such as stabilisation by sea-grass and turbidite events may have played more significant parts at different times. Significant shifts in biofacies on fourth order time scales indicate longer term changes in the character of the Murray Basin. Nutrient levels are considered to be the most important factor in controlling the faunal assemblages as the biofacies exhibit significant fluctuations between the eutrophic and oligotrophic ends of the Trophic Resource Continuum. The extreme variations in apparent environments as indicated by the changes in faunal assemblages can be explained if the biofacies zones are similar to those of the continental shelf but more condensed. The overall fauna also exhibits several large scale changes in diversity as well as a shift from infaunal to epifaunal dominated up-section. This may relate to third order changes in sea level leading up to the Miocene Climatic Optimum.

Last updated Wednesday, 11 August 2004