Fossil Fern (Positive/Negative) Alethopteris serlii Pennsylvanian Francis Creek Shale...

Fossil Fern (Positive/Negative) Alethopteris serlii Pennsylvanian Francis Creek Shale Mazon Creek Area, Will County, Illinois, USA This duo of fern fossils from the renowned Mazon Creek locality in Illinois is preserved in rock shells in a nodular fashion. Measuring 7 inches (18 cm) in length, each half of this exquisite pairing displays superb, highly-detailed preservation. The individual brownish leaves are in amazing condition, with a contrasting whitish linear patterning following the stem lines. One side is much thicker than the other, and both the exteriors are a combination of layered cement-gray with an undercoating near the edge of a reddish hue. Overall Measurements: 7.01 x 2.76 x 0.72 inches (17.80 x 7.00 x 1.82 cm) HID09710052018 © 2022 Heritage Auctions | All Rights Reserved