This is Mazon Monday post #173.  What’s your favorite Mazon Creek fossil?  Tell us at email:esconi.info@gmail.com.

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Halicyne max is a species of Cycloidea from Mazon Creek.  Other Cycloidea species known from Mazon Creek are Cyclus americanus, Cyclus obesus, and Apionicon apiodes.  Of these, the most commonly known is Cyclus americanus.  Halicyne max was described in 1997 by Frederick Schram, Ronald Vonk, and Cees H. J. Hof in the paper “Mazon Creek Cycloidea”, which appeared in the Journal of Paleontology.

Abstract

The Mazon Creek Cycloidea contain four taxa: Cyclus americanus Packard, 1885, Cyclus obesus, new species, Halicyne max, new species, and Apionicon apioides, new genus, new species. We conclude, based on a cladistic analysis, that cycloids are specialized maxillopodan crustaceans and a possible sister group to the Copepoda. They may have filled a niche similar to modern day crabs.

H. max was described after the “Richardson’s Guide to the Fossil Fauna of Mazon Creek” was published, so there was just a small mention in Chapter 12 “Crustacea” on page 170.  That chapter was co-authored by Frederick Schram, who probably added it as peek into his future paper.

Jack Wittry mentions H. max in the “The Fossil Fauna of Mazon Creek” on page 95.

Halicyne max Schram et al., 1997
Subphylum Crustacea Class Maxillopoda. Order Cyclidae

Halicyne max is often mistaken for Cyclus americanus. It can be quickly distinguished from C. americanus by its lack of a posterior notch in the shield, as well as missing the accompanying pair of short, stout processes extending from the notch.

H. max has an almost circular shield that is decorated with small distinct bumps or projections. Though seldom observed, it also has a shelf-like scalloped marginal rim, with spinose protrusions.

Specimens

These are from “The Fossil Fauna of Mazon Creek”.