Isotelus Molts

Working an outcrop in the Clays Ferry Formation that is in the same bed, and close to, another outcrop that I have collected extensively(see here, here, and here), I came across some curious molts of an Isotelus gigas.

The Clays Ferry Fm was deposited in a relatively shallow subtidal environment, and throughout most of the area, the formation straddles the Mohawkian/Cincinnatian boundary(early Late Ordovician). Due to deposition below wave base in typical weather, most of the fossil are complete and a diverse assemblage can be found in the column.

The Bed form which this piece comes is composed primarily of orthoconic cephalopods, Isotelus, a few bivalves, and an occasion Flexicalymene trilobite.

What I find curious about the molts is found on pygidium and thorax of the smaller dorsal specimen. I have annotated it with a white line to highlight the area.

There is a crack and indentation that runs from the anterior posterior(Jeeez, I just caught that) margin through the pygidium, and from there it appears as if it continues on through the pleurons. As there is no suture along that area of the thorax, I would assume that the distal portions of the pleurons would be adjacent to the rest of the critter, but they are not there, So that has left me wondering if the structure is pre-molt, or if it is an artifact of lithification. Any Ideals?


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3 Responses to “Isotelus Molts”

  1. Solius Symbiosus Says:

    Re the strike in the post: I should know better. While, I know little of human anatomy, I have long argued that the posterior of man is the foot, and then, there is the whole dorsal/ventral thing in us.

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    • Solius Symbiosus Says:

      Generally, I would delete your post as spam as it contributes nothing to the discussion and doesn’t appear to be a ping back. But in fairness, I am leaving it up– lest I be accused of being unfair to the religionists.

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