Fossil Conifer Research Articles

High conifer diversity in Oligo-Miocene New Zealand

Eight species of Podocarpaceae foliage are recognised from the late Oligocene or early Miocene Newvale site, South Island, New Zealand, and the following five new species are described: two of Dacrydium Lamb. and one each of Dacrycarpus (Endl.) de Laub., Phyllocladus Rich. ex Mirb. and Halocarpus Quinn. The latter is the first macrofossil record of this New Zealand endemic genus. All these conifers, plus Agathis Salisb., Microcachrys Hook.f. and Podocarpus Pers., co-occurred in the local vegetation at Newvale. In conjunction with prior records of macrofossils and pollen, these fossils indicate that the late Paleogene to early Neogene conifer flora of New Zealand was very diverse, with all but one of the extant genera present, together with several regionally or globally extinct genera, and multiple species of many of these genera. This fossil diversity is similar to the Paleogene fossil conifer diversity observed in south-eastern Australia (and particularly Tasmania) and in parts of North America.

Growth architecture and silhouette of Jurassic conifers from La Matilde Formation, Patagonia, Argentina

Simple morphological traits are used to describe the architecture of a tree: the growth and branching process, the morphological differentiation of the axes and the position of reproductive structures. The main purpose of this contribution is to describe the growth architecture of the Jurassic conifer trees present at the most basal part of the La Matilde Formation in the locality of Monumento Natural Bosques Petrificados, Patagonia, Santa Cruz province, Argentina, and to compare it with that of extant and fossil conifers. This study is based on a large number of in situ petrified trunks, impressions and external molds of leafy branches and female cones in intimate association or organic connection with the trunks. The cones were assigned to Araucaria cf . A. mirabilis (Speg.) Windhausen emend. Calder (Araucariaceae) based on morphological and anatomical characters. The “ Araucaria mirabilis” trees had 3 branching categories, corresponding to the typical pattern in extant Araucariaceae, although 4 branching categories cannot be completely discarded. The main, orthotropic stem (TA1) had rhythmic growth and branching, bearing 3–4, probably up to 6–7 plagiotropic branches in pseudowhorls. The lower part of the trees shows no branch-scars; therefore, self-pruning would have been present. Lateral branches (A2) had rhythmic branching: the branchlets (A3) were distributed regularly on the leading branch, with an alternate arrangement, conforming two orthostichies on the same horizontal plane. The female cones were borne terminal at the tip of peduncles, but lateral in position with respect to A2 branches. Reiteration patterns are present: total reiterations (bifurcated trunks and big, orthotropic branches in trunks with normal plagiotropic branches) and partial reiterations (epicormic branching) were observed. The root system consisted of 6 horizontal roots, no tap root was observed. Two architectural patterns or “morphotypes” were recognized at one of the forest levels studied, in keeping with other pieces of evidence (type of wood, foliage, and cones). The “Araucarioid morphotype or morphotype A” includes most of the studied specimens (i.e. “ Araucaria mirabilis” trees); showing pseudowhorls of plagiotropic branches. These characters correspond to Massart's model, with certain modifications in the adult trees due to reiteration processes. Morphotype B was observed in bigger trunks with a distinctive costulated surface, which bear only orthotropic branches irregularly arranged, and without reiteration evidences; they could be assigned to Attim's model and possibly represent a different conifer taxon, though subrepresented. Partial and total reiteration patterns are described for the first time for Jurassic, Gondwanic conifers. Moreover, Massart's model can be followed from Upper Palaeozoic Walchiaceae to Mesozoic Araucariaceae.

Structure and relationships of the Jurassic conifer seed cone Hughmillerites juddii gen. et comb. nov.: Implications for the origin and evolution of Cupressaceae

Anatomically preserved Jurassic conifer seed cones originally described as Conites juddi Seward and Bancroft are reinvestigated and assigned to Hughmillerites juddii gen. et comb. nov. using the original specimens and new material from the type locality. This allows for a more thorough characterization of seed cone structure, for systematic placement of the species, and for establishing homologies of cupressaceous bract/scale complexes. Incomplete cones range 2.2–3.6 cm in diameter and 3.0–4.3 cm long, and have distinctly woody axes bearing helically arranged bract/scale complexes with a thickened bract tip. Mature complexes display three inverted seeds attached to the adaxial surface immediately proximal to three free ovuliferous scale tips. In each bract/scale complex there is a single large resin canal abaxial to the vascular bundle and three or more smaller adaxial resin canals at the level of seed attachment. Seeds are inverted at maturity, display 180° rotational symmetry, and show differentiation of sclerotesta and sarcotesta. The results of a phylogenetic analysis support placement of H. juddii among the basal grade of taxodioid Cupressaceae ( Farjon, 2005). A transformational series of ovuliferous bract/scale complexes from voltziacean Voltziales to crown group Cupressaceae is presented to reveal the pattern and antiquity of evolution for modern cupressaceous conifer seed cone morphologies. Developmental studies of living cupressaceous seed cones indicate that the range of mature morphologies is strongly correlated with differences in the timing and rate of development for the bract, scale, and ovules, thus supporting the hypothesis that heterochrony plays a major role in the evolution of bract/scale form. This hypothesis is further supported by our growing understanding of developmental regulatory genetics. There are no currently recognized synapomorphies for living + fossil conifers. Nevertheless, these combined results do not support the hypotheses that some conifers have ancestrally simple seed cones nor that there have been parallel origins of Northern and Southern Hemisphere conifers. The overall body of evidence from both extinct and living conifers strongly supports the hypotheses of deep homology for seed cones and of monophyly for conifers s.s.

Pinus prekesiya sp. nov. from the upper Miocene of Yunnan, southwestern China and its biogeographical implications

Pinus prekesiya Xing, Liu et Zhou sp. nov. was described as a new species on the basis of two well preserved ovulate cones from the upper Miocene of central Yunnan, southwestern China. It is the first fossil record of three dimensionally preserved Pinus ovulate cones from China. Morphological comparisons with 15 previously published Cenozoic cones and seven related extant pine species reveal that the fossil cones are identified as a new species, P. prekesiya sp. nov., which belongs to subsection Pinus of subgenus Pinus. The new species shows a combination of characters of P. kesiya and P. yunnanensis, but has a closer affinity with P. kesiya which occurs in the humid region of Yunnan and therefore suggests a more humid climate in central Yunnan during the late Miocene than today. The general cooling trend during the late Neogene and topographic change due to the dramatic Tibetan uplift might have caused a vicariant origin of P. kesiya and P. yunnanensis from the ancestral P. prekesiya.

Geinitzia reichenbachii (Geinitz, 1842) Hollick and Jeffrey, 1909 and Sedites rabenhorstii Geinitz, 1842 (Pinopsida; Late Cretaceous) reconsidered and redescribed

Two conifer species from the Upper Turonian of the Saxonian and North Bohemian parts of the Bohemian Cretaceous Basin are redescribed using the type specimens and additional material from the type horizon. In both cases characters of the gross-morphology of foliage shoots and leaf epidermal cell structure observed by LM and SEM are studied. Geinitzia reichenbachii is characterized by uniform falcate leaves that spread abruptly from the axis. They are 4-sided in cross section and have slightly decurrent leaf bases and a single central resin canal. The amphistomatic leaves show adaxially two properly developed stomatal bands with densely arranged stomata and abaxially two stomatal bands repeatedly interrupted. The apertures of the usually incomplete amphicyclic stomatal apparati are randomly orientated relative to the long leaf axis, but oblique and transversal orientation prevails. G. reichenbachii is typified by a neotype and an emended diagnosis is given. Based on detailed comparison to Geinitzia formosa from the Santonian of Quedlinburg, Germany, G. reichenbachii is assigned to Geinitzia Endlicher, 1847 which is considered a natural genus of extinct conifers and type of the Geinitziaceae. This application becomes legitimate because the conservation of the name Geinitzia has been proposed recently by Zijlstra et al. (2010). Sedites rabenhorstii is only known from two small specimens representing ultimate shoots. It is proved that it is a fossil conifer completely distinct from G. reichenbachii. S. rabenhorstii shows epidermal cell characters that have been hitherto described from the genus Glenrosa, a putative Cheirolepidiaceae. S. rabenhorstii differs from Glenrosa in leaf phyllotaxis. The leaves are arranged in four rows, probably in opposite pairs in decussate phyllotaxis. The free leaf part is spreading, straight, triangular in cross section and has an obtuse apex. The leaf base is decurrent. The leaves are amphistomatic with stomata deeply sunken in communal stomatal chambers containing finger-like processes or trichome papillae across the opening. In conclusion, Sedites is maintained as a morpho-genus for fossil conifers and an emended generic diagnosis is given.

Modifications of the transfer technique for studying complex plant structures

The transfer technique is a method for exposing compression fossils that entails embedding the specimen in an adhesive material and dissolving the matrix in appropriate acids. This technique has been used for many years, and played an important role in several classic paleobotanical studies. However, in recent years it appears to have fallen into relative disuse and is not discussed at all in recent compilations of paleobotanical techniques. This is unfortunate, as the method is often extremely effective, especially for revealing the detailed structure of complex plant organs. In this paper, case studies using fossil conifer ovulate cones are presented. The first entails a modification of the classic transfer technique using a polyester resin as the embedding medium on an unnamed cone from the Triassic of Pennsylvania. The second study entails producing serial sections through a polyester resin embedded cone of Telemachus from the Triassic of Antarctica in a manner analogous to the classic cellulose acetate peel method. This modification is most useful when the organic material is too fragile for the more classic method. The results of these case studies are presented in the hope of re-stimulating use of the transfer technique in paleobotany.

Antitermitic Activities of Abietane-type Diterpenes from Taxodium distichum Cones

Eight known abietane-type diterpenes were isolated from the weak acidic fraction of the n-hexane extract from cones of Taxodium distichum, one of the extant, living fossil conifers. They were identified as 6,7-dehydroroyleanone (1), taxodal (2), taxodione (3), salvinolone (4), 14-deoxycoleon U (5), 5,6-dehydrosugiol (6), sandaracopimaric acid (7), and xanthoperol (8). The structures of these compounds were determined by comparison of NMR spectral data with published data. The antitermitic (termicidal and antifeedant) activities of the compounds 1-8 against the subterranean termite, Reticulitermes speratus Kolbe, were evaluated. Compounds 1 and 3 showed potent termicidal activity, and 5 and 8 showed potent antifeedant activity. Compound 1 was found to be one of the representative bioactive compounds in the n-hexane extract of T. distichum cones. Compounds 1-8, with the exception of 7, were oxides of ferruginol (9). Therefore, the presence of various oxidation forms of the abietane-type structure reflects their various bioactivities.

Cretaceous pCO 2 estimation from stomatal frequency analysis of gymnosperm leaves of Patagonia, Argentina

Stomatal frequency of fossil conifers and ginkgoals cuticles were considered as potential indicators of the pCO 2 values in the Patagonian palaeoatmosphere during the Cretaceous. Samples are from continental deposits of early Upper Aptian age (Anfiteatro de Ticó and Punta del Barco formations) and Upper Albian–Lower Cenomanian age (Kachaike Formation), both outcropping in Andean and extra-Andean portions of Santa Cruz province, Argentina. It can be inferred that the CO 2 atmospheric content was similar during both stages, or was slightly higher toward the Late Albian–Early Cenomanian. The CO 2 content estimated from the conifers is between ~ 700 and 1400 ppmv (or lower from the mid-Aptian ginkgoals). This CO 2 range is consistent with those predicted worldwide by previous studies (stomatal indices, biogeochemical models and carbon isotopes), and implies a CO 2 content 2.3–4.0 times higher than present. The high atmospheric CO 2 content during the Middle Aptian and Late Albian–Early Cenomanian was probably linked to a warming process at high latitudes during these times. This is consistent with the floristic development recorded during both stages in Patagonia.

Lower Cretaceous conifers from Apple Bay, Vancouver Island: Picea-like leaves, Midoriphyllum piceoides gen. et sp. nov. (Pinaceae)This paper is one of a selction of papers published on the Special Issue on Systematics Research.

A diverse assemblage of fossil conifer leaves was identified in calcareous marine concretions from the Lower Cretaceous (Valanginian–Hauterivian) Apple Bay locality, Vancouver Island. Of the hundreds of isolated leaf fragments, most show affinities to Pinaceae. Leaves with closest similarities to Picea (spruce) were studied using cellulose acetate peels. Picea-like leaves vary in cross-section from rhomboidal, pentagonal, triangular, to ovoid. One fused vascular bundle with a centrally located ray and abaxial sclerenchyma is surrounded by a circular endodermis and transfusion tissue. Mesophyll is plicate containing two lateral external resin canals surrounded by a sclerenchyma sheath. Hypodermal fibres are one to three layers thick, except in areas of stomata. Leaves are amphistomatic, with sunken guard cells. Vascular bundles are identical anatomically to Picea; however, plicate mesophyll is similar to that in leaves of Pinus. Extensive sclerenchyma in the hypodermis and surrounding resin canals differs from that in most extant Picea. The major difference between these leaves and those of Picea is leaf shape. These fossil leaves probably belong to an extinct pinaceous conifer, and are described as Midoriphyllum piceoides gen. et sp. nov. Similar evidence from Cretaceous seed cones suggests that like the angiosperms, the Pinaceae were undergoing rapid mosaic evolution during the Lower Cretaceous.

A simple and convenient determination of perylene preserved in the Late Neogene wood from northeastern Tennessee using fluorescence spectroscopy

A new and convenient fluorescence spectroscopic method has been developed for the separation and determination of perylene in fossil wood recovered from a late Miocene to early Pliocene Gray Fossil Site in Tennessee, USA. This is the first report where perylene was separated from fossil samples from this newly discovered fossil site. The chemical structure of perylene was elucidated and confirmed by UV–visible and 1H NMR spectroscopies, and ESI-TOF high accuracy mass spectrometry. The fluorescence of perylene was used to measure the contents of perylene in the fossil conifer and oak wood, which were found to be 5.34 and 0.78 μg/g, respectively. The results suggested that the amount of perylene in the fossil conifer wood was 7-fold higher than that in the oak wood. The method, which uses highly sensitive fluorescence spectroscopy, should provide a new approach for the analysis of other fossil and geochemical samples containing perylene.

Molecular Taphonomy of Metasequoia

Abstract Chemical analysis of the leaves of modern Metasequoia and other gymnosperms revealed the presence of structural polyesters, guaiacyl lignin units and polysaccharides, but no long chain recalcitrant aliphatic constituent. Analysis of Tertiary fossil Metasequoia showed the presence of polysaccharides, lignin and a long chain aliphatic polymer. Tertiary fossil conifers similarly revealed the preservation of lignin and a long chain aliphatic polymer (up to C33) with limited preservation of polysaccharides. Experimental maturation of modern pine needles generated a composition with a long chain aliphatic polymer and additional phenolic compounds similar to those seen in the fossils. Experimental maturation of the structural polyester cutin and a pure model C16 and C18 fatty acid mixture yielded fatty acids and an aliphatic polymer less than C20 suggesting that polymers greater than C20 may be incorporated into the fossil macromolecule from longer-chain plant waxes. Thermochemolysis of the fossil conif...

Terpenoids as chemosystematic markers in selected fossil and extant species of pine (Pinus, Pinaceae)

The compositions of terpenoids from the seed cones and resins of selected fossil and modern species of pine (Pinus, Pinaceae) were analysed using gas chromatography-mass spectrometry (GC-MS) to study the preservation of chemosystematic markers (biomarkers) in fossil conifers. Diterpenoids of the abietane, pimarane, isopimarane, and labdane types are the major components in the solvent extracts of all fossil and extant pines. Mono- and sesquiterpenoids of the bornane and cadalane classes and two phytosterols were also identified. The terpenoid patterns of the fossil species largely match the terpenoids observed in modern pines. The characteristic features of the fossil and extant Pinus species are abietane-, pimarane-, and isopimarane-type diterpenoids with a high abundance of abietic acids. Several biomolecules were preserved unaltered in the Eocene and Oligocene pine cones. In addition to the biomolecules, the fossil pines contain a series of degradation products (geomolecules) that were generated from their biological precursors before and after burial. The generation of the geomolecules is governed by various oxidative and reductive processes, such as microbial degradation and clay catalysis. In conclusion, the comparative analysis of solvent-extractable biomarkers in fossil and related extant species is a valuable tool for (palaeo)chemosystematic studies of conifers. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 154, 129–140.

Nomenclatural types and taxonomy of Gothan’s Arctic fossil conifer wood

A century ago Gothan described fossil woods from the Arctic and established several new species and genera that were subsequently widely used. The type material has, however, never been reviewed. Investigations in Berlin and Stockholm resulted in the re-location of the original material which allows us to propose lectotypifications for the names of six species recognized by Gothan, three of which represent types of Gothan's generic names, Anomaloxylon, Protocedroxylon, and Protopiceoxylon. The types (holotypes or lectotypes) are illustrated here, some of them for the first time with micrographs. Taxonomic investigation of Gothan's species with Abietineentupfelungen, an anatomical feature of ray cells, suggests that Cedroxylon transiens and Anomaloxylon magnoradiatum should be regarded as taxonomic synonyms of Protocedroxylon araucarioides, and Cedroxylon cedroides as a taxonomic synonym of Protopiceoxylon exstinctum.

Biomolecules preserved in ca. 168 million year old fossil conifer wood

Biomarkers are widely known to occur in the fossil record, but the unaltered biomolecules are rarely reported from sediments older than Paleogene. Polar terpenoids, the natural products most resistant to degradation processes, were reported mainly from the Tertiary conifers, and the oldest known are Cretaceous in age. In this paper, we report the occurrence of relatively high concentrations of ferruginol derivatives and other polar diterpenoids, as well as their diagenetic products, in a conifer wood Protopodocarpoxylon from the Middle Jurassic of Poland. Thus, the natural product terpenoids reported in this paper are definitely the oldest polar biomolecules detected in geological samples. The extracted phenolic abietanes like ferruginol and its derivatives (6,7-dehydroferruginol, sugiol, 11,14-dioxopisiferic acid) are produced only by distinct conifer families (Cupressaceae s. l., Podocarpaceae and Araucariaceae), to which Protopodocarpoxylon could belong based on anatomical characteristics. Therefore, the natural product terpenoids are of great advantage in systematics of fossil plant remains older than Paleogene and lacking suitable anatomical preservation.

The pollen cones of Ginkgo from the Early Cretaceous of China, and their bearing on the evolutionary significance

A well-preserved pollen cone of the genus Ginkgo was found in the Yixian Formation (Early Cretaceous) of Liaoning Province, China, and is described as the new species Ginkgo liaoningensis. The pollen cone, catkin-like, consists of a main axis bearing scales at its base and spirally arranged sporophylls bearing 3–4 (−2) oval or elliptical sporangia. The sporangia are pendulous and dehiscent by a longitudinal slit. The mature pollen grains are monocolpate and elongate-elliptical, and the juvenile pollen grains are found in the tetrad stage. The characteristics of G. liaoningensis are very similar to those of the living Ginkgo biloba, but the sporophylls of G. liaoningensis bear 3–4 (−2) sporangia, whereas those of G. biloba bear mostly two sporangia. G. liaoningensis differs from fossil cones of Ginkgo huttoni from the Jurassic of Yorkshire, UK, and an unnamed specimen of Ginkgo from the Upper Cretaceous of Alberta, Canada, in the size and number of sporangia. The comparison between G. liaoningensis (fossil) and G. biloba (living) supports the reduction hypothesis of ovule organs in Ginkgo, with the number of sporangia having experienced the process of reduction from three or four to two since the Early Cretaceous.

Taxonomic investigations on permineralized conifer woods from the Late Paleozoic Angaran deposits of northeastern Inner Mongolia, China and their palaeoclimatic significance

A diverse fossil conifer wood assemblage was described from the Late Paleozoic Angaran deposits in Inner Mongolia (=Nei Mongol) of northeastern China. The fossil wood materials were collected from the Upper Carboniferous Baoligemiao Formation in Sunitezuo Qi and the Middle Permian Zhesi Formation in Xi Ujimgin Qi, northeastern Inner Mongolia, including four species. Among them, Sinopalaeospiroxylon baoligemiaoense gen. et sp. nov. represents a new taxon of secondary xylem with Araucarioid-type and transitional type of radial wall pitting, and tertiary taxoid spiral thickenings. It is characterized by the pinioid pitting and nodular thickening on the end wall on the horizontal wall of rays. Sclerospiroxylon neimongolense sp. nov. is represented by a xylem cylinder containing the secondary and primary xylem and pith. The tracheids on the radial wall yield Araucarioid-type pitting as well as a taxoid tertiary spiral thickening. The primary xylem is of endarch, and the pith consists of heterogenous cells. The sclerochyma cells are scattered among the parenchymatous tissues. Zalesskioxylon zhesiense sp. nov. is a wood species with very similar anatomical features to those of the genus Araucarioxylon. It differs, however, in having simple and no-bordered cross-filed pitting in Z. zhesiense. Chapmanoxylon xiugiense (Zhang and Zheng) comb. nov. is recognized based upon wood xylems containing Araucarioxylon-type secondary xylem, endarch primary xylem and a pith yielding homogenous parenchyma cells. These conifer wood taxa show more or less growth rings in the secondary xylem. Such fossil woods from the Late Paleozoic deposits of northeastern Inner Mongolia imply a warm moderate vegetation type. It is a composition part of the Northern Biogeographic Realm in China showing seasonal variation of the palaeoclimate.

Pollen cone anatomy of Classostrobus crossii sp. nov. (Cheirolepidiaceae)

Abstract Discovery of a permineralized fossil cone in Mesozoic deposits of southern England provides an opportunity to document the first detailed evidence of internal pollen cone anatomy for the extinct conifer family Cheirolepidiaceae. The specimen, described here as Classostrobus crossii sp. nov., occurs in a calcareous nodule recovered from Middle Jurassic marine sediments of the Lower Callovian Sigaloceras calloviense biozone, Kellaways, near Cirencester, England. The cone is 2.0 cm long and 1.8 cm wide. Sporophylls diverge helically from the axis. Each sporophyll displays a narrow stalk and a distal lamina approx. 11 mm long that tapers to a pointed tip. There is also a basal keel that bends inward at the bottom and sides to form a shallow pocket. A single vascular bundle diverges from the cone axis, extends distally into the sporophyll stalk at the contact of two distinctly different histological zones, and further expands into the distal lamina as transfusion tracheids. Several pollen sacs are attached abaxially at the juncture of the sporophyll stalk and keel. Pollen is roughly spheroidal, 26–35 μm in diameter, with unequal polar caps separated by a striated belt with a subequatorial furrow. This specimen helps clarify the range of variation in the morphology of Mesozoic conifer pollen cones.

Molecular preservation of plant and insect cuticles from the Oligocene Enspel Formation, Germany: Evidence against derivation of aliphatic polymer from sediment

The 25 Ma lacustrine deposit of Enspel, Germany, is important for molecular taphonomy as weevils from this site have yielded the oldest preserved traces of chitin. These weevil cuticles show excellent morphological and ultrastructural preservation. Plant cuticle is also preserved but it is obscured or distorted by diatom impressions. Molecular analysis of dicotyledonous angiosperm leaf from the Enspel deposit revealed the presence of polysaccharide, guaiacyl and syringyl related lignin, and possibly degraded protein moieties in the insoluble macromolecular component. Analysis of fossil conifer leaf showed the same moieties, but syringyl related lignin units were absent. Py-GC/MS revealed C 9–33 n-alkyl components from both types of leaf, with C 13,14,29 homologues being the most abundant n-alkanes. TMAH pyrolysis yielded a fatty acid distribution ranging in carbon number from C 6–30, with the C 16,18,14 components being the most abundant. Analysis of fossil weevil cuticle also revealed the presence of an aliphatic polymer as evidenced by C 9–33 n-alkyl components in the pyrolysate and C 6–26 FAMEs (predominantly even-numbered C 14−18 components) in the TMAH pyrolysate. Pyrolysates of the sediments contain alkanes with distributions similar to those observed in the fossils; however, TMAH pyrolysates of sediments were distinct from those of the fossils with C 20–22 components being the most abundant in the conifer-bearing sediment and the even-numbered C 22–26 components dominating in the weevil-bearing sediment. Thus, the aliphatic polymers in the fossils and sediment are different, apparently comprised of moieties of different chain length. This suggests that the aliphatic polymer in the plant and insect fossils is not derived from migration from the organic-rich host sediment.

Epicormic Shoot Traces in the Secondary Xylem of the Triassic and Permian Fossil Conifer Species Woodworthia Arizonica — Short Communication

Specimens of Woodworthia arizonica Jeffrey trees from the Late Triassic of Arizona, U.S.A. and the Permian of Brazil, typically have horizontal vascular traces that have extremely close contacts with the tracheids of the secondary xylem. In modern gymnospermous and angiospermous trees, such traces terminate on preventitious buds deeply embedded in their bark. Such buds develop into epicormic shoots, after substantial loss of foliage through fire or other damage.

Hanskerpiagen. nov. and phylogenetic relationships among the most ancient conifers (Voltziales)

AbstractA new fossilized walchian (Voltziales) conifer plant from the Late Pennsylvanian Hamilton Quarry of Kansas, U.S.A. combines morphological characters of the morphogenusWalchiaand the fossil plant genusOtovicia, with cuticular characters like those of the fossil plant genusErnestiodendron, and seed cone morphology like that of the fossil plant genusEmporia. Internal anatomical characters are basically similar to the other walchian genera for which such features are known, but some are taxonomically informative. Numerical cladistic analysis reveals that this novel combination of characters defines a new fossil plant genus and species of walchian conifersHanskerpia hamiltonensis. This analysis provides a test of hypotheses for relationships among walchian and other ancient conifers. Results of this analysis support some previously proposed relationships among the most primitive conifers and other Paleozoic coniferophytes. However, the analysis also calls to question the validity of all previously proposed familial circumscriptions for walchian conifers, and highlights the perplexing systematic challenges posed by the most ancient fossil conifers. The unexpected species richness of voltzialean conifers is interpreted as having resulted from the evolutionary ecology of unstable environments.