Annularia stellata
Division Pteridophyta, Class Equisetopsida, Order Equisetales, Family Calamitaceae
Geological Time: Pennsylvanian (~300 m.y.a.)
Size: Plant fossil is 95 mm long by 42 mm across (maximum) Matrix: 115 mm by 75 mm nodule half
Fossil Site: Mazon Creek, Francis Creek Shale, Coal City, Illinois
Code: MZF31
Price: Sold
 Description:
The Mazon Creek deposits of the region near Braidwood, Illinois rival
the other famous Lagerstatte 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. |
