Understanding the evolution of Early Palaeozoic faunas remains problematic as only a handful of well-preserved, isolated Ordovician localities are known. An extremely well-preserved Middle Ordovician (mid-Darriwillian) radiolarian fauna from the top of the Table Point Formation in the Piccadilly Quarry, western Newfoundland provided a rare opportunity to investigate details not yet observed in most lower Palaeozoic radiolarian faunas. This exposure is a well-known graptolite and sponge spicule locality but, until now the radiolarians have never been examined in any detail. In this study age diagnostic conodonts and diverse assemblages of disarticulated sponge spicules were recovered along with exceptionally well-preserved, densely latticed and multiple shelled radiolarian. However, species level identification and detailed systematic investigations are currently based on combinations of external as well as internal morphological characteristics. This is because radiolarian growth begins internally. Thus, similar internal features represent true phylogenetic links. The introduction of 3D X-ray micro-tomography makes it possible to observe the complex internal details of specimens non-destructively. This allows us to more accurately and quantitatively describe radiolarians reproducibly, and with measureable precision at submicrometre scales. Along with a systematic investigation of radiolarians freed by acetic acid digestion from their host rocks, detailed internal structure of several problematic radiolarian specimens were investigated using 3D X-ray micro-tomography in order to answer outstanding systematic and biostratigraphic questions.

 

Funding: UQRS
Advisors: Prof Jonathan AitchisonProf Jamie Shulmeister

 

Project members

Sarah Kachovich

Sarah Kachovich

PhD candidate