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Nummulites, all the way down

posted 17 Jan 2018, 20:43 by Jamie Derkenne   [ updated 17 Jan 2018, 23:24 ]
Stare at something long enough, and you may start to see patterns and connections that simply aren't there.

Nummulites are large coin shaped fossils, that look like coiled rope. The fossils are formed from a single celled organism's shell which is minutely divided by septa into chambers. They are the shells of the fossil and present-day marine protozoan Nummulites, a type of foraminiferan. Nummulites commonly vary in diameter from 1.3 cm to 5 cm and are common in Eocene to Miocene marine rocks, particularly around southwest Asia and the Mediterranean. They are valuable as index fossils.

Nummulites are relatively common in limestone rocks around the Mediterranean, and sometimes you need to look hard to see the delicate features of these fossils. 

Randolph Kirkpatrick was a British spongiologist, cnidariologist and bryozoologist. He was assistant keeper of lower invertebrates at the British Natural History Museum from 1886 until his retirement in 1927. He published a limited number of papers on the sponges of Antarctica and the Indian Ocean. However, his most significant work was carried out on Merlia, a species of coralline sponge (a sponge which secretes a coral-like limestone skeleton). He was the first to correctly interpret these unusual sponges, but his work was largely ignored until the 1960s when T. F. Goreau and his colleagues W. D. Hartman and Jeremy Jackson rediscovered the coralline sponges in the reefs of the West Indies.

The reason his work on this type of sponge was ignored for so long as that Kirkpatrick has spent a lot of time looking at Nummulites. Everywhere he looked in his limestone specimens he found nummulites. He started finding nummulite fossils in other rocks, including igneous and metamorphic rocks, which can't contain fossils because of the huge temperatures and pressures such rocks have been subjected to. Kirkpatrick eventually concluded in 1913 that all rocks - literally all rocks - were formed from nummulites. The entire planet was an accretion of nummulite fossil skeletons. He preferred to call the Earth a 'Nummulosphere'.

A PDF of his work can be found on the link below this article.


Jamie Derkenne,
17 Jan 2018, 20:43