A new fossil Acmopyle with accessory transfusion tissue and potential reproductive buds: Direct evidence for ever-wet rainforests in Eocene Patagonia.

PREMISE: Acmopyle (Podocarpaceae) comprises two extant species from Oceania that are physiologically restricted to ever-wet rainforests, a confirmed fossil record based on leaf adpressions and cuticles in Australia since the Paleocene, and a few uncertain reports from New Zealand, Antarctica, and South America. We investigated fossil specimens with Acmopyle affinities from the early Eocene Laguna del Hunco site in Patagonia, Argentina. METHODS: We studied 42 adpression leafy-shoot fossils and included them in a total evidence phylogenetic analysis. RESULTS: Acmopyle grayae sp. nov. is based on heterophyllous leafy shoots with three distinct leaf types. Among these, bilaterally flattened leaves uniquely preserve subparallel, linear features that we interpret as accessory transfusion tissue (ATT, an extra-venous water-conducting tissue). Some apical morphologies of A. grayae shoots are compatible with the early stages of ovuliferous cone development. Our phylogenetic analysis recovers the new species in a polytomy with the two extant Acmopyle species. We report several types of insect-herbivory damage. We also transfer Acmopyle engelhardti from the middle Eocene Río Pichileufú flora to Dacrycarpus engelhardti comb. nov. CONCLUSIONS: We confirm the biogeographically significant presence of the endangered West Pacific genus Acmopyle in Eocene Patagonia. Acmopyle is one of the most drought-intolerant genera in Podocarpaceae, possibly due to the high collapse risk of the ATT, and thus the new fossil species provides physiological evidence for the presence of an ever-wet rainforest environment at Laguna del Hunco during the Early Eocene Climatic Optimum.

The skull of Sanajeh indicus, a Cretaceous snake with an upper temporal bar, and the origin of ophidian wide-gaped feeding

Recent phylogenetic analyses differ in their interpretations of the origin and interrelationships of snakes, resulting in polarized views of snake ecology, habit and acquisition of features associated with wide-gaped feeding (macrostomy). Here, we report a new specimen of the Late Cretaceous nest predator Sanajeh indicus that helps to resolve the origin of macrostomy. The new specimen preserves an ossified upper temporal bar and a posteriorly expanded otooccipital region that lacks a free-ending supratemporal bone and retains a lizard-like palatomaxillary arch that allows limited movements during swallowing. Phylogenetic analyses of a large-scale total evidence dataset resolve Sanajeh near the base of Pan-Serpentes, as the sister group of Najash, Dinilysia and crown-group Serpentes. The Cretaceous Tetrapodophis and Coniophis represent the earliest-diverging members of Pan-Serpentes. The Cretaceous hindlimbed pachyophiids and Cenozoic Australian ‘madtsoiids’ are inside crown Alethinophidia, whereas mosasaurs are recovered invariably within anguimorphs. Our results suggest that the wide-gape condition in mosasaurs and snakes might have evolved independently, as functionally distinct mechanisms of prey ingestion. The intermediate morphology preserved in Sanajeh indicates that ingestion of large prey items (macrophagy) preceded wide-gaped, unilateral feeding (macrostomy), which appeared 35 Myr later, in the common ancestor of pachyophiids, Cenozoic Australian ‘madtsoiids’ and alethinophidians.

Eocene Araucaria Sect. Eutacta from Patagonia and floristic turnover during the initial isolation of South America.

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.

Resolving the overall pattern of marattialean fern phylogeny.

PREMISE OF THE STUDY: Recent clarification of the distribution of Marattiales through time provides the impetus for "total evidence" phylogenetic analyses of a major fern clade with a rich fossil record. These analyses serve as empirical tests for results from systematic analyses of living species and also of the belief that relationships among living species accurately reflect the overall pattern of phylogeny for clades with an extensive fossil record and a large percentage of extinction. METHODS: Species of living and fossil Marattiaceae are analyzed employing a "total evidence approach" via maximum parsimony. Analyses were conducted using TNT implemented through WinClada. KEY RESULTS: Systematic analyses of living species and of living + extinct species provide roughly concordant topologies for living taxa. However, living species of Marattiales are only one component of a much larger clade with two major subclades. One consists of Psaroniaceae and extends through time to at least the Early Cretaceous. The other consists of Marattiaceae and includes all living species. Various analyses support the generic-level clades of living species from earlier analyses, but the arrangement of such clades varies from analysis to analysis. CONCLUSIONS: Marattiales is a monophyletic group that is extremely common in late Paleozoic and early Mesozoic deposits, with a stem group Psaroniaceae and a crown group Marattiaceae. Because Marattiaceae represents only a small component of overall marattialean diversity, living species alone neither account for evolutionary changes within the clade over time, nor accurately reflect the overall pattern of marattialean fern phylogeny.

Phylogenetic investigation of the complex evolutionary history of dispersal mode and diversification rates across living and fossil Fagales.

As a primary determinant of spatial structure in angiosperm populations, fruit dispersal may impact large-scale ecological and evolutionary processes. Essential to understanding these mechanisms is an accurate reconstruction of dispersal mode over the entire history of an angiosperm lineage. A total-evidence phylogeny is presented for most fossil fruit and all extant genera in Fagales over its c. 95 million yr history. This phylogeny - the largest of its kind to include plant fossils - was used to reconstruct an evolutionary history directly informed by fossil morphologies and to assess relationships among dispersal mode, biogeographic range size, and diversification rate. Reconstructions indicate four transitions to wind dispersal and seven to biotic dispersal, with the phylogenetic integration of fossils crucial to understanding these patterns. Complexity further increased when more specialized behaviors were considered, with fluttering, gliding, autorotating, and scatter-hoarding evolving multiple times across the order. Preliminary biogeographic analyses suggest larger range sizes in biotically dispersed lineages, especially when pollination mode was held constant. Biotically dispersed lineages had significantly higher diversification rates than abiotically dispersed lineages, although transitions in dispersal mode alone cannot explain all detected diversification rate shifts across Fagales.