This is Mazon Monday post #205. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Cyathocarpus hemitelioides is one of the rarer ferns from the Mazon Creek biota. C. hemitelioides was named in 1834 by Adolphe-Theodore Brongniart (1801 - 1876), who was a French paleontologist, considered by many to be the father of paleobotany.
There are questions about whether it is even a valid name. Pecopteris (Cyathocarpus) hemitelioides has at times been mistaken for Pecopteris (Cyathocarpus) arborescens (arborea), Crenulopteris subcrenulata, and Pecopteris (Diplazites) unita. It should be noted that the Mazon Creek type specimens differ from Brongniart's type example.
C. hemitelioides appears on page 104 and 105 of Jack Wittry's "A Comprehensive Guide to the Fossil Flora of Mazon Creek".
Cyathocarpus hemitelioides (Brongniart) Mosbrugger, 1983
1834. Pecopteris hemitelioides Brongniart: p. 314, pl. 108, figs. 1, 2
1888. Pecopteris hemitelioides Brongniart; Zeiller: p. 133, pl. 11; figs. 6, 7
1924. Asterotheca hemitelioides Brongniart; Kidston: p. 519, pl. 117, figs. 1, 2, 4, 5
1938. Asterotheca robbi Bell: p. 74, pl. 72, figs. 3-6; pl. 73, fig. 1, 2; pl. 74, fig. 1; pl. 76, fig. 1
1958. Asterotheca hemitelioides Brongniart; Langford: p. 159, fig. 267
1958. Asterotheca candolleana (non Brongniart); Langford: p. 160, fig. 271 (re-figured here as Fig. 5); non text
1962. Pecopteris (Asterotheca) hemitelioides Brongniart; Bell: p. 34, pl. 21, fig. 3
1971. Scolecopteris Pfefferkorn: p. 21, fig. 8, non fig. 7; pl. 12, figs. 1-4
1979. Asterotheca hemitelioides Brongniart; Janssen: p. 132, fig. 114DESCRIPTION: The ultimate pinna is linear-lanceolate. The rachis has scattered pits which may represent the bases of hairs. At about two-thirds of the way along its length, the pinna gently tapers to a blunt apex. The pinnules are vaulted, vary in length on the same pinna, pubescent when well-preserved, alternate, lie perpendicular or slightly oblique with parallel sides, and terminate in a blunt, rounded apex. The thick midvein is straight, non-decurrent, and extends almost to the apex. The lateral veins are oblique, simple or rarely fork once at the base (see Fig. 2 inset), and are straight or sightly recurved. Occasionally at the pinnule margins, the lateral veins display expanded tips known as hydathodes or water stomata (see Fig. 5 inset). This feature has been mistaken for a small fork or synangia. On fertile examples, the synangia grew on a recurved stalk, and are most frequently found lying sideways and parallel to the lateral veins on the abaxial surface of the pinnule. As they matured, the sori descended and became more upright. The sori have an asterothecoid appearance with 4 or 5 sporangia. The isolated spores are correlated with Laevigatosporites globosus (Pfefferkorn et al., 1971).
REMARKS: Cyathocarpus hemitelioides is uncommon. The use of the name C. hemitelioides for this form clearly needs critical reexamination. The fertile structures and pinnule shapes seen in the Mazon Creek flora do not appear to be like those in Brongniart's type example. The name is retained for now, using the same interpretation as Kidston (1924) and Zeiller (1888) before him, on forms which have similar features to those seen here.
Specimens
Field Museum specimens
From Wittry
