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\"When Wally West, the adolescent nephew of the Flash's fiancee accidentally gained powers of superspeed, he became the Scarlet Speedster's sidekick. Growing up as his hero's protege, Kid Flash had a childhood of amazing action and adventure. But on the day that The Flash died, Wally's carefree adolescence abruptly ended and his life as an adult began. THE FLASH BY MARK WAID BOOK ONE looks back at Wally's earliest days as the Kid Flash and explores the gamut of his emotions and experiences from his first day as a child hero to his succession of Barry Allen as the new Flash. A journey full of humor and drama, this story shows just how much Wally West loves being the fastest man alive\"-- Provided by publisher.

The spiny-finned teleost fishes (Acanthomorpha) include nearly one-third of all living vertebrate species and assume a bewildering array of bodyplans, but the macroevolutionary assembly of modern acanthomorph biodiversity remains largely unexplored. Here, I reconstruct the trajectory of morphological diversification in this major radiation from its first appearance in the Late Cretaceous to the Miocene using a geometric morphometric database comprising more than 600 extinct species known from complete body fossils. The anatomical diversity (disparity) of acanthomorphs is low throughout the Cretaceous, increases sharply and significantly in the wake of the Cretaceous–Palaeogene (K–P) extinction, and shows little change throughout subsequent Cenozoic intervals. This pattern of morphological diversification appears robust to two potential biasing factors: the ‘Lagerstätten effect’, and the non-random segregation of rare and common taxa along phenotypic axes. Dissecting the trajectory of acanthomorph radiation along phylogenetic lines reveals that the abrupt post-extinction increase in disparity is driven largely by the proliferation of trophically diverse modern groups within Percomorpha, a spiny-fin subclade containing more than 15 000 living species and identified as showing a substantially elevated diversification rate relative to background vertebrate levels. A major component of the Palaeogene acanthomorph radiation reflects colonization of morphospace previously occupied by non-acanthomorph victims of the K–P. However, other aspects of morphological diversification cannot be explained by this simple ecological release model, suggesting that multiple factors contributed to the prolific anatomical radiation of acanthomorphs.

Giant suspension feeders such as mysticete whales, basking and whale sharks, and the extinct (indicated by '†') †pachycormiform teleosts are conspicuous members of modern and fossil marine vertebrate faunas. Whether convergent anatomical features common to these clades arose along similar evolutionary pathways has remained unclear because of a lack of information surrounding the origins of all groups of large-bodied suspension feeders apart from baleen whales. New investigation reveals that the enigmatic ray-finned fish †Ohmdenia, from the Lower Jurassic (Toarcian, 183.0–175.6 Ma) Posidonia Shale Lagerstätte, represents the immediate sister group of edentulous †pachycormiforms, the longest lived radiation of large vertebrate suspension feeders. †Ohmdenia bisects the long morphological branch leading to suspension-feeding †pachycormiforms, providing information on the sequence of anatomical transformations preceding this major ecological shift that can be compared to changes associated with the origin of modern mysticetes. Similarities include initial modifications to jaw geometry associated with the reduction of dentition, followed by the loss of teeth. The evolution of largest body sizes within both radiations occurs only after the apparent onset of microphagy. Comparing the fit of contrasting evolutionary models to functionally relevant morphological measurements for whales and fpachycormiform fishes reveals strong support for a common adaptive peak shared by suspension-feeding members of both clades.

Evolution: How flatfish see eye-to-eye The asymmetry of flatfish is an exceptional morphological specialization that arises in development: starting from a symmetrical larva/juvenile, the skull is remodelled so that one eye migrates over the top of the skull to sit next to its fellow on one (or other) side of the animal. The evolutionary origins of this arrangement have been unclear. Matt Friedman re-examined Eocene (47-million-year-old) fossils of the fish Amphistium and describes a new genus that represents the most primitive flatfish known. In these fish, the migrating eye never gets further than the dorsal midline, even in fully adult fishes. This is a graphic example of a transitional form spotted in the fossil record, confirming that the evolution of the specialized flatfish bodyplan was a gradual process. A re-examination of the Eocene fish Amphistium and a description of a new genus prove that they are the most primitive members of the flatfish family. In these fish, the migrating eye never gets farther than the dorsal midline, even in fully adult fishes, providing perhaps the most graphic and dramatic examples known of a transitional form spotted in the fossil record. All adult flatfishes (Pleuronectiformes), including the gastronomically familiar plaice, sole, turbot and halibut, have highly asymmetrical skulls, with both eyes placed on one side of the head. This arrangement, one of the most extraordinary anatomical specializations among vertebrates, arises through migration of one eye during late larval development. Although the transformation of symmetrical larvae into asymmetrical juveniles is well documented 1 , 2 , 3 , 4 , 5 , 6 , 7 , the evolutionary origins of flatfish asymmetry are uncertain 1 , 2 because there are no transitional forms linking flatfishes with their symmetrical relatives 8 , 9 . The supposed inviability of such intermediates gave pleuronectiforms a prominent role in evolutionary debates 10 , 11 , 12 , 13 , 14 , 15 , 16 , leading to attacks on natural selection 11 and arguments for saltatory change 14 , 15 . Here I show that Amphistium and the new genus Heteronectes , both extinct spiny-finned fishes from the Eocene epoch of Europe, are the most primitive pleuronectiforms known. The orbital region of the skull in both taxa is strongly asymmetrical, as in living flatfishes, but these genera retain many primitive characters unknown in extant forms. Most remarkably, orbital migration was incomplete in Amphistium and Heteronectes , with eyes remaining on opposite sides of the head in post-metamorphic individuals. This condition is intermediate between that in living pleuronectiforms and the arrangement found in other fishes. Amphistium and Heteronectes indicate that the evolution of the profound cranial asymmetry of extant flatfishes was gradual in nature.

Fossils of early gnathostomes (or jawed vertebrates) have been the focus of study for nearly two centuries. They yield key clues about the evolutionary assembly of the group's common body plan, as well the divergence of the two living gnathostome lineages: the cartilaginous and bony vertebrates. A series of remarkable new palaeontological discoveries, analytical advances and innovative reinterpretations of existing fossil archives have fundamentally altered a decades-old consensus on the relationships of extinct gnathostomes, delivering a new evolutionary framework for exploring major questions that remain unanswered, including the origin of jaws.

Despite the attention focused on mass extinction events in the fossil record, patterns of extinction in the dominant group of marine vertebrates--fishes--remain largely unexplored. Here, I demonstrate ecomorphological selectivity among marine teleost fishes during the end-Cretaceous extinction, based on a genus-level dataset that accounts for lineages predicted on the basis of phylogeny but not yet sampled in the fossil record. Two ecologically relevant anatomical features are considered: body size and jaw-closing lever ratio. Extinction intensity is higher for taxa with large body sizes and jaws consistent with speed (rather than force) transmission; resampling tests indicate that victims represent a nonrandom subset of taxa present in the final stage of the Cretaceous. Logistic regressions of the raw data reveal that this nonrandom distribution stems primarily from the larger body sizes of victims relative to survivors. Jaw mechanics are also a significant factor for most dataset partitions but are always less important than body size. When data are corrected for phylogenetic nonindependence, jaw mechanics show a significant correlation with extinction risk, but body size does not. Many modern large-bodied, predatory taxa currently suffering from overexploitation, such billfishes and tunas, first occur in the Paleocene, when they appear to have filled the functional space vacated by some extinction victims.

High-resolution scans of fossilized fish skulls suggest that modern ray-finned fishes originated later than previously thought and necessitate reconsideration of the evolution of this major vertebrate group. Untying ropefish origins The bichirs ( Polypterus ), also known as ropefish, are a relic group of very primitive fishes now confined to freshwater habitats in Africa. With their combination of lobe fins, lungs and thick scales, bichirs have been allied with Devonian lobefins and even amphibians, but it is now generally accepted that they are the living sister group of all other ray-finned fishes (Actinopterygii). However, their fossil record is suspiciously meagre for such a well-armoured fish. It goes back to only the Cretaceous, leaving a very long ghost lineage back to the Devonian, when crown actinopterygians are thought to have evolved. Some have compared bichirs with scanilepiforms, a group of primitive actinopterygians from the Triassic, but the resemblances have been superficial. Now a computed tomography (CT) scan of one of these scanilepiforms, Fukangichthys , and comparisons with related forms, shows that bichirs do indeed belong to this group. A revised actinopterygian phylogeny bumps the origins of bichirs upwards from the Devonian to the Triassic, with the implication that crown actinopterygians also evolved later, in the Carboniferous rather than the Devonian. Modern ray-finned fishes (Actinopterygii) comprise half of extant vertebrate species and are widely thought to have originated before or near the end of the Middle Devonian epoch (around 385 million years ago) 1 , 2 , 3 , 4 . Polypterids (bichirs and ropefish) represent the earliest-diverging lineage of living actinopterygians, with almost all Palaeozoic taxa interpreted as more closely related to other extant actinopterygians than to polypterids 5 , 6 , 7 , 8 , 9 , 10 . By contrast, the earliest material assigned to the polypterid lineage is mid-Cretaceous in age (around 100 million years old) 11 , implying a quarter-of-a-billion-year palaeontological gap. Here we show that scanilepiforms, a widely distributed radiation from the Triassic period (around 252–201 million years ago), are stem polypterids. Importantly, these fossils break the long polypterid branch and expose many supposedly primitive features of extant polypterids as reversals. This shifts numerous Palaeozoic ray-fins to the actinopterygian stem, reducing the minimum age for the crown lineage by roughly 45 million years. Recalibration of molecular clocks to exclude phylogenetically reassigned Palaeozoic taxa results in estimates that the actinopterygian crown lineage is about 20–40 million years younger than was indicated by previous molecular analyses 1 , 2 , 3 , 4 . These new dates are broadly consistent with our revised palaeontological timescale and coincident with an interval of conspicuous morphological and taxonomic diversification among ray-fins centred on the Devonian–Carboniferous boundary 12 , 13 , 14 . A shifting timescale, combined with ambiguity in the relationships of late Palaeozoic actinopterygians, highlights this part of the fossil record as a major frontier in understanding the evolutionary assembly of modern vertebrate diversity.

A new analysis of a 415-million-year-old fossil fish head originally described as from an early osteichthyan (bony fish) puts it instead as the sister group of the gnathosomes (jawed vertebrates), and suggests that the extinct acanthodians were relatives of cartilaginous fishes. Fishing for jawed-vertebrate origins The early evolution of the jawed vertebrates (gnathostomes) is a hot topic in palaeontology. Here Brazeau and colleagues use computed tomography scanning to take a new look at a 415-million-year-old braincase and skull roof from the Early Devonian of Siberia, originally described in 1992 by Hans-Peter Schultze as coming from an early osteichthyan (bony fish). They find that the underlying braincase shows a mixture of features seen separately in osteichthyans, chondrichthyans or in neither. Phylogenetic analysis places the fish at base of the gnathostomes and suggests that the enigmatic acanthodians — a wholly extinct group of fossil fishes — were relatives of cartilaginous fishes. The phylogeny of Silurian and Devonian (443–358 million years (Myr) ago) fishes remains the foremost problem in the study of the origin of modern gnathostomes (jawed vertebrates). A central question concerns the morphology of the last common ancestor of living jawed vertebrates, with competing hypotheses advancing either a chondrichthyan- 1 , 2 , 3 or osteichthyan-like 4 , 5 model. Here we present Janusiscus schultzei gen. et sp. nov., an Early Devonian (approximately 415 Myr ago) gnathostome from Siberia previously interpreted as a ray-finned fish 6 , which provides important new information about cranial anatomy near the last common ancestor of chondrichthyans and osteichthyans. The skull roof of Janusiscus resembles that of early osteichthyans, with large plates bearing vermiform ridges and partially enclosed sensory canals. High-resolution computed tomography (CT) reveals a braincase bearing characters typically associated with either chondrichthyans (large hypophyseal opening accommodating the internal carotid arteries) or osteichthyans (facial nerve exiting through jugular canal, endolymphatic ducts exiting posterior to the skull roof) but lacking a ventral cranial fissure, the presence of which is considered a derived feature of crown gnathostomes 7 , 8 . A conjunction of well-developed cranial processes in Janusiscus helps unify the comparative anatomy of early jawed vertebrate neurocrania, clarifying primary homologies in ‘placoderms’, osteichthyans and chondrichthyans. Phylogenetic analysis further supports the chondrichthyan affinities of ‘acanthodians’, and places Janusiscus and the enigmatic Ramirosuarezia 9 in a polytomy with crown gnathostomes. The close correspondence between the skull roof of Janusiscus and that of osteichthyans suggests that an extensive dermal skeleton was present in the last common ancestor of jawed vertebrates 4 , but ambiguities arise from uncertainties in the anatomy of Ramirosuarezia . The unexpected contrast between endoskeletal structure in Janusiscus and its superficially osteichthyan-like dermal skeleton highlights the potential importance of other incompletely known Siluro-Devonian ‘bony fishes’ for reconstructing patterns of trait evolution near the origin of modern gnathostomes.