New Occurrences of the Controversial Late Triassic Plant Fossil Sanmiguelia

New paper extending the biostratigraphic range of the enigmatic Late Triassic plant Sanmiguelia. These new finds also alter the plant-based biostratigraphic scheme proposed by Ash in 1980.
 

Ash, S.R. and S. T. Hasiotis, S.T. 2013. New occurrences of the controversial Late Triassic plant fossil Sanmiguelia Brown and associated ichnofossils in the Chinle Formation of Arizona and Utah, USA. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 268: 65–82.

 

Abstract: Fragments of the rare and distinctive palm-like leaves of the controversial Late Triassic plant Sanmiguelia have been discovered recently in both Petrified Forest National Park, Arizona and Arches National Park, Utah. Although, the new specimens do not clarify the classification of this intriguing fossil, they do confirm that it occurs in all members of the Chinle Formation except for the very lowest units, the Shinarump, Mesa Redondo, and Temple Mountain members. Furthermore, their discovery in Petrified Forest National Park extends the known geographical distribution of the fossil into east-central Arizona and demonstrates that it is a characteristic member of the Late Triassic flora of the American southwest and requires a revision of the Chinle floral zone scheme proposed and revised earlier by Ash (1980). In Petrified Forest National Park the leaves are associated with several types of ichnofossils including Scoyenia, Arenicolites, Cylindrichum, cf. Scolicia, cf. Beaconites, Selenchnites, and other trace fossils in open nomenclature. These trace fossils suggest that Sanmiguelia was preserved in high moisture, imperfectly drained, water-margin setting inhabited by phytosaurs, snails, horseshoe crabs, and a variety of arthropods such as beetles and dipteran larvae and record high water table conditions punctuated by flooding and overbank deposition. The findings reported here generally support and improve on previous interpretations of the paleoenvironment inhabited by the Sanmiguelia plant.

A New Neocalamites from the Upper Triassic of China

Zan, S.-Q., Axsmith, B. J, Escapa, I., Fraser, N. C., Liu, F.-X., and D.-E. Xing. 2012. A new Neocalamites (Sphenophyta) with prickles and attached cones from the Upper Triassic of China. Palaeoworld (accepted manuscript). http://dx.doi.org/10.1016/j.palwor.2012.04.001

Abstract - Remains of the extinct sphenophyte (horsetail) Neocalamites are most widespread in the Middle–Upper Triassic and are typically represented by stem and leaf fragments. Here we report on spectacular new finds of Neocalamites from the Late Triassic Yangcaogou Formation in Liaoning Province, China that include bedding surfaces dominated by nearly complete aerial stems with attached leaf whorls and rare bractless cones. They reveal a monopodial growth habit for the stems, which are covered with downward projecting prickles that probably provided protection against herbivores. These features provide the basis for a new proposed species, Neocalamites horridus. The nodes bear whorls of very long leaves mainly free to their bases, and one specimen bears an attached cone on a long peduncle. Identical dispersed cones have also been recovered. The leaves of adjacent monopodial stems most likely interlocked to support growth in large stands akin to the role now played by branches in large modern Equisetum species. The new Chinese Neocalamites is among the most confidently reconstructed species, and indicates a greater diversity of sphenophyte morphology during the Mesozoic than previously realized.

Amazing Preservation of a Permian Forest Redux

Here is the abstract and link (open access) to the previously mentioned article.  It is too bad that with instantaneous preservation of a Permian ecosystem that no animals are mentioned as found. I also mistakenly stated in my previous post that the site was in China. It is actually from Mongolia.

Wang, J., Pfefferkorn, H. W., Zhang, Y., and Z. Feng. 2012.  Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia. PNAS, published online before print. doi: 10.1073/pnas.1115076109 


Abstract - Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m2 of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.

Amazing Preservation of a Permian Forest

The upcoming issue of PNAS has an article documenting amazing preservation of a Permian paleobotanical locality in China, the result of rapid burial by volcanic ash.  The actual article is not up yet but you can read about the study here.

Rare Occurrence of the Winged Seed Fraxinopsis from the Dockum Group of Texas

New paper from my friend Sid Ash.

Ash, S. R. 2011. Anomalous occurrence of the Gondwanan winged seed Fraxinopsis in a new Late Triassic (Norian) flora from west Texas, USA. –106. doi:10.1016/j.revpalbo.2011.05.007 Abstract - The small Late Triassic flora described here from a new locality in Palo Duro Canyon, west Texas, USA is noteworthy because it includes specimens of a new species of the Gondwanan winged seed Fraxinopsis, F. patharrisiae sp. nov. This is only the second time that Fraxinopsis has been found in Laurasia and thus adds support to the theory that at least limited floral migrations did take place between Gondwana and Laurasia during the Late Triassic. In addition to Fraxinopsis the locality has yielded a new species of the platyspermic seed Samaropsis, S. texensis sp. nov., the remains of the cycadophyte leaf Zamites powellii, and the leafy shoots and pollen and seed cones of Palodurophyton quanahensis gen. et sp. nov., a conifer of unknown relationships that has cheirolepidian-like epidermal features. This flora occurs in the Tecovas Formation in the lower part of the Dockum Group of Late Triassic (Norian) age. The description of the flora contributes to our understanding of the Dockum flora and its distribution in the American southwest and adds to our knowledge of the Late Triassic flora of western Laurentia as well.
Review of Palaeobotany and Palynology 166:94

Cycadalean and Bennettitalean Foliage from the Triassic Madygen Lagerstätte

Moisan, P., Voigt, S., Pott, C., Buchwitz, M., Schneider, J. W., and H. Kerp. 2011. Cycadalean and bennettitalean foliage from the Triassic Madygen Lagerstätte (SW Kyrgyzstan, Central Asia). Review of Palaeobotany and Palynology 164:93-108. doi:10.1016/j.revpalbo.2010.11.008

Abstract - Plant fossils recently collected from the Middle–Late Triassic Madygen Formation in SW Kyrgyzstan, Central Asia are described in detail. Based on the combination of gross morphology and epidermal/cuticular anatomy, four different taxa are identified, assigned to the Cycadales, i.e. Pseudoctenis lanei and Bennettitales, Pterophyllum pinnatifidum, P. firmifolium and Otozamites sp. All taxa are new for the Madygen Formation. Remarkable is the first occurrence of Pseudoctenis and two Pterophyllum species in the Triassic of Central Asia. The fossils are generally well preserved, but without cuticles. Nevertheless, epidermal and cuticular features can be recognized because the cuticles left behind imprints in the very fine-grained matrix. Silicon casts, examined under a stereomicroscope and with SEM, revealed xeromorphic features that are traditionally considered as indicators of arid conditions. However, comparisons of the functionality of the xeromorphic features in living plants show that these features occur in xerophytic, as well as in hygrophytic and halophytic plants. Sedimentological data from Madygen show that the fossil flora grew in alluvial plains, delta plains, and shallow lacustrine environments. The xeromorphic features are consequently interpreted as functional adaptations to environmental influences involved in the self-cleaning of the leaf surface, regulation of excessive radiation and leaf temperature and as an effective mechanical defense against phytophagous insects.

Carbon-isotope Variability of Triassic Amber, as Compared with Wood and Leaves

Dal Corso, J., Preto, N., Kustatscher, E., Mietto, P., Roghi, G., and H. C. Jenkyns. In Press Carbon-isotope variability of Triassic amber, as compared with wood and leaves (Southern Alps, Italy). Palaeogeography, Palaeoclimatology, Palaeoecology(2011).  doi:10.1016/j.palaeo.2011.01.007

Abstract - The carbon-isotope signatures of Carnian (Late Triassic) amber drops from Rifugio Dibona (Southern Alps, Italy) were studied and compared with that of other Middle-early Late Triassic fossil plant remains, namely wood and leaves. Amber, wood and leaf carbon-isotope data are highly variable within the same beds. δ13Camber values vary by up to 5.4‰ and are enriched by ~ 2.5‰ with respect to associated wood. δ13Cwood and δ13Cleaf ranges are narrower than that of amber (~ 2–3‰) and the isotopic offset within each bed is similar over time. The high Triassic amber carbon-isotope variability is similar to that of recent resin. Despite the high variability, δ13Cwood and δ13Cleaf illustrate a Middle-early Late Triassic secular positive trend that is similar to that of marine δ13Cinorg data and must record the carbon-isotope evolution of the ocean–atmosphere system.

End-Permian Biotic Disturbances: Floral Changes From the Permian Through Middle Triassic of Pakistan

Hermann, E., Hochuli, P. A., Bucher, H., Brühwiler, Hautmann, M., Ware, D., and G. Roohi. In Press. Terrestrial ecosystems on North Gondwana following the end-Permian mass extinction. Gondwana Research (2011). doi:10.1016/j.gr.2011.01.008
 Abstract - The impact of the end-Permian mass extinction on terrestrial ecosystems is still highly controversial. Here, new high-resolution palynological data from biostratigraphically well-dated Upper Permian to Middle Triassic successions of the Salt Range and Surghar Range (Pakistan) are presented. Our results reveal seven successive floral phases between the Late Permian and the Middle Triassic. At the onset of the Mesozoic, the flora is characterised by high abundances of lycopods associated with pteridosperms and conifers. This association prevails up to the middle Smithian and is followed by a prominent spore spike similar to the global spore spike reported from the Permian-Triassic boundary. Like that of the end-Permian, the middle Smithian spore spike is associated with a negative isotope excursion and is succeeded by a major marine faunal extinction event in the late Smithian. The recurrent patterns observed at the Permian-Triassic boundary and in the middle–upper Smithian suggest a common cause such as massive ejections of volcanic gases. The increasing abundance of conifers still associated with common lycopods in the Spathian suggests fading volcanically induced environmental perturbations and stabilisation of terrestrial ecosystems ca. 2.1 My after the end-Permian event.

What End-Permian Terrestrial Mass Extinction? Negative Evidence from South China

Xiong, C., and Q. Wang. 2011. Permian–Triassic land-plant diversity in South China: Was there a mass extinction at the Permian/Triassic boundary? Paleobiology 37:157-167; DOI: 10.1666/09029.1


Abstract - Diversity dynamics of the Permian–Triassic land plants in South China are studied by analyzing paleobotanical data. Our results indicate that the total diversity of land-plant megafossil genera and species across the Permian/Triassic boundary (PTB) of South China underwent a progressive decline from the early Late Permian (Wuchiapingian) to the Early-Middle Triassic. In contrast, the diversity of land-plant microfossil genera exhibited only a small fluctuation across the PTB of South China, showing an increase at the PTB. Overall, land plants across the PTB of South China show a greater stability in diversity dynamics than marine faunas. The highest extinction rate (90.91%) and the lowest origination rate (18.18%) of land-plant megafossil genera occurred at the early Early Triassic (Induan), but the temporal duration of the higher genus extinction rates (>60%) in land plants was about 23.4 Myr, from the Wuchiapingian to the early Middle Triassic (Anisian), which is longer than that of the coeval marine faunas (3–11 Myr). Moreover, the change of genus turnover rates in land-plant megafossils steadily fluctuated from the late Early Permian to the Late Triassic. More stable diversity and turnover rate as well as longer extinction duration suggest that land plants near the PTB of South China may have been involved in a gradual floral reorganization and evolutionary replacement rather than a mass extinction like those in the coeval marine faunas.

New Data on the Early Triassic Land Flora Recovery

Yu, J., Broutin, J., Huang, Q., and L. Grauvogel-Stamm. 2010. Annalepis, a pioneering lycopsid genus in the recovery of the Triassic land flora in South China. Comptes Rendus Palevol 9:479-486. doi:10.1016/j.crpv.2010.09.004 Abstract - Fossil plants are scarce in the Earliest Triassic marine deposits of western Guizhou and eastern Yunnan. Only Annularia shirakii, Lobatannularia sp., Paracalamites stenocostatus, Gigantopteris sp., Pecopteris sp. were reported from the base of the Kayitou Formation dated as Early Induan by marine fauna. Recently, we discovered numerous representatives of the genus Annalepis in the same Lowermost Triassic beds: A. latiloba, A. brevicystis, A. angusta, Annalepis spp. occur associated with a basal Triassic marine fauna. This discovery fills the biostratigraphic gap between the Late Permian “Gigantonoclea guizhouensis-Ullmannia cf. bronnii-Annularia pingloensis” and the late Lower Triassic “Neuropteridium–Albertia–Voltzia” assemblages reported from South China. It represents an important datum dealing with the very beginning of a new terrestrial flora installation after the Permian flora disappearance following the Permian–Triassic boundary mass extinction. This “starting point” of a new vegetal cover in South China is to be taken into account in reconstructing through space and time the settlement process of the Mesozoic floristic provinces.

Preserved Bark on Middle Triassic Gymnosperm Wood from Antarctica

Bark is rarely preserved in fossil trees so this is pretty significant.

Decombeix, A.-L., Taylor, E. L., and T. N. Taylor. 2010. Anatomy and affinities of permineralized gymnospermous trunks with preserved bark from the Middle Triassic of Antarctica. Review of Palaeobotany and Palynology 163:26–34. doi:10.1016/j.revpalbo.2010.09.002

Abstract - Permineralized gymnosperm axes with pycnoxylic wood from the Middle Triassic Fremouw Formation of the Central Transantarctic Mountains, Antarctica, are assigned to the corystosperms (seed ferns) and conifers. Both groups have been previously described from this formation based on juvenile stems with attached leaf bases and decorticated trunks. Here we describe large axes with preserved bark from the Fremouw Peak permineralized peat locality. The specimens are characterized by a small parenchymatous pith with clusters of sclereids, a thick cylinder (> 10 cm) of pycnoxylic wood, and 1–2 cm of bark containing distinctive clusters of sclereids and a complex system of cortical vascular bundles. Comparison with axes previously described from the Middle Triassic of Antarctica shows that the new specimens are most similar to Kykloxylon, a corystosperm genus based on young stems bearing Dicroidium leaves, and with a portion of axis previously described as Rhexoxylon like. We suggest that both the new specimens and the Rhexoxylon-like axis represent proximal parts of a Dicroidium/Kykloxylon plant that possibly had a fluted trunk base, and we discuss the problem of delimiting features in corystosperm axes.

New Seed Ferns and Cycadophytes from the Middle Triassic of Germany

Kustatscher, E.,  and J. H. A. van Konijnenburg-van Cittert. 2010. Seed ferns and Cycadophytes from the Triassic Flora of Thale (Germany). Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 258: 195–217.

Abstract: This is the second paper on the Middle Triassic flora from Thale, dealing with the seed ferns and cycadophytes. Scytophyllum bergeri Bornemann is one of the common elements in the flora, in contrast to Sagenopteris sp. which is rare in the assemblage. However, it is the first evidence of Sagenopteris for the German Basin. The specimen described as ?Peltaspermum sp. is the only peltasperm ovuliferous organ known to date with attached ovule-bearing discs from the Middle Triassic of Europe. The cycad Apoldia tener (Compter 1883) Zijlstra et al. 2009 (formerly Sphenozamites tener Compter) is by far the most common fossil plant in the assemblage. Nilssonia cf. neuberi Stur ex Pott et al. is relatively rare. The genus Bjuvia is emended to accommodate more species of large entire leaves characterised by amphistomy and cycadalean stomatal morphology. This includes Bjuvia thalensis n. sp., which is a common element in the Thale flora but is unknown from elsewhere. Narrow, long entire leaves from the Middle and Upper Triassic of Europe have been described under the name Taeniopteris angustifolia Schenk, but have now been transferred to Taeniopteris kelberi n. sp. for nomenclatorial reasons. The macrosporophyll Dioonitocarpidium pennaeformis (Schenk) Ruhle von Lilienstern also occurs in the Thale flora. Two cycadalean leaf species (Apoldia tener and Bjuvia thalensis) from Thale flora sometimes have stomata with only two subsidiary cells instead of the usual 4-6, a feature that in gymnosperms occurs mainly in the Bennettitales.

...and one more from the End-Triassic Event.

Mander, L., Kuerschner, W. M., and J. C. McElwain. 2010. An explanation for conflicting records of Triassic–Jurassic plant diversity. PNAS Early Edition, www.pnas.org/cgi/doi/10.1073/pnas.1004207107. Suppl.files at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1004207107/-/DCSupplemental.

Abstract - Macrofossils (mostly leaves) and sporomorphs (pollen and spores) preserve conflicting records of plant biodiversity during the end-Permian (P-Tr), Triassic–Jurassic (Tr-J), and end-Cretaceous (K-T) mass extinctions. Estimates of diversity loss based on macrofossils are typically much higher than estimates of diversity loss based on sporomorphs. Macrofossils from the Tr-J of East Greenland indicate that standing species richness declined by as much as 85% in the Late Triassic, whereas sporomorph records from the same region, and from elsewhere in Europe, reveal little evidence of such catastrophic diversity loss. To understand this major discrepancy, we have used a new high-resolution dataset of sporomorph assemblages from Astartekløft, East Greenland, to directly compare the macrofossil and sporomorph records of Tr-J plant biodiversity. Our results show that sporomorph assemblages from the Tr-J boundary interval are 10–12% less taxonomically diverse than sporomorph assemblages from the Late Triassic, and that vegetation composition changed rapidly in the boundary interval as a result of emigration and/or extirpation of taxa rather than immigration and/or origination of taxa. An analysis of the representation of different plant groups in the macrofossil and sporomorph records at Astartekløft reveals that reproductively specialized plants, including cycads, bennettites and the seed-fern Lepidopteris are almost absent from the sporomorph record. These results provide a means of reconciling the macrofossil and sporomorph records of Tr-J vegetation change, and may help to understand vegetation change during the P-Tr and K-T mass extinctions and around the Paleocene– Eocene Thermal Maximum.

Increased fire activity at the Triassic/Jurassic Boundary Due to Climate Driven Floral Change

Belcher, C. M, Mander, L., Rein, G., Jervis, F. X., Haworth, M., Hesselbo, S. P., Glasspool, I. J., and J. C. McElwain. 2010. Increased fire activity at the Triassic/Jurassic boundary in Greenland due to climate-driven floral change. Nature Geoscience 3:426-429.

Abstract - One of the largest mass extinctions of the past 600 million years (Myr) occurred 200 Myr ago, at the Triassic/Jurassic boundary. The major floral and faunal turnovers have been linked to a marked increase in atmospheric carbon dioxide levels, probably resulting from massive volcanism in the Central Atlantic Magmatic Province. Future climate change predictions suggest that fire activity may increase, in part because higher global temperatures are thought to increase storminess. Here we use palaeontological reconstructions of the fossil flora from East Greenland to assess forest
flammability along with records of fossil charcoal preserved in the rocks to show that fire activity increased markedly across the Triassic/Jurassic boundary. We find a fivefold increase in the abundance of fossil charcoal in the earliest Jurassic, which we attribute to a climate-driven shift from a prevalence of broad-leaved taxa to a predominantly narrow leaved assemblage. Our fire calorimetry experiments show that narrow leaf morphologies are more flammable than broad leaved morphologies.We suggest that the warming associated with increased atmospheric carbon dioxide levels favoured a dominance of narrow-leaved plants, which, coupled with more frequent lightening strikes, led to an increase in fire activity at the Triassic/Jurassic boundary.

New Triassic Papers in Rivista Italiana di Palaeontolgia e Stratigrafia.

There are a trio of Triassic papers in the new issue of Rivista Italiana di Paleontologia e Stratigrafia.

Renesto, S. 2010. A new specimen of Nothosaurus from the latest Anisian (Middle Triassic) Besano Formation (Grenzbitumenzone) of Italy. Rivista Italiana di Paleontologia e Stratigrafia 116(2).

Abstract - A nearly complete but disarticulated skeleton of a small sized nothosaur is described. The specimen was collected in 2003 from an outcrop of the Besano Formation (Grenzbitumenzone of Swiss authors) of latest Anisian (Middle Triassic) age, in the Monte San Giorgio Area, northern Italy. The osteology of the postcranial skeleton supports the assignment to the genus Nothosaurus, and also excludes its belonging to Nothosaurus giganteus/Paranothosaurus amsleri already known from coeval localities of the Besano Formation in the Swiss part of the Monte San Giorgio area. Despite the lack of most of the skull, which contains diagnostic characters at the species level for Nothosaurus, the few preserved cranial elements suggest similarities with N. juvenilis which skull, and only known part, is also of comparable size. This specimen is particularly significant because it improves the knowledge of the osteology of N. juvenilis and because the second Nothosaurus species, smaller than N. giganteus/P. amsleri, suggests coexistence of sympatric species characterized by size and, probably, trophic differentiation within the genus Nothosaurus in the Monte San Giorgio area as occurred in the coeval Germanic Basin.

Tintori, A., Sun, Z.-Y., Lombardo, C., Jiang, D.-Y., Sun, Y.-L., and Hao, W.-C., 2010. A new basal neopterygian from the Middle Triassic of Luoping County (South China). Rivista Italiana di Paleontologia e Stratigrafia 116 (2).



Abstract - A new taxon belonging to Neopterygians is described, based on very nicely preserved specimens from the rich vertebrate levels recently discovered in Luoping County, Yunnan Province, South China. This new assemblage dates to Pelsonian (Anisian, Middle Triassic), about the same age of the Panxian Fauna from the nearby Guizhou Province. The Luoping Fauna, yielding this new taxon, is turning out to be one of the most important fish faunas of the whole Middle Triassic and the oldest evidence of the fish radiation of this time span. This new genus of basal neopterygian shows unique derived characters, especially for the almost naked body, with a single row of urodermals covering the body lobe in the tail and a row of very small and thin scales bearing the lateral line canal along the flank. Also in the axial skeleton the new taxon shows peculiar characters such as the neural spines perfectly aligned to each paired neural arches and abdominal ribs well developed. Concerning skull bones, no suborbitals have been detected.
Stockar, R., and Kustatscher, E. 2010. The Ladinian flora from the Cassina Beds (Meride Limestone, Monte San Giorgio, Switzerland): preliminary results. Rivista Italiana di Paleontologia e Stratigrafia 116 (2).


Abstract - A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO WHL, Canton Ticino, Southern Alps) has yielded a small collection of Ladinian plant fossils, together with vertebrate (mostly fish) and invertebrate remains. The flora contains at least five species; conifer remains assignable to the genera Elatocladus, Voltzia and ?Pelourdea are the most common elements. A new species, Elatocladus cassinae n. sp., is formally described. Co-occurring with the conifers are seed ferns (Ptilozamites) and a few putative cycadalean remains (?Taeniopteris). Among the identified genera, only Voltzia has previously been reported from Monte San Giorgio. The fossils presented in this paper indicate that a diversified flora thrived in the region during the Ladinian. Floral composition and preservation patterns are suggestive of a taphonomically-biased record and a relatively far-away source area.

New Data on Rising Carbon Dioxide Levels Through the Triassic-Jurassic Transistion

Bonis, N. R., Van Konijnenburg-Van Cittert, J. H. A., and W. M. Kürschner. in press. Changing CO2 conditions during the end-Triassic inferred from stomatal frequency analysis on Lepidopteris ottonis (Goeppert) Schimper and Ginkgoites taeniatus (Braun) Harris, Palaeogeography, Palaeoclimatology, Palaeoecology (2010), doi:10.1016/j.palaeo.2010.05.034

End-Triassic fluctuations in atmospheric carbon dioxide (CO2) concentration were reconstructed by the use of stomatal frequency analysis on a single plant species: the seedfern Lepidopteris ottonis (Goeppert) Schimper. Stomatal index showed no distinct intra- and interpinnule variation which makes it a suitable proxy for past relative CO2 changes. Records of decreasing stomatal index and density from the bottom to the top of the Rhaetian– Hettangian Wüstenwelsberg section (Bavaria, Germany) indicate rising CO2 levels during the Triassic–Jurassic transition. Additionally, stomatal frequency data of fossil ginkgoalean leaves (Ginkgoites taeniatus (Braun) Harris) suggest a maximum palaeoatmospheric CO2 concentration of 2750 ppmv for the latest Triassic.

Discovery of an Entire Fossil Cycad from the Late Triassic of China

One of the frustrating things about fossil plants is that when the die they tend to break down rapidly and fall apart. Thus finding an entire plant is rare and therefore the leaves, stems, and reproductive structures are often found separately and provided different taxonomic names. Even at Petrified Forest National Park we do not know for certain what foliage belongs with our main types of fossil wood, although we do have isolated preserved foliage. A recent article in Chinese Science Bulletin (Springer) documents an entire cycad from the Late Triassic of China. This well preserved specimen includes the leaves, pinnae, stem, and a male cone as well as preserving their arrangement. An amazing and important find, unfortunately the article is just a note and not a full description and discussion. According to the article this is forthcoming.

You can download the PDF here for free until the end of November 2009 courtesy of Springer. The image above is from the article.

Wang, X., Li., N., Wang, Y. D., and S. Zheng. 2009. The discovery of whole-plant fossil cycad from the Upper Triassic in western Liaoning and its significance.
Chinese Science Bulletin 54: 3116―3119. doi: 10.1007/s11434-009-0384-z

Abstract - A recently discovered megafossil of whole plant cycad is briefly reported here. The specimen is collected from the Yangcaogou Formation (Upper Triassic) in Changheying, Beipiao, Liaoning. The whole plant is preserved intact on a sandstone slab, 89 cm long and 130 cm wide, including leaves up to 82 cm long and a male cone physically attached to the stem apex. Analysis on the morphology, arrangement and venation of leaf and pinna, male cone and its relationship with other parts indicates that the fossil is closely related to living Zamiaceae in Cycadales. This cycad fossil is hitherto most completely preserved cycad specimen including both vegetative and reproductive organs. Its discovery contributes much to our understanding of the morphology and evolution of cycads, palaeoclimate as well as palaeoenvironment.

Thanks to Randy Irmis for sending this on.