Evolution illustrated by foraminifera 1

Natural Selection

The theory of evolution wants to explain how we - meaning all living organisms - came to be in all our complexity and variation. In a group of organisms the environmental conditions will favour some individuals while others will not reproduce as well. If heritable characters are the cause a shift in the frequency of these heritable characters within a population will occur after some generations. This process is called natural selection.

fossil Globigerina sp.
Italy, Pleistocene
Natural selection leads to specific foraminiferal faunas in specific environments

Open Sea offers little nutrition, which makes survival very difficult though competition is low and predators are rare. Many planktonic foraminifers use symbiont algae, who deliver energy through photosynthesis. In return they gives shelter for the little algae in its chambers, which need to be transparent, so that the sunlight may pass. Its globose construction allows up and downward drift in the watercolumn, probably needed to follow food, avoid predators and UV radiation.

recent Globigerinoides ruber from Mexican pacific ocean.

read the whole story at www.foraminifera.eu/evolution.html

Oligocene foraminifera from Atzendorf, Germany

Prof. Mueller, Geologisch - Palaeontologische Sammlung, University of Leipzig provided a sample from Atzendorf near Stassfurt, Germany. It dates back 30 mya to the Rupelian stage, lower Oligocene. Most foraminifera are small, below 500µm in size and lived benthic. An example is Bolivina fastigia seen to the left. See the whole collection at http://www.foraminifera.eu/atzendorf.html


Some planktonics (well preserved) are found, I classify them as Globigerina globularis (see image to the right. There are several Spiroplectinellas respresenting the agglutinating foraminifera.

I am not much familiar with faunal interpretation, but would interprete from the faunal composition: 5-10% planktonics indicate open waters, which correlate with the overall smaller sized benthonics.

Incoming samples week 9-10

A core sample from Cape Hatteras with 72 single plastic bags representing 190m in depth came in. A chart on the abundance of foraminifera at all depth-levels will help to start with the most promising parts. The core ranges from recent to probably Miocene. This valuable sample definitely needs a close investigation and processing.

Reussella

Reussella - a small perforate taxa is very common in the material from Kemp Beach, Queensland. The genus with a pyramidal test is reported in the fossil record since Middle Eocene (~ 40 Mio. years). The image shows one side and the basis of the pyramid - maybe a bit confusing.

The sample send from Australia by Kirsten is very rich in diversity and total amount of foraminifera. Further images will be added.




Earlier I found a fossilized Reussella in material from Torrente Stirone , Italy in material provided by Michael - one of the first contributors. The image better illustrates the pyramidal form. It's about 1 Mio. years old from Pleistocene.

Please send me your Oligocene or Eocene Reussellas :)

3rd Course on Foraminifera fully booked

The 3rd Course on Foraminifera in Urbino, Italy for 80 international participants is fully booked. The organizer Fabrizio told me, that the advert on foraminifera.eu has been a great help. Last year I participated in the 2nd course with about 25 participants. Read my personal report on this very intense course in the pretty medieval town of Urbino. Consider your participation in the 4th course 2011 :)



Dr. Fabrizio Frontalini has been the first scientific contributor for foraminifera.eu in the very beginning. He sent very nice images from the Adriatic Sea and Venice Lagoon such as this from a Bulimina marginata. Among other subjects he is working on foraminifera as indicators of pollution. Read the minilecture on foraminifera and pollution to learn more.

Cribrostomoides crassimargo

from the bottom of the Russian Barents Sea comes this agglutinating Foraminfera:

Cribrostomoides crassimargo
(Norman, 1892)

Common in the Arctic. The test is build using small grains cemented together.

The specimen is provided by Katya from Moscow.
Thanks a lot Katya ! I will need some time to work on the other specimens.

Lagenammina atlantica from the Faroe-Shetland Channel

Onno Groß president of DEEPWAVE a NGO for the protection of the oceans has provided numerous SEM-images of benthic foraminifera found at the shelf+continental slope of the Faroe-Shetland channel. The depth ranges from 155m to 1200m.
(see station-list to the right).







A prominent bathyal species for the North Atlantic is Lagenammina atlantica. This specimen has used volcanic glas to build its test.

Find the whole collection at www.foraminifera.eu/faroe.html