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Several new specimens of Protoischnurus axelrodorum Carvalho and Lourenco and Araripescorpius ligabuei Campos from the Crato Formation, Brazil, are described. The preservation and recognition of new morphological features allows a re-diagnosis of both species and a modification of their familial placement. Protoischnurus axelrodorum is the oldest species belonging to the scorpionoid family Hemiscorpiidae Pocock (= Ischnuridae Simon; = Liochelidae Fet and Bechly) and the first Cretaceous record.

• Read more about Higher Systematics of Scorpions from the Crato Formation, Lower Creataceous of Brazil

Trilobites, a dominant component of marine faunas during the Cambrian and Ordovician and which survived until the end of the Permian (542-251 Ma) have been used in many macroevolutionary analyses. Here, we use a discovery curve to document the sampling history of trilobites, which we consider a proxy for Palaeozoic faunas in general. At higher taxonomic ranks, orders, suborders and superfamilies, the fossil record has been completely sampled, while the family rank also shows a high level of sampling completeness, having reached an asymptote in 1970.

• Read more about The Effects of Sampling Bias on Palaeozoic Faunas and Implications for Macroevolutionary Studies

The Cambrian index fossil Treptichnus pedum is reported from the Puerto Blanco Formation near Pitiquito, Sonora, Mexico, and new occurrences of the Neoproterozoic index fossil Cloudina are reported from the underlying La Cienega Formation. Considered together, these fossils constrain the location of the Ediacaran/Cambrian boundary in Mexico.

• Read more about Ediacaran and Cambrian Index Fossils from Sonora, Mexico

Vetulicolians have variously been considered to be unusual arthropods, stem-group deuterostomes or relatives of the tunicates. They are known from a number of Cambrian Lagerstatten, and are particularly diverse in the Chengjiang biota of Yunnan Province, China. We recognize two classes, Vetulicolida and Banffozoa, which together form a monophyletic group. Within the Chinese collections we also identify two new species and recognize one new genus: Vetulicola monile sp. nov. and Bullivetula variola gen. et sp. nov.

• Read more about The Systematics and Phylogenetic Relationships of Vetulicolians

In this paper, I examine the dynamics of species richness in a model system in which multiple species compete in a metacommunity (multiple patches linked by dispersal). Patches lie along an environmental gradient, and new species are introduced into the system by speciation of existing species. This model is used to explore how the ecological similarity of species influences the patterns in community structure that result and to determine whether patterns in fossil and systematics data may be signatures for different types of community structure.

• Read more about The Macroevolutionary Consequences of Ecological Differences Among Species

Scale and hierarchy must be incorporated into any conceptual framework for the study of macroevolution, i.e. evolution above the species level. Expansion of temporal and spatial scales reveals evolutionary patterns and processes that are virtually inaccessible to, and unpredictable from, short-term, localized observations.

• Read more about Scale and Hierarchy in Macroevolution

The distribution of organic forms is clumpy at any scale from populations to the highest taxonomic categories, and whether considered within clades or within ecosystems. The fossil record provides little support for expectations that the morphological gaps between species or groups of species have increased through time as it might if the gaps were created by extinction of a more homogeneous distribution of morphologies.

• Read more about Desparity: Morphological Pattern and Developmental Context

Whether macrovolution is reducible to microevolution is one of the persistent debates in evolutionary biology. Although the concept of emergence is important to answering this question, it has not been extensively discussed within palaeobiology. A taxonomy of emergence concepts is presented to clarify the ways in which emergence relates to this debate.

• Read more about Is Macroevolution More Than Successive Rounds of Mircoevolution?

The fossil record documents two mutually exclusive macroevolutionary modes separated by the transitional Ediacaran Period. Despite the early appearance of crown eukaryotes and an at least partially oxygenated atmosphere, the pre-Ediacaran biosphere was populated almost exclusively by microscopic organisms exhibiting low diversity, no biogeographical partitioning and profound morphological/evolutionary stasis. By contrast, the post-Ediacaran biosphere is characterized by large diverse organisms, bioprovinciality and conspicuously dynamic macroevolution.

• Read more about Macroevolution and Macroecology Through Deep Time

The long-term diversification of life probably cannot be modelled as a simple equilibrial process: the time scales are too long, the potential for exploring new ecospace is too large and it is unlikely that ecological controls can act at global scales. The sum of many clade expansions and reductions, each of which happens according to its own dynamic, probably approximates more a damped exponential curve when translated into a global-scale species diversification curve.

• Read more about How Did Life Become So Diverse? The Dynamics of Diversifiction According to the Fossil Record and Molecular Phylogenetics