About the Origin of Cycads and Some Enigmatic Angiosperm-Like Fructifications from the Early-Middle Triassic (Anisian) Braies Dolomites (Northern Italy)
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ABOUT THE ORIGIN OF CYCADS AND SOME ENIGMATIC ANGIOSPERM-LIKE FRUCTIFICATIONS FROM THE EARLY-MIDDLE TRIASSIC (ANISIAN) BRAIES DOLOMITES (NORTHERN ITALY) by MICHAEL WACHTLER1 Wachtler, M.: Origin of Cycadales 1 Dolomythos Published online by the Dolomythos Museum, Innichen, South Tyrol, Italy. Dolomythos includes results of original research on systematic, evolutionary, morphological and ecological biology, including paleontology. Syntheses and other theoretical papers, based on re- search, are also welcome. Dolomythos is intended primarily for papers by the staff of the Dolomy- thos Museum or on research using material in this Museum. Editors: Edith Campei, Michael Wachtler Dolomythos is published at frequent but irregular intervals. Manuscripts, orders for publications, and all correspondence concerning publications should be sent to: Museum Dolomythos Rainerstraße 11 39038 Innichen Italy mail: [email protected] Please cite this article as: Wachtler, M., (05/2010): About the origin of Cycads and some enigmatic Angiosperm-like fructifi- cations from the Early-Middle Triassic (Anisian) Braies Dolomites (Northern Italy), Dolomythos, 1: 3-55, Innichen. 1 Michael Wachtler, P. P. Rainerstrasse 11, 39038 Innichen, Italy, e-mail michael@wachtler. com. Dolomythos, 2010 2 ABOUT THE ORIGIN OF CYCADS AND SOME ENIGMATIC ANGIOSPERM-LIKE FRUCTIFICATIONS FROM THE EARLY-MIDDLE TRIASSIC (ANISIAN) BRAIES DOLOMITES (NORTHERN ITALY) by Michael Wachtler1 1 Michael Wachtler, P. P. Rainerstrasse 11, 39038 Innichen, Italy, e-mail [email protected]. cycads. It bears entire leaves with an acu- Abstract minate to rounded apex. Cataphyll-like sterile leaves and ovule-bearing organs with Background. two rows of ovules on the abaxial surface form the megasporophyll. The fossil record of Cycadales and early An- Bjuvia primitiva n. sp. is thought to be a giosperm-like fructifications is fragmentary. real cycad with small, whole to sometimes- Many of our efforts to understand the evolu- frayed leaves. Bjuvia olangensis sp. nov. tion of this enigmatic plant group are ham- was the largest growing cycad in the Early- pered by the poor fossil record. Beginning Middle Triassic Dolomites. It produced huge, from 1999 the author recovered large quan- lacerated to segmented leaves. The stems tities of well-preserved cycadalean remains ended in a single strong taproot and and also other enigmatic strobili and fructifi- branching coralloid roots. Dioonitocarpidium cations in Early Middle to Middle Triassic (Ani- cycadea n. sp. and Dioonitocarpidium loretzi sian) sediments. Therefore it was possible to n. sp. are female sporophylls belonging to view their unusual story in a new light. Bjuvia primitiva and Bjuvia olangensis. The- tydostrobus marebbei gen. nov. sp. nov. is suggested to be the male cycadalean cone Methodology and Paleobiology. pertaining to Bjuvia. It resembles modern Several Anisian Cycads and other fructifica- cycad-strobili with its microsporophylls ar- tions with sometimes unknown affinity were ranged spirally on a central axis and micro- described and the paleobiology of the habi- sporangia on the lower surface, near the tat investigated. Pizperesia tannae gen. nov. apex. Nilssonia braiesensis n. sp. has clear- n. sp. is an enigmatic fructification with spi- segmented leaflets leading to the typical fo- rally free arranged hammer like pollen-scales liage-system of today’s Cycadales. on the upper part of a branch and flowerlike structures on the lower part. The single organs give the idea of densely reduced and com- Conclusions/Significance. pressed small fern-fronds. Pizperesia raetiae This 241.5 million year old world represents gen. nov. n. sp. bears microleaves with ag- the most complete ancient cycadalean world gregated sporangia on the lower surface, near ever found. All the main parts of cycads, the apex. However, its fleshly wedge-shaped such as the leaves, stems, roots, male and scales resemble single male cycad scales. female strobili, but also the juvenile and Ladinia simplex n. gen. n. sp. is suggested mature life-circuit as well as animal associa- to be a transition form between ferns and tion and also possible parental plants, were Wachtler, M.: Origin of Cycadales 3 discovered in large quantities. Research on sil bearing levels. They contained rich Early their characteristics allows a fairly com- Mesozoic floras, but also reptile remains, new plete reconstruction of the life history and ichnofaunas, and also marine biota (e.g. bi- associated habitat. It is of particular im- valves, brachiopods, ammonoids and fish portance to phylogenetic and cladistic skeletons). The first results were published in studies that in the Early to Middle Triassic the 2002 (Broglio Loriga et al.). evolution-cycle of cycads was nearly finished and they differed only in small de- tails from the extant species. The approach Geological age. to the relationships in cycad evolution and In the area studied the plant-bearing beds the early angiosperm habitat were studied begin about 75 m above a massive carbonate and hypotheses established. Future studies platform previously known as ‘Algenwellenka- and new fossil records would provide more lk’, and now attributed to the Gracilis Forma- clarity about several questions concerning tion (De Zanche et al. 1992; Gianolla et al. unresolved problems. 1998). The following, so-called Dont Forma- tion, is more than 200 m thick and bears Online: May 2010. several lens-shaped plant horizons that reach a consistent thickness of about one metre. Key words: fossil cycads, early angiosperms, They alternate with silty and marly limestone Dolomites, Italy, Middle Triassic, Anisian. or carbonate layers, in which only sparse terrestrial plant remains occur. All the suc- cessions were deposited in an original basi- nal, lagoonal, peritidal or continental habit. Introduction. Studies on brachiopods (Bechstädt and The geological and paleontological rich- Brandner 1970) and foraminifers (Fugagnoli ness of the Braies Dolomites has been well and Posenato 2004) suggest a Pelsonian age known since 1875 when the German ge- for the studied section; integrated studies ologist Hermann Loretz described various between palynomorphs and ammonoids nar- marine invertebrates (brachiopods, mol- row the time interval for the deposition of luscs). He was supervised by Edmund von the fossiliferous horizon down to the bound- Mojsisovis (1882) with his basic work about ary between the Middle and Upper Pelsonian ammonoids. But the most widely accepted (Kustatscher et al. 2006). long-standing research was edited by Ju- But also in the slightly younger Richthofen lius Pia in 1937 (Stratigraphie und Tektonik Conglomerate (Avanzini, Gianolla and Neri, der Pragser Dolomiten in Südtirol). Further 2007) and Morbiac Dark Limestone (Delfrati studies (Bechstädt and Brandner, 1970; and Farabegoli, 2000), both Illyrian in age, De Zanche et al., 1992) completed the plant-remains could be found, often inside knowledge about this area in the Eastern rich ichnofaunas also containing dinosauro- part of the Dolomites, which UNESCO in- morph trample layers. cluded in the world heritage list in 2009 for Over the years an extraordinary rich plant its geological beauty. assemblage has come to the surface with Surprisingly until 1999 only a few plant frag- several highlights as its abundance of Lyco- ments were described from this extensive phytes with four new species up to now area between the Braies Valley and the (Isoetites brandneri, Lepacyclotes bechs- Gadertal Valley. (Fig. 1) That year Michael taedtii, Selaginellites leonardii) and especial- Wachtler discovered the first rich plant hori- ly the arborescent Lycopia dezanchei as an zon under the crest of Kühwiesenkopf. (Fig. interesting connecting link between Carbonif- 2a) In subsequent years he extended his re- erous and recent lycopodales. But also Sphe- search to the nearby Hochalpenkopf, Mau- nophyta (Equisetites) and Coniferales (sev- rerkopf, Flatschkofel, Dreifingerspitze, all over eral Voltzia-genera, Aethophyllum), as well the borough of Olang, then around the Piz da as new fern species (Gordonopteris lorigae) Peres mountain up to Marebbe (Fig. 2b) cov- were discovered. Up to now more than 30 ering a distance of over 20 km. Everywhere different plants document the importance of inside this area in typical Anisian (lower Mid- this novel ‘Fossillagerstätte’. Some, such as dle Triassic) successions he found plant fos- the ferns Neuropteridium and Anomopteris, Dolomythos, 2010 4 (Italy) or in the Museum Dolomythos at In- nichen (San Candido). They all have the specimen code “KÜH” (for Kühwiesenkopf) or PIZ (For Piz da Peres) followed by a serial number. Materials and Methods. The research is based on more than 1,000 rock-slabs of cycadalean parts ranging OlangToblach from only a few centimetres up to one metre or more. Only in rare cases, and Piz da Peres Braies with further evolution, Cycad-leaves get Kühwiesenkopf cuticles. Up to now (2009) the Cycad-fossil record is Dolomites characterized by: Bjuvia primitiva leaves: about 400 pieces Bozen Bjuvia olangensis: about 300 pieces Nilssonia braiesensis: about 50 pieces Ladinia simplex: about 200 pieces Bjuvia trunks: about 10 pieces Fig. 1: Map of the Braies Dolomites area in Northern Dioonitocarpidium: about 30 pieces, (includ- Italy with Piz da Peres and Kühwiesenkopf. ing about 10 whole cones) Thetydostrobus: (about 10 pieces) Pizperesia: (about 20 pieces, mostly single scales) or seedferns like Sagenopteris and Scytho- With a long-lasting sense of observation