Selena Y. Smith

Permineralized Pine Cones from the Cretaceous of Vancouver Island, British Columbia

Two abraded, cylindrical cone specimens found in calcareous concretions from the Cretaceous Spray Formation (Late Campanian) of Vancouver Island, British Columbia, were sectioned using the cellulose acetate peel technique and characterized anatomically. Their sclerenchymatous pith is surrounded by a ring of separate secondary xylem bundles that lack resin canals. The outer cortical zone is sclerenchymatous and covered in a dense ramentum of trichomes that is also present on ovuliferous scale and bract bases. Vascular traces to the ovuliferous scales and bracts arise independently. The bract, with a terete trace and two lateral resin canals, lacks a distinct abaxial lobe. Ovuliferous scales are sclerotic with resin canals adaxial, abaxial, and between the vascular bundles. The ovuliferous scales have an interseminal ridge that is prominent and thick near the micropylar end of the seed, thins out near the seed chalaza, and attaches to the seed wing tissue. There are two winged seeds per scale, and the edges of the ovuliferous scale turn upward and partly enclose the seeds near the micropylar end. Seeds have a ridged sclerotesta; nucellus, megagametophyte, and embryos with eight cotyledons are preserved. Cone structure most closely resembles fossil Pinaceae of the genus Pityostrobus. These cones have a unique combination of characters that distinguish them from the previously described taxa and are described as Pityostrobus beardii sp. nov. A phylogenetic analysis using morphological data from the ovulate cones of extant and fossil taxa of Pinaceae with Cryptomeria japonica (L. f.) D. Don and Sciadopitys verticillata (Thunb.) Siebold et Zucc. as outgroups was undertaken to assess the phylogenetic position of P. beardii within Pinaceae. Pityostrobus beardii appears to be most closely related to Pityostrobus hokodzensis from the Cretaceous of Russia. These cones provide further evidence that the Pinaceae, like the angiosperms, were undergoing a rapid Cretaceous radiation.

Virtual taphonomy using synchrotron tomographic microscopy reveals cryptic features and internal structure of modern and fossil plants

While more commonly applied in zoology, synchrotron radiation X-ray tomographic microscopy (SRXTM) is well-suited to nondestructive study of the morphology and anatomy of both fossil and modern plants. SRXTM uses hard X-rays and a monochromatic light source to provide high-resolution data with little beam-hardening, resulting in slice data with clear boundaries between materials. Anatomy is readily visualized, including various planes of section from a single specimen, as clear as in traditional histological sectioning at low magnifications. Thus, digital sectioning of rare or difficult material is possible. Differential X-ray attenuation allows visualization of different layers or chemistries to enable virtual 3-dimensional (3D) dissections of material. Virtual potential fossils can be visualized and digital tissue removal reveals cryptic underlying morphology. This is essential for fossil identification and for comparisons between assemblages where fossils are preserved by different means. SRXTM is a powerful approach for botanical studies using morphology and anatomy. The ability to gain search images in both 2D and 3D for potential fossils gives paleobotanists a tool—virtual taphonomy—to improve our understanding of plant evolution and paleobiogeography.

Cretaceous and Eocene poroid hymenophores from Vancouver Island, British Columbia.

Two fossil poroid hymenophore fragments, one from the Cretaceous Period and the other from the Eocene Epoch, are described. The permineralized specimens were obtained from marine calcareous concretions on Vancouver Island, British Columbia, Canada, and were studied using the cellulose acetate peel technique. Size and distribution of pores in the hymenophores, as well as the hyphal anatomy of the dissepiments and some hymenial elements, were examined. In the Cretaceous specimen, Quatsinoporites cranhamii sp. nov., pores are round to elliptical, three per mm, and 130–540 μm diam. Dissepiments consist of narrow, simple septate, hyphae. Neither basidia nor basidiospores are present, but acuminate hymenial cystidia, up to 54 μm in length, are common. The Eocene specimen, Appianoporites vancouverensis sp. nov., has a pore density of six per mm and pores are 130–163 μm in diam. Dissepiments consist of narrow, simple septate, thin-walled hyphae. Neither basidia nor basidiospores are present, but acuminate, thick-walled hymenial cystidia, up to 32 μm in length, are common. The poroid hymenophore is a characteristic of a number of extant basidiomycete taxa, including the Boletales, Polyporales and Hymenochaetales. It is unlikely that the fleshy, ephemeral, terrestrial basidiomata of the Boletales would be preserved in a marine environment, and thus the specimens are interpreted as belonging to basidiomycete lineages, with persistent, leathery or corky basidiomata. The simple septate hyphae, the minute pores and presence of cystidia most closely resemble taxa of the Hymenochaetales. These fossils unequivocally push back the minimum age of homobasidiomycetes and extend their paleogeographical range.

Seed fertilization, development, and germination in Hydatellaceae (Nymphaeales): Implications for endosperm evolution in early angiosperms.

New data on endosperm development in the early-divergent angiosperm Trithuria (Hydatellaceae) indicate that double fertilization results in formation of cellularized micropylar and unicellular chalazal domains with contrasting ontogenetic trajectories, as in waterlilies. The micropylar domain ultimately forms the cellular endosperm in the dispersed seed. The chalazal domain forms a single-celled haustorium with a large nucleus; this haustorium ultimately degenerates to form a space in the dispersed seed, similar to the chalazal endosperm haustorium of waterlilies. The endosperm condition in Trithuria and waterlilies resembles the helobial condition that characterizes some monocots, but contrasts with Amborella and Illicium, in which most of the mature endosperm is formed from the chalazal domain. The precise location of the primary endosperm nucleus governs the relative sizes of the chalazal and micropylar domains, but not their subsequent developmental trajectories. The unusual tissue layer surrounding the bilobed cotyledonary sheath in seedlings of some species of Trithuria is a belt of persistent endosperm, comparable with that of some other early-divergent angiosperms with a well-developed perisperm, such as Saururaceae and Piperaceae. The endosperm of Trithuria is limited in size and storage capacity but relatively persistent.

A New Species of Pityostrobus from the Lower Cretaceous of California and Its Bearing on the Evolution of Pinaceae

A single cylindrical, abraded cone specimen has been found associated with ammonites of the Lower Cretaceous Budden Canyon Formation near Ono, California. The specimen was embedded in bioplastic and sectioned using the cellulose acetate peel technique. The pith is composed of parenchyma and scattered sclereids and is bounded by a ring of resin canals. The secondary xylem of the cone axis, with a ring of small‐diameter resin canals, is continuous. The cortex is composed primarily of parenchyma with an outer sclerotic zone 10–16 cells thick and has 27–30 dilating resin canals. Vascular traces to the ovuliferous scale and bract diverge separately from the vascular cylinder and are accompanied by a single resin canal from the pith that is positioned between the arms of the horseshoe‐shaped ovuliferous scale trace. The bract trace is terete, accompanied by two lateral resin canals from the cortical axial system, and enters the free part of the bract. The ovuliferous scale is almost completely sclerotic, with resin canals both abaxial and adaxial to the vascular strands. A large interseminal ridge is present between the two winged seeds on each scale. This cone represents a new species of Pityostrobus and is described as Pityostrobus californiensis sp. nov. A phylogenetic analysis using morphological data from the ovulate cones of all the extant and fossil taxa of Pinaceae, as well as those of Cryptomeria japonica, Sciadopitys verticillata, and Pararaucaria patagonica, was done. Relationships of the fossil species of Pityostrobus, Obirastrobus, and Pseudoaraucaria to the living taxa of Pinaceae were assessed. The idea that Pityostrobus represents an artificial assemblage of pinaceous taxa is supported by the analyses. The genus Obirastrobus cannot be distinguished from Pityostrobus species, while Pseudoaraucaria species appear as a clade. The difficulty of basing fossil taxa purely on cone characteristics is discussed in light of the analyses.

Establishing a fossil record for the perianthless Piperales: Saururus tuckerae sp. nov. (Saururaceae) from the Middle Eocene Princeton Chert

Investigations of small permineralized flowers from the Middle Eocene Princeton Chert, British Columbia, Canada have revealed that they represent an extinct species of Saururus. Over 100 flowers and one partial inflorescence were studied, and numerous minute perianthless flowers are borne in an indeterminate raceme. Each flower is subtended by a bract, and flowers and bracts are borne at the end of a common stalk. Five stamens are basally adnate to the carpels. Pollen is frequently found in situ in the anthers. Examined under SEM and TEM, pollen grains are minute (6-11 μm), monosulcate, boat-shaped-elliptic, with punctate sculpturing and a granulate aperture membrane. The gynoecium is composed of four basally connate, lobed carpels with recurved styles and a single ovule per carpel. Flower structure and pollen are indicative of Saururaceae (Piperales), and in phylogenetic analyses using morphological characters, the fossils are sister to extant Saururus. The fossil flowers are described here as Saururus tuckerae sp. nov. These fossil specimens add to the otherwise sparse fossil record of Piperales, represent the oldest fossils of Saururaceae as well as the first North American fossil specimens of this family, and provide the first evidence of saururaceous pollen in the fossil record.

Early Events in Monocot Evolution: A well-supported phylogenetic framework for the monocot order Alismatales reveals multiple losses of the plastid NADH dehydrogenase complex and a strong long-branch effect

The order Alismatales is a cosmopolitan and enormously diverse clade of monocotyledons, comprising ~4500 extant species in 13 families, as currently defined (Stevens, 2001þ; Janssen and Bremer, 2004; APG III, 2009). Some of the oldest monocot fossils (late Barremian and early Albian; 125–112 Ma) have been assigned to this lineage (Friis et al., 2004, 2010), and most phylogenetic studies (e.g. Chase et al., 2006; Givnish et al., 2006, 2010; Graham et al., 2006) resolve Alismatales as the sister group of all monocots except Acorus (Acorales: Acoraceae). Refining our understanding of the phylogenetic backbone of Alismatales will therefore be important for understanding the early evolutionary history of the monocots. The overall composition of Alismatales remained relatively constant until a recent expansion to include Araceae and Tofieldiaceae (e.g. Dahlgren and Clifford, 1982; Tomlinson, 1982; Les et al., 1997; APG I, 1998; APG II, 2003; APG III, 2009;

A new species of Millerocaulis (Osmundaceae) from the lower cretaceous of California

A small permineralized osmundaceous stem has been collected from marine sediments of the Early Cretaceous (Aptian), Upper Chickabally Member of the Budden Canyon Formation near Ono, California. The specimen, 8.5 cm long and 5.4 cm wide, represents a stem surrounded by a mantle of stipular leaf bases and adventitious roots. A large number of sections were studied through the use of the cellulose acetate peel technique. The stem was erect, \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Aroid Seeds from the Middle Eocene Princeton Chert (Keratosperma allenbyense, Araceae): Comparisons with Extant Lasioideae

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