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See detailComposition and dynamics of the great Phanerozoic Evolutionary Floras
Cleal, Christopher J.; Cascales - Miñana, Borja ULg

in Lethaia (2014), 47(4), 469-484

Factor analysis of a data set representing the global distribution of vascular plant families through time shows the broad pattern of vegetation history can be explained in terms of five Evolutionary ... [more ▼]

Factor analysis of a data set representing the global distribution of vascular plant families through time shows the broad pattern of vegetation history can be explained in terms of five Evolutionary Floras. The Rhyniophytic (=Eotrachyophytic) Flora represents the very earliest (Silurian and earliest Devonian) vascular plants, notably the Rhyniophytopsida. The Eophytic Flora represents the early (Early-Middle Devonian) mainly homosporous land plants, notably the Zosterophyllopsida, Trimerophytopsida and early Lycopsida. The Palaeophytic Flora represents the Late Devonian and Carboniferous vegetation, which saw the introduction of heterospory among the spore producing plants and of early gymnosperms. The Mesophytic Flora first appeared in the Late Carboniferous and Permian macrofossil record, although there is palynological evidence of these plants having grown earlier in extra-basinal habitats and was dominated by gymnosperms with more modern affinities. The Cenophytic Flora that first appeared during Cretaceous times was overwhelmingly dominated by angiosperms. The end-Devonian, end-Triassic and end-Cretaceous mass-extinction events recognized in the marine fossil record had little impact on the diversity dynamics of these Evolutionary Floras. Rather, the changes between floras mainly reflect key evolutionary innovations such as heterospory, ovules and angiospermy. [less ▲]

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See detailDiversity dynamics of Zosterophyllopsida
Cascales - Miñana, Borja ULg; Meyer-Berthaud, Brigitte

in Lethaia (2014), 47(2), 205-215

The Zosterophyllopsida were major contributors to the diversification of early land plants. We present the first detailed analysis of the diversity dynamics of these plants from an updated database of all ... [more ▼]

The Zosterophyllopsida were major contributors to the diversification of early land plants. We present the first detailed analysis of the diversity dynamics of these plants from an updated database of all currently recognized zosterophyllopsid species. A set of quantitative methods classically used in palaeodiversity studies was applied to two data sets. The first one, 'Zosterophyllopsida sensu stricto', corresponds to the clade identified by Hao & Xue (The Early Devonian Posongchong Flora of Yunnan. (2013), Science Press). In the second, called 'Zosterophyllopsida sensu lato', barinophytalean-type plants and taxa for which zosterophyllopsid affinities are suspected are added. The number of localities is used to explore sampling bias. Results show that sampling effect is minimal for the Early Devonian. For this time interval, both data sets record consistent patterns of changes suggesting that, whatever their affinities, all taxa included in the Zosterophyllopsida sensu lato show similar evolutionary trends. The diversity dynamics of zosterophyllopsids are characterized by a radiation during the Lochkovian, maximal values in the Pragian and a decline starting in the Emsian. The proportion of zosterophyllalean taxa with terminal sporangia is high until the Late Lochkovian when gosslingialean taxa without terminal sporangia evolved. During the Middle and Late Devonian, when diversity patterns are strongly affected by sampling, zosterophyllopsid diversity is low and characterized by a high proportion of barinophytacean and gosslingialean taxa, the latter becoming extinct in the Early Frasnian. © 2013 The Lethaia Foundation. [less ▲]

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See detailPlant fossil record and survival analyses
Cascales - Miñana, Borja ULg; Cleal, Christopher J.

in Lethaia (2012), 45(1), 71-82

Survival analysis is a classic palaeobiological method widely used on the animal fossil record. This study reports the first application of survivorship analyses on the plant fossil record from a global ... [more ▼]

Survival analysis is a classic palaeobiological method widely used on the animal fossil record. This study reports the first application of survivorship analyses on the plant fossil record from a global viewpoint and provides a new comparative approach of this methodology. The results reveal three important plant extinction events in the history of plant life at a global scale. The results also clearly suggest that the origination events are more intensive than extinction processes and that the origination moment of several lineages of vascular plants is an important factor that conditions their longevity. This study supports the general idea that vascular plants tended to be less affected by the environmental changes that caused mass extinction in other groups of organisms. □Extinction events, fossil record, survival patterns, taxonomic survivorship curves, vascular plants. © 2011 The Authors, Lethaia © 2011 The Lethaia Foundation. [less ▲]

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See detailInferring internal anatomy from the trilobite exoskeleton: the relationship between frontal auxiliary impressions and the digestive system
Lerosey-Aubril, Rudy; Hegna, Thomas; Olive, Sébastien ULg

in Lethaia (2011), 44(2),

The digestive system of trilobites is rarely preserved. As a result, many aspects of its organization remain unknown. Fortunately, the exoskeleton sometimes preserves evidence of soft-tissue attachment ... [more ▼]

The digestive system of trilobites is rarely preserved. As a result, many aspects of its organization remain unknown. Fortunately, the exoskeleton sometimes preserves evidence of soft-tissue attachment sites that can be used to infer internal anatomy. Among them are the frontal auxiliary impressions (FAIs), probable soft-tissue insertion sites located on the fronto-median glabellar lobe of some trilobites. FAIs are herein described in the Carboniferous trilobite Phillipsia belgica Osmo´ lska 1970 – representing the only known example of such structures in the Proetida and their youngest occurrence. A taphonomic scenario is proposed to explain their variable preservation. Although particularly common in the Phacopina, FAIs or FAI-like structures are also found in several orders that differ greatly. Comparisons with modern analogues suggest that FAIs might represent attachment sites for extrinsic muscles associated with a differentiated crop within the foregut. A review of purported remains of the trilobite digestive system indicates that it usually consisted of a tube-like tract flanked by a variable number of metamerically paired diverticulae. Its anterior portion is not particularly individualized, except in a few specimens that might hint at the presence of a crop. This differentiation of a crop might have constituted a secondarily evolution of the foregut in trilobites, occurring independently in different clades. Accompanied by a strengthening of associated extrinsic muscles, this modification of the foregut might explain the presence of more conspicuous muscle insertion sites on the glabella. Study of FAIs might therefore provide new data on the anatomy of the foregut in trilobites and evidence of diverse feeding habits. [less ▲]

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See detailTrends and patterns in the evolution of vascular plants: Macroevolutionary implications of a multilevel taxonomic analysis
Cascales - Miñana, Borja ULg; Muñoz-Bertomeu, Jesús; Ros, Roc et al

in Lethaia (2010), 43(4), 545-557

Studying the macroevolutionary patterns of vascular plants from the Silurian to the present-day provides a global record of plant life history. Evolutionary rates (origination, extinction and ... [more ▼]

Studying the macroevolutionary patterns of vascular plants from the Silurian to the present-day provides a global record of plant life history. Evolutionary rates (origination, extinction and diversification) for families, orders, classes and divisions were analysed, as was abundance and richness for 21 time intervals. An accumulative analysis, based on the total plant fossil record, the accumulated extinctions and relative diversity, was also carried out. The diversification rate shows a uniquely constant and progressive reduction from the end of the Carboniferous to the Permian when the lowest values are registered. Very small peaks seem to reflect Cretaceous extinction for families. At family level, only two time intervals present higher extinctions, than originations. Richness and accumulative analyses reveal that only 32% of the families analysed became extinct, and that approximately 90% of them disappeared at the end of the Palaeozoic. Our results indicate that plants did not undergo mass extinction events in the 'big five' sense, but rather, mass ecological reorganization the absence of important extinction events or evolutionary innovations producing diversification patterns without abrupt changes. Diversification, evolutionary, extinction, fossil record, innovations, radiation, vascular plants. © 2010 The Authors, Journal compilation © 2010 The Lethaia Foundation. [less ▲]

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See detailPredatory boreholes in Tournaisian (Lower Carboniferous) spiriferid brachiopods
Mottequin, Bernard ULg; Sevastopulo, George

in Lethaia (2009), 42

A brachiopod fauna from the uppermost part of the Tournaisian Tournai Formation (Belgium) contains an undetermined species of Crurithyris (Spiriferida, Ambocoeliidae), which displays numerous bored shells ... [more ▼]

A brachiopod fauna from the uppermost part of the Tournaisian Tournai Formation (Belgium) contains an undetermined species of Crurithyris (Spiriferida, Ambocoeliidae), which displays numerous bored shells. About 8% of the 432 specimens with conjoined valves display single, small (≤ 1 mm) boreholes, which are smooth-sided, cylindrical or weakly conical, circular to slightly elliptical in plan view, perpendicular to the shell surface and generally complete. Of the 35 bored articulated specimens, 27 were drilled on the ventral valve. Most of the boreholes are located in the posterior half of the shell, and no case of edge-drilling has been observed. The boreholes were drilled by a predator, or possibly a parasite, which selected individuals greater than 2.5 mm long. Crurithyris sp. may have represented an attractive (in terms of energy cost) and easy target for a small-sized predator because of its thin shell and ornament of minute spines. [less ▲]

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See detailSphinxiocarpon, a new name for Sphinxia Li, Hilton & Hemsley, 1997 - not Reid & Chandler, 1933
Wang, Qi; Xue, Jinzhuang; Prestianni, Cyrille ULg

in Lethaia (2007), 40(4), 393-393

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