Body size is one of the most studied phenotypic attributes because it is biologically important and easily measured. Despite a long history of study, however, the pattern of body-size change in diverse higher taxa over the Phanerozoic remains largely unknown because few relevant data sets span more than a single geological period or provide comprehensive, global coverage. In this study, we measured representative specimens of 3414 brachiopod genera illustrated in the Treatise on Invertebrate Paleontology. We applied these size data to stage-resolved stratigraphic ranges from the Treatise and the Paleobiology Database to develop a Phanerozoic record of trends in brachiopod size. Using a model comparison approach, we find that temporal variation in brachiopod size exhibits two distinct modes—a Paleozoic mode of size increase and a post-Paleozoic mode indistinguishable from a random walk. This transition reflects a change in the identities of the most diverse brachiopod orders rather than a shift in mode within any given order. Paleozoic size increase reflects a small, persistent bias toward the origination of new genera larger than those surviving from the previous stage and is identifiable as a statistically supported trend in three orders representing both Class Strophomenata (Order Productida) and Class Rhynchonellata (orders Atrypida and Spiriferida). Extinction exhibits no consistent bias with respect to size. The shift in evolutionary mode across the end-Permian mass extinction adds to long-standing evidence from studies of diversity and abundance that this biotic catastrophe suddenly and permanently altered the evolutionary history of what was, until that time, the most diverse animal phylum on Earth.

Insect taphonomy is a topic that has drawn interest because of its potential biases on diversity patterns and the ecological information recorded by ancient insect faunas. Other than the onset of common amber fossilization in the Cretaceous, very little is known about long-term trends in the nature and quality of insect preservation and, as a result, the effects of taphonomic biases are poorly constrained. We assembled a database of nearly 7000 Carboniferous–Pliocene insect adpression (compression and impression) species from the primary literature to assess changes in insect taphonomy over time and test biotic and environmental controls on preservation. We grouped the fossils into 10-Myr bins and scored preservation of holotype specimens as either articulated bodies or isolated wings; articulated specimens with a body implied a generally higher quality of preservation. Paleozoic and Triassic insect holotypes are known overwhelmingly from isolated wings (only 12% articulated bodies), but our database shows a significant increase in the percentage preserved as articulated bodies, to more than 70%, beginning about 160 Myr ago in the Late Jurassic. This transition could reflect variations in the robustness of different insect orders and shifts in the taxonomic composition of insect faunas, but all the major orders in the database exhibit significant increases in articulation. Instead, a shift to increased preservation in lacustrine paleoenvironments, which contain a greater proportion of articulated body fossils, explains most of the trend. The pronounced Late Jurassic increase in articulation has implications for evolutionary and ecological reconstructions, for example, suggesting that preserved insect diversity may be biased downward in the earlier part of their history when articulation was poor.

Ecologists and paleontologists alike are increasingly using the fossil record as a spatial data set, in particular to study the dynamics and distribution of geographic range sizes among fossil taxa. However, no attempts have been made to establish how accurately range sizes and range-size dynamics can be preserved. Two fundamental questions are: Can common paleo range-size reconstruction methods accurately reproduce known species’ ranges from locality (i.e., point) data? And, are some reconstruction methods more reliable than others? Here, we develop a methodological framework for testing the accuracy of commonly used paleo range-size reconstruction methods (maximum latitudinal range, maximum great-circle distance, convex hull, and alpha convex hull) in different extinction-related biogeographic scenarios. We use the current distribution of surface water bodies as a proxy for “preservable area,” in which to test the performance of the four methods. We find that maximum great-circle distance and convex-hull methods most reliably capture changes in range size at low numbers of fossil sites, whereas convex hull performs best at predicting the distribution of “victims” and “survivors” in hypothetical extinction scenarios. Our results suggest that macroevolutionary and macroecological patterns in the relatively recent past can be studied reliably using only a few fossil occurrence sites. The accuracy of range-size reconstruction undoubtedly changes through time with the distribution and area of fossiliferous sediments; however, our approach provides the opportunity to systematically calibrate the quality of the spatial fossil record in specific environments and time intervals, and to delineate the conditions under which paleobiologists can reconstruct paleobiogeographical, macroecological, and macroevolutionary patterns over critical intervals in Earth history.

We describe three giant palaeobatrachid fossil tadpoles of the genus Palaeobatrachus (Nieuwkoop-Faber [NF] stages 60–64) from the Miocene of Randecker Maar, Germany. The largest was 150 mm at the beginning of metamorphosis (stage 60), whereas the smallest was 100 mm and approaching the end of metamorphosis (stage 64). In contrast, normal palaeobatrachid tadpoles and their pipid relatives, both extinct and extant, rarely exceed 60 mm in length. We review here both ecological and pathological conditions that are conducive to the development of gigantism in tadpoles. Tadpoles that lack a thyroid gland become exceptionally large and arrest development at early hindlimb stages (NF stages 53–56). However, the advanced metamorphic stages of the giant Palaeobatrachus tadpoles indicate that they were able to metamorphose, and thus were not athyroid. Environmental factors—pond size and permanence, predators, duration of the growing season—may all contribute to tadpole gigantism in certain extant anuran species. We identify suites of ecological features that distinguish extant anurans with large tadpoles from high-latitude and high-altitude permanent lakes in temperate regions (e.g., certain Rana and Telmatobius) from tropical species, such as Pseudis paradoxa, whose tadpoles normally achieve large size in temporary seasonal ponds. The paleoecology of Randecker Maar suggests that Palaeobatrachus tadpoles lived in a permanent semitropical lake, but one with few predators.

Stephen Jay Gould made impressive contributions to macroevolutionary theory; one of the topics in this area that particularly interested him was how to define and recognize species selection. Here we explore how and why Gould's ideas on concepts related to species selection evolved over 30 years, from the punctuated equilibria paper of 1972 to his “Structure of Evolutionary Theory” magnum opus published in 2002. Throughout his career his ideas on species selection shifted between three phases. Initially, Gould favored a definition of species selection that was more descriptive. Later, he came to distinguish between species sorting, which he called species selection in the broad sense, and true species selection, which is tied to the concept of species-level aptations. Finally, he came to view species selection in a broader, more inclusive way, effectively merging the two earlier viewpoints. His ideas on species selection changed over the years because he was trying to square his views on complex concepts like adaptation, natural selection, emergence, and the independence of macroevolutionary theory. Gould's thoughts on species selection not only help to define the history of debate on the concept but also help set a course for the future.

A large body of paleontological literature concerns the importance of ontogeny as a source of morphological variation for evolution; morphologies that appear during one stage of an organism's development are made available for use in another simply by modifying the developmental program. Paleontologists need to know why this occurs, so they can study the process of evolution in extinct animals and so they can discuss the fossil record in terms that are applicable to modern forms. If most cases of heterochrony can be attributed to life-history evolution then the fossil record provides evidence of the nature of selection (in particular the age-specific mortality) that extinct animals experienced. The hypothesis of interest here is that species in which maturity is accelerated will also show generalized morphology and small size, while those with delayed maturity will have more specialized morphology and large size.

Four species of the ostracode genus Cyprideis were studied to determine whether differences in age at maturity are correlated with heterochrony in the expected manner. For each species the changes in size and shape through geological time were evaluated in the statistical context of modern geographic and seasonal variation. Living populations were sampled regularly to detect differences in seasonality and to estimate the duration of development.

Evolution of ontogeny is apparent at the level of species in this group, but it is not simply related to differences in life-history. In comparisons among species, we find evidence of heterochrony where there is no difference in the age at maturity, and a difference in age at maturity where there is no heterochrony. Similarly, three of the four species show the expected positive correlation between size and age at maturity, yet the fourth species is relatively large and matures rapidly. Cyprideis does not support the generalization that life-history evolution causes heterochrony, and casts doubt on the inference of life-history evolution from heterochrony where the data are drawn exclusively from extinct forms.

Fibrous ligament and aragonitic shell material have been found preserved in two specimens of radiolitid rudists [cf. Radiolites angeoides (De Lapeirouse)] from the Lower to Middle Coniacian of Tirol, Austria. The invaginated ligament apparently comprised two torn and overgrown non-functional strings, one in each valve, connected medially by a thin strip of active ligament. The original dimensions of the active ligament have been estimated, for shells of 4 to 5 cm commissural diameter, at 0.58 mm2 cross-sectional area and 1.3 mm length, with the shell closed. Using data on the adductor muscle of Recent oysters and the results of compression tests carried out on samples of oyster fibrous ligament, it is estimated that these radiolitid shells opened less than 1 mm in life; their gaping was highly restricted. This is taken to support the proposal that the expanded mantle margins (principally that of the right, attached valve) were responsible for food particle entrapment, rather than the gills as in most other bivalves. It is suggested that a tentaculate mantle flange was extruded through the narrow gap between the valves during feeding. The pair of pronounced radial bands on the posterior flanks of the shell are interpreted as marking pseudofaecal and faecal ejection sites. Finally, it is speculated that slime (possibly poisonous or foul-tasting) on the mantle tentacles inhibited predators.

The fossil record has been used to show that in some geologic intervals certain traits of taxa may increase their survivability, and therefore that the risk of extinction is not randomly distributed among taxa. It has also been suggested that traits that buffer against extinction in background times do not confer the same resistance during mass extinction events. An open question is whether at any time in geologic history extinction probabilities were randomly distributed among taxa. Here we use a method for detecting random extinction to demonstrate that during both background and mass extinction times, extinction of marine invertebrate genera has been nonrandom with respect to species richness categories of genera. A possible cause for this nonrandom extinction is selective clustering of extinctions in genera consisting of species which possess extinction-biasing traits. Other potential causes considered here include geographic selectivity, increased extinction susceptibility for species in species-rich genera, or biases related to taxonomic practice and/or sampling heterogeneity. An important theoretical result is that extinction selectivity at the species level cannot be smoothly extrapolated upward to genera; the appearance of random genus extinction with respect to species richness of genera results when extinction has been highly selective at the species level.

The fossil record provides an important source of data on adaptive radiations, and indeed some of the earliest theoretical insights on the nature of these radiations were made by paleontologists. Here we focus on the diverse Devonian Metacryphaeus group calmoniid trilobites, known from the Malvinokaffric Realm, which have been considered a classic example of an adaptive radiation preserved in the fossil record. We use a geometric morphometric analysis in conjunction with phylogenetic and biogeographic patterns and data on speciation rates. Using ancestral character state reconstruction during speciation events, we quantify patterns of morphological change in order to assess the role ecological and geographical factors may have played in mediating this radiation. We found no significant differences between the amount of morphological change that occurred during speciation events when ancestors and descendants were in the same area as opposed to when they occupied different areas. Further, the magnitude of morphological divergence did not change through time or with cladogenetic rank. These patterns, in conjunction with the fact that the radiation occurs in a geographically heterogeneous region subjected to repeated episodes of sea-level rise and fall, suggest that at the macroevolutionary scale this radiation may have been motivated more by phenomena that facilitated geographic isolation than by competition.

Attempts to use Fourier methods to quantify ammonoid suture shape have failed to yield robust, repeatable results because sutures are complex curves that violate the assumptions of Fourier mathematics. In particular, sampled sutures are artificially truncated such that the first and last sampled points are not equivalent, the folds are non-stationary, and a position along a horizontal reference axis may map to multiple amplitudes along the suture path. Here I introduce an alternative Fourier method—the windowed short-time Fourier transform (STFT)—that accommodates these characteristics of complex curves. For each suture, digitized landmarks were parameterized using a tangent angle function and then smoothed by convolving with an apodization function. Piece-wise Fourier transforms were then calculated and averaged, resulting in a robust, unique quantification of line morphology. STFT coefficients and estimated power spectra describing the relative weights of harmonics were generated for 576 Paleozoic-basal Triassic ammonoid genera, representative of the range of suture morphotypes. While insensitive to major episodes of taxonomic turnover (Frasnian/Famennian, end-Devonian, and Permian/Triassic extinctions), the summed power data support the previously observed trend toward increasing suture complexity through time. Moreover, partitioning the summed power statistic into harmonic ranges allows novel insight into Paleozoic suture evolution. In particular, the data show significant shifts in the dominant morphotypes during periods of rebound and radiation and suggest that basal Triassic ammonoids possessed unique suture morphotypes when compared with those of the Paleozoic.

Phyletic speciation arising from a shift between adaptive peaks in the selective surface is modeled. At a locus initially monomorphic, a new allele is introduced that triggers phenotypic evolution by making a new adaptive peak available. A phenotypic model is used to describe the evolution of a quantitative character that is important for fitness but not directly affected by the new allele. Recursion equations are derived for both the allele frequency and the mean of the quantitative character. It is shown that the dynamics of the quantitative trait fit a “punctuated equilibrium” pattern of evolution. Phyletic speciation is seen to occur over a time span so short as to make observation of the transition in the fossil record unlikely.

A central premise of bioclimatic envelope modeling is the assumption of niche conservatism. Whereas such assumptions are testable in modern populations, it is unclear whether niche conservatism holds over deeper time spans and over very large geographic ranges. Hyaenids occupied a diversity of ecological niches over time and space, and until the end-Pleistocene they occurred in Europe and most of Asia, with Asian populations of Crocuta suggested as being genetically distinct from their closest living relatives. Further, little is known regarding whether and how the dietary ecology of extinct populations of Crocuta differed from those of their extant African counterparts. Here, we use a multiproxy approach to assess an assumption of conserved dietary ecology in late Pleistocene extant spotted hyenas via finite element analysis, dental microwear texture analysis, and a novel dental macrowear method (i.e., whether teeth are minimally, moderately, or extremely worn, as defined by degree of dentin exposure) proposed here. Results from finite element simulations of the masticatory apparatus of Chinese and African Crocuta demonstrate lower skull stiffness and higher stress in the orbital region of the former when biting with carnassial teeth, suggesting that Chinese Crocuta could not process prey with the same degree of efficiency as extant Crocuta crocuta. Dental microwear texture data further support this interpretation, as Chinese Crocuta have intermediate and indistinguishable complexity values (indicative of hard-object feeding) between the extant African lion (Panthera leo) and extant hyenas (C. crocuta, Hyaena hyaena, and Parahyaena brunnea), being most similar to the omnivorous P. brunnea. The use of dental macrowear to infer dietary behavior may also be possible in extinct taxa, as evinced by dietary correlations between extant African feliforms and dental macrowear assignments. Collectively, this multiproxy analysis suggests that Chinese Crocuta may have exhibited dietary behavior distinct from that of living C. crocuta, and assumptions of niche conservatism may mask significant dietary variation in species broadly distributed in time and space.

The mammalian fossil record of Spain is long and taxonomically well resolved, offering the most complete record of faunal change for the Neogene of Europe. We evaluated changes in diversification, composition, trophic structure, and size structure of large mammals over the middle and late Miocene with methods applied to this record for the first time, including ordination of fossil localities to improve temporal resolution and estimation of confidence intervals on taxa temporal ranges. By contrast, analysis within the traditional Mammal Neogene (MN) biochronology obscures important aspects of diversification. We used inferred temporal ranges of species and evaluated per capita rates of origination, extinction, diversification, and turnover over 0.5-Myr time intervals.

Three periods of significant faunal change occurred between 12.0 and 5.5 Ma: (1) From 12.0 to 10.5 Ma, elevated origination rates led to an increase in diversity without significant change in ecological structure. Immigrants and geographic-range shifts of species to lower latitudes during an interval of global cooling contributed to these faunal changes. (2) From 9.5 to 7.5 Ma, high extinction rates followed by high origination rates coincided with significant changes in taxonomic composition and ecological structure. These changes represent the Vallesian Crisis, with replacement of a fauna of forest affinities (with frugivores and browsers) by a fauna of open woodlands (with grazers and mixed feeders). (3) From 6.5 to 5.5 Ma, high extinction rates reduced diversity without substantial changes in ecological structure, and large mammal faunas became highly endemic across the northern Mediterranean region. This interval includes the Messinian Salinity Crisis, the desiccation of the Mediterranean basin. Extinction may have been caused by geographic isolation and aridification, with evolution of endemic lineages giving rise to new species in the early Pliocene. These distinct macroevolutionary patterns of faunal change correspond to different geographic scales of inferred climatic and tectonic drivers.

Allometric analysis of the size-shape relationships in the Pliocene-Pleistocene planktic foraminiferal Globorotalia (Globoconella) puncticulata-inflata plexus reveals several heterochronic modes underlying the morphological evolution of the clade. The ancestral lineage, G. puncticulata, is a peramorphocline, showing a pre-displacement mode of heterochrony between 3.5 Ma and 3.0 Ma and an acceleration mode from 3.0 to 2.7 Ma. A different peramorphosis process, isometric giantism (hypermorphosis), in the ontogeny of the ancestral stocks of Globoconella occurred at about 3.5 Ma and gave rise to the G. inflata lineage. The descendant lineage, G. inflata, appears to have adopted a paedomorphosis trend by delaying the onset of the neanic stage in ontogeny during the period of 3.5 to 2.35 Ma, resulting in a series of transposition allometries. During the interval of 2.4 to 1.73 Ma, the allometries shifted to the opposite direction, signifying a pre-displacement trend. Evolutionary stasis marks the evolution during 1.73 to 0.25 Ma. Neoteny concluded the final evolutionary stage of the G. inflata lineage during the latest Quaternary (0.26 to 0.05 Ma). The enormous plasticity and fluctuations in morphology of G. inflata are attributed to the highly positive allometric growth during the ontogeny and the wide-range transposing allometries in the phyletic history. The major changes in heterochronic mode coincide with paleoceanographic events, suggesting that the morphological evolution in the Globoconella clade has been modulated by changes in paleoceanographic conditions.

The latest Aalenian–early Bajocian time interval (ca. 171-169 Ma) is marked by a global reorganization of oceanic plates with the Central Atlantic opening and the formation of the Pacific plate. This time interval is also marked by a global geochemical perturbation of δ13C with a negative excursion at the Aalenian/Bajocian boundary and a positive excursion during the early Bajocian. Evolutionary diversifications of marine invertebrate taxa, namely ammonites, radiolarians, and coccolithophorids, are recorded at that time. Concerning coccolithophorids, this interval witnesses the diversification and expansion of the most successful Mesozoic genus: Watznaueria. In this study, we explore the potential environmental, ecological, and biological forcing at the origin of Watznaueria diversification and its effect on the coccolith assemblages through quantification of the absolute and relative abundances of calcareous nannofossils in two Middle Jurassic key sections: Cabo Mondego (Portugal) and Chaudon-Norante (France). In both sections, we find an increase in nannofossil absolute abundance and flux at the beginning of the lower Bajocian, coeval with an increase in absolute and relative abundances of Watznaueria spp., followed by a plateau in the middle and upper part of the lower Bajocian. The increase of Watznaueria spp. is synchronous with a decrease in relative abundance of other major coccolith taxa, whereas the absolute abundance of these species did not decrease. During the climatically driven early Bajocian eutrophication event, Watznaueria spp. integrated into the calcareous nannoplankton community in two successive evolutionary steps involving first W. contracta and W. colaccicchii, and second W. britannica and W. aff. manivitiae. Step 1 was driven by an increase in niche carrying capacities linked to the early Bajocian eutrophication. Step 2 was driven by specific adaptation of the newly evolved Watznaueria species to bloom in nutrient-rich environments not exploited before. These evolutionary events have initiated the 100-Myr reign of Watznaueria over the calcareous nannoplankton community.

Fossil specimens can be recovered easily only from exposed localities, so rock exposure area should represent a better proxy for rock availability than the frequently used outcrop (i.e., map) area. Data collected via remote sensing and GIS show that map area does not consistently correlate with exposure area in different regions. Proportional rock exposure is not geographically consistent and is influenced by a number of variables that are independent of outcrop area, including proximity to the coast, elevation, bedrock age, land use and lithology. These variables appear to be non-independent in their influence on rock exposure, and are not consistent in their effects across continents. The inconsistency in the correlation between outcrop and exposure area, and the variability in the influence of different factors on rock exposure, suggests that using outcrop area as a sampling proxy is poorly supported. The weaknesses in using outcrop area as a sampling proxy, highlighted by the lack of correlation with exposure area, suggest that a single accurate global sampling proxy may never be attained and it is premature to assume that paleodiversity curves can be corrected using such proxies. It is therefore preferable to work on a regional scale, comparing regional fossil collection data with a number of proxies representing all aspects of sampling. The lack of correlation between outcrop and exposure area suggests that the covariance detected between outcrop area and paleodiversity might be better explained by a common-cause model, and that geological megabiases may not have had as profound an effect on paleodiversity curves as previously thought.

Magadina cumingi (Davidson) lives in an environment of high current energy and mobile sediments using the pedicle as an elevating device. This previously undescribed substrate relationship is reflected in pedicle form, the muscular system, distribution of secondary thickening and characters of the beak. The cardinalia provide the evidence of key differences in the muscular system from an attached species Magellania australis (Quoy and Gaimard) and a free lying species with atrophied pedicle Neothyris lenticularis (Deshayes). The possession of an open foramen in articulate brachiopods is not synonymous with permanent attachment.

Cladistic analysis of osteological and dental characters in a monophyletic group of Miocene and younger tayassuids demonstrates a pattern of changes in the degree of sexual dimorphism in canine tooth diameter and zygomatic arch width, and in phenotypic correlations between these characters. Primitively, tayassuids have canine teeth that are sexually dimorphic and discretely bimodal in size, and zygomatic arches that are narrow in both sexes. Many late Miocene and Pliocene tayassuids have broad, winglike zygomatic processes. In some species, these processes are large in both sexes, but in others, those of females are much smaller than those of males. The presence of large processes in both sexes is primitive relative to the condition of strong sexual dimorphism. In five separate clades, the zygomatic processes of both sexes become reduced in size, and the degree of sexual dimorphism in canine size becomes reduced as well. The pattern is congruent with predictions derived from a theoretical model of the evolution of sexual dimorphism, and it further indicates the emergence of a new phenotypic correlation between two previously uncorrelated characters, canine size and zygoma size. The advent of this new correlation coincides with the advent of pronounced sexual dimorphism in zygomatic processes. Although such a pattern could be explained by genetically modifying phenotypic expression of homologous characters in one sex or the other, an epigenetic modification of expression is equally plausible: the evolution of sexual dimorphism in homologous characters could be accomplished by placing phenotypic expression of an originally monomorphic character under the control of steroid sex hormones. This hypothesis is consistent with evidence from many vertebrate groups, and it provides testable predictions.

656 mandibles and isolated teeth of the bovid Pachytragus solignaci Robinson from two localities in the Miocene Beglia Formation, Gafsa, Tunisia, have been individually aged on the basis of ontogenetic development and state of dental wear. The sample probably represents normal but seasonally restricted mortality. Life table analysis indicates an annual mortality rate of 25–30%, increasing in old animals. Dental dimensions are affected by stabilizing selection which sets in as the tooth comes into function, earlier mortality being nonselective in that respect.

In this paper we present a method for estimating soil pCO2 in ancient environments using the measured carbon-isotope values of pedogenic carbonates and plant-derived organic matter. The validity of soil pCO2 estimates proves to be highly dependent on the organic δ13C values used in the calculations. Organic matter should be sourced from the same paleosol profiles as sampled carbonates to yield the most reliable estimates of soil pCO2. In order to demonstrate the potential use of soil pCO2 estimates in paleoecological and paleoenvironmental studies, we compare samples from three Upper Jurassic localities. Soil pCO2 estimates, interpreted as a qualitative indicator of primary paleoproductivity, are used to rank the Late Jurassic terrestrial environments represented by the Morrison Formation in western North America, the informally named Lourinhã formation in Western Europe, and the Stanleyville Group in Central Africa. Because modern terrestrial environments show a positive correlation between primary productivity and faunal richness, a similar relationship is expected in ancient ecosystems. When the relative paleoproductivity levels inferred for each study area are compared with estimates of dinosaur generic richness, a positive correlation emerges. Both the Morrison and Lourinhã formations have high inferred productivity levels and high estimated faunal richness. In contrast, the Stanleyville Group appears to have had low primary productivity and low faunal richness. Paleoclimatic data available for each study area indicate that both productivity and faunal richness are positively linked to water availability, as observed in modern terrestrial ecosystems.