Fossil Wood Assemblages Research Articles

First fossil woods and palm stems from the mid-Paleocene of Myanmar and implications for biogeography and wood anatomy.

The rise of angiosperm-dominated tropical rainforests has been proposed to have occurred shortly after the Cretaceous-Paleogene transition. Paleocene fossil wood assemblages are rare yet provide important data for understanding these forests and whether their wood anatomical features can be used to document the changes that occurred during this transition. We used standard techniques to section 11 fossil wood specimens of Paleocene-age, described the anatomy using standard terminology, and investigated their affinities to present-day taxa. We report here the first middle Paleocene fossil wood specimens from Myanmar, which at the time was near the equator and anchored to India. Some fossils share affinities with Arecaceae, Sapindales (Anacardiaceae, Meliaceae) and Moraceae and possibly Fabaceae or Lauraceae. One specimen is described as a new species and genus: Compitoxylon paleocenicum gen. et sp. nov. This assemblage reveals the long-lasting presence of these aforementioned groups in South Asia and suggests the early presence of multiple taxa of Laurasian affinity in Myanmar and India. The wood anatomical features of the dicotyledonous specimens reveal that both "modern" and "primitive" features (in a Baileyan scheme) are present with proportions similar to features in specimens from Paleocene Indian localities. Their anatomical diversity corroborates that tropical flora display "modern" features early in the history of angiosperms and that their high diversity remained steady afterward.

An early Miocene (Aquitanian) mangrove fossil forest buried by a volcanic lahar at Barro Colorado Island, Panama

We describe remains on an Early Miocene mangrove forest, based on a fossil wood assemblage, discovered on Barro Colorado Island, Panama. Sedimentological and stratigraphic analysis suggests that the fossil trees grew in marginal marine to coastal fluvial settings and were buried under a volcanic lahar flow in a single event. Radiometric analyses of a tuff associated with the fossils gives a date of ∼22.79 Ma indicating an assignment to the Aquitanian stage of Early Miocene. At this time, central Panama was part of a long and narrow peninsula with intense volcanic activity that connected it with North America and was separated from South America by the Central American Seaway. A total of 121 fossil wood specimens were located. Wood anatomy indicates that most of the identifiable specimens belonged to the same morphotype, which has anatomical traits similar to Sonneratia (Lythraceae), a mangrove tree that is native to Southeast Asia. We named this morphotype as a new fossil species: Sonneratioxylon barrocoloradoensis Pérez-Lara., sp. nov. Biomechanical estimates indicate that S. barrocoloradoensis had a mean tree height of 25 m with some specimens reaching 40 m, in contrast to modern Sonneratia and other extant mangrove forests, which generally have lower mean heights. The dominance of S. barrocoloradoensis, its similarity to Sonneratia, and the depositional setting suggest that the fossil wood assemblage on Barro Colorado Island comprised a mangrove forest growing along the coast of the volcanic chain of central Panama.

Fossil woods from Corcovado (Eocene?), Argentinean Patagonia: angiosperm diversity and biodeterioration

Summary Angiosperm fossil woods of putative Eocene age from Corcovado, Chubut Province are described. They are placed in four taxonomic units: Weinmannioxylon trichospermoides and cf. Caldcluvioxylon of the Cunoniaceae, Myrceugenellites maytenoides of the Myrtaceae, and Nothofagoxylon ruei of the Nothofagaceae. The taxa in the assemblage are in accordance with similar fossil wood assemblages previously described from the Eocene and Oligocene of Patagonia. All the taxa are anatomically similar to trees that live today in Patagonia. Some of the woods show decay patterns by different saproxylic organisms. These include arthropod borings with coprolites and fungal remains in fungi-decayed tissues that are consistent with an active saproxylic community involved in the recycling of wood in the depositional paleoenvironment.

A unique Late Cretaceous fossil wood assemblage from Chilean Patagonia provides clues to a high‐latitude continental environment

AbstractFossil plants, including large trunks, stems, some branches, and twigs, were collected from the Maastrichtian (68.9 Ma), upper Dorotea Formation in the Magallanes–Austral Basin, 16 km north of the Cerro Guido–Las Chinas complex in the southern Chilean Magallanes region. These fossil trunks range from 0.2 to 2.2 m in length. Petrographic slides were made in three sections (transverse, radial and tangential) and analysed under a light microscope to study the permineralized fossils. The woods and stems belong to Austroginkgoxylon gen. et sp. nov., Agathoxylon antarcticum, Podocarpoxylon paradoxi sp. nov., Podocarpoxylon mazzonii, Palmoxylon subantarcticae and Notomalvaceoxylon magallanense gen. et sp. nov. The growth rings of gymnosperms and anatomical characters of angiosperms were analysed to obtain palaeoecological data. Interactions between gymnosperm roots growing into the secondary xylem of an angiosperm (nurse logs) are recorded. The data obtained from the fossil woods suggest warm and humid conditions in this southern South American locality during the Late Cretaceous, providing a unique opportunity to study continental environments at high southern latitudes, which are poorly represented on a global scale.

Miocene Cupressinoxylon from Gökçeada (Imbros), Turkey with Protophytobia cambium mining and the study of ecological signals of wood anatomy.

The recognition of the Miocene Climate Optimum (MCO) in terrestrial palaeoenvironments of the Eastern Mediterranean is restricted to Lesbos and Lemnos Islands, Greece. This area is significant for its wood microfossils. A recently-discovered fossil wood assemblage from Gökçeada (Imbros) Island, Turkey, including tree species similar to the Greek findings, is thought to have an early Miocene age. Here, we revise the age of the latter plant fossiliferous locality, re-evaluate the area for the study of MCO for the terrestrial palaeoecosystems of the Eastern Mediterranean and the nomenclature errors referring to the occurrence of fossil wood. We present the plant-insect-environment interactions using detailed anatomical descriptions, of an extinct conifer and its extinct cambium miner feeding traces observed in its secondary xylem. Three thin sections were prepared with standard palaeoxylotomical techniques from a small section of the silicified wood; the sections were observed under a light microscope. The anatomy of the conifer and its damage patterns were compared with those of extant and fossil Cupressaceae and Agromyzidae, respectively. The common anatomical features of the studied wood specimen and Hesperocyparis macrocarpa (Hartw.) Bartel and a shared characteristic (the number of the cross-field pits - a feature we consider of diagnostic value) with Xanthocyparis vietnamensis Farjon & T.H. Nguyên led to its assignment to the Hesperocyparis-Xanthocyparis-Callitropsis clade. The detailed study of the wound scars and anatomical abnormalities, the anatomical-environmental associations, and structural-functional reactions follow the identification of the wood's anatomy sensu Carlquist providing decisive results. Based on the distinctive characteristics presented, we identify our macrofossil as Cupressinoxylon matromnense Grambast, a stem or an extinct lineage of the Hesperocyparis-Xanthocyparis vietnamensis-Callitropsis nootkatensis clade with feeding traces of the fossil cambium miner of the genus Protophytobia Süss (Diptera: Agromyzidae), and anatomical damage and reaction tissue on adventitious shoots. The use of Protopinaceae and Pinoxylon F. H. Knowlton from the eastern Mediterranean are re-evaluated and corrections are provided. The age of the studied plant fossiliferous locality in Gökçeada is revised as middle Miocene, allowing the proposal of an eastern Mediterranean MCO hotspot, including Lesbos, Lemnos, and Gökçeada (Imbros) Islands.

Life in the woods: Taphonomic evolution of a diverse saproxylic community within fossil woods from Upper Cretaceous submarine mass flow deposits (Mzamba Formation, southeast Africa)

Organisms that colonize wood are subject to a taphonomic tragedy—the richer and more diverse they become, the greater the deterioration of the host wood and the less likely such communities are to be fossilized. Moreover, palaeobotanical studies of fossil wood usually focus on the plant tissue, neglecting the evidence of parasitic, saproxylic, and other contained organisms. Such a case involved a relatively well-known fossil wood assemblage from the Santonian (Late Cretaceous, ca 84 Ma) of southeast Africa. In a set of 150 thin sections of silicified wood stored in the Senckenburg Museum for more than half a century, we discovered evidence of a diverse biotic community comprising bacteria, fungi, nematodes, several types of arthropods, and marine bivalves. These body fossils and traces, together with growth-ring features, fossil log size and shape, and the distribution of glauconite, facilitated interpretation of the multi-stage evolution of a wood-hosted biocoenosis of unprecedented diversity. This record is unique for the Mesozoic and is of importance for understanding the taphonomic pathways to preservation and the evolution and diversification of saproxylic and other wood-hosted communities in terrestrial and marine settings.

New data on the geographic and stratigraphic range of the Mesozoic fossil wood genera Protocedroxylon and Xenoxylon in the Arctic region

Protocedroxylon Gothan and Xenoxylon Gothan are two biogeographically important Mesozoic fossil wood genera. They are the witnesses of a boreal flora whose periodic extensions towards the south characterize Mesozoic climatic oscillations. However, previously documented Arctic records of these taxa are known mostly by poorly dated specimens. A new well-preserved and well-dated fossil wood material is described from the Upper Jurassic deposits of Franz Josef Land Archipelago (Russian Arctic). We studied this new material and evidenced two taxa, Protocedroxylon araucarioides Gothan and Xenoxylon phyllocladoides Gothan. We re-examined the fossil woods of Xenoxylon with the same provenance described by Shilkina (1967) as X. barberi (Seward) Kräusel and re-assigned them to the X. phyllocladoides-group. A review of Protocedroxylon and Xenoxylon from northern high palaeolatitudes allows us to better understand the spatial and temporal extension of the flora that yielded to the Protocedroxylon and Xenoxylon fossil wood assemblage.

Further contribution to the early Miocene woody flora of Galatian Volcanic Provincefrom Doğanyurt Village, Ankara (Turkey)

The Galatian Volcanic Province (GVP) located in central-north Anatolia had a rich woody flora. The purpose of the present study is to contribute to the early Miocene woody flora of the GVP from two fossil sites from Doğanyurt Village of the city of Beypazarı in the Province of Ankara. The fossil sites, which are near to each other, have small pieces of fossil woods. Total 16 fossil woods were collected from two neighbour sites. Three thin sections as transversal, tangential and radial sections from each sample were taken, and they were identified microscopically. As a result, ten fossil species were identified, three of which are new (Cercioxylon mediterraneum Akkemik, Iamandei & Çelik, sp. nov., Cryptocaryoxylon irregularis Akkemik, Iamandei & Çelik, sp. nov., and Myricoxylon doganyurtensis Akkemik, Iamandei & Çelik sp. nov.) and the rest fossil species (Glyptostroboxylon rudolphii Dolezych & van der Burgh, Taxodioxylon gypsaceum (Göppert) Kräusel, Pinuxylon Gothan, Aceroxylon aceroides Akkemik, Pistacioxylon ufukii Akkemik, Salicoxylon galatianum Akkemik, and Ulmoxylon cf. carpinifolia Greguss) are found also in these two fossil sites. The fossil Myrica, identified for the first time in Turkey as a wood, has many leaf fossils from the early Miocene sites. The most common fossil trees in the Miocene time of GVP, which are G. rudolphii and T. gypsaceum, were also identified in these new sites. The fossil wood assemblage may indicate that the area had a subtropical climate in lowland, with riparian and swamp growth conditions.

Early Miocene paleoclimate in southern Patagonia inferred from fossil woods

Patagonia has a rich record of fossil woods that are a unique data store of paleoclimatic information. We studied the wood flora recovered from the Río Leona Formation (early Miocene) of southern Patagonia near El Calafate and Río Turbio localities, Santa Cruz Province, Argentina. The fossil wood assemblage was analyzed using various methodologies (anatomy analysis, Vulnerability and Mesomorphic indices, and the Coexistence Approach) to determine paleoclimate variables including mean annual temperature (MAT) and mean annual precipitation (MAP). The anatomy analysis developed by Wiemann et al. (1998, 1999) is based mostly on woods from the Northern Hemisphere. We applied those equations to extant woods from the southernmost region of South America to test their functionality and to compare them with the results obtained from the fossils. These equations gave limited results. Climate signals from fossil woods suggest a microthermal climate for the region with MAT of 8–12 °C and MAP of 80–170 cm/year. In addition, part of the results points towards an environment with water in abundance (i.e., Coexistence Approach and some wood characters influenced by the environment) and other results suggest wood tolerance to hydric stress (i.e., Vulnerability Index, Mesomorphy Index, and wood characters influenced by the environment). These suggest an environment with rainy and dry seasons, which is also supported by the presence of well-marked growth ring boundaries and false rings. These conditions can be found today in central Chile, a region that shares some vegetation elements with the Río Leona Formation and has a Mediterranean climate.

Erratum to: The Piedra Chamana fossil woods and leaves: a record of the vegetation and palaeoenvironment of the Neotropics during the late Middle Eocene.

Background and aims The Piedra Chamana fossil forest in northern Peru is an assemblage of angiosperm woods and leaves preserved in volcaniclastic rocks dated to 39 Mya (late Middle Eocene). We analysed the anatomical and morphological features of the fossils to reconstruct the palaeoenvironment during this time of global warmth, taking advantage of the co-occurrence of woods and leaves to compare different proxies and analytical approaches. Methods Wood characters analysed include vessel-related functional traits, traits linked to Baileyan trends, and quantitative features such as vessel diameter and density. Diameter-distribution and diameter and position plots are used to represent vessel diameter and arrangement. Leaf margin and area analysis provides additional climate estimates. Key results The fossil woods show many similarities with modern tropical-forest woods and tropical fossil-wood assemblages; closest correspondence within the Neotropics is to semi-deciduous lowland tropical forest with moderate precipitation (~1000-1200 mm). Features unusual for the modern South American tropics are mainly vessel-related characters (semi-ring porosity, grouped vessels, helical vessel thickenings, short vessel elements) linked to water stress or seasonal water availability. Leaf analysis indicates mean annual temperature of 31 °C (n = 19, 100 % entire-margined) and mean annual precipitation of 1290 mm (n = 22, predominantly microphylls and notophylls). Conclusions The palaeovegetation was clearly lowland tropical forest with a dry aspect, but anomalous aspects of the wood anatomy are consistent with the high temperatures indicated by the leaves and are probably explained by differences in seasonality and water stress compared to the present-day Neotropics. A close modern analogue may be in very seasonal regions of Asia. Pronounced monsoonal (summer-rain) conditions may relate to a location (palaeolatitude of 13°S) outside the near-equatorial tropics.

The Piedra Chamana fossil woods and leaves: a record of the vegetation and palaeoenvironment of the Neotropics during the late middle Eocene.

The Piedra Chamana fossil forest in northern Peru is an assemblage of angiosperm woods and leaves preserved in volcaniclastic rocks dated to 39 Mya (late Middle Eocene). We analysed the anatomical and morphological features of the fossils to reconstruct the palaeoenvironment during this time of global warmth, taking advantage of the co-occurrence of woods and leaves to compare different proxies and analytical approaches. Wood characters analysed include vessel-related functional traits, traits linked to Baileyan trends, and quantitative features such as vessel diameter and density. Diameter-distribution and diameter and position plots are used to represent vessel diameter and arrangement. Leaf margin and area analysis provides additional climate estimates. The fossil woods show many similarities with modern tropical-forest woods and tropical fossil-wood assemblages; closest correspondence within the Neotropics is to semi-deciduous lowland tropical forest with moderate precipitation (~1000-1200 mm). Features unusual for the modern South American tropics are mainly vessel-related characters (semi-ring porosity, grouped vessels, helical vessel thickenings, short vessel elements) linked to water stress or seasonal water availability. Leaf analysis indicates mean annual temperature of 31 °C (n = 19, 100 % entire-margined) and mean annual precipitation of 1290 mm (n = 22, predominantly microphylls and notophylls). The palaeovegetation was clearly lowland tropical forest with a dry aspect, but anomalous aspects of the wood anatomy are consistent with the high temperatures indicated by the leaves and are probably explained by differences in seasonality and water stress compared to the present-day Neotropics. A close modern analogue may be in very seasonal regions of Asia. Pronounced monsoonal (summer-rain) conditions may relate to a location (palaeolatitude of 13°S) outside the near-equatorial tropics.

Conifer fossil woods from the Santa Marta Formation (Upper Cretaceous), Brandy Bay, James Ross Island, Antarctica

Conifer fossil woods from the Santonian to lower Campanian Santa Marta Formation are anatomically studied in detail. The wood flora is dominated by conifers, mainly Araucariaceae. Conifer fossil woods represent 84% of the samples (26 of 31) of the assemblage. The remaining samples are dicotyledon woods which are not included in this study. Woods are mostly calcified and preservation is often excellent. Fossil woods include three species of Agathoxylon, Phyllocladoxylon antarcticum, Cupressinoxylon hallei and a new species of Cupressinoxylon, C. rotundum Pujana sp. nov. The conifer-dominated forests are consistent with the pollen and macrofloras previously described from sediments of the same stratigraphic unit. This fossil wood assemblage contributes to understand the floristic changes that took place in the Cretaceous forests.

Palaeobotanical study of Polichnitos region, southern part of Lesbos Island, Greece (preliminary results on angiosperm wood).

The present contribution brings new scientific data for the palaeoflora of Lesbos based on new collections of plant fossils which were discovered in 2011 at six new localities from the southern part of Lesbos Island. This study resumes the published data both on the palaeovegetation of the Petrified Forest and the palaeogeography of Lesbos Island during the Neogene. The new palaeobotanical study with more than seventy new samples of fossilized wood from the broader area of Polichnitos region gives new information about the palaeobotanical and palaeontological content of this area. It is reported for the first time here the existence of a diversified fossil wood assemblage from the southern part of the Island as long as the identification of three types of lauraceous wood according to their idioblasts characteristics.

Fossil coniferous wood from the Early Cretaceous Jehol Biota in western Liaoning, NE China: New material and palaeoclimate implications

The Early Cretaceous Jehol Biota, one of the most important Mesozoic lagerstätten in East Asia, is especially well-known for occurrences of fossil feathered dinosaurs and early angiosperms. However, the terrestrial biodiversity, especially the fossil wood record, is poorly known. In this study, several structurally preserved coniferous wood specimens from the Lower Cretaceous Yixian Formation are investigated, based on collections from the Heichengzi Basin in Beipiao of western Liaoning, Northeast China. Four species referred to four genera of fossil wood are described, including Taxodioxylon heichengziense sp. nov., Thujoxylon beipiaoense sp. nov., Sciadopityoxylon liaoningense Ding and Protocedroxylon shengjinbeigouense sp. nov. These new records enlarge the fossil wood diversity of the Yixian Formation up to 10 species in 9 genera, and provide further insights into the forest vegetation composition of the Early Cretaceous Jehol Biota. Systematic analysis of the floral constitution indicates that the petrified forests of the Yixian Formation are dominated by conifers, represented by Araucariaceae, Podocarpaceae, Sciadopityaceae, Pinaceae and Cupressaceae in the western Liaoning region. Palaeoclimatical analysis of the fossil wood assemblage implies that the western Liaoning region was dominated by a cool temperate, wet and seasonal climate with variable interannual water supply in the western Liaoning region during the Early Cretaceous.

First report of a phytogeographically mixed (transitional) Middle–Late Permian fossil wood assemblage from the Hami area, northwest China, and implications for Permian phytogeographical, paleogeographical and paleoclimatic evolution in central Asia

A diverse and well-preserved fossil wood assemblage is described, for the first time, from the Middle Permian Taerlang Formation and the Upper Permian Quanzijie Formation in the vicinity of the Tianshan Town, Hami City of northwestern China. On the basis of wood microstructure, the fossil woods are classified into three genera and five species, including one new genus: Prototianshanoxylon gen. nov. and two new species: Prototianshanoxylon erdaogouense sp. nov., Prototianshanoxylon hamiense sp. nov. The new genus is characterized by window-like cross-field pitting and mixed tracheid radial wall pitting that suggest a transitional type between araucarioid-type and protopinoid-type pittings.Phytogeographically, the fossil wood assemblage is characterized by an admixture of elements of both temperate Angaran (represented by wood specimens with moderately to well defined growth rings in their secondary xylem) and tropical–subtropical north subregion of the Cathaysian floras (with wood specimens lacking well-defined growth rings). Such a phytogeographically mixed fossil wood assemblage is interpreted to represent a transitional and complex climate condition between a cool temperate and tropical to subtropical zones, showing both seasonal variation and unstable climate conditions. Previously, similarly mixed floras have already been found to exist widely in northern China ranging in age from Early to Late Permian, but the mechanisms thought to be responsible for their formation were varied and remain controversial. In this study, the formation of these mixed Permian floras of North China is linked to the closure of the Tianshan–Hingan seaway coupled with the collision and amalgamation of Siberia with North China and the Tarim block, in a manner much like closing a pair of scissors with the closure of the seaway proceeding gradually and progressively from west to the east.

Reconstruction of a fossil forest reveals details of the palaeoecology, palaeoenvironments and climatic conditions in the late Oligocene of South America

This research focuses on the three-dimensional reconstruction of an in situ forest based on fossil wood assemblages recovered in the Rancahué Formation (Upper Oligocene), Neuquén, Argentina. Atherospermataceae, Lauraceae, Nothofagaceae, Eucryphiaceae, Cunoniaceae and Myrtaceae specimens are described. The mapping of a forest floor section and in situ tree diameters enabled the estimation of the following palaeoecological quantitative data: tree density, dominance, basal area, biomass, diametric classes, canopy height, and age classes. Palaeoclimatical data was determined on the basis of physiognomic anatomical features using multivariate anatomical analyses. These results were compared with other proxies including Carlquist's index, Coexistence Approach (CA), Nearest Living Relatives (NLRs), and growth-rings analyses. The structural data from the Aluminé forest inferred from these analyses includes: tree density of 463–701trees/ha, mean height of 15.22m, dominance of the genus Nothofagoxylon (89.66m2/ha), total basal area of 158.20m2/ha, biomass between 43 and 712tn/ha and mean age of 223years (specimens between 31 and 700years old). These results are comparable to those of mature low-to-middle altitude extant forests dominated by Nothofagus and developed under humid-temperate conditions. Based on the NLRs method, the Aluminé forest has a floristic composition similar to the present-day Valdivian forest. The persistence of Nothofagus as the dominant element in temperate rainforests correlates with regimes where large-scale disturbances, such as volcanism and earthquakes are prevalent. The fossil taxa are closely related to the extant Laurelia, Persea, Eucryphia, Nothofagus, Weinmannia, Myrceugenia and Luma. The forest shows intermixed deciduous and evergreen elements, and taxa with shade-intolerance and intermediate shade tolerance. Also, the majority of these taxa need soils with available water. The integrated analysis of multiple sets of proxy data suggests that the late Oligocene forest grew under temperate and humid climate, while the eco-anatomical features and sedimentary data provide information about the environmental stress conditions of its development and the violent causes of burial.

Mid-Cretaceous (Albian–Cenomanian) fossil woods from Hwawon-myeon in Jeollanam-do, Korea, and their palaeoclimatic implications

Two coniferous fossil wood taxa are reported from the Hwawon Formation (middle Cretaceous) at Hwawon-myeon in Jeollanam-do, Korea: Agathoxylon sp. and Taxodioxylon sp. Agathoxylon has a clear affinity with the Araucariaceae and its occurrence in the Hwawon Formation suggests that a dry and tropical–subtropical climate prevailed in this area during the middle Cretaceous. The presence of traumatic resin canals in the Taxodioxylon specimens indicates that flooding occurred repeatedly as part of an alternation between dry and rainy seasons. The low diversity observed for the Cretaceous fossil wood assemblages from the Korean Peninsula could be explained by the palaeoclimatologically stressful environment, as a dry tropical–subtropical climate prevailed over the region at that time.

Daijima-type conifer wood assemblage of the Hatamura Formation (Middle Miocene) in the Akita Prefecture, Japan

The paleofloral change from the Aniai-type to the Daijima-type during the Miocene is the most distinctive and representative one of the six floral changes in the Japanese Archipelago during the Tertiary. These floral types are based mainly on compressed or imprinted leaf fossils. In Korea, the transition-type between the Aniai- and Daijima-type floras has been proposed based on the fossil wood assemblages, and the Hatamura Formation, which is the same age as the Daijima Formation, has yielded abundant fossil woods. To confirm whether the fossil wood assemblages are in agreement with the paleofloras inferred from fossil leaves, the fossil woods from the Hatamura Formation were studied. We found that warm temperate and daijiman elements, such as Keteleeria, Taxodioxylon cunninghamioides, T. sequoianum and Pinus, were present in the Hatamura Formation. Therefore, it can be concluded that the fossil wood types from the Hatamura Formation agree well with the Daijima-type Flora. This result, in turn, verifies the existence of transitional flora between the Aniaiand Daijima-types in Northeastern Asia.

Diversity and ontogeny of Pitus tree-trunks in the early Mississippian rocks of the Isle of Bute, Scotland: The importance of sample size and quantitative analysis for fossil wood systematics

In a recent paper, we described tree trunks of Pitus primaeva from early Mississippian (?late Tournaisian) strata of the Isle of Bute, Scotland based on a small sample size (n = 3) and semi-quantitative analysis. In this follow-up study, we analyse a much larger population of specimens (n = 34) and conduct Principal Component Analysis (PCA) of quantitative anatomical data to discriminate ontogenetic and phylogenetic variants. This larger study reveals the existence of six morphotypes, which represent ontogenetic variants of three distinct biological taxa, Pitus antiqua, P. withamii, and P. primaeva/ P. rotunda. Of these, P. primaeva/ P. rotunda is overwhelmingly dominant (~ 90%) and we hypothesise that the ontogenetic relationship of P. primaeva to P. rotunda, is that of a tree trunk to its stump or root. Our work, which uncovers an unusually high diversity of Pitus taxa for a single locality, emphasises the need for large, quantitative studies in order to capture total diversity and elucidate ontogenetic variability in fossil wood assemblages. It also significantly extends the lower stratigraphic range for P. withamii, which was previously known only from late Visean-early Serpukhovian strata. Facies analysis of the Montford site, coupled with growth ring observations, shows that the Pitus trees grew on seasonally dry, well-drained floodplains, and were joined by dense stands of Archaeocalamites during intermittent volcanic eruptions.

Fossil Woods from the Miocene in the Yamagata Prefecture, Japan

Eighty-two silicified fossil woods were collected from Miocene formations on the western coast of the Yamagata Prefecture, Japan. Twenty-two taxa (5 conifers and 17 dicotyledons) were identified. Five new species (Chamaecyparis parathyoides, Pterocarya parvipora, Populus soyaensis, Schima protowallichii, Lagerstroemia odaniense) and two species not previously known from the Miocene of Yamagata are described. This brings the number of fossil wood taxa from the Miocene of Yamagata to 39. Warm temperate elements such as Keteleeria, Liquidambar, Distylium and Lagerstroemia were found in the formations studied. The fossil wood assemblages from four Miocene formations (except Onisakatoge Formation from which only one sample was collected) suggest that the woody flora changed gradually during the Miocene from a mixture of cool and warm temperate elements to a warm temperate assemblage. These changes agree well with the vegetation changes during the Miocene in Japan; from the Aniai type to the Daijima-type.