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Posted by guide on September 08, 1998 at 07:19:23: In Reply to: Found Fossil posted by Marion on August 13, 1998 at 21:21:28: I am publishing here the views of a botanist regarding Marion's great find. Enjoy! ----------------------------------------------------- The second specimen of Monanthesia stantoni (Ward) Delevoryas? by Mel Turner Marion’s fossil seemed to be part of a petrified cycadeoid stem. Cycadeoids [Bennettitales] include several genera of "cycad-like" Mesozoic seed plants [they’re perhaps more related (distantly) to flowering plants than to true cycads]. The genus Cycadeoidea has stout trunks covered in a thick layer of leaf bases and scales/hairs in which cones [often called "flowers"] were embedded. The side view of this fossil seems to show that it’s mostly of this leaf-base mantle with little of the actual stem present on the inside [sections should show anatomy of the leaf bases and cones]. Although it looks much like a typical Cycadeoidea, this fossil differs significantly in having a small cone in every leaf axil, instead of fewer, larger cones. I think we now have a good idea about the fossil’s identity. The first clue was in: -- Taylor, T. N. 1981. Paleobotany. An introduction to fossil plant biology. McGraw-Hill, NY. Page 400 has a photo of something very similar, labeled "portion of Monanthesia trunk”. On p. 402 the text says: "In another genus, Monanthesia, (Fig.14-9B), each leaf contains a cone in the axil.” The photo compared very well with this fossil., and so we now had a strong candidate in the genus Monanthesia of the family Cycadeoideaceae. So, the next step was to find out more on this genus, its history, taxonomy, stratigraphy, and biogeography, and about any other collections from California. Taylor had cited: -- Delevoryas, T. 1959. Investigations of North American cycadeoids: Monanthesia. American Journal of Botany 46: 657-666. This paper gives more info. on the genus, and was the first to name it correctly following the rules of nomenclature ["Monanthesia" was first coined by Wieland in 1934, but the name wasn’t validly published. Wieland called the same group "Navajoa" in 1928; that name was also invalid]. Delevoryas’ paper describes the anatomy of specimens from northwestern New Mexico, and notes some anatomical differences between Monanthesia and Cycadeoidea,, but says: ” Probably the flowering habit is the most important difference. The presence of a cone in every axil is a feature only of the New Mexico specimens, and of a few other stems from different localities.“ The fact that the cones are all in one developmental stage [unlike other Cycadeoidea] suggests the plants were monocarpic [a monocarpic plant is one that grows to maturity, flowers once, and dies, as in many century plants [Agave] or bamboos]. Hence the name, from “mono” [one] + “anthesis” [bloom]. Delevoryas recognized M. magnifica for the New Mexico specimens [including Wieland’s “M. blanca” and “M. aequalis”]. Regarding Wieland’s 6 other possible Monanthesia species, one, Cycadeoidea dartoni, does not actually have a cone in every leaf axil and lacks Monanthesia-type leaf base anatomy. He couldn’t study the anatomy of Cycadeoidea niobrarensis and C. fisherae, but did name C. massieana, C. nigra, and C. stantoni as Monanthesia species. There was no mention of the geography of these other species, but M. stantoni will turn out to be from northern California. A recent revision of British cycadeoids: --Watson, Joan & Caroline A. Sincock. 1992. Bennettitales of the English Wealden . Monograph of the Palaeontographical Society. no. 586-588 London: Palaeontographical Society. says [p. 187] that both Cycadeoidea [ L. Jurassic to esp. L. Cret., Europe, India, and esp. USA] and Monanthesia [L. Cret] occur as both short and tall trunks. They cite Tidwell, et al. (1981) as indicating that the New Mexico specimens “must have come from deposits of Lower Cretaceous age. This would accord with the occurrence of closely similar specimens in the English Wealden (Cycadeoidea saxbyana), the Potomac group of Maryland (Cycadeoidea fisherae), and a tall Monanthesia-type trunk collected by Tidwell (personal communication, 1991) in the Lower Cretaceous of Utah.” Cycadeoidea saxbyana from the Isle of Wight [p.192, & plate 19] resembles Marion’s fossil. A section [nice] shows the cones among the leaf bases. [sections of Marion’s specimen might be worthwhile]. -- Tidwell, W. D. , S. R. Ash, & L. Parker. 1981. Cretaceous and Tertiary floras of the San Juan Basin. In: Lucas, S. G. J. K. Rigby, & B. S. Kues, [eds.], Advances in San Juan Basin Paleontology. University of New Mexico Press, Albuquerque. [not seen; argues for a L. Cret. age for M. magnifica ] -- Tidwell, W. D. 1998. Common fossil plants of western North America. 2nd ed. Smithsonian Institution Press. Washington. Plate 43 has a reconstruction of a large log of Monanthesia, a trunk cross section, and a close-up of the surface [this new fragment is better-looking]. On p. 198: "Specimens of the genus Monanthesia have been collected from the San Juan Basin, New Mexico; near Moab, Utah [apparently Cedar Mountain Formation], and the Black Hills, South Dakota. They consist of a columnar stem 7 feet (2.2 meters) tall, having a uniform diameter of up to 20 inches (51 centimeters) ... So far there’s been no mention of any collections from California. That changes: -- Wieland, G. R. 1906-16. American fossil cycads. 2 vols. [Washington, DC] Carnegie Institution of Washington. On page 111 of vol. 2 [1916] it describes Cycadeoidea stantoni Ward: “The Cycadeoidea obtained by Dr. T. W. Stanton in Colusa County, California, at the ranch of Mr. B. P. Pryor, in the Grapevine Valley, 6 miles west of Sites, on the road to Stony Ford, is in many respects an interesting specimen. Especially its isolation makes it desirable to recover, if possible, other examples or associated species.” [he quotes Stanton’s story that the specimen probably came from a plowed field with rocks containing Lower Chico [Formation] invertebrates, that it may have been carried there by Grapevine Creek, and that “the possible sources of the specimen seem to be limited to the Knoxville, the Horsetown, and the lower Chico, with the probabilities in favor of one of the last two named.” and “The general characters and surface features of the C. Stantoni type are quite exactly described by Professor Ward. The armor is well conserved on one side only, its most striking feature being the series of bract-surrounded peduncles occupying all the leaf-base axils. “ Here we have a possible species name for Marion’s plant, from not-so-far-away. I haven’t seen Ward’s publication [cited below], but it [and the specimen] ought to be checked. Still, even if the original of C. stantoni closely matches Marion’s fossil there remains the question of whether it is distinct from earlier-named species of both N. America & Europe. -- Ward, L. F. 1905. Status of the Mesozoic floras of the United States. Second paper. Monographs of the United States Geological Survey 48: 1-616. Not seen, but the original description of Cycadeoidea stantoni is on pages 273- 277 with a picture on plate 70. -- Wieland, G. R., 1928. In: Carnegie Institute of Washington. Year Book no. 27 (1927-1928): 390-391. [On his new NM finds, columnar monocarpic cycadeoids of striking size that are “surely among the most remarkable petrified flowering plants ever recovered.” The specimens were described as up to 7 ft long and 1.5 ft thick. “So far, the monocarpic cycadeoids have numbered only six, all being single incomplete specimens from far-separated localities and more or less of necessity referred to separate species as follows:” [more info. was added from other papers --MT] 1] Cycadeoidea dartoni Como [= close of Jurassic] Black Hills, SD [Delevoryas: not Monanthesia] 2] Cycadeoidea fisherae Potomac (Arundel) Maryland 3] Cycadeoidea stantoni hor. indet. [= “horizon undetermined”?] (L. Cretaceous?) Colusa Co., California. 4] Cycadeoidea masseiana “scaly clays”, Apennines, Italy 5] Cycadeoidea nigra hor. indet. (U. Cret.?) near Boulder, Colorado 6] Cycadeoidea niobrarensis Niobrara Chalk, Kansas [Called C. hespera in Wieland, 1934] [We’d now have to add the Isle of Wight’s C. saxbyana and Tidwell’s Utah specimen to the above]. -- Wieland, G. R., 1934. Fossil cycads, with special reference to Raumeria reichenbachiana Goeppert sp. of the Zwinger of Dresden, by G. R. Wieland . Palaeontographica, Beitrage zur Naturgeschichte der Vorzeit; Sonderabdruck ; Bd. LXXIX, Abt. B. [first use of Monanthesia] So, the indications are that Marion’s is a significant find, as is suggested by the following: [regarding Monanthesia]: “All these “types” have thus been “finds”, quite as rare as so many meteorites.” -- Wieland, (1928) [regarding C. stantoni]: “Especially its isolation makes it desirable to recover, if possible, other examples or associated species.” and: “It is a singular coincidence that the five most conspicuous examples of monocarpic trunks are from such widely separated regions as Galicia, Italy, Dakota, Colorado, and California, in each instance but a single specimen having been recovered. Is there not here a strong incentive to the collector to revisit and examine with the utmost care these several localities? “ -- Wieland, (1916) If M. stantoni is indeed a separate species, then Marion’s fossil may be the first collection of it since the original one made near the turn of the century [that is, if hers is also M. stantoni, which is a premature conclusion]. It could be worthwhile to go back to her site [or to Stanton’s] to look for more of it, especially if the whole trunk was as impressive as Tidwell’s and Wieland’s 7-footers... regards Mel Turner mturner@acpub.duke.edu

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