Annularia stellata
Division Pteridophyta, Class Equisetopsida, Order Equisetales, Family Calamitaceae
Geological Time: Pennsylvanian (~300 m.y.a.)
Size (25.4 mm = 1 inch): Plant fossil is 80 mm long by 50 mm across (maximum) Matrix: 115 mm by 80 mm nodule half
Fossil Site: Mazon Creek, Francis Creek Shale, Coal City, Illinois
Code: MZF24
Price: Sold
 Description:
The Mazon Creek deposits of the region near Braidwood, Illinois
rival the other famous Lagerstatten of the Burgess Shale, Solnhofen,
and Liaoning for the variety of detailed life preserved. Many exquisitely-preserved
specimens are found in the ironstone nodules that make up the deposits.
The majority of collecting areas are the spoil heaps of abandoned
coal mines. This particular nodule comes from Mazon Creek itself.
This fine specimen is a member of the Calamitales which belong
to the Sphenophytes. Whorls of small leaflets are arranged concentrically
around a thin stem and are called Annularia or Asterophyllites.
Calamites itself is the name originally given to a stem section,
but now applies to the entire plant. These were indicative of humid
to wet habitats such as along rivers and lake shores. This is a
fine example which fills its enclosing nodule with three star-shaped
leaf whorls. See my other offerings for a smaller Annularia specimen. |
