Corydoras revelatus a Fossil Discovery

by
Allan James


question I am often asked is "what age does does a Corydoras live to" this set me thinking of the origins of our little whiskered friends and the discovery that they lived on our earth (well in the water anyway!) at least 50-60 million years ago.


Green Tertiary rock


The last of the dinosaurs disappeared from the earth around 65 million years ago so our fossil friend Corydoras revelatus lived in the Tertiary period just after this, alongside the hairy mammal. It was discovered in Argentina in Sunchal, Juyuy province, by a well known entomologist, Professor T.D.A.Cockerell of the University of Colorado, Boulder, in 1925. He was actually searching along with his wife for fossil insects at the time before he came across our plated friend.

The green Tertiary rock measured 32mm and the imprint 27mm and it bears the outline of a Corydoras (Sands,D. 1983) What was noticed was that a flaw in the rock suggested that the dorsal spine was longer (Isbrücker) and the problem of the one dimensional shape of the fossil made it the subject of a new species, Corydoras revelatus Cockerell, 1925. It is now housed in the British Natural History Museum, London.

 

Corydoras revelatus fossil

 

The entomologist T.D.A."Theo" Cockerell (1866-1948) was better known for his work on the wild bees of Colorado and wrote many papers on these insects. He has even a mosquito from Florida named after him.

Theo was the brother of the noted scholar Sir Sydney Cockerell who was high up the ladder of British society at the time.

 

Fossil with information tag

 

How is a fossil formed?. Well this Corydoras died and was covered by the mud at the bottom of the river. The river would have dried up and the sediment compressed and hardened. The next process would be minerals which would seep through the bones which gradually change into rock. Millions of years later the fossil appears as the covering rock is worn away by wind and water.


Acknowledgment:  Jim Makin for supplying images for this article.

References:

Sands, David; Catfishes of the World, Volume 1 Callichthyidae.

Botanical Electronic News

Photo Credits:

Top 2:    Eric McCabe

Bottom: Steve Pritchard

 

 

 

 

 

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