Wednesday, February 14, 2018

Giant Cephalopod Midden or Mosasaur Feces

Back in 2011, and again in 2013,  Mark and Dianna McMenamin postulated a giant cephalopod created a midden with the bones of Icthyosaurs.  The internet came alive with much fanfare,  comments, news, etc. probably because of the size the cephalopod would have had to been to form such a midden.

Well, back in 1954 two well-known cephalopod paleontologists, John B. Reeside and William A. Cobban (one prominent then, and one then becoming prominent), postulated  that concretions in the Mowry and Aspen Shales were possibly "fecal matter of some large carnivore--reptile, fish or cephalopod", and "The diet of the carnivore would have had to be almost entirely ammonites and fish, and the carnivore would perhaps, like the living octopus, have had to frequent a sort of lair, to which it repaired and in which the mucous-bound fecal matter could accumulate" (Reeside & Cobban 1954, 1960).

Some of these concretions were over 2 meters in diameter, so you have a mosasaur like that in the movie Jurassic World, a very large fish, or another Kraken.  Though nowhere near the size of the Triassic Kraken.

I wonder, had there been the internet in 1954, would there have been the same or similar response?

Plate 28 from Reeside & Cobban 1960
The fossils were found in fossiliferous concretions containing thousands of ammonites, along with a few bivalves and bones of a few fish and a few pterodactyls in some.  These fossiliferous concretions were rare among the many non-fossiliferous concretions.  The authors reported that some concretions contained well over 4200 ammonites, from 10mm to 400mm in diameter, and these probably represented less than half the original content.  Most fossils were preserved in 3D with most of the living chambers crushed or missing, and some had damage to the phragmocone.

It was these fossils that Reeside and Cobban used in their 1960 paper to show the advantages of a population approach in taxonomy to a strictly typological one, especially for ammonoids with a large amount of intraspecific variation.  A significant moment for the lumpers of the world.


McMemamin, M. A. S., and McMenamin, D. L. S., 2011.  Triassic Kraken: The Berlin Icthyosaur Death Assemblage Interpreted as a Giant Cephalopod Midden: Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 310

McMemamin, M. A. S., and McMenamin, D. L. S., 2013.  The Kraken's Back: New Evidence Regarding Possible Cephalopod Arrangement of Icthyosaur Skeletons: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 900

Reeside, J. B., Jr., and Cobban, W. A., 1954. Ammonite accumulations in the Cretaceous Mowry and Aspen shales: Science, v. 119, p. 255.

Reeside, J. B., Jr., and Cobban, W. A., 1960. Studies of the Mowry Shale (Cretaceous) and Contemporary formations in the United States and Canada: U.S. Geological Survey Professional Paper 355, 126 p.