bluuebunny/crossref_metadata_2025 huggingface dataset:
Preferential survivorship of brooding corals in a regional extinction
Authors: Edinger Evan N. , Risk Michael J.
Published: July 2016

Approximately half of the Caribbean Oligocene reef coral fauna became locally extinct during the Early Miocene; roughly two thirds of the genera driven to local extinction still survive in the Indo-Pacific. Coral genera with lecithotrophic larvae (brooders) preferentially survived, over those with planktotrophic larvae (broadcasters). Among 37 genera for which we inferred reproductive mode, 73% of brooding genera survived the Oligocene/Miocene extinction events, while only 29% of the broadcasting genera survived. The proportion of brooders to broadcasters also increased markedly. During the late Oligocene, 47% of Caribbean reef coral genera were broadcasters, but in the middle Miocene, only 32% of the genera were broadcasters.

Survivorship in Puerto Rican reefs was correlated with tolerance of cold and turbid conditions. Genera tolerant of both cold water and turbidity had much higher survival rates than those tolerant of turbidity alone. Only 25% of the genera that could tolerate neither cold water nor turbidity survived. Most of the eurytopic genera were brooders, while most of the stenotypic genera were broadcasters.

We present two hypotheses that may account for the preferential survivorship of brooders: the recruitment hypothesis, and the dispersal hypothesis. The recruitment hypothesis holds that brooders survive preferentially because lecithotrophic larvae have higher recruitment success than do planktotrophic larvae in marginal habitats, such as upwelling zones. This is supported by the correlation of brooding and eurytopy. The dispersal hypothesis suggests that brooders survive preferentially because lecithotrophic larvae, which typically inherit zooxanthellae from the egg, have a longer larval lifespan and, hence, a wider potential dispersal range, than planktotrophic larvae, which typically capture zooxanthellae from the water column. Biogeographic range data, however, do not support this second hypothesis: modern Indo-Pacific brooding and broadcasting genera have nearly identical ranges, and many brooding species have narrower longitudinal ranges than do broadcasting species. Preferential survivorship of brooding corals contrasts sharply with survivorship patterns among molluscs during extinction events; among molluscs, broadcasters are favored over brooders.

A major increase in upwelling at the Oligocene/Miocene boundary was probably responsible for this extinction/geographic restriction event. Preferential survival of brooding and mixed mode coral genera appears to be a product of their being better able to recruit and survive in marginal conditions such as upwelling zones.
Signal strength, timing, and self-deafening: the evolution of echolocation in bats
Authors: Fenton M. B. , Audet D. , Obrist M. K. , Rydell J.
Published: July 2016

We propose that the ancestors of bats were small, nocturnal, sylvatic gliders that used echolocation for general orientation. Their echolocation calls were short, low intensity, broadband clicks, which translated into a very short operational range. In the lineage that gave rise to bats, a switch to stronger, tonal signals permitted the use of echolocation to detect, track, and assess flying insects in subcanopy settings. We propose that these animals hunted from perches and used echolocation to detect, track, and assess flying insects, which they attacked while gliding. In this way, the perfection of echolocation for hunting preceded the appearance of flapping flight, which marked the emergence of bats. Flapping flight had appeared by the Eocene when at least eight families are known from the fossil record. Stronger signals and adaptations to minimize self-deafening were central to the perfection of echolocation for locating flying prey. Echolocation constituted a key innovation that permitted the evolution and radiation of bats. At the same time, however, its short effective range imposed a major constraint on the size of bats. This constraint is associated with flight speed and the very small time intervals from detection of, and contact with a flying target. Gleaning and high duty cycle echolocation are two derived approaches to hunting prey in cluttered situations, places where echoes from background and other objects arrive before or at the same time as echoes from prey. Both had appeared by the Eocene.
Testing evolutionary constraint hypotheses with early Paleozoic gastropods
Authors: Wagner Peter J.
Published: July 2016

The evolution of higher taxa among early Paleozoic gastropods is similar to that among early metazoans as a whole, as higher taxa diversified rapidly and early. There are two issues pertinent to this pattern. First, were greater morphologic changes concentrated in the early phases of evolution? Second, does the pattern better fit models of increasing phylogenetic constraints or increasing ecologic restrictions? This paper presents a phylogeny-based method designed to test whether amounts of morphologic evolution decreased over time. It also explores whether the data better fits models of increasing phylogenetic (i.e., developmental or genetic) constraint or increasing ecologic restriction. Two metrics of morphologic separation (i.e., the morphologic difference between sister-species) are used: (1) Euclidean distance in morphospace and (2) transition magnitude. The latter metric is calculated by a multivariate analysis of sister-species contrasts, which determines both types and magnitudes of morphologic transitions. The advantage of using transition magnitudes is that it balances the effects of transitions that either affect more morphometric characters or occur more frequently. Both metrics indicate that larger morphologic separations between sister-species were concentrated early in gastropod evolution. Among gastropods, gross shell morphology often reflects basic trophic strategy and function whereas basic internal anatomy does not. Transition magnitudes can be broken down into transitions associated with differences in basic trophic strategies and shell functional biology (“external”), and those associated with differences in basic internal anatomy (“internal”). Internal transition magnitudes show a highly significant decrease over time (p< 10–04) whereas external transition magnitudes show a much less significant decrease over time (p< 0.10) and no significant decrease after the earliest Ordovician (p≅ 0.50). The results therefore suggest that increasing phylogenetic constraints played a greater role in the early evolution of gastropods than did increasing ecologic ones.
Mesozoic avian bone microstructure: physiological implications
Authors: Chinsamy Anusuya , Chiappe Luis M. , Dodson Peter
Published: July 2016

We report on the bone microstructure of the Late Cretaceous birdsPatagopteryx deferrariisiand members of the Enantiornithes. These birds represent the most primitive birds ever studied histologically. The occurrence of growth rings indicating alternating periods of slowed and fast growth suggests that these basal birds had slower growth rates, and differed physiologically from their modern relatives. Our findings also call into question previous ideas suggesting that nonavian theropods developed a full avian degree of homeothermic endothermy, which was later inherited by birds. On the contrary, our findings suggest that birds developed classic endothermy relatively late in their phylogenetic history.
A biomechanical model for the morphogenesis of regular echinoid tests
Authors: Dafni Jacob
Published: July 2016

Experiments were conducted to test the hypothesis that biomechanical constraints determine the morphology of regular echinoids. Hard-bottom-dwellingTripneustes gratilla elatensiswere transferred to an artifical sandy habitat to evaluate whether the change in substrate affects their height to diameter ratio (H/D). Within 1–2 months their H/D ratio increased significantly. This change was shown to be reversible to some extent. Surgical damage to the ambulacral system of one ray caused inactivation of tubefeet and atrophy of injured ambulacra. Test shape was also affected: the damaged ray was lower, and the nondamaged ambulacra deflected toward the treated one, producing bilateral symmetry as in recorded cases of teratology. Study ofT. g. elatensistetramers showed that while “perfect” tetramery was apparently associated with genetic aberration, “imperfect” tetramery results from mechanical injury at an early ontogenetic stage. Micromorphological study shows that in the longitudinal sutures, normally under tension, long and slender trabeculae develop, associated with long and well-aligned collagenous sutural fibers, while the latitudinal trabeculae and fibers are short and less organized. A mechanical effect is suggested by the oval cross-section of the fiber-anchoring trabeculae. Further, echinoid plates interact like soap bubbles, whereas the entire test behaves like a balloon, fastened to the substrate by the ambulacral tubefeet. All these observations support earlier hypotheses on the biomechanical control of echinoid test growth. A model is proposed in which the expansion of the inner mass, counteracted by the mechanical activity of the ambulacral tubefeet, mesenterial threads, and lantern muscles, affects sutural growth, thus controlling echinoid morphogenesis.

A morphometric survey among regular echinoids reveals an inverse relationship between ambulacral width and relative ambital height. Although both increase of ambulacral width and lowering of ambitus-line are evolutionary trends, it is suggested that they are a response to a mechanical effect. H/D ratio was not related to ambulacral width on the phylogenetic level. It is therefore suggested that the latter correlation is ontogenetically controlled. Aspects of irregular echonoid evolution, such as bilateral symmetry, flattening, and formation of the ambulacral petaloid, also are explained by this model.
Are brachiopods better than bivalves? Mechanisms of turbidity tolerance and their interaction with feeding in articulates
Authors: Thayer Charles W.
Published: July 2016

The dominance of Paleozoic articulate brachiopods in once-muddy environments may be explained by an array of mechanisms and structures that reject nonfood particles, in some cases without interruption of feeding: (1) behavioral flexibility of the lophophore and its individual filaments; (2) persistent, variable-speed rejection currents on the mantle, which sometimes concentrate pseudofeces in topographically controlled vortices; (3) costae and alae (which have many other probable functions); (4) inhalant currents elevated above substrate; (5) marginal setae.

Some mantle currents parallel (and presumably augment) lophophore feeding currents; others diverge up to 90° to provide rejection while feeding continues. Contrary to previous reports, the lateral cilia seem to be involved in rejection and may reverse.

Repeated claims for the superiority of the gill of suspension-feeding bivalves over the “weak” individual filaments of the lophophore are probably false. In suspension-feeding bivalves, simultaneous feeding and rejection are likely to be hindered by fused gill elements and mucus-trapping of food. The energetically efficient articulates are predicted to have a competitive advantage over suspension-feeding bivalves when oxygen or food is limiting, as, for example, after a bolide impact.
Tempo and mode of morphologic evolution near the origin of the radiolarian lineage Pterocanium prismatium
Authors: Lazarus David
Published: July 2016

Morphometric examination of cladogenesis and phyletic evolution in two late Neogene sister lineages of marine microfossils (Pterocanium prismatium and P. charybdeum, Radiolaria) from two equatorial Pacific sediment cores was undertaken to better understand the rate of cladogenesis and its relation to subsequent phyletic change. The origin of P. prismatium from P. charybdeum ∼4 ma ago has been estimated to take place over an interval of ∼500,000 yr. Results show that the speciation event consists of two distinct phases. The first phase, cladogenesis, occurred relatively rapidly (on the order of 50,000 yr). A second phase of relatively rapid divergent phyletic evolution away from the common ancestral state followed in both descendant branches and continued for at least 500,000 yr after completion of the cladogenetic event. Net evolutionary rates over the next 2 ma appear to be much lower. Individual characters change by as much as 2 population standard deviations during cladogenesis, and by a total of approximately 3 standard deviations over 2.5 ma of phyletic evolution. Up to 5 population standard deviations of change during ≦ 50,000 yr of cladogenesis, and 7 additional standard deviations of phyletic change over 500,000 yr are observed in multivariate (discriminant function) indices of morphologic difference. The measured pattern does not appear to be either strictly “punctuated” or strictly “gradual,” but instead shows features of both hypotheses.
Tempo of evolution in a Neogene bryozoan: rates of morphologic change within and across species boundaries
Authors: Cheetham Alan H.
Published: July 2016

Inadequacies in stratigraphic resolution or completeness can make true rates of morphologic change through geologic time impossible to estimate precisely. However, relative rates may be sufficient to test whether the tempo of change within species can account for morphologic differences across species boundaries, and hence to distinguish between gradual and punctuated patterns of evolution. The conditions under which these patterns can be distinguished statistically are explored by simulating varying degrees of within-species rate variability relative to across-species morphologic difference. The statistical methods are then applied to multiple-character morphologic data from closely spaced sequential populations of the Neogene bryozoan Metrarabdotos, using discriminant analysis to compare overall morphologies. In nine comparisons of ancestor-descendant species pairs, all show within-species rates of morphologic change that do not vary significantly from zero, hence accounting for none of the across-species difference. In all cases the ratio of within-species fluctuation to across-species difference is low enough to allow the punctuated pattern to be distinguished with virtual certainty. In at least seven of the cases, ancestor species persisted after giving rise to descendants, in conformity with the punctuated equilibrium mode of evolution.
The hierarchical expansion of sorting and selection: sorting and selection cannot be equated
Authors: Vrba Elisabeth S. , Gould Stephen Jay
Published: July 2016

In a nonhierarchical world, where selection on organisms regulated all nonrandom evolutionary change, the traditional equation of selection (a cause of sorting) with sorting itself (differential birth and death among varying organisms within a population) would rarely lead to error, even though the phenomena are logically distinct (for sorting is a simple description of differential “success,” and selection a causal process). But in a hierarchical world, with entities acting as evolutionary individuals (genes, organisms, and species among them) at several levels of ascending inclusion, sorting among entities at one level has a great range of potential causes. Direct selection upon entities themselves is but one possibility among many. This paper discusses why hierarchy demands that sorting and selection be disentangled. It then presents and illustrates an expanded taxonomy of sorting for a hierarchical world. For each of three levels (genes, organisms, and species), we show how sorting can arise from selection at the focal level itself, and as a consequence either of downward causation from processes acting on individuals at higher levels or upward causation from lower levels. We then discuss how hierarchy might illuminate a range of evolutionary questions based on both the logical structure of hierarchy and the historical pathways of its construction—for hierarchy is a property of nature, not only a conceptual scheme for organization.
Mass Extinctions as Statistical Phenomena: An Examination of the Evidence Using χ2 Tests and Bootstrapping
Authors: Hubbard Alan E. , Gilinsky Norman L.
Published: July 2016

Although much natural historical evidence has been adduced in support of the occurrence of several mass extinctions during the Phanerozoic, unambiguous statistical confirmation of the mass extinction phenomenon has remained elusive. Using bootstrapping techniques that have not previously been applied to the study of mass extinction, we have amassed strong or very strong statistical evidence for mass extinctions (see text for definitions) during the Late Ordovician, Late Permian, and Late Cretaceous. Bootstrapping therefore verifies three of the mass extinction events that were proposed by Raup and Sepkoski (1982). A small amount of bootstrapping evidence is also presented for mass extinctions in the Induan (Triassic) and Coniacean (Cretaceous) Stages, but high overall turnover rates (including high origination) in the Induan and uncertain estimates of the temporal duration of the Coniacean force us to conclude that the evidence is not compelling.

We also present the results of more liberal X2 tests of the differences between expected and observed numbers of familial extinctions for stratigraphic stages. In addition to verifying the mass extinctions identified using bootstrapping, these analyses suggest that several stages that could not be verified as mass extinction stages using bootstrapping (including the last three in the Devonian, and the Norian Stage of the Triassic) should still be regarded as candidates for mass extinction. Further analysis will be required to test these stages in more detail.
Time and taphonomy: quantitative estimates of time-averaging and stratigraphic disorder in a shallow marine habitat
Authors: Flessa Karl W. , Cutler Alan H. , Meldahl Keith H.
Published: July 2016

We examined the radiocarbon age, taphonomic condition and stratigraphic position of shells of the venerid bivalveChionespp. from the tidal flats of Bahia la Choya, Sonora, Mexico. Shells in Bahia la Choya are time-averaged. Thirty shells yielded radiocarbon dates from modern (A.D. 1950 or younger) to 3569 years before present. The median calendar age of inner flat shells is 483 years; the median age of tidal channel shells is 427 years. We interpret such long shell survival to be the result of frequent shallow burial. Such burial retards bioerosion of shells.

The taphonomic condition of shells varied with environment. Shells from the surface of the inner flats were better preserved than shells from the tidal channel. Shells are more likely to be physically worn and biologically degraded in the waters of the channel than on the quieter and more frequently exposed inner tidal flat. Taphonomic condition is an unreliable indicator of a shell's time-since-death. Poorly-preserved shells on the inner flats tended to be old, but in general shell condition was much more variable than shell age. A shell's condition is more likely the result of its total residence time on the surface than its time-since-death (surface time plus burial time).

Two composite short (44 cm and 50 cm) cores revealed varying degrees of stratigraphic disorder (the departure from perfect correlation between relative stratigraphic position and relative age). One of eight shells in the inner flats core was disordered; four of nine shells in the tidal channel were disordered. The actual age range of surface shells approximates the age range of shells in cores. Stratigraphic disorder is a consequence of both time-averaging and physical and biogenic mixing.

Time-averaging controls the degree of precision possible in paleoecological studies. Environmental changes and ecological phenomena occurring within a span of 3500 years would not be recognized in deposits like those of Bahia la Choya. Time-averaging and stratigraphic disorder also constrain the temporal resolution possible in microstratigraphic studies of evolution. The extent of time-averaging and stratigraphic disorder will dictate an appropriate sample interval. In order to prevent temporal overlap between successive samples in deposits like Bahia la Choya, sample spacing should not be less than approximately 0.5 m.
On discerning the cause of late Pleistocene megafaunal extinctions
Authors: Beck Michael W.
Published: July 2016

I examine the late Pleistocene megafaunal extinctions by testing the only extinction model with strong a priori predictions, the blitzkrieg model (Martin 1973; Mosimann and Martin 1975). I first test an assumption of the blitzkrieg and other extinction models that the megafaunal extinctions occurred in the terminal Wisconsin (12-10 Ka). This assumption has been disputed by Grayson (1989, 1991), but I find that both a reanalysis of Grayson's data and an analysis of new reliable data support a terminal Wisconsin extinction.

The blitzkrieg model predicts that the ranges of megafauna in North America were constricted as the semicircular front of hunters moved southeastward; hence the extinctions should be time-transgressive from northwest to southeast. I test this prediction in three separate analyses that examine (1) the location of terminal sites for each taxon relative to all their other late Wisconsin fossil sites, (2) the location of terminal sites for each taxon relative to all their other reliably dated late Wisconsin fossil sites, and (3) the spatio-temporal pattern of all the reliably dated terminal Wisconsin sites without regard to taxonomy. The geographic distribution of the megafaunal remains does not support the blitzkrieg hypothesis in any of the three analyses. Moreover, all of the patterns in the data are in a direction opposite to that predicted by the blitzkrieg hypothesis. I examine how these conclusions affect both climatic and predation models, particularly in relation to the testability of other extinction hypotheses.
Is predation intensity reduced with increasing depth? Evidence from the west Atlantic stalked crinoidEndoxocrinus parrae(Gervais) and implications for the Mesozoic marine revolution
Authors: Oji Tatsuo
Published: July 2016

The number of regenerated arms was counted on specimens of two distinct phenotypes of the stalked crinoidEndoxocrinus parrae(Gervais) from a wide bathymetric range in the Caribbean (178-723 m). In one phenotype, the sample was divided into two groups, one from shallower (< 500 m) depths, the other from deeper (≥ 500 m); in the other phenotype the group divided at 550 m. In both phenotypes, the frequency of regenerated arms is significantly higher in specimens from shallower water than in those from deeper water. If the regenerated arms inEndoxocrinus parraewere the result of sublethal predation, as previously suggested, then predation intensity is higher in shallow water than deep water. These results are consistent with the idea of the late Mesozoic marine revolution—that there has been stronger predation on various invertebrates in shallow-water environments since the late Mesozoic. The stalked crinoids may have been unable to cope with increased predation in shelf environments, and they migrated to offshore environments.
Biodiversity, speciation, and extinction trends of Proterozoic and Cambrian phytoplankton
Authors: Vidal Gonzalo , Moczydłowska-Vidal Małgorzata
Published: July 2016

The degradation-resistant organic-walled cell envelopes of acritarchs are the most abundant microfossils in Proterozoic and Cambrian rocks. These microfossils reveal diversity fluctuations that illuminate the nature of the record of primary producers near the Proterozoic/Phanerozoic boundary. Neoproterozoic radiations, some 1000–542 m.y. ago, reached levels comparable to those observed in the Cambrian Period. The microbiotas from rock successions from 13 Cambrian biochrons display significant fluctuations in the total number of microfossil taxa belonging to discrete microfossil assemblages. The assemblages reveal that Cambrian protist assemblages evolved over relatively short time spans, apparently out of low-diversity remnant populations after gradual declines in diversity. The characteristic microbiotas of the terminal Neoproterozoic and the Early, Middle, and Late Cambrian blossomed over relatively narrow time ranges, subsequently collapsing to nearly the initial levels. By virtue of the decreasing time spans involved in the late Vendian, Early, Middle, and Late Cambrian respectively, the tempo of specific turnover appears to have varied considerably. Speciation levels gradually decreased during Early and Middle Cambrian times and during Early Cambrian times were accompanied by rising levels of extinction. This latter feature seems to have reversed during Middle Cambrian times, lasting well into Late Cambrian times. Acritarchs were at the base of the marine trophic chain together with bacteria and other protists that are largely unrepresented in the fossil record. For this reason, the rise of diverse Cambrian protistan plankton must have been essential for early marine metazoan differentiation. Indeed, patterns of total diversity, speciation, and extinction of Cambrian acritarchs clearly mirror those of contemporaneous marine invertebrate faunas at the generic level.
Selectivity of foraminiferal extinction in the late Eocene
Authors: Banerjee Amit , Boyajian George E.
Published: July 2016

Late Eocene foraminiferal extinction shows diverse patterns of selective morphologic and latitudinal extinction. Taxa with discoidal shape, calcareous tests, and narrow and low-latitudinal ranges are at significantly greater risk of extinction. Elevated extinction intensities in calcareous tests are mainly due to the presence of larger benthic foraminifera that evolved in late Paleocene and diversified through the lower to middle Eocene. Selectivity of late Eocene foraminiferal extinction indicates that this extinction event was not a globally uniform event. Although this result does not verify an extraterrestrial impact or any other proposed cause of extinction, it does constrain the causes of late Eocene extinction. Furthermore, the geography of late Eocene foraminiferal extinction, and previously studied Cenomanian/Turonian extinction, demonstrates that mass extinctions exhibit different patterns of selectivity.
Variability, selection, and constraints: development and evolution in viverravid (Carnivora, Mammalia) molar morphology
Authors: Polly P. David
Published: July 2016

Developmental constraints presumably operate by influencing patterns of variability: when development causes some features to vary more than others and when the level of variability is correlated with evolutionary change, then development can be said to constrain evolution. This idea was tested by examining the relationship between tooth variation and three other factors: developmental processes, tooth function, and evolutionary change. Data came from two lineages of viverravid carnivorans (Viverravidae, Carnivora) from the Paleogene of North America. Variability in cusp position was significantly correlated with position in the developmental cascade, with the amount of intercusp growth (when growth is relatively greater in some cusps than others), and with amount of evolutionary change. This indicates that tooth development exerts a local constraint on phenotypic variability and on the evolutionary response to functional selection, but comparative data suggest that the developmental constraint itself may evolve. Intense directional or stabilizing selection may modify the developmental cascade so that the constraint is either removed or modified to permit new evolutionary patterns. Thus development does not constrain evolution in an absolute sense, but rather introduces modifiable patterns of covariance among crown features. Both development and function seem to play important, intertwined roles in coordinating evolutionary change in mammalian molars.
Locomotion in non-avian dinosaurs: integrating data from hindlimb kinematics, in vivo strains, and bone morphology
Authors: Carrano Matthew T.
Published: July 2016

Analyses of non-avian dinosaur locomotion have been hampered by the lack of an appropriate locomotor analog among extant taxa. Birds, though members of the clade Dinosauria, have undergone significant modifications in hindlimb osteology and musculature. These changes have resulted in a uniquely developed system of limb kinematics (involving a more horizontal femoral posture and knee-dominated limb motion), which precludes the direct use of extant birds as models for non-avian dinosaur locomotion. Analyses of locomotor data from extant birds and mammals suggest a causal link between general hindlimb kinematics, bone strains, and limb bone morphology among these taxa. A model is proposed that relates the amount of torsional loading in femora to bone orientation, such that torsion is maximal in horizontal femora and minimal in vertical femora. Since bone safety factors are lower for torsional shear strains than for longitudinal axial strains, an increase in torsion can potentially affect bone morphology dramatically over evolutionary time. Interpreting the nearly identical limb bone dimensions and limb element proportions of non-avian dinosaurs and mammals in the light of this relationship supports the prediction of similar vertical femoral postures and hip-driven limb kinematics in these two groups.

This information can be used to interpret patterns of locomotor evolution within Dinosauria. The evolution of quadrupedalism with large body size and the acquisition of cursorial or graviportal limb morphologies occurred repeatedly but did not affect the underlying uniformity of dinosaur locomotor morphology. Only derived coelurosaurian theropods (paravians) developed significant modifications of the basic dinosaurian patterns of limb use. Changes in theropod hindlimb kinematics and posture apparently began shortly prior to the origin of flight, but did not acquire a characteristically modern avian aspect until after the later acquisition of derived flight characteristics.
The stratigraphic distribution of graptolites in the classic upper Middle Ordovician Utica Shale of New York State: an evolutionary succession or a response to relative sea-level change?
Authors: Goldman Daniel , Mitchell Charles E. , Joy Michael P.
Published: July 2016

The stratigraphic distribution of graptoloid species within the upper Middle Ordovician strata of New York State represents a complex pattern of origination, extinction, faunal migration, and fluctuating relative abundances. In particular, the observed patterns of species turnover at graptolite biozone boundaries are apparently strongly correlated with lithofacies, sampling strategies, and the depositional effects of relative sea-level change.

Vertical facies changes that occur within third-order depositional sequences and fourth- or fifth-order parasequences are mirrored by changes in the graptoloid faunal composition. Large-scale faunal turnovers at biozone boundaries tend to occur either at sequence boundaries or at flooding surfaces within sequences (e.g., the base of Highstand System Tracts). The base of theCorynoides americanusandClimacograptus (D.) spiniferusZones coincide with major onlap events, and theOrthograptus ruedemanniZone fauna appears just below a Lowstand Systems Tract. Within individual biozones, smaller-scale changes such as the fluctuating relative abundances of graptoloid species coincide with higher-order parasequence cyclicity. These distribution patterns resemble recent computer-generated models for the sequence stratigraphic distribution of hypothetical taxa.

By combining good biogeographic control with a detailed sampling program, we are able to see through the patterns attributable to depositional cyclicity and identify the different components of faunal turnover (migration, speciation, and extinction).
Mammal-like reptiles: spreading the word
Authors: Ruben John A.
Published: July 2016

It is somewhat dismaying, if not surprising, that so many trained biologists know that dinosaurs may have been “hot-blooded,” yet are completely unaware of even the existence of the mammal-like reptiles, the Therapsida. The reasons for the dearth of widespread knowledge of the therapsids are probably fairly mundane: the mammal-like reptiles are less spectacular in appearance than dinosaurs, and good therapsid fossil localities are restricted primarily to the southern hemisphere. As a result, therapsids seldom become the subjects of museum displays or classroom student presentations. Moreover, biology textbooks, whether at the high school or college level, almost invariably devote more space for recounting the “dinosaur story” than to discussing the therapsid reptiles (1). Consequently, although application of biological systems data to the fossil record has become increasingly popular and useful in the last decade, many neontologists who might potentially make substantial contributions to our knowledge of therapsid biology remain oblivious to the significance of these animals. This is particularly unfortunate—therapsids are, of course, the direct predecessors of mammals, and, as such, the more we understand the mammal-like reptiles the more likely we are to understand the origins and functions of our own anatomical, physiological, and behavioral systems.
Bimodality of evolutionary rates
Authors: Ginzburg Lev R.
Published: July 2016

A simple theoretical argument shows that the evolutionary process will look gradual if it is considered on too fine or too coarse a time scale. There exists an intermediate time scale in which the distribution of evolutionary rates will appear as bimodal.
Growth rate and habitat ofNautilus pompiliusinferred from radioactive and stable isotope studies
Authors: Cochran J. Kirk , Rye Danny M. , Landman Neil H.
Published: July 2016

The growth rate ofNautilus pompiliusin its natural environment has been determined from radioactive disequilibrium between210Pb (half-life 22.3 yr) and its granddaughter210Po (half-life 138 d) in septa of two juvenile specimens.210Pb and210Po data from the most recently formed shell material of both specimens indicate that210Pb from sea water is incorporated into septa during septal formation and210Po is excluded. Therefore the210Po/210Pb activity ratio serves as a chronometer to estimate the age of each septum and the time between formation of septa. In the specimens studied the average time between sucessive points in septal deposition is 75 d for the nine most recent septa of one specimen and 23 d for the six most recent septa of the other specimen. These different growth rates, if representative of the ontogeny of each animal, suggest that the timing of septal deposition probably is dependent on the rate of shell and tissue growth coupled with buoyancy requirements and is not a unique period for allNautilus.The habitat and ontogeny ofNautilusmay be inferred from the pattern of stable isotopes of oxygen and carbon in the septa. Both specimens show a pronounced break in δ18O from nearly uniform light values in the first seven septa to heavier values (∼1%) after the seventh septum. We interpret this break to correspond to the hatching ofNautilus.A temperature (i.e. water depth) interpretation of the δ18O data for septa after the eighth is complicated by a positive correlation between δ18O and δ13C. This may reflect horizontal migration of the animal or a kinetically controlled fractionation of carbon and oxygen isotopes during septal formation.
The chamber formation cycle inNautilus macromphalus
Authors: Ward Peter , Greenwald Lewis , Magnier Yves
Published: July 2016

The chamber formation cycle in externally shelled, chambered cephalopods consists of mural ridge formation, secretion of the siphuncular connecting ring, septal calcification, and cameral liquid removal. Radiographic observation of the chamber formation cycle in specimens ofNautilus macromphalusallows direct observation of the various processes of the chamber formation cycle in a chambered cephalopod, and gives direct measures of rates. New chamber formation inN. macromphalusinitiates when slightly more than half of the cameral liquid has been removed from the last formed chamber. At this volume, the liquid within the chamber drops from direct contact with the permeable connecting ring to a level where it is no longer in direct contact and must move onto the connecting ring due to wettable properties of the septal face and septal neck. This change from “coupled” to “decoupled” emptying coincides with the formation of a mural ridge at the rear of the body chamber, in front of the last formed septum. With completion of the mural ridge, the septal mantle moves forward from its position against the face of the last formed septum and attaches to the new mural ridge, where it begins calcifying a new septum in front of the newly created, liquid-filled space. Emptying of the new cameral liquid from this space commences when the calcifying septum has reached from one-third to two-thirds of its final thickness. The cessation of calcification of the septum coincides with a liquid volume in the new chamber of approximately 50%, at which point the cycle begins anew. During the chamber formation cycle apertural shell growth appears to be continuous. Since apertural shell growth is the prime factor leading to increased density in seawater, and hence decreased buoyancy, the period in the chamber formation cycle between the onset of septal calcification and the onset of emptying would be a time of greatly decreasing buoyancy. This is avoided by the removal of decoupled liquid from previously produced chambers. In this way constant neutral buoyancy is maintained. The time between chamber formation events in aquarium maintainedN. macromphalusappears to be between 70 and 120 d.
Prey Selection by naticid gastropods: experimental tests and application to the fossil record
Authors: Kitchell Jennifer A. , Boggs Christofer H. , Kitchell James F. , Rice James A.
Published: July 2016

Because predation by drilling gastropods is uniquely preservable in the fossil record, it represents important evidence for the study of coevolution. Previous studies of drilling gastropod predation have been largely descriptive and sometimes contradictory. We formulate and test a model of prey selection by naticid drilling gastropods. The model adequately predicts both prey species selection and prey size selection. Prey preferences parallel prey profitabilities, determined by calculating prey species-specific and predator size-specific cost-benefit functions. The model also specifically suggests the evolution of potential refugia from predation and the evolution of potential predatory attributes. Application of the model to several Miocene and Pliocene assemblages studied by Thomas (1976) corroborates the feasibility and utility of this approach in examining the evolutionary record of naticid predation, which extends from the Late Mesozoic. Apparent evolutionary stasis and convergent morphological trends among prey species may be consistent with continuous selection pressures against predation.
Direct measurement of age in fossil Gryphaea: the solution to a classic problem in heterochrony
Authors: Jones Douglas S. , Gould Stephen Jay
Published: July 2016

We have known since Trueman's classic work of 1922 that the Lower Jurassic Gryphaea of Britain exhibit phyletic size increase and heterochronic change in shape. Since Hallam's revisionary work in the 1960s, we have recognized that pronounced and generalized juvenilization of form accompanied this increasing size. This extensive literature provides invertebrate paleontology's most famous example of a biometrically documented, continuous anagenetic trend within a discrete lineage. But Gryphaea has also provoked great frustration because a key datum, required for a full solution, had been theoretically recognized but practically unavailable. We could identify the evolution of shape as paedomorphic, but could not specify the mode of heterochrony for this paedomorphic result because we could not standardize samples by common age or developmental stage.

In this paper, we provide sclerochronological data on sizes and shapes at specified ages marked by annual growth bands in two Jurassic sequences of Gryphaea: the classic Lower Jurassic series showing phyletic size increase with paedomorphosis, and an independent Middle–Upper Jurassic series illustrating neither size increase nor heterochrony. We prove that size increase in the classic series occurs entirely by faster growth (larger descendant sizes at the same ages as ancestors), and not by extended age (for descendants lived no longer than ancestors). The well-marked paedomorphosis of form probably arose as a correlated consequence of growing larger by extending and maintaining rapid juvenile growth rates—thus marking the heterochronic mode as a case of neoteny. The independent upper sequence, acting as a different replicate in a natural experiment, shows neither size increase nor heterochrony but does exhibit (in contrast with the classic sequence) evolution toward greater longevity.

Hallam's flow tank experiments indicated a strong adaptive advantage in shell stability for both larger size and paedomorphic form. Neotenous development provides an evolutionary pathway to the simultaneous acquisition of both favored traits—thus showing that “constraints” due to “correlations of growth” (Darwin's own phrase for the phenomenon) may be positive in promoting joint evolutionary advantages, and not only neutral (in carrying spandrels along with primary adaptations), or negative (by imposing inadaptive “baggage” upon trends in form through developmental correlation with selected traits).
X. Observations on two Roman Stations in Essex. By the Rev. Mr. Drake. In a Letter to the Secretary
Authors: Drake
Published: July 2016

The Roman roads that pass through this county of Eissex, are thus described by the fifth Iter of Antonine:

Caesaromagus M. P. XXVIII.

Colonia M. P. XXIV.
XII. An Account of an old Piece of Ordnance, which some Fishermen dragged out of the Sea near the Goodwin Sands, in 1775. By Edward King, Esq, F.R.S. In a Letter to the Rev. Dr. Milles
Authors: King Edward
Published: July 2016

A few months ago I ventured to communicate to the Society, through your hands, some observations on the structure of ancient castles, and the mode of fortifying them; apprehending an enquiry of that nature might possibly have a tendency to illustrate the more early periods of our history, and to fling light upon the relations of many particular events, which are interesting in themselves, but not capable of being fully understood, without some acquaintance with the ancient manners, customs, and arts, that prevailed in those times. The very favourable reception which that attempt met with, induces me now to trouble you still further, with a short account of a single fragment of antiquity, a very extraordinary piece of old Ordnance; which, although it may, at first sight, be deemed an object unworthy the attention of the Society, may perhaps contribute to illustrate some few historical facts, equally with more magnificent and important remains. And I connot help adding, that perhaps the collecting a number of such ancient fragments, of various ages, and preserving faithful accounts of them, may even be a means of furnishing a very useful comment on history.
XXXVII. Observations on an ancient Building at Warnford, in the County of Southampton. By Henry Penruddocke Wyndham, Esq. In a Letter to the Secretary
Authors: Wyndham Henry Penruddocke
Published: July 2016

In reflecting on the works of several writers on our British antiquities who have gone before us, the public must allow great merit to the laudable zeal and painful industry shewn in their researches. It is, however, to be lamented, that, though a great deal of useful knowledge and curious information is to be derived from them, yet an injudicious mixture of matter in some, an imperfect collection in others, and an ill arrangement in most, have left much to be reformed, and much to be supplied, by the care and exactness of other writers.
XV. Observations on the same Inscription. By Dr. Adee, in a letter to the Rev. Dr. Milles
Authors: Adee
Published: July 2016

I have paid attention to the inscription which you submitted to me. I am sorry I cannot ascent to the explanations which other learned gentlemen have offered; neither am I well satisfied with my own. Inscriptions ingeneral, Greek ones particularly, are accompanied with great embarrassments, owing to their shortness, the ignorance of carvers, and the inaccuracy of transcribers and publishers. Few copies are fac similes. Though this inscription may be looked on as such, I apprehend nothing can make grammar or sense of it, but reading it in this manner:
XXIV. Copy of the Draught of a Proclamation in the Year 1563, relating to Persons making Portraits of Queen Elizabeth. From the Original Draught in the Paper Office, in the Hand-writing of Secretary Cecil, with his Corrections, and among his Papers: Communicated by Sir Joseph Ayloffe, Bart
Authors: Ayloffe Joseph
Published: July 2016

For as much as thrugh the natural desire that all sorts of subjects and people, both noble and mean, have to procure the portrait and picture of the Queen's Majestie, great nomber of Paynters, and some Printers and Gravers, have allredy, and doe dayly attempt to make in divers manners portraietures of hir Majestie in paynting, graving, and pryntyng, wherein is evidently shewn that hytherto none hath sufficiently expressed the naturall representation of hir Majesties person, favor, or grace, but for the most part have also erred therein, as thereof dayly complaints are made amongst hir Majesties loving subjects, in so much that for redress hereof hir Majestie hath lately bene so instantly and so importunately sued unto by the Lords of hir Consell and others of hir nobility, in respect of the gret disorder herein used, not only to be content that some speciall coning payntor might be permitted by access to hir Majestie to take the natural representation of hir Majestie whereof she hath bene allwise of hir own right disposition very unwillyng, but also to prohibit all manner of other persons to draw, paynt, grave, or pourtrayit hir Majesties personage or visage for a time, untill by some perfect patron and example the same may be by others followed.
XXIX. Conjectures on an antient Tomb in Salisbury Cathedral. By Mr. Gough
Authors: Gough
Published: July 2016

On the south side of the nave of Salisbury cathedral, under the fourth arch from the west, lies a monument of blue speckled marble, with, the figure of a bishop in pontificalibus, his right hand lifted up to give the blessing, his left hand holding the crosier. On the perpendicular sides or edge all round is cut an inscription, in large capitals; and, on the front of the robe, another in letters somewhat similar. The slab lay to deeply bedded in the stone foundation on which the pillars of the nave reft, that the first of these inscriptions had intirely escaped the notice of the curious, or if any had noticed it, the lower half of the letters being out of sight, rendered it unintelligible. Last summer I procured it to be raised, and the pavement disposed round it in such a manner, that it can henceforth receive no injury, but will remain the second oldest monument in that church, if the conjectures I have formed upon it are founded in truth.
XXXIII. Some Account of certain Tartarian Antiquities. In a Letter from Paul Demidoff, Esquire, at Petersburgh, to Mr. Peter Collinson, dated September 17, 1764
Authors: Demidoff Paul
Published: July 2016

The Russians, in effecting a practicable road to China, discovered in Latitude 50 north, between the rivers Irtish and Obalet, a desert of a very considerable extent, overspread in many parts with Tumuli, or Barrows. This desert constitutes the southern boundary of Siberia.