This is Mazon Monday post #252. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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Venation in Reticulopteris munsterii
Reticulopteris munsterii var. dawsonii was a seed fern found in the Mazon Creek fossil deposit. It is fairly uncommon. Except for the venation, the pinnules resemble Macroneuropteris scheuchzeri. In M. scheuchzeri the veins run in parallel, while Reticulopteris munsterii has reticulated venation, which appears more web-like. Reticulated venation patterns are common in modern angiosperms.
Reticulopteris muensterii was originally described as Neuropteris carrii by Leo Lesquereux in 1884. It was later reclassified under the Linopteris genus by Adolf Carl Noé (1873-1939) due to its venation. Linopteris (see Mazon Monday #242) also has complex anastomosed venation that form a mesh-like pattern, which is quite a bit different than Reticulopteris. Walter A, Bell (1889 - 1969) in 1938 changed the species name to muensterii in 1938. Noé, of the University of Chicago, is known for his extensive work with Carboniferous coal balls. Bell, a Canadian paleontologist and geologist, is famous for his work on coal fields of Nova Scotia and is largely considered the founding father of Canadian Carboniferous stratigraphy.
Jack Wittry mentions R. munsterii on page 218 in his book "A Comprehensive Guide to the Fossil Flora of Mazon Creek".
Reticulopteris muensterii var. dawsonii Bell, 1938
1884. Neuropteris carrii Lesquereux: p. 731 partial text, pl. 94, fig. 7, non figs. 4-6,
1925. Linopteris neuropteroides (non Potonié); Noé: p. 62, pl. 22, fig. 4
1938. Linopteris muensteri var. dawsoni Bell: p. 66, pl. 59, figs. 5-8; pl. 60, figs. 1, 2
1958. Linopteris muensteri; Langford: p. 224, fig. 393
1969. Neuropteris tenuifolia (non Brongniart); Darrah: non text, pl. 45, figs. 3, 4DESCRIPTION: The ultimate pinnae are lanceolate. The rachis is finely striate. The pinnules are alternate, oblique, overlap, and vary in shape from blunt and oval near the apex to oblong and lanceolate near the base. The midvein is moderately strong and straight, and extends to about three-fourths of the pinnule length. It is accompanied by several smaller trunk veins that enter from the rachis on the lower side. The lateral veins are distant at the midvein, arch slightly, and branch about five times, becoming dense near the margins. They will occasionally touch (but do not intercon- nect) to form a random, reticulated pattern of narrow and elongated areolae.
REMARKS: Reticulopteris munsterii var. dawsonii is uncommon. This variety differs from the typical munsterii by its closer venation and thinner areolae. Generally, close examination is needed for the reticulated pattern of the veins to be visible. In all other features, they appear neuropterid-like.
Specimens
Field Museum FMNH PP56700 (From Wittry)
Field Museum FMNH PP58192