This is the "Fossil Friday" post #53. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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A Mazon Creek fossil from Pit 11 is in the spotlight for this week. We have an interesting contribution from ESCONI member Chris Berg. He found this on his one trip to Pit 11 this spring. The species of this Y-shaped fossil is Kankakeea grundyi. It's thought to be a vegetative reproductive organ and has been associated with Crenulopteris acadica. Chris's specimen is a dead ringer for the picture on page 239 of the "Comprehensive Guide to the Fossil Flora of Mazon Creek". This is a rare find with very nice preservation! Thanks for sharing, Chris!
Here is the description from the book.
Kankakeea grundyi Pfefferkorn, 1973
1870. Hymenophyllites thallyformis Lesquereux: p. 417, pl. 16, fig. 5 (non fig. 3)
1963. Hymenotheca sp.; Langford: p. 273, fig. 919a
1973. Kankakeea grundyi Pfefferkorn: pl. 25, figs. 1-6; pl. 26, figs. 1-6
DESCRIPTION: These are Y-shaped stalks that widen from the base toward the tip. At the tip are two, up to four, rounded and blunt lobes. On the surface of the axis are elongated bumps that run parallel to its length. Hairs are also seen in some specimens. This form is highly variable in size, shape, and surface pattern.
REMARKS: Kankakeea grundyi is rare and known only from the Mazon Creek area and the upper Carboniferous of France. It is thought to represent a bud used for vegetative reproduction, that, once shed, would grow a new fern. Fig. 1 is an example of K. grundyi attached to the rachis of a fertile specimen of Crenulopteris acadica. This is evidence that both forms of reproduction occurred in this species, and on occasion, at the same time. Also see Rhacophyllum cornutum.
