Terrestrialization in the Ordovician

This contribution reviews the evidence for terrestrial organisms during the Ordovician (microbial, land plant, fungal, animal) and for the nature of the terrestrial biota. The evidence regarding the origin and early diversification of land plants combines information from both fossils and living organisms. Extant plants can be utilized in: (1) phylogenetic analyses to provide evidence for the nature of the algal–land plant transition and the characteristics of the most basal land plants; (2) evolutionary developmental biology studies of the characters that enabled the invasion of the land; (3) molecular clock analysis to provide evidence regarding timing of the origin and diversification of land plants. We conclude that the Ordovician was a critical period during the terrestrialization of planet Earth that witnessed the transition from a microbial terrestrial biota to one dominated by a vegetation of the most basal land plants

Fossil biogeography: a new model to infer dispersal, extinction and sampling from palaeontological data.

Methods in historical biogeography have revolutionized our ability to infer the evolution of ancestral geographical ranges from phylogenies of extant taxa, the rates of dispersals, and biotic connectivity among areas. However, extant taxa are likely to provide limited and potentially biased information about past biogeographic processes, due to extinction, asymmetrical dispersals and variable connectivity among areas. Fossil data hold considerable information about past distribution of lineages, but suffer from largely incomplete sampling. Here we present a new dispersal-extinction-sampling (DES) model, which estimates biogeographic parameters using fossil occurrences instead of phylogenetic trees. The model estimates dispersal and extinction rates while explicitly accounting for the incompleteness of the fossil record. Rates can vary between areas and through time, thus providing the opportunity to assess complex scenarios of biogeographic evolution. We implement the DES model in a Bayesian framework and demonstrate through simulations that it can accurately infer all the relevant parameters. We demonstrate the use of our model by analysing the Cenozoic fossil record of land plants and inferring dispersal and extinction rates across Eurasia and North America. Our results show that biogeographic range evolution is not a time-homogeneous process, as assumed in most phylogenetic analyses, but varies through time and between areas. In our empirical assessment, this is shown by the striking predominance of plant dispersals from Eurasia into North America during the Eocene climatic cooling, followed by a shift in the opposite direction, and finally, a balance in biotic interchange since the middle Miocene. We conclude by discussing the potential of fossil-based analyses to test biogeographic hypotheses and improve phylogenetic methods in historical biogeography

First record of the mangrove palm Nypa from the northeastern Ebro Basin, Spain : with taphonomic criteria to evaluate the drifting duration

Fossil fruits pertaining to the mangrove palm genus Nypa Steck, (Arecaceae, Arecales) were collected from a new plant-bearing assemblage in the Arguis Formation (Fm.), northeastern Ebro Basin (Arguis, Huesca Province, Spain). This formation is Bartonian to early Priabonian in age and comprises pro-delta and carbonate platform deposits. The new assemblage consists of nine specimens of fossil Nypa fruits and one monocotyledon leaf fragment. Over half of these fossil fruits are nearly-complete (i.e. with preserved mesocarps) while the other represent endocarps. From the point of view of morphology and size they resemble other European records of this genus. The type of remain preserved (fruits or endocarps), presence of abrasion, Teredo borings and sedimentary facies provide criteria to infer contrasting lengths of transport (drifting). However, they indicate in all cases that these fossil fruits were afloat in seawater for a considerable time. The discovery of Nypa fruits suggests a tropical-subtropical climate in the area, as well as the presence of a coastal environment and littoral forests during deposition. This interpretation corroborates previous findings from the nearby Eocene outcrops of the Catalan Central Depression (Eastern Pyrenees range)

A factor analysis approach to modelling the early diversification of terrestrial vegetation

peer reviewedData from a new comprehensive macrofossil-based compilation of early plant genera are analyzed via a Q-mode factor analysis. This compilation ranges from the Silurian to the earliest Carboniferous and illustrates the key vegetation changes that took place during the configuration of early terrestrial ecosystems. Results reveal that four factors can be used to explain more than 90% of the variance in the data. These factors are interpreted as the major phases of the early land plant evolution: a first Eotracheophytic flora (Silurian-Lochkovian) dominated by basal eutracheophytes and rhyniophytoids, an early Eophytic Flora (Early Devonian) dominated by zosterophylls, a transitional late Eophytic Flora (Middle Devonian-earliest Carboniferous) dominated by lycopsids and cladoxylopsids, and finally, the earliest phase of the Palaeophytic Flora (Late Devonian-earliest Carboniferous) dominated by the first seed plants. These floras present different but complementary diversity patterns, which help us to understand the overall trajectory of changes in plant diversity. Results further show how the maximum peaks of diversity appear linked to the rise of each new flora but, interestingly, these diversifications are not associated with any exponential declines of the previously dominant one. This new four-phase diversification model reflects the early steps of Earth's greening

Colonial palynomorphs from the Upper Ordovician of north-eastern Iran : ‘thalli’, coenobial Chlorophyceae (Hydrodictyaceae) or cyanobacteria?

This study documents ‘colonial’ palynomorphs from the Upper Ordovician Ghelli Formation of north-eastern Iran. The aggregates of organic-walled microfossils come from the Katian Armoricochitina nigerica–Ancyrochitina merga chitinozoan biozones of this formation. The ‘colonial’ microfossils can be classified as acritarchs and/or cryptospores, but they cannot be attributed to a particular biological group. Some specimens resemble ‘thalli’ of putative spores, such as Grododowon orthogonalis Strother 2017. Other clusters may suggest an affinity to green algal groups, in particular to colonial chlorophyceaen algae, most probably belonging to Hydrodictyaceae. Some specimens also show morphological similarities with cyanobacterial groups. There is so far no evidence to relate these ‘colonial’ palynomorphs to primitive land plants, but we hypothesise that they were possibly produced by ancient green algal lineages with some kind of subaerial existence

FIRST PALAEOBOTANICAL DATA FROM THE UPPER DEVONIAN BOLLONCILLOS FORMATION (ZARAGOZA PROVINCE, NE IBERIAN PENINSULA)

peer reviewe

Welcome to papers from the Second International Meeting of Agora Paleobotanica

Second International Congress of Agora PaleobotanicaInternational audienceThis special issue of Historical Biology includes research papers from the Second International Congress of Agora Paleobotanica. This event was entitled ‘A Congress in the Countryside’ and was held at the Interpretation Center of Rock Art of Ariño (Teruel Province), Spain, during 9–13 July 2013 (Figure 1), thanks to the support provided by José Royo Lasarte and the mayor of Ariño, Joaquin Noé Serrano. This was the first time this congress was held in Spain and was organised by the Group of Iberian Palaeobotan