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Leaves are some of the most iconic plant fossils. They are vascularized (contain xylem and phloem) structures that help a plant with photosynthesis. Many botanists call non-vascularized photosynthetic structures microphylls as in the case of mosses. A leaf is a separate organ from the stem however the plant’s true stem is often different from what is commonly called a stem. For instance, in flowering plants a leaf often consists of a blade, the large part, and a petiole, the thin part that attaches to a branch which is sometimes incorrectly called a stem. Ferns have their own set of terminology with stipe referring to the petiole and rachis referring to the primary vain in the the blade. In conifers leaves can be needles or scales.
I’m interested in seeds and cones. I know that Aurucaria cones are not uncommon, what about Magnolia or other gymnosperms?
Hi Jackie,
Yes, we do find Araucaria cones. Permineralized pine cones are not unusual in some areas as well. Additionally we find the winged seeds of many other conifer species (spruce, fir…) in shale deposits. We also have examples of stoboli (general word for cone) and/or seeds seeds of Ginkgo, cycads, and members of the Gnetophyta which today includes Gnetum, Ephedra and Welwitschia. Magnolia is actually a flowering plant but we do find Magnolia seeds. They have characteristic grooves which let us identify them down to the species level.
@mackenzie-smith I am seeking help identifying these leaves. They are from the Tullock Member of the Fort Union Formation. Site is northern edge of Miles City, Montana. I have gone to Rsearcher Gate and found a number of papers but none have images of these leaves. The leaves in the larger plate are about 3 x 7 cm. Secondary viens stater at base as palmate and the alternate along main vein. Secondary veins divide near margin . Toothe is serrate Mixed in with these leaves are Sequoia leaves and bark and grass or maybe pine needles. Rock is a clay shale.
Hello @david-powers! Sorry for the delayed response. It appears to me the best match is Dicotylophyllum hansonium from Peppe and Hickey 2014. However, there do seem to be some differences. Either you fossil has better preservation of the tertiary fabric than their specimens or it’s different. One of their figured specimens appears to have asymmetrical venation off of the secondaries (though this could be an artifact of preservation) which I did not see in yours. But the palmate, acrodromous venation and toothed margin all fit. This genus is a morphogenus, if I recall correctly, and so we don’t know what it’s related to. Hope that helps!
Hey @mackenzie-smith, thank you for the reply. I had looked at Dicotylophyllum hansonium from Peppe and Hickey 2014. At first I thought my specimens matched until I brought the photo in the report to a 100 res. and notice some differences between the example and mine. This is the best match considering leafs of a tree can be different in shape up to maturity and where they are on the tree.
I have other plates containing these an other leave. How know maybe I will find better specimens.
Thank you for your help.
Cheers
David
The differences in my leaves to those in the paper bugged me. So I contacted Dan Peppe PhD the co author of the paper you referenced. Believing he would have more insight and information for IDing these leaves. I am happy to say he answered my email. He sent me a Paper
REPRODUCTIVE AND VEGETATIVE ORGANS OF BROWNIEA GEN. N. (NYSSACEAE)
FROM THE PALEOCENE OF NORTH AMERICA
Steven R. Manchester1 and Leo J. Hickey
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611-7800, U.S.A.; and
Peabody Museum of Natural History, Yale University, New Haven, Connecticut 06520, U.S.A.https://www.researchgate.net/publication/249158109
These fossil leaves more closely match the Browniea Gen .
Between your help and Peppe’s these leaves are now identified.
Thank you
David C Powers
Great! @david-powers I’m glad you were able to ID it! 🙂
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