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The Podocarpaceae are a morphologically diverse conifer family that have a cryptic fossil record reported since the Permian. We reviewed the fossil record of Podocarpaceae, tested the affinities of its oldest records using phylogenetic analyses, compiled macrofossil occurrence records, and investigated the diversity, distribution, and morphology of Podocarpaceae through time. We found that Permian, Triassic, and some Jurassic fossils referred to Podocarpaceae should not be placed in the family. Our total-evidence phylogenetic analyses, which sampled all major conifer lineages, recovered the Triassic Rissikia and the Jurassic Nothodacrium as stem-group conifers and the Jurassic Mataia as part of the Araucariales stem group. We further discuss the phylogenetic position of the Mesozoic enigmatic conifers Pararaucaria (Cheirolepidiaceae) and Telemachus (Voltziales), which were recovered most frequently in the conifer stem group. We conclude that the earliest reliable Podocarpaceae occurrences are from the Jurassic of both hemispheres and have scale-like leaves. Most extant genera appear in the fossil record between the Late Cretaceous and the Early Cenozoic. Many extant leaf morphologies appear in the Early Cretaceous, coeval with angiosperm diversification, consistent with the hypothesis that expanded leaves in Podocarpaceae are adaptive responses for light harvesting in angiosperm-dominated environments today. [ABSTRACT FROM AUTHOR]

Premise of research. A new Early Jurassic species of Cupressaceae is reconstructed from the Cañadón Asfalto Formation in Argentina, based on impressions of foliage and attached and dispersed seed and pollen cones. Methodology. Over 230 specimens were examined using reflected-light microscopy and epifluorescence. Relevant extant taxa were studied for structural comparisons using herbarium specimens and living material from botanical gardens. Relationships of the new conifer were assessed in the context of currently known fossil and living taxa and used to evaluate morphological trends in the early evolution of Cupressaceae. Pivotal results. The new species, Austrohamia asfaltensis D.L. Contreras, I.H. Escapa, R.C. Iribarren, & N.R. Cúneo, has helically arranged, dorsiventrally flattened leaves that are rotated into semiplanar orientation, seed cones consisting of helically arranged coriaceous ovuliferous complexes that each bear two seeds and have a distinct abaxial keel and acuminate apex, and pollen cones that occur in clusters subtended by keeled bracts. Specimens show evidence that normal vegetative shoot growth continues from the pollen cone clusters, a condition that appears to characterize living Cunninghamia and some extinct conifers but not Taiwania. The new species is assignable to the genus Austrohamia , which shares a combination of characteristics consistent with the Cunninhamioideae and Taiwanioideae subfamilies of the Cupressaceae. It is distinct from other Austrohamia species, most notably by having seed cones that are twice as large and with many more ovuliferous complexes. Conclusions. The new species expands the known morphological diversity of Austrohamia , which is the oldest recorded genus of Cupressaceae based on reproductive material, and provides a new early occurrence of the family in the Southern Hemisphere. The development of a whole-plant concept enabled morphological comparisons over a broad range of traits and with taxa known from different combinations of organs, which has provided additional insights into the early evolution of Cupressaceae. [ABSTRACT FROM AUTHOR]

Macrofossil impressions of caytonialean leaves and micro- and megasporangiate organs from the Early Jurassic Taquetrén locality in Patagonia, Argentina, are described based on more than 300 hand specimens. Leaves of the organ-genus Sagenopteris are described using both discrete and continuous features allowing us to erect the species Sagenopteris trapialensis sp. nov. Associated microsporangiate organs of Caytonanthus type are the first recorded for South America and are characterized by a unique combination of architecture, size and type of dehiscence. Two specimens, one resembling an isolated Caytonia cupule, and the other a Caytonia axis, are also described. The availability of a collection with numerous specimens has proven to be an important tool in order to fully understand the intraspecific morphological plasticity of the studied species. The striking morphological resemblance of both vegetative and reproductive organ-genera with their Northern Hemisphere counterparts suggests that they were part of the same lineage, which was widely distributed during the Jurassic. Well-defined whole-plant concepts are still needed to advance the goal of deciphering the internal relationships of caytonialeans in particular, and their relationships with other groups of seed-plants in general, and thorough macro-morphological characterization of the organs that compose them, as we present here, may be of valuable use in achieving it. [ABSTRACT FROM AUTHOR]

Premise of research. Numerous leaf remains of pteridosperms occur at a new locality of the Early Jurassic Cañadón Asfalto Formation, in Patagonia, Argentina. Fossils consist of adpressions with superb cuticular preservation and are herein assigned to Lepidopteris (Peltaspermaceae). Methodology. Fossils were studied using normal light, epifluorescence, and scanning electron microscopy. The cuticles of 25 specimens were chemically prepared following standard methods. The remains were described in detail and compared with other pteridosperm genera and Lepidopteris species. Pivotal results. We erect Lepidopteris scassoi sp. nov. Elgorriaga, Escapa et Cúneo, based on its novel combination of characters. Among other features, L. scassoi has a bipinnate-tripinnatifid architecture, smooth rachis, 1–3 pairs of intercalary pinnules, and entire to deeply lobed pinnules with pinnate venation. Fronds are amphistomatic with a 0.5–0.7∶1 adaxial to abaxial ratio; stomata occur scattered on rachides and pinnules and have a ring of usually seven subsidiary cells with papillae oriented toward the stomatal pit; and the guard cells are sunken. A single solid papilla is usually present on epidermal cells of pinnules and pinnae. Structures resembling isolated Peltaspermum disks, with similar stomata as L. scassoi , were found in the same locality. Conclusions. We interpret L. scassoi and other members of its lineage as fast-growing, long-lived shrubby to herbaceous plants that thrived in waterside environments. Lepidopteris scassoi represents the youngest occurrence of the genus by more than 20 Myr. Lepidopteris and Dicroidium lineages, dominant in Southern Hemisphere Triassic ecosystems, show a similar overall pattern of origination (Late Permian), diversification (late Early-Middle Triassic), and decline (Late Triassic), with relict occurrences during the Early Jurassic. The systematic affiliation of a considerable number of Mesozoic pteridosperm records remains contentious, and future efforts should be oriented toward a better understanding of the position of each group on the gymnosperm tree of life. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which includes articles on topics including analysis of polytrichacean moss phylogeny, overall patterns of phylogeny for marattialean ferns and dipteridacean ferns and flowering plant evolution and phylogeny from fagalean inflorescences.

Premise of the Study: The fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylogenetic analyses have included fossil Agathis species. Methods: We describe macrofossils from Patagonia of Agathis vegetative and reproductive organs from the early Danian, as well as leaves with Agathis affinities from the latest Maastrichtian. A total evidence phylogenetic analysis is performed, including the new Danian species together with other fossil species having agathioid affinities. Key Results: Early Danian Agathis immortalis sp. nov. is the oldest definite occurrence of Agathis and one of the most complete Agathis species in the fossil record. Leafy twigs, leaves, pollen cones, pollen, ovuliferous complexes, and seeds show features that are extremely similar to the living genus. Dilwynites pollen grains, associated today with both Wollemia and Agathis and known since the Turonian, were found in situ within the pollen cones. Conclusions: Agathis was present in Patagonia ca. 2 million years after the K‐Pg boundary, and the putative latest Cretaceous fossils suggest that the genus survived the K–Pg extinction. Agathis immortalis sp nov. is recovered in a stem position for the genus, while A. zamunerae (Eocene, Patagonia) is recovered as part of the crown. A Mesozoic divergence for the Araucariaceae crown group, previously challenged by molecular divergence estimates, is supported by the combined phylogenetic analyses including the fossil taxa. [ABSTRACT FROM AUTHOR]

Premise of the Study: Equisetum is the sole living representative of Sphenopsida, a clade with impressive species richness, a long fossil history dating back to the Devonian, and obscure relationships with other living pteridophytes. Based on molecular data, the crown group age of Equisetum is mid‐Paleogene, although fossils with possible crown synapomorphies appear in the Triassic. The most widely circulated hypothesis states that the lineage of Equisetum derives from calamitaceans, but no comprehensive phylogenetic studies support the claim. Using a combined approach, we provide a comprehensive phylogenetic analysis of Equisetales, with special emphasis on the origin of genus Equisetum. Methods: We performed parsimony phylogenetic analyses to address relationships of 43 equisetalean species (15 extant, 28 extinct) using a combination of morphological and molecular characters. Key Results: We recovered Equisetaceae + Neocalamites as sister to Calamitaceae + a clade of Angaran and Gondwanan horsetails, with the four groups forming a clade that is sister to Archaeocalamitaceae. The estimated age for the Equisetum crown group is mid‐Mesozoic. Conclusions: Modern horsetails are not nested within calamitaceans; instead, both groups have explored independent evolutionary trajectories since the Carboniferous. Diverse fossil taxon sampling helps to shed light on the position and relationships of equisetalean lineages, of which only a tiny remnant is present within the extant flora. Understanding these relationships and early character configurations of ancient plant clades as Equisetales provide useful tests of hypotheses about overall phylogenetic relationships of euphyllophytes and foundations for future tests of molecular dates with paleontological data. [ABSTRACT FROM AUTHOR]

Premise of the Study: Dipteridaceae is a lineage of ferns that has existed from the early Mesozoic and is known for its extensive fossil record. By integrating information from all described extant and extinct genera into a single phylogenetic study, this paper aims to examine the taxonomy of the group on a whole and explore character evolution within the lineage across time. Methods: A morphological matrix of 51 characters was developed for 72 species (43 extinct and 29 extant) based on published information. Morphological characters were combined with nucleotide sequences for four chloroplast genes (rbcL, atpA, atpB, and rps4) for extant taxa, and combined parsimony analyses were conducted to infer evolutionary trends in the group. Key Results: Dipteridaceae was found to be monophyletic and characterized by highly anastomosing minor veins forming a meshwork of areoles with free‐included veinlets. Based on our analyses, we recognize six previously described genera (i.e., Goeppertella, Thaumatopteris, Clathropteris, Digitopteris, Dipteris, and Cheiropleuria) and one new genus (i.e., Sewardalea). Fossils currently described as Dictyophyllum, Kenderlykia, Hausmannia, and Protorhipis are ambiguously placed on the tree and are recognized as possibly unnatural morphogenera. Conclusions: Overall, the evolutionary trend in Dipteridaceae has been toward increasing complexity in the venation pattern and laminal fusion. Only the Hausmannia‐type frond with dichotomizing primary veins and relatively fused lamina persisted in the later part of the Mesozoic to the present. Within the crown group, we see evidence of re‐radiation of frond forms in Dipteris and Cheiropleuria. [ABSTRACT FROM AUTHOR]

Premise of the Study: We describe a new araucarian species, Araucaria lefipanensis, from the Late Cretaceous flora of the Lefipán Formation, in Patagonia (Argentina) based on reproductive and vegetative remains, with a combination of characters that suggest mosaic evolution in the Araucaria lineage. Methods: The studied fossils were found at the Cañadón del Loro locality. Specimens were separated into two leaf morphotypes, and their morphological differences were tested with MANOVA. Key Results: The new species Araucaria lefipanensis is erected based on the association of dimorphic leaves with cuticle remains and isolated cone scale complexes. The reproductive morphology is characteristic of the extant section Eutacta, whereas the vegetative organs resemble those of the sections Intermedia, Bunya, and Araucaria (the broad‐leaved clade). Conclusions: The leaf dimorphism of A. lefipanensis is similar to that of extant A. bidwillii, where dimorphism is considered to be related to seasonal growth. The leaf dimorphism in A. lefipanensis is consistent with the paleoclimatic and paleoenvironmental reconstructions previously suggested for the Lefipán Formation, which is thought to have been a seasonal subtropical forest. The new species shows evidence of mosaic evolution, with cone scale complexes morphologically similar to section Eutacta and leaves similar to the sections of the broad‐leaved clade, constituting a possible transitional form between these two well‐defined lineages. More complete plant concepts, especially those including both reproductive and vegetative remains are necessary to understand the evolution of ancient plant lineages. This work contributes to this aim by documenting a new species that may add to the understanding of the early evolution of the sections of Araucaria. [ABSTRACT FROM AUTHOR]

Background The origin of the Equisetum strobilus has long been debated and the fossil record has played an important role in these discussions. The paradigm underlying these debates has been the perspective of the shoot as node-internode alternation, with sporangiophores attached at nodes. However, fossils historically excluded from these discussions (e.g. Cruciaetheca and Peltotheca) exhibit reproductive morphologies that suggest attachment of sporangiophores along internodes, challenging traditional views. This has rekindled discussions around the evolution of the Equisetum strobilus, but lack of mechanistic explanations has led discussions to a stalemate. Scope A shift of focus from the node-internode view to a perspective emphasizing the phytomer as a modular unit of the shoot, frees the debate of homology constraints on the nature of the sporangiophore and inspires a mechanism-based hypothesis for the evolution of the strobilus. The hypothesis, drawing on data from developmental anatomy, regulatory mechanisms and the fossil record, rests on two tenets: (1) the equisetalean shoot grows by combined activity of the apical meristem, laying down the phytomer pattern, and intercalary meristems responsible for internode elongation; and (2) activation of reproductive growth programmes in the intercalary meristem produces sporangiophore whorls along internodes. Conclusions Hierarchical expression of regulatory modules responsible for (1) transition to reproductive growth; (2) determinacy of apical growth; and (3) node-internode differentiation within phytomers, can explain reproductive morphologies illustrated by Cruciaetheca (module 1 only), Peltotheca (modules 1 and 2) and Equisetum (all three modules). This model has implications - testable by studies of the fossil record, phylogeny and development - for directionality in the evolution of reproductive morphology (Cruciaetheca-Peltotheca-Equisetum) and for the homology of the Equisetum stobilus. Furthermore, this model implies that sporangiophore development is independent of node-internode identity, suggesting that the sporangiophore represents the expression of an ancestral euphyllophyte developmental module that pre-dates the evolution of leaves. [ABSTRACT FROM AUTHOR]

A new species of anatomically preserved Cupressaceae is described from the Upper Cretaceous Raritan Formation (New Jersey, USA). The fossils are charcolified isolated ovuliferous complexes that were studied by means of a combination of SEM images and micro-computed tomography (micro-CT), allowing the observation of morphological and anatomical characters. Each ovuliferous complex bears 3-4 anatropous winged seeds, disposed in one row on a thin medial part of the adaxial side of the ovuliferous complex. Based on the combination of characters such as ovuliferous complex morphology, arrangement of vascular tissues and resin canals, seed number and their morphology, orientation and disposition, these fossils are placed within a new species of the fossil genus Athrotaxites. The developmental stage of the specimens is analyzed base on comparisons with living representatives of the subfamily Athrotaxoideae (i.e., Athrotaxis spp.), which supports a post-pollination stage for these fossils. In addition, the new species is compared with other extant and extinct representatives of basal cupressaceous subfamilies. This new record from the Upper Cretaceous sediments of New Jersey further supports a wider distribution of the subfamily Athrotaxoideae during the middle part of the Mesozoic, as it has been also noted for other basal representatives of the family Cupressaceae. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Puzzling rocks and complicated clocks: how to optimize molecular dating approaches in historical phytogeography" by Q Wang, and K.-S. Mao in a 2016 issue.

We here describeMarattiopsis patagonicasp. nov. (Marattiaceae) based on vegetative and fertile foliage impressions from the Lower Jurassic of Chubut Province, Patagonia, Argentina. The new species exhibits a unique combination of vegetative and reproductive features, including a prominent basal auricle; finely undulate, denticulate, to serrulate pinnule margins; interstitial fibres (venuli recurrentes) alternating with regular veins; submarginal position and distinctive relative length of synangia (about 12–20% of the pinnule width); and relatively small number of sporangia pairs per synangium (usually 14 or 16). The new species is assigned to the morphogenusMarattiopsis, since it shows no characters that would allow an unambiguous placement in any of the modern genera,Marattias.s.,Ptisana, orEupodium. The newly established paraphyly of theMarattias.l. species has a profound impact on the classification of fossil species. In this context, we provide a brief assessment of the significance of the fossilMarattiopsisfor phylogenetic and biogeographical interpretations. It appears that essentially modern marattioid ferns, includingMarattiopsis, which are commonly considered to be typical elements of tropical areas of the northern hemisphere during the Mesozoic, may have left an important but largely ignored fossil record in subtropical Gondwana. [ABSTRACT FROM AUTHOR]

283I.283II.284III.284IV.287V.288288References288 Summary: Evolutionary divergence‐age estimates derived from molecular ‘clocks’ are frequently correlated with paleogeographic, paleoclimatic and extinction events. One prominent hypothesis based on molecular data states that the dominant pattern of Southern Hemisphere biogeography is post‐Gondwanan clade origins and subsequent dispersal across the oceans in a metaphoric ‘Green Web’. We tested this idea against well‐dated Patagonian fossils of 19 plant lineages, representing organisms that actually lived on Gondwana. Most of these occurrences are substantially older than their respective, often post‐Gondwanan molecular dates. The Green Web interpretation probably results from directional bias in molecular results. Gondwanan history remains fundamental to understanding Southern Hemisphere plant radiations, and we urge significantly greater caution when using molecular dating to interpret the biological impacts of geological events. [ABSTRACT FROM AUTHOR]

The relevance of improving the knowledge on Triassic conifers resides in that the modern clades originated during the Late Triassic-Early Jurassic. More than 30 conifer-like fossil woods are known from the Triassic strata of Argentina. Whereas some have not been linked to any family, others have been related to the "Protopinaceae", Taxaceae, Podocarpaceae, Araucariaceae, Cupressaceae, or Hirmeriellaceae (=Cheirolepidiaceae). The diversity of woods with anatomy close to derived conifers contrasts with the scarce Triassic record of leaves and micro and megasporangiate cones, which could be explained by a combination of taphonomic and evolutionary causes. In order to provide information to resolve this controversy, the anatomy and systematic affinities of Triassic permineralized conifer-like trunks and woods described to date for Argentina were reassessed. As a result of this review, it emerged that the woods previously assigned to Podocarpaceae and Taxaceae do not have enough preserved characters to support such assignment, or they have characters that are homoplasic in the context of Mesozoic gymnosperms and therefore their affinity is ambiguous. On the contrary, the reevaluation of the woods related to the Araucariaceae, Cupressaceae and Hirmeriellaceae (=Cheirolepidiaceae) allows us to support their affinity with these families. [ABSTRACT FROM AUTHOR]

* Premise of the study: Agathis is an iconic genus of large, ecologically important, and economically valuable conifers that range over lowland to upper montane rainforests from New Zealand to Sumatra. Exploitation of its timber and copal has greatly reduced the genus's numbers. The early fossil record of Agathis comes entirely from Australia, often presumed to be its area of origin. Agathis has no previous record from South America. * Methods: We describe abundant macrofossils of Agathis vegetative and reproductive organs, from early and middle Eocene rainforest paleofloras of Patagonia, Argentina. The leaves were formerly assigned to the New World cycad genus Zamia. * Key results: Agathis zamunerae sp. nov. is the first South American occurrence and the most complete representation of Agathis in the fossil record. Its morphological features are fully consistent with the living genus. The most similar living species is A. lenticula, endemic to lower montane rainforests of northern Borneo. * Conclusions: Agathis zamunerae sp. nov. demonstrates the presence of modern-aspect Agathis by 52.2 mya and vastly in creases the early range and possible areas of origin of the genus. The revision from Zamia breaks another link between the Eocene and living floras of South America. Agathis was a dominant, keystone element of the Patagonian Eocene floras, along side numerous other plant taxa that still associate with it in Australasia and Southeast Asia. Agathis extinction in South America was an integral part of the transformation of Patagonian biomes over millions of years, but the living species are disappearing from their ranges at a far greater rate. [ABSTRACT FROM AUTHOR]

Premise of research. Phylogenetic relationships of Araucariaceae (Coniferophyta, Araucariales) are revised on the basis of the first combined data matrix for the family. Methodology. Taxon sampling includes 39 ingroup species (31 extant, 8 fossils) and outgroup species of all the remaining conifer families. Five fossil Araucaria species, one species of the genus Araucarites, and two species of the extinct genera Wairarapaia and Emwadea were included in the analyses. Character sampling includes 23 genomic regions (19 plastid, 2 nuclear, and 2 mitochondrial) and 62 morphological characters (52 discrete and 10 continuous). The phylogenetic analyses were conducted with equally weighted parsimony. Additionally, several analyses under different taxon- and gene-sampling regimes were analyzed for identifying the causes of the long-lasting controversies in the interrelationships of the three extant genera of Araucariaceeae. Pivotal results. Monophyletic Araucariaceae is the sister group of Podocarpaceae, forming the order Araucariales. Monophyly of Araucaria and Agathis is also strongly supported by the data. The results of both molecular and combined analyses indicate that Wollemia and Agathis form a clade (pagathioid clade) sister to Araucaria. Within Araucaria, the analyses support the monophyly of the four currently recognized sections: Araucaria, Bunya, Intermedia, and Eutacta. Results support the monophyly of living and fossil Araucaria (including Araucarites), whereas the remaining extinct genera are placed as the stem of the agathioid clade. In terms of the sensitivity analyses performed, results suggest that inconsistencies among previous results would be related to ingroup sampling. Conclusions. By means of a combined phylogenetic analysis, we have been able to obtain a strongly supported and well-resolved phylogeny of Araucariaceae that includes both living species and fossil species for the group. This study shows the feasibility and usefulness of phylogenetic analyses that incorporate multiple sources of evidence (molecules/morphology, living/fossil species, discrete/continuous characters). [ABSTRACT FROM AUTHOR]

Reflectance Transforming Imaging (RTI) produces photographs in which the angle of the light can be changed at will, allowing to investigate remotely minute details of the 3D structure of sub-planar objects. Here we apply this technique to the type specimen of Gingkophyllum grassetii , a vegetative shoot with putative ginkgophyte affinities from the early Permian of Lodève (France). Gingkophyllum grassetii , the type species of the genus, was originally described by Saporta in 1875 and has never been illustrated other than by drawings representing only portions of the shoot. Using RTI, we describe and illustrate the specimen and discuss some key features, such as the arrangement of the leaves on the shoot or the presence of abundant secretory structures. Through an historical account, we show how the lack of illustration led to confusion about the morphology of Ginkgophyllum and we discuss the importance of reinvestigating type specimens of Paleozoic ginkgophyte taxa in order to clarify their taxonomy and better understand their evolutionary history. The sharing of RTI files is one example of approaches that can be further developed to improve remote access to specimens. • Ginkgophyllum grassetii , the type species of the genus, is a putative Permian ginkgophyte. • Lack of published photos led to confusions about Ginkgophyllum morphology and taxonomy. • We re-investigate the type specimen using Reflectance Transforming Imaging. • We provide new information on the morpho-anatomy of the specimen. • RTI files could be further used to improve remote access to collection specimens. [ABSTRACT FROM AUTHOR]

The discovery of 16 cylindrical conifer seed cones at the Estancia Vilán locality in the Late Jurassic Cañadön Calcáreo Formation of Chubut Province, Patagonia, Argentina, provides anatomically preserved specimens, allowing for the description of a second species of Pararaucaria (Cheirolepidiaceae). The new species, Pararaucaria delfueyoi, is similar in general features to the type species, Pararaucaria patagonica, but has a specifically diagnostic combination of characters that include cone size, seed number, features of histology, and seed size. Specimens are cylindrical with a narrow axis that bears helically arranged bract/scale complexes. The bract and scale diverge from the axis at ~90° and separate from each other almost immediately. The ovuliferous scale extends toward the margin of the cone and then arches over to enclose two inverted nonwinged seeds within a pocket of tissue. Although the specimens are abraded such that the distal regions of the ovuliferous scales are not preserved, this combination of morphological and histological characters allows for the assignment of P. delfueyoi to the Cheirolepidiaceae with confidence. The co-occurrence of this cone with an undescribed species of Araucaria extends the geographic and stratigraphic ranges of this association, which previously has been known only from the Middle Jurassic of Santa Cruz Province of Patagonia. This extends the knowledge of anatomical variation among seed cones of Cheirolepidiaceae and improves our understanding of homology relationships for conifer seed cone structures. [ABSTRACT FROM AUTHOR]

The conifer family Cupressaceae encompasses seven subfamilies. Five of them were once considered to constitute the family Taxodiaceae, later eliminated because of its paraphyletic nature but remaining as an informal category for early‐diverging Cupressaceae lineages. Among the taxodiaceous subfamilies, Athrotaxoideae shows a unique morphology in its ovuliferous complexes (OCs) and a phylogenetically unexplored fossil record. We describe the new genus and species Patagotaxodia lefipanensis, based on OC adpressions associated with leafy branches collected at the Maastrichtian section of the Lefipán Formation (Patagonia, Argentina), and we refer it to Athrotaxoideae. We include Patagotaxodia in total evidence phylogenetic analysis to test its affinity, and we recover it within the subfamilies Athrotaxoideae or Cunninghamioideae. However, we argue that the characters supporting the athrotaxoid affinity are more meaningful in a taxodiaceous systematic context. This placement is also supported by taxon inclusion‐exclusion experiments. We discuss the position of other Cretaceous athrotaxoid records. With basis on the morphological insights provided by the OC morphology of extant and extinct Athrotaxoideae, we study the evolution of the OC morphology in the family in a phylogenetic context and discuss the results in the light of the fossil record of the family. We discuss how and when the different morphologies appeared in the family. Based on phylogenetic, temporal, morphological, and ontogenetic evidence, we conclude that the OC morphology shown by the subfamily Athrotaxoideae is intermediate between two of the most common morphologies within extant and extinct Cupressaceae species, one of which would show adaptative advantages over basal morphologies. [ABSTRACT FROM AUTHOR]

• Premise of the study: Seed cone morphology and anatomy reflect some of the most important changes in the phylogeny and evolutionary biology of conifers. Reexamination of the enigmatic Jurassic seed cone Pararaucaria patagonica reveals previously unknown systematically informative characters that demonstrate affinities with the Cheirolepidiaceae. This paper documents, for the first time, internal anatomy for seed cones of this important extinct Mesozoic conifer family, which may represent the ghost lineage leading to modern Pinaceae. • Methods: Morphology and anatomy of cones from the Jurassic La Matilde Formation in Patagonia are described from a combination of polished wafers and thin section preparations. New photographic techniques are employed to reveal histological details of thin sections in which organic cell wall remains are not preserved. Specific terminology for conifer seed cones is proposed to help clarify hypotheses of homology for the various structures of the cones. • Key results: Specimens are demonstrated to have trilobed ovuliferous scale tips along with a seed enclosing pocket of ovuliferous scale tissue. Originally thought to represent a seed wing in P. patagonica, this pocket-forming tissue is comparable to the flap of tissue covering seeds of compressed cheirolepidiaceous cones and is probably the most diagnostic character for seed cones of the family. • Conclusions: Pararaucaria patagonica is assigned to Cheirolepidiaceae, documenting anatomical features for seed cones of the family and providing evidence for the antiquity of pinoid conifers leading to the origin of Pinaceae. A list of key morphological and anatomical characters for seed cones of Cheirolepidiaceae is developed to facilitate assignment of a much broader range of fossil remains to the family. This confirms the presence of Cheirolepidiaceae in the Jurassic of the Southern Hemisphere, which was previously suspected from palynological records. [ABSTRACT FROM AUTHOR]

Abstract: We describe a distinct type of heteromorphic basal frond element in four species of the seed-fern foliage Dicroidium, based principally on a survey of plant-fossil collections from the Triassic of Antarctica. The modified foliar elements are conspicuously enlarged, and arise at wide angles and obliquely to the frond plane. Those of D. elongatum and D. crassinerve arise more or less directly from the petiole base; they are overall wedge- to fan-shaped with variably dissected margins and fan-shaped venation. Those of D. odontopteroides and D. dubium are (sub)circular, reniform, or obcordate, also with fan-shaped venation, or divided into narrow tongue-shaped segments with alethopteroid venation. The basal elements of some species commonly occur isolated. By analogy with comparable structures among other plant groups, we conclude that the basal elements represent a distinct, early leaf-ontogenetic architectural unit in the frond bauplan of Dicroidium, which provides an important additional character for a more accurate delimitation and systematic classification. Similar structures also occur on the corystosperm reproductive organs Umkomasia and Pteruchus. It appears that the basal elements were particularly common among high-latitude Dicroidium trees that flourished in a strongly seasonal light regime. We hypothesize that the modified elements may represent the initial foliar outgrowths during spring flush, ensuring a rapid re-initiation of sap flow and metabolic activity after the extended period of winter dormancy. [Copyright &y& Elsevier]

Two new compression-impression species of the Osmundaceae described from reproductive and vegetative remains are erected for the first time from the Early Jurassic of Argentina. Todites cacereii sp. nov. and Osmundopsis rafaelii sp. nov. demonstrate that two main osmundaceous reproductive morphologies; i.e., differentiated reduced or unreduced fertile laminae were already present and widespread in Gondwana by this time. On the basis of a discussion of relevant morphological characters, the phylogenetic meaning of the fossils Todites and Osmundopsis is explored. Likewise, the systematics and taxonomy of fossil taxa and their relationships with modern ones are discussed in light of current hypotheses. In this regard, because clear synapomorphies or apomorphies are not yet fully understood, it is suggested that fossil representatives are better placed in morphotaxa (Todites, Osmundopsis) than in any current genus. Nonetheless, the clear record of characters of the leptopteroid clade by the early Jurassic proves to be older than previously assumed, which also points to an earlier time of origination for the osmundaceous ferns. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

A common problem in phylogenetic analysis is the presence of unstable taxa that are depicted in multiple positions in optimal topologies. These uncertainties are reflected in strict consensus trees with polytomies that hamper the interpretation of the phylogenetic results. We propose a protocol for detecting unstable branches (either terminal taxa or clades) and identifying particular characters related to their instability in cladistic analysis. This procedure is based on an iterative evaluation of the agreement of triplets among the optimal topologies (i.e. most-parsimonious trees, MPTs) and examination of character optimizations on these trees. Different types of characters underlying the unstable behaviour of taxa are detected: those with conflicting scorings that support alternative positions of problematic taxa and those with missing data in the unstable taxa that could reduce their instability if they are scored. The entire process is automated through a TNT script that provides a list of characters related to the instability of each unstable taxon. The outcome of this procedure can be used as a guide for further research efforts focused on the revision or addition of (morphological or molecular) phylogenetic data for elucidating the affinities of unstable taxa. © The Willi Hennig Society 2009. [ABSTRACT FROM AUTHOR]

We discuss a recent assessment by Dörken et al. (2021) regarding the affinities of the Eocene fossil species Huncocladus laubenfelsii from Laguna del Hunco (Patagonia, Argentina). We originally (Andruchow-Colombo et al. , 2019) assigned this species to the conifer family Podocarpaceae as the first certain South American macrofossil record of the phyllocladoid lineage (Huncocladus + Phyllocladus), based on a combination of numerous macro- and micromorphological vegetative characters. However, Dörken et al. (2021) rejected the podocarpaceous affinity of H. laubenfelsii and considered it to be more closely related to the cycad genera Bowenia or Eobowenia. Their assessment was based almost entirely on two cuticular characters, with only superficial consideration of the abundant additional evidence available that included several diagnostic macromorphological features. We review the two characters mentioned by these authors, and other features, and find that their suggestion is contradicted by the available evidence, maintaining our original assignment. Critical characters include presence/absence of a midvein, secondary venation pattern, arrangement and general morphology of the photosynthetic structures, and morphology and disposition of epidermal cells. [ABSTRACT FROM AUTHOR]

Premise of research. The southern conifer family Podocarpaceae inhabits wet environments and is highly diverse in its vegetative and megasporangiate structures. The Podocarpaceae are today divided into a tropical clade and a prumnopityoid clade. We study the morphology and anatomy of leaves and megasporangiate cones at postpollination and the maturity of two native Patagonian Podocarpaceae, Saxegothaea conspicua (tropical clade) and Lepidothamnus fonkii (prumnopityoid clade). We aim to add to the knowledge of the South American Podocarpaceae and to interpret their unique morphologies to aid in our understanding of the deep and cryptic fossil record of the family and its relationships with other conifer families. Methodology. Specimens of S. conspicua and L. fonkii were collected in natural and cultivated populations of southern Chile and imaged using different macro- and microscopic techniques, including epifluorescence, bright-field, and scanning electron microscopy. Pivotal results. Leaf and megasporangiate cone anatomy and morphology are described in detail for both species. For S. conspicua , we observed a helical to slightly planate leaf arrangement with leaf reorientation, expanded leaves without accessory transfusion tissue, an apparent lack of vascularization of the epimatium (which is bikeeled and does not surround the ovule completely), and nonsaccate pollen germinating on the bract toward the protruding nucellus. For L. fonkii , we observed the absence of leaf hypodermis and resin canals, the presence of a micropylar hook in the ovule and seed integument, bisaccate pollen germinating within the ovule, cone bracts reduced in number and size, and a basal receptacle-like structure. Conclusions. Leaf arrangement in Saxegothaea shows an intermediate condition between the primary helical phyllotaxis common in the family and the secondary planate arrangement seen in most podocarps with expanded leaves. Lepidothamnus fonkii was determined to have a false receptacle (i.e., a receptacle-like structure originated from vegetative basal bracts rather than by sterile ovuliferous complexes). The presence of a false receptacle in L. fonkii is a morphological novelty in Podocarpaceae. [ABSTRACT FROM AUTHOR]

Premise: The sooty molds are a globally distributed ecological group of ascomycetes with epiphyllous, saprotrophic habit, comprising several phylogenetically distant taxa (i.e., members of the classes Dothideomycetes and Eurotiomycetes). Their fossil record extends almost continuously back to the early Cretaceous; however, they are hypothesized to have originated in the early Mesozoic. Here, we describe new specimens of sooty molds associated with conifer leaves from Jurassic hot spring deposits of Patagonia, Argentina. Methods: Thin sections of chert samples from the La Matilde Formation, Deseado Massif (Santa Cruz, Argentina) were observed using light microscopy. Results: The fungi occur on the surface and axils of leafy twigs with podocarpaceous affinities, forming dense subicula comprised by opaque moniliform hyphae. Additionally, several asexual and sexual reproductive structures are observed. On the basis of vegetative (i.e., dense subicula composed of moniliform hyphae; hyphae composed of opaque cells deeply constricted at the septa) and reproductive characters (i.e., poroconidial and sympodioconidial asexual stages and diverse spores), two morphotypes were identified with affinities within lineages of the subphylum Pezizomycotina that encompass the ecological group of sooty molds, and a third morphotype was within the phylum Ascomycota. Conclusions: This finding extends the fossil record of sooty molds to the Jurassic and their geographic fossil range to the South American continent. In particular, their association with podocarpaceous conifers is shown to be ancient, dating back to the Jurassic. This new record provides an additional reference point on the diversity of interactions that characterized Jurassic forests in Patagonia. [ABSTRACT FROM AUTHOR]

Premise: Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Eutacta usually are represented by isolated organs, making diagnosis difficult. Araucaria pichileufensis E.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect. Eutacta and later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship of A. pichileufensis to Sect. Eutacta and the conspecificity of the Araucaria material among these Patagonian floras have not been tested using modern methods. Methods: We review the type material of A. pichileufensis alongside large (n = 192) new fossil collections of Araucaria from LH and RP, including multi‐organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect. Eutacta. Results: We describe Araucaria huncoensis sp. nov. from LH and improve the whole‐plant concept for Araucaria pichileufensis from RP. The two species respectively resolve in the crown and stem of Sect. Eutacta. Conclusions: Our results confirm the presence and indicate the survival of Sect. Eutacta in South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crown Eutacta. The differentiation of two Araucaria species demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene. [ABSTRACT FROM AUTHOR]

Premise of research. Today, mosses are the second most speciose lineage of land plants and are important components of many ecosystems. However, in spite of their diversity and ecological importance in the modern biota, mosses are rare in the fossil record, especially prior to the Cenozoic. Therefore, every new report of a pre-Cenozoic moss deeply enriches our understanding of their evolution. Pre-Cenozoic permineralized mosses represent particularly exciting discoveries because a thorough understanding of the organism is possible. Here, we present the first permineralized Jurassic moss. Methodology. A single chert block from the Cañadón Nahuel locality of the Jurassic (178–151 Ma) Deseado Massif in Santa Cruz Province, Patagonia, was polished, and the plants within were examined, revealing a moss gametophyte shoot. A thin section of this chert block was cut and subsequently examined using light microscopy. Pivotal results. We describe Heinrichsiella patagonica gen. et sp. nov., an acrocarpous moss with a novel combination of gametophyte features that suggests basal affinities within either the family Polytrichaceae or the family Timmiellaceae. Both of these families are members of a grade within subphylum Bryophytina basal to subclass Bryidae. Heinrichsiella is the oldest member of this grade by at least 15 million years. Conclusions. Heinrichsiella patagonica is the first report of a moss from the Jurassic Deseado Massif hydrothermal cherts of Patagonia. This fossil reveals that stem group members of extant acrocarpous moss families lived during the Jurassic, implicating the Jurassic as a critical time for understanding the evolution of higher-level moss taxa. [ABSTRACT FROM AUTHOR]

Premise of research. The Río Genoa Formation of Argentine Patagonia hosts Early Permian fossil assemblages that document levels of plant diversity rare among coeval floras. Ongoing work to exhaustively characterize the diversity of these assemblages is key to understanding Permian vegetation and plant evolution. A new fern type identified in the Río Genoa Formation exhibits a novel combination of characters that required taxonomic assessment. Methodology. Observations and measurements of vegetative and reproductive morphology of compression fossils were used in a comparative framework to address the taxonomic placement of the fossils. Pivotal results. The new fern, Floratheca apokalyptika gen. et sp. nov., is characterized by small pinnules with a free base, weakly lobed margin, highly decurrent midvein, and rarely branched lateral veins, as well as radially symmetrical synangia with stellate dehiscence, consisting of six spindle-shaped sporangia. This unique combination of characters distinguishes Floratheca from the more than 25 Permo-Carboniferous marattialean genera known from compressions. Floratheca exhibits variable synangium morphology during development and variation in pinnule base morphology due to a combination of adaxial-abaxial asymmetry of ultimate rachises and taphonomic effects. Conclusions. Floratheca is one of only three late Paleozoic bona fide marattialean compression genera endemic to Gondwana and the second late Paleozoic endemic South American marattialean with preserved fertile structures. Floratheca adds to an increasing diversity of fossils that diminish the disparity between the Southern and Northern Hemispheres, in terms of the extent and intensity of exploration of the plant fossil record, currently skewed taxonomically toward Northern Hemisphere taxa. Variability of synangium and pinnule base morphology in Floratheca cautions against potential taxonomic inflation produced by establishment of new taxa based on small numbers of specimens and incomplete understanding of development and taphonomy. [ABSTRACT FROM AUTHOR]

Huncocladus laubenfelsii gen. et sp. nov. is described from the early Eocene (52 million years old) Laguna del Hunco site in Patagonia, Argentina, on the basis of a compression fossil with cuticle remains. The taxon has several similarities with Phyllocladus , together with characters that are absent in extant Phyllocladus species but are otherwise typical of the enclosing scale-leaved clade. Consequently, Huncocladus is interpreted as a relative of Phyllocladus , possibly belonging to its stem group. This view is supported by a phylogenetic analysis of Podocarpaceae, which recovers Huncocladus as sister to Phyllocladus within the here-termed phyllocladoid clade (Phyllocladus + Huncocladus). Huncocladus laubenfelsii is the first macrofossil record of the phyllocladoid lineage in South America or anywhere in the western hemisphere, vastly extending its historical range and constituting an additional lineage shared between Eocene Patagonia and extant and extinct Australasian and South-east Asian rainforests. The disappearance of phyllocladoids from South America adds to the general extinction pattern described previously for southern hemisphere Podocarpaceae, associated with the family's low drought tolerance in the face of climate change (i.e. aridification). Huncocladus is the oldest record of the phyllocladoids, and it represents a new reference point for temporal calibration and biogeographic inference for the evolution of conifers and Australasian rainforests. [ABSTRACT FROM AUTHOR]

The idea that South America was an island continent over most of the Cenozoic, during which its unusual mammalian faunas evolved in isolation, is outstandingly influential in biogeography. Although large numbers of recent fossil discoveries and related advances require that the original isolation concept be significantly modified, it is still repeated in much current literature. The persistence of the idea inspired us to present here an integrated paleobiogeographic account of mammals, reptiles, and plants from the Jurassic to the Paleogene of Patagonia, which has by far the richest fossil record on the continent. All three groups show distribution patterns that are broadly consistent with South America's long separation history, first from Laurasia by the Late Jurassic, then from Africa and India-Madagascar during the late Early Cretaceous, and finally from Antarctica and Australia during the early-middle Eocene, after which "isolation" finally commenced. We highlight areas of promising future research and provide an updated view of South American isolation. [ABSTRACT FROM AUTHOR]

We present a whole-plant concept for a genus of voltzialean conifers on the basis of compression/impression and permineralized material from the Triassic of Antarctica. The reconstruction of the individual organs is based on a combination of organic connections, structural correspondences, similarities in cuticles and epidermal morphologies, co-occurrence data, and ex situ palynology. The affiliated genera of organs include trunks, branches, and roots (Notophytum); strap-shaped leaves with parallel venation {Heidiphyllum compressions and permineralized Notophytum leaves); seed cones (Telemachus and Parasciadopitys); pollen cones (Switzianthus); and bisaccate pollen of Alisporites type. Structural similarities lead us to suggest that Parasciadopitys is the permineralized state of a Telemachus cone and should be treated as a junior synonym. Biotic interactions involving the reconstructed conifer genus include plant-insect interactions (oviposition by Odonata) and not less than five different types of plant-fungal interactions, including two distinct endomycorrhizal associations, two probable seed parasites, and epiphyllous fungi. A representative whole plant is reconstructed as a 10-15-m-tall, seasonally deciduous forest tree with a vertical, narrow-conical crown shape. We interpret these Telemachus trees as the dominant components of peat-forming conifer swamps, forest bogs, and immature bottomland vegetation in the Triassic high-latitude river basins of southern Gondwana. In architecture, growth habit, and many ecological characteristics, the Telemachus conifers appear to be comparable to extant larch (Larix). Owing to the large amount and often exquisite preservation of the material, this conceptual whole-plant genus represents one of the most completely reconstructed ancient conifer taxa to date. [ABSTRACT FROM AUTHOR]

A Middle-Late Jurassic fossil plant assemblage is described from the Bahía Laura Complex at the Laguna Flecha Negra locality, Santa Cruz Province. The fossil assemblage is autochthonous, preserved in volcaniclastic sediments in the fringes of a geothermal landscape. Taxonomic study of the palaeoflora revealed 17 taxa. The recognized species have been previously described in Jurassic localities of Gondwana and illustrate the diversity of plant communities that lived in a volcanic setting. The dominant elements of this flora are microphyllous conifers of the families Araucariaceae and Cheirolepidiaceae. Fossil leaves of Cycadeoidales co-dominate the community. There is a low diversity and abundance of ferns. Composition of the plant community is compared to coetaneous floras of the Bahía Laura Complex to analyse geographical variations in the diversity of Middle-Late Jurassic assemblages of Santa Cruz Province, and a relative uniformity is recognized. Forest landscapes were dominated by conifer trees, with cycadeoids as small trees or shrubs. The herbaceous understory was dominated by fern communities with low species diversity; Equisetales and Isoetales appeared as subordinated elements. Microphyllous conifers and cycadophytes, as well as a low diversity of ferns, are indicative of relatively dry weather. • New Middle-Late Jurassic megaflora is described for Patagonia Argentina. • Forest landscapes appear to be dominated by conifer trees and small cycads. • Megafloras of the Bahía Laura Complex are analysed and compared. • Climatic signature of megafloras indicate dryer weather than the Late Triassic. [ABSTRACT FROM AUTHOR]

Premise of research. Well-preserved Triassic plant fossils from Antarctica yield insights into the physiology of plant growth under the seasonal light regimes of warm polar forests, a type of ecosystem without any modern analogue. Among the many well-known Triassic plants from Antarctica is the enigmatic Petriellaea triangulata, a dispersed seedpod structure that is considered a possible homologue of the angiosperm carpel. However, the morphology and physiology of the plants that produced these seedpods have so far remained largely elusive. Methodology. Here, we describe petriellalean stems and leaves in compression and anatomical preservation that enable a detailed interpretation of the physiology and ecology of these plants. Pivotal results. Our results indicate that the Petriellales were diminutive, evergreen, shade-adapted perennial shrubs that colonized the understory of the deciduous forest biome of polar Gondwana. This life form is very unlike that of any other known seed-plant group of that time. By contrast, it fits remarkably well into the "dark and disturbed" niche that some authors considered to have sheltered the rise of the flowering plants some 100 Myr later. Conclusions. The hitherto enigmatic Petriellales are now among the most comprehensively reconstructed groups of extinct seed plants and emerge as promising candidates for elucidating the mysterious origin of the angiosperms. [ABSTRACT FROM AUTHOR]