Search

Conifers of the taxodiaceous grade of Cupressaceae were more diverse and widespread during the Mesozoic than they are today. The earliest diverging subfamily, Cunninghamioideae, only includes a single extant genus, but has at least 10 fossil genera. Here, two additional cunninghamioid genera are characterized on the basis of permineralized seed cones from the Upper Cretaceous of Hokkaido, Japan. These conifers display seed cone characters typical of cunninghamioids; however, they have a mosaic of characters that are not seen in any reported conifer of Cupressaceae. They are, therefore, designated as two new extinct species: Ohanastrobus hokkaidoensis gen. et sp. nov. and Nishidastrobus japonicum gen. et sp. nov. These newly reported conifers expand the taxonomic and morphological diversity of cunninghamioids. The stratigraphic and paleobiogeographic records of cunninghamioids and other fossil Cupressaceae with foliate seed cones indicate they peak in diversity during the Cretaceous. The living genera Taiwania and Cunninghamia appear during the Albian and Campanian, respectively, and maintain a nearly continuous fossil record through to today, while nearly all other extinct genera of Cupressaceae with foliate cones disappear by the close of the Campanian. As more ancient cunninghamioids are recovered, our understanding of macroevolutionary patterns of this once diverse lineage will be further elucidated. Key words: conifers, cunninghamioids, Cupressaceae, Cretaceous, fossils, seed cones. Les coniferes de la famille des Cupressaceae taxodiacees etaient plus diversifies et repandus au cours du Mesozoique qu'ils ne le sont aujourd'hui. La sous-famille divergente la plus ancienne, les Cunninghamioideae, ne comprend qu'un seul genre existant, mais compte au moins 10 genres fossiles. Ici, deux autres genres de cunninghamioides sont caracterises a partir de cones a graines permineralises provenant du Cretace superieur a Hokkaido, au Japon. Ces coniferes presentent des caracteres de cone a graines typiques des cunninghamioides ; toutefois, ils ont une mosaique de caracteres qui ne sont vus chez aucun conifere signale chez les Cupressaceae. Ils sont ainsi designes comme deux nouvelles especes eteintes : Ohanastrobus hokkaidoensis gen. et sp. nov. et Nishidastrobus japonicum gen. et sp. nov. Ces coniferes nouvellement signales elargissent la diversite taxonomique et morphologique des cunninghamioides. Les enregistrements stratigraphiques et paleobiogeographiques des cunninghamioides et d'autres Cupressaceae fossiles avec des cones a graines folies indiquent qu'ils ont atteint un pic de diversite pendant le Cretace. Les genres vivants Taiwania et Cunninghamia apparaissent respectivement a l'Albien et au Campanien, et conservent un registre fossile presque continu jusqu'a aujourd'hui, tandis que presque tous les autres genres eteints de Cupressaceae a cones folies disparaissent a la fin du Campanien. Au fur et a mesure que des cunninghamioides plus anciens sont retrouves, notre comprehension des modeles macro-evolutifs de cette lignee autrefois diversifiee sera davantage elucidee. [Traduit par la Redaction] Mots-cles : coniferes, cunninghamioides, Cupressaceae, Cretace, fossiles, cones., Introduction The taxodiaceous grade of the Cypress family (Cupressaceae) is comprised of five charismatic lineages (designated as subfamilies) that have extensive fossil records originating in the Mesozoic. The taxodiaceous subfamilies--the [...]

Anatomically preserved lycophytes of the Lycopodiales and Selaginellales have been discovered among a diverse assemblage of plants and fungi in carbonate marine concretions at the Apple Bay locality along the shore of Holbert Inlet near the northern end of Vancouver Island, British Columbia, Canada. Lycopodialean stems are plectostelic and actinostelic, branch dichotomously, and are similar to both Lycopodicaulis oellgaardii and Lycoxylon spp. The Selaginella specimens represent the first anatomically preserved Selaginellales with excellent internal cellular preservation in the fossil record, and are described as Selaginella quatsinoense Rothwell et Stockey sp. nov. Stems have three and five exarch, monarch stelar segments, each of which is surrounded by an aerenchymatous endodermis with trabeculae. The leaf base is indented on the adaxial surface, suggesting the position of a ligule. These fossils document that species with diagnostic internal anatomy of modern Lycopodiales and Selaginellales evolved no later than the Valanginian of the early Cretaceous. [ABSTRACT FROM AUTHOR]

Premise of research. Ten anatomically preserved conifer seed cone specimens are preserved on the surfaces of, and within, three interlocking rock fragments of terrestrial limestone discovered as float along the Colville River on the North Slope of Alaska, providing additional evidence for the diversification of taiwanioid Cupressaceae during the Upper Cretaceous–Cenozoic interval. Methodology. Specimens on rock surfaces were measured and photographed, and then serial anatomical thin sections were prepared by the cellulose acetate peel technique. Three-dimensional images of selected specimens were also captured using micro–computed tomography (micro-CT). Pivotal results. The structure of these seed cones is similar to that of living Taiwania cryptomerioides in cone shape, the presence of subtending scalelike leaves, helically arranged and imbricating foliate ovuliferous complexes (OCs), the absence of a separate ovuliferous scale tip, variation in numbers of OCs, and by having two adaxially positioned winged seeds per complex. However, abruptly upturned OC, details of OC vasculature, and distinctive histological features reveal that these seed cones represent a new species of the extinct genus Mukawastrobus. Conclusions. When added to the existing record of fossil seed cones, the new species Mukawastrobus arnoldii highlights the recent discovery that among early-diverging lineages of Cupressaceae, there has been considerable Cretaceous, Paleogene, and Neogene evolution that is reflected by variations among subtle characters that are not recognizable in any but the most completely preserved specimens. [ABSTRACT FROM AUTHOR]

Premise of research. Early Cretaceous (Valanginian) rocks exposed at Apple Bay (Vancouver Island, Canada) have yielded numerous anatomically preserved bryophytes that have expanded our knowledge of the pre-Cenozoic fossil record of this group. A new moss type with tricostate leaves from Apple Bay combines characters not encountered in moss species recorded previously, warranting in-depth characterization of a new taxon. Methodology. Carbonate concretions containing permineralized fossil material were sectioned using the cellulose acetate peel technique. The resulting acetate peels providing serial sections through the bryophyte specimens were used to reconstruct the habit of the plant and its leaves in two and three dimensions. Pivotal results. We describe a new species of moss in the family Tricostaceae, Tricosta priapiana sp. nov. The anatomy and morphology of the new species justify expanding and refining the diagnoses of Tricostaceae and Tricosta , especially with respect to perigonial branches and the morphology of branch buds. The presence of pseudoparaphyllia surrounding the branch buds supports the pleurocarpous affinities proposed previously for the Tricostaceae. Conclusions. Tricosta priapiana adds to the diversity of tricostate mosses, an extinct group that was intriguingly diverse in the Mesozoic. Nevertheless, the tricostate state is probably a convergent trait, or a trait that may have evolved independently in acrocarpous and pleurocarpous moss lineages in response to similar selective pressures. Still, it remains unclear what such selective pressures may have been, as the paleoclimates and habitats that hosted the tricostate mosses are not well circumscribed, precluding comparisons among the different species and their closest analogs among living multicostate mosses. [ABSTRACT FROM AUTHOR]

Premise of research. Two permineralized inflorescences have been found in calcium carbonate concretions from the Eocene Appian Way locality on Vancouver Island, British Columbia, increasing sampling density and helping clarify the pattern of phylogeny for Alismatalean monocots. Methodology. Serial sections of specimens were prepared by the cellulose acetate peel technique and studied with light microscopy. Phylogenetic analyses using a morphological matrix of living and fossil Araceae and Acoraceae were performed using TNT version 1.5 to help establish relationships of the fossil inflorescences. Pivotal results. Inflorescences are cylindrical spikes, >37 mm long and 8.1 mm wide, with a peduncle at least 14.5 mm long, bearing numerous helically arranged, bisexual sessile flowers with hooded tepals. Fruits are trilocular, with basal axile placentation and one seed per locule. Remnants of probable stamens are present in most flowers. Conclusions. Flower structure was compared to those of other petalloid, spicate, bisexual flowers in the monocot families Acoraceae and Araceae (Alismatales). The number of carpels is similar to that in Acorus (Acoraceae) and Spathiphyllum (Araceae, Monsteroideae) and some Pothoideae. Single-seeded ovaries are common in Araceae, while the locules in Acorus contain several apically attached seeds. Phylogenetic analyses place Appianospadix in Proto-Araceae near the base of the aroid tree. This inflorescence with a unique combination of characters is described as Appianospadix bogneri , a new genus and species of Alismatales (family: Araceae). [ABSTRACT FROM AUTHOR]

Premise: An anatomically preserved fossil fern sporeling has been discovered in a Lower Cretaceous marine concretion from Vancouver Island, British Columbia, Canada, providing an opportunity to characterize rhizome growth from an extinct species. Methods: The specimen was studied from serial transverse sections prepared by the cellulose acetate peel technique. Results: The rhizome ranges from ~0.7 to 1.1 mm in diameter, has a sclerenchymatous pith, a stele that attains a dictyoxylic architecture, and sclerenchymatous outer cortex, features that are characteristic of osmundaceous rhizomes. Cauline xylem forms a medullated protostele or solenostele at some levels, but is dissected into discrete xylem bundles at others. Fronds diverge in a helical phyllotaxis, range up to 1.1 mm in greatest dimension, and have a C‐shaped trace and outer cortex of sclerotic cells. Inside the sclerenchyma of the petioles are two lateral sclerotic strands and a sclerotic bundle adaxial to the trace. Together, these characters reveal the occurrence of a new species, Todea minutacaulis and provide evidence for developmental changes that occur in the rhizome as the sporeling increased in size. Conclusions: Small size of the specimen, medullated protostelic‐dictyoxylic solenostelar vascular architecture, and incompletely sclerified cells apically reveal that osmundaceous sporeling development has remained constant since at least the Early Cretaceous. Together with Todea tidwellii and Osmunda vancouverensis that also are present in the Apple Bay flora, this sporeling documents the occurrence of a multispecies assemblage of osmundaceous ferns and demonstrates that the genus Todea was diversifying rapidly by the Early Cretaceous. [ABSTRACT FROM AUTHOR]