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Evolutionary prospection in Neogene planktonic foraminifera - prolongation

(SNF project, 3 years, start: 1 February 2009, end: 31 January 2012, prolongation until 31 January 2013, thesis completed). Thesis available under under http://edoc.unibas.ch/diss/DissB_10611/

 

 

Key words:

Evolution, planktonic foraminifera, Neogene, IODP, morphometry, digital image analysis, automation

 

 

Lay summary

Menardiform globorotalids are a special group of Neogene planktonic foraminifera (=marine, pelagic protitsts, that secrete a calcitic shell) comprising extant as well as extinct species. In the modern oceans Globorotalia menardii inhabits tropical areas worldwide and their shells are typical constituents in the underlying pelagic sediments. Menardiform shells show strong morphological variability, especially during the Late Miocene through Pleistocene when many extinct menardiform species with a short range existed, which makes this group interesting for the study of the biogeography and evolution.

 

The present project consists of 3 parts:

Firstly, a PhD study investigating the morphological and ontogenetical variability of menardiform shells in a time-slice at 3.2 Ma. This time-slice was selected because of favorable conditions during the Upper Pliocene warmth optimum, the presence of a high menardiform diversity including the finale of the G. menardii-G. multicamerata lineage, and because this time precedes major oceanographic reorganizations in the upper ocean due to the closure of the Isthmus of Panama.

 

In the second subproject the morphologies of G. menardii shells and those of its descendent G. multicamerata are analyzed at ODP Sites 925B (Ceara Rise, western tropical Atlantic) and 667A (Sierra Leone Rise, eastern tropical Atlantic). These two sites are key locations in order to document evolutionary trends in this foraminiferal group.

 

Morphometric investigations are carried out using a microfossil orientation- and imaging automate called AMOR and software called AVM and MorphCol (see Knappertsbusch, 2004-2011).

In the third subproject we were already able to further improve AMOR (from Automated Measurement system for for shell mORphology) in close collaboration with students and staff of the Institute of Automation at the University of Applied Sciences (FHNW) in Windisch/Brugg (Knappertsbusch et al., 2009). These developments help us to measure more efficiently the large number of shells needed for statistical morphometrics.

The project is complemetary to previous studies from DSDP Sites 502 and 503 on both sides of the Isthmus of Panama (Knappertsbusch, 2007) and in a global Holocene morphometric survey of G. menardii (Brown, 2007). All these studies are part of our research agenda to investigate the biogeography of morphological evolution through time in marine calcareous plankton ("evolutionary prospection", see Knappertsbusch, 2011, Knappertsbusch and Mary, 2012) and under http://edoc.unibas.ch/diss/DissB_10611/.