bluuebunny/crossref_metadata_2025 huggingface dataset:
Foraminiferal turnover in neritic environments in the Oligocene of Southern Australia
Authors: Moss Graham D.
Published: January 2018

This study explores an excellent mid-latitude Oligocene calcareous neritic succession that spans the Eocene/Oligocene boundary to the Miocene. Rapid changes in sea level and climate should have a palpable influence on macroevolution and the Eocene-Oligocene transition marks one of the most substantial changes for the Cainozoic.

Stratigraphic ranges of some 130 benthic and 20 planktic species occurring in two contrasting marine environments, one relatively restricted (low plankton - Murray Basin) and another more open (high plankton - Otway Basin) to oceanic processes, were identified and correlated with signals derived from changes in the physical environment. The signals include: the ‘Exxon’ sea-level curve, deep sea stable isotope curves, and prominent lithological changes.

There is a significant turnover of species at the Eocene/Oligocene boundary. This event impacts on all assemblages and correlation metrics indicate that there is an ‘across-the-board’ response. Interestingly, the turnover corresponds to a local Saint Vincent Basin lithological change from the grey-green, organic rich facies of the Blanche Point Formation to the red-yellow-brown, well oxidized, quartz and bryozoa rich facies of the Port Willunga Formation. This switch is in turn coincident with the saltatory positive deviation in the δ18O top and bottom water curves derived from oceanic sections.

The turnover pattern is not repeated at the major sea level fall predicted for the mid Oligocene (at 30 million years), neither is there any comparable lithological transition. Geographically widespread species (common to all environments) cross this supposed prominent type one sequence boundary, there is a signal but the impact on the fauna is less than that detected for the Eocene/Oligocene boundary. Those faunas that were more restricted to open ocean processes exhibited shorter stratigraphic ranges and appeared to be controlled primarily by sea level fluctuation and salinity changes. There is evidence to suggest that foraminiferal faunas of the more restricted environment in southern Australia were less responsive to the well mixed, thermohaline driven ocean of the Oligocene. Generally, Oligocene benthic assemblages are dominated by Cibicides, Notorotalia and Buliminid species in consistently high numbers, indicating a high dominance of relatively few taxa, that is, large populations and low diversity. Faunas of open ocean assemblages demonstrate relatively subdued turnover patterns compared to those of more restricted environments.

The Late Eocene displays parallel patterns of foraminiferal turnover and the Oligocene is characterised by inter-basin contrasts. In comparison to the Eocene, faunas appear to be more robust in the psychrosphere constrained ocean of the Oligocene. It is proposed that these patterns indicate that the Latest Eocene was dominated by species adapted to a specialist life strategy while the Oligocene reflect patterns more often associated with opportunist colonization.
Long survival of stalk pieces of Metacrinus rotundus Carpenter, a modern stalked crinoid, in an aquarium
Authors: Oji Tatsuo , Amemiya Shonan
Published: January 2018

Previous underwater observations have demonstrated that detached stalk pieces with a few noditaxes are often found in the habitats of modern isocrinid crinoids. They sometimes stand on the substrate by grasping hard objects by cirri. According to the growth of the stalk, the distal parts are repeatedly detached from the main body and discarded on the sea floor. There has been no information about the “fate” of such isolated stalk pieces. Abundance of stalk pieces of crinoids in the geologic column must be considered with reference to the modern analogue.

We have collected by dredging specimens of modern stalked crinoid Metacrinus rotundus Carpenter from the depths of 135-150 m in Suruga Bay, central Japan. Specimens were transferred to a large temperature controlled aquarium (13°) within several hours after capture. While keeping the animals, a few specimens have autotomized the distal stalk, and isolated pieces with a few noditaxes were left in the aquarium. They have kept the same postures and still attached to pebbles by cirri for approximately one year. No further disarticulation nor regeneration occurred to the stalk pieces.

Section of the stalk piece stained by hematocyanin showed that the nuclei were well colored and the fragmental stalk was considered as living. This result strongly suggests a possibility that such fragmental stalks can live for a long time in the natural environment. Abundant occurrence of stalk elements from the geologic record have been attributed to a taphonomic process; selective accumulation of a part of the body after death, but the present results imply that these stalk pieces could live alone for a long time on the sea floor.
Paleoclimate, controls on Upper Devonian source rock sequences and stacked extinctions
Authors: Ormiston Allen R. , Klapper Gilbert
Published: January 2018

High quality (>2% TOC) Upper Devonian source rocks are developed in several sequence types. The commonest type, accounting for 70% of the studied examples is the transgressive sequence with a basal hiatus. Others include shallowing upward sequences (12%), lacustrine sequences in fault-controlled basins (7%), distal slope sequences (7%), and evaporite capped sequences (4%).

Starting from the synthesis of Johnson, Klapper, and Sandberg (1985) it has been possible to demonstrate correlativity of Upper Devonian transgressive episodes globally. The marked association of epeiric sea Upper Devonian source rocks with transgressions heightens interest in their causation. Could they have been produced by glacio-eustatic sea-level change as Stanley (1984; 1988) implies? Quantitative paleoclimate modeling and isotopic paleotemperatures for the Upper Devonian suggest not. Modeling using CCM1 at NCAR, including five year seasonal cycles, suggests the absence of any large southern hemisphere ice volume. Because much of the Upper Devonian land mass was either in equatorial or high latitude regions, there was little development of monsoonal climates. Midlatitude cyclonic activity was also much less than at present, meaning less polar transport of moisture and drier polar areas. Precipitation maxima largely coincided with topographic elevations. In contrast to the Late Ordovician to earliest Silurian, there was no Upper Devonian perennial snow cover even over the high latitude southern land mass. This was in spite of winter land temperatures as low as -40°. in eastern Gondwana. In that area and elsewhere, there was thin winter snow cover which melted in late spring resulting in no build-up of snow cover to produce glaciation. This was mainly the consequence of low winter precipitation in Gondwana. High latitude sea surface temperatures were certainly cold enough to displace or exclude some organisms. However, in low latitude areas where Upper Devonian extinctions also took place, modeled sea surface temperatures range between 27° and 34°. Such areas would have been refuges for any organisms displaced by cold, high latitude waters. The higher temperature values of low latitudes are convergent with the isotopic paleotemperatures determined by Brand (1989) using well preserved Upper Devonian brachiopods. Brand's determinations suggest temperatures even reaching lethal values for many plankton (37°). The extinction of reefs by the close of Frasnian time could have been partly a result of such elevated temperatures. Stacked extinctions of conodonts (Ziegler and Lane, 1987) and acritarchs may have been a further result. The loss of reefs, an important consumer of plankton, may have permitted a relative increase in plankton abundance crossing from more oceanic areas into epeiric seas, possibly contributing to high quality source rock deposition.
The Sirius Passet Fauna, an Early Cambrian Lagerstätte from North Greenland
Authors: Peel John S. , Conway Morris Simon , Ineson Jon R.
Published: January 2018

The Sirius Passet Fauna of North Greenland is one of the oldest Cambrian lagerstätten from the North American continent. It is known from a single locality in Peary Land (83°N, 40°W), on the shores of the Arctic Ocean, where outer shelf mudstones from the lower part of the Buen Formation (Early Cambrian) yield a rich assemblage of mainly poorly skeletised organisms with preserved soft parts. The steeply-dipping fossiliferous mudstones occur in close proximity to horizontally-bedded platform carbonates of the underlying Portfjeld Formation (Early Cambrian) in a structurally complex terrane. The boundary between the fossiliferous mudstones and the platform carbonates apparently defines the original northern margin of the carbonate platform and is not, as previously suggested, a structural feature, although some minor tectonic modification can not be excluded. Thus, the fossiliferous mudstones were apparently deposited in a transitional slope setting basinward of the shelf edge.

As currently known, the Sirius Passet Fauna comprises about 40 species, based on a collection of almost 5,000 slabs collected during brief visits to the isolated locality in 1989 and 1991. Arthropods dominate, with bivalved bradoriids and the trilobite Buenellus higginsi Blaker, 1988 being the numerically most abundant taxa. Weakly skeletised Naraoia-like and Sidneyia-like arthropods often preserve limbs and gills, as do bivalved arthropods similar to Waptia. Choia is the most common of several sponges. Worms include both priapulids and polychaetes, with a large palaeoscolecidan being conspicuous.

Fully articulated specimens of halkieriid worms, clad in an armour of hundreds of individual sclerites, are most notable amongst several problematic taxa. Rare specimens of possible onychophorans are also present, while brachiopods, hyoliths and other shelly fossils are rare or absent.

The Sirius Passet Fauna seems to show little taxonomic similarity to the Middle Cambrian Burgess Shale of western Canada or the Chengjiang Fauna from the Lower Cambrian of China at the generic level. Together with the latter fauna, however, it confirms both the general picture of Cambrian life presented by the Burgess Shale, and the existence of this great diversity of weakly skeletised arthropods already in the Early Cambrian.
Comparative physiology of suspension feeding in living articulate brachiopods and bivalves - implications for large-scale evolutionary patterns
Authors: Rhodes Melissa C.
Published: January 2018

The hypothesis that biotic interactions have escalated over geologic time suggests that taxonomic groups such as bivalves, which developed representatives with high-energy life habits, preempted resources and drove “obsolete” low-energy groups, such as articulate brachiopods, into ecological refugia. Articulates had been the dominant benthos in a broad range of Paleozoic habitats. Modern refugia include areas of darkness and low primary productivity, such as fjords, caves, and polar regions. If the escalation hypothesis is true, then the modern articulates concentrated in these habitats should have extremely low energy budgets. The more energetic bivalves should be abundant higher in the photic zone and have higher energy budgets.

The equation Consumption = Growth (metabolizing tissue) + Reproduction + Respiration + Faeces + Excreta (nitrogenous) describes the energy balance in an organism. Energy acquisition is a critical factor for the persistance of individuals and species. Scaling equations relating particle filtration rates (consumption) to tissue mass were developed experimentally for two northern and two southern hemisphere species of brachiopods. Similar equations were developed for a northern and a southern hemisphere mussel species. The scaling equations allow correction for size differences which would otherwise confound physiological comparisons between species. Both northern and southern hemisphere brachiopod species were collected from deep, dark fjords or soft bottom habitats with Paleozoic style faunas. The mussels were collected from the same areas, but occurred higher in the photic zone.

Results indicate that the articulate brachiopods have a significantly lower ability to collect food particles from the water than do the mussels, for animals of similar body mass. These results support the hypothesis that escalated biotic interactions account, in part, for the ecological replacement of the formerly dominant Paleozoic articulate brachiopods by Mesozoic and Recent suspension-feeding bivalves.
Role of microorganisms in the production of lime mud and implications for interpretation of ancient micrite deposits
Authors: Robbins L.L. , Yates K.
Published: January 2018

Geologists have long been plagued by the lack of evidence for the origin of ancient micrite deposits: any paleontological evidence is typically obscured or lacking altogether. The role of modern marine picoplankton gives insight into the origin of one mode of lime mud formation and may aid in the interpretation of ancient marine deposits.

Whitings, patches of floating lime mud in supersaturated seawater on carbonate platforms, obtained from the Bahama Bank were analyzed utilizing biochemical techniques and Transmission Electron Microscopy. All Whitings indicated a close association between picoplankton cellular material and calcium carbonate crystals. Culture experiments indicated the presence of at least ten different picoplankton species in Whitings water. Two major genera found were the blue-green algae, Synechococcus and Synechocystis. Field and laboratory experimental data indicated that these cells and cellular organics play a major role in Whitings formation. The cells may undergo epicellular precipitation of calcium carbonate induced by photosynthesis. Environmental conditions necessary for this process have been delineated through field data and laboratory experiments.

While picoplankton organics are rarely preserved over geologic time, the product of their life habit, namely lime mud, is preserved as micrite. Thick occurrences of micrite deposited in marine environments are widespread throughout the geologic record, ranging in age from Precambrian to Recent. Although rare, fossilized blue-green algae have been observed in Archean rocks and may be the only evidence that implicates these organisms in lime mud formation. The Whitings phenomenon serves as an excellent example in which a specific type of organism may be a prolific contributor to the rock record, and yet leaves no direct paleontological evidence of its involvement.
Early angiosperm fossil leaves in Chubut Group, Cretaceous, Argentina
Authors: Romero Edgardo J. , Palma Ricardo
Published: January 2018

The oldest angiosperm leaves from Patagonia were reported from Baquero Formation (Barremian-Aptian) in a mesofitic flora of more than one hundred gymnosperm and fern species. The next younger records are from the Chubut Group, a thick assemblage of pyroclastic sediments, with sand and conglomerate facies and frequent paleosols. In the Sierra de San Bernardo area sediments are mainly tufaceous and fluvial, deposited under an arid climate in shallow lakes and swamps of the alluvial plains. The sea was hundreds of kilometers to the West. Four Formations were described: Matasiete (Aptian), Castillo and Bajo Barreal (Senonian) and Laguna Palacios (Campanian-Maastrichtian). We explored in the Senonian Formations, and studied a few outcrops that can be sorted as:

a) Monospecific, with only Onychiopsis sp., in palustral sediments. b) Strongly dominated by Eauisetum sp, and few remains of two dicot species with large, entire margined, low rank leaves, in palustral sediments. c) Strongly dominated by two species of angiosperms with small leaves, associated with remains of conifers in tufaceous beds deposited in the alluvial plain. d) Dominated by a few species of dicots, with medium size, entire margined leaves. Also with about 10 species of ferns, gymnosperms and lobate angiosperms. They are in alluvial plains sediments. e) More balanced associations, with several abundant species, including angiosperms with lobate and leaves. They are in fluvial sediments.

Although angiosperm radiation and taphonomy undoubtedly accounts for differences of plant composition between outcrops, it seems apparent that the record of early angiosperms in Chubut Group is represented by remains of many different plant associations, with few species, adapted to different environments, that probably coexisted, and developed under an arid climate, far from the sea.
Paleobiology of the Ediacara Fauna
Authors: Runnegar Bruce
Published: January 2018

Long regarded as the earliest evidence for animal life, the fossils of the Ediacara fauna have come under increasingly close scrutiny as the result of a proposal made by A. Seilacher in 1983. At that time Seilacher suggested that the Ediacara fauna represents an extinct line of animal life (the Vendozoa) which pioneered a body form and modes of nutrition not seen in the Phanerozoic. More recently, Seilacher and others have suggested that most typical members of the Ediacara fauna were not even animals but were extinct foliate creatures analogous to algae or fungi which relied on endogenous photosymbionts or chemosymbionts for food and energy.

It would not be surprising if the Ediacaran organisms contained bacterial or eukaryotic endosymbionts as endosymbiosis at the organelle or unicell level is the norm rather than the exception for many protists and diploblastic metazoans. However, it is difficult to find the evidence to test this endosymbiont hypothesis because the Ediacaran fossils are merely impressions of soft bodies in sandstone or siltstone.

As there are no clear modern homologs of most of the Ediacaran organisms it is necessary to resort to logic and experiment to understand them. This has proved to be a formidable task but some progress is being made with complex forms such as Dickinsonia and Phyllozoon. Although no core member of the Ediacara fauna is unequivocally an early animal, there are more similarities to animals than to algae or fungi. There is no evidence at all that the vendozoans are fourth form of eukaryotic multicellular life.
Trace fossils from the Late Proterozoic of North Carolina: early conquest of deep-sea bottoms
Authors: Seilacher Adolf , Pflüger Friedrich
Published: January 2018

The trace fossil Oldhamia reflects systematic strip mining of an infaunal, worm-like sediment feeder. It is known from many parts of the world in Cambrian complexes, whose flysch-like and accreted character suggests deposition on a deep continental slope. In similar rocks of the North Carolina Slate Belt. Oldhamia is associated with rare specimens of the Ediacara-type body fossil Pteridinium, as well as tool marks of a problematic stiff organism reminiscent of graptolite stipes (Vendospica).

This occurrence (1) extends the stratigraphic range of Oldhamia into the Late Proterozoic. It also reminds us that, by that time, worm-like, endobenthic bilaterians (2) had become behaviorally specialized and (3) had colonized shelf and deep-sea bottoms well before the Cambrian evolutionary explosion. (4) Since bioturbators were small and did burrow strictly along bedding planes, their mixing effect was as yet negligible. (5) The new tool-mark fossils tell us that complex, organic-walled and perhaps colonial organisms were around in addition to sand-corals (Psammocorallia), possibly sponges and the probably plasmodial Vendobionta.
An iterative evolutionary pattern in the gastropod genus Melanopsis
Authors: Staley Andrew W. , Geary Dana H. , Müller Pál , Magyar Imre
Published: January 2018

Iterative patterns of morphological evolution present a unique opportunity to explore the causal mechanisms of evolution. We report here on an iterative morphological trend within a clade of prosobranch gastropods.

We studied the Melanopsis impressa lineage from Middle to Late Miocene marginal lake sediments of the Pannonian basin (central and eastern Europe). The descendants of M. impressa evolved a type of whorl shouldering in at least two different instances. The first instance occurs in the Late Miocene Pannonian Stage, when the smooth and conical M. impressa gives rise to M. fossilis, a species characterized by strong shouldering. The disappearance of M. fossilis coincides with a major contraction in the areal extent of the lake and with a shift from brackish to fresh water at the end of the Pannonian Stage. Melanopsis impressa may have survived this event in marginal drainage environments; during the subsequent Pontian Stage, M. impressa or a close relative gives rise to a second shouldered descendant (M. petrovici-M. cylindrica complex).

The constructional aspects of shouldering are different in each case. In the first instance, shouldering is characterized by a broad and rounded ridge in the middle of the adapical half of the body whorl, usually associated with a depressed area adapically. In contrast, shouldering in the second instance is a simple, rounded or angled spiral prominence on the adapical half of the whorl.

Repeated development of a character in a single lineage might suggest that the parallelism is due to an intrinsically defined pathway. The different constructional aspects of shouldering in our examples, however, suggest that it was the selective regime that was repetitive. The brackish paratethyan sea of the Pannonian Stage and the smaller, freshwater lake of the subsequent Pontian Stage differed in many respects, but hydrodynamic or predatory selection pressures may have evoked similar morphological responses.
The role of environment in the diversity and evolutionary turnover rates of the Foraminiferida
Authors: Starratt S.W.
Published: January 2018

Taxonomic databases are important tools in the study of faunal diversity and evolution. The usefulness of the inferences drawn from these databases is diminished when the role of environment is not considered. Analysis of the foraminiferal database at the genus and family levels is used to demonstrate the effect of water depth on presumed changes in taxonomic diversity and evolutionary turnover rates.

This paleoenvironmental effect is particularly noticeable when foraminiferal faunas of the late Paleozoic and the Mesozoic and Cenozoic intervals are compared. The late Paleozoic fauna is dominated by the Fusulinina and shallow-water (0–200 m) Textularuna. Standing diversity fluctuates greatly, and evolutionary turnover is high. This reflects short-term fluctuations in sea level which led to the rapid formation and destruction of narrow ecological niches. Evolutionary turnover appears to be related to reef growth during this time. This trend may also reflect an increased number of k-selected specialists which serve as proxy indicators for a slow-circulating oligotrophic ocean system. Shallow-water taxa may also be predisposed to extinction due to their reliance on symbiotic algae. The extinction event at the end of the Permian resulted in the loss of almost 70% of the standing generic diversity. This included the complete loss of the Fusulinina as well as a number of shallow-water textularids. Cohort survivorship curves are steep and taxon ages short during this time.

The diversity increase over the past 245 million years has largely been due to the addition of deep-water (200-10,000 m) taxa. This was particularly true during the Late Cretaceous and early Eocene, and may reflect the relatively high eustatic sea level during those intervals. The relationship between reef development and evolutionary turnover rates is less clear during this time interval. Although the extinction event that marked the end of the Cretaceous resulted in a greater loss in absolute taxonomic diversity than occurred at the end of the Permian, the relative loss in generic diversity was only about 21% due to the large number of deep-water taxa. When the entire fauna is considered, cohort survivorship curves are less steep and taxon ages are longer than in the late Paleozoic, but when only the shallow-water taxa are considered, the results are similar to those for the late Paleozoic.
The atlas-axis complex of the Late Paleozoic Diadectomorpha and basal amniotes: defining the primitive condition of the atlas-axis complex of amniotes
Authors: Sumida Stuart S. , Lombard R. Eric. , Berman David S
Published: January 2018

During the past decade, phylogenetic analyses of Late Paleozoic tetrapods have consistently demonstrated that the Permo-Pennsylvanian tetrapod suborder Diadectomorpha is closely related to more traditionally defined amniotes. Recent analyses provide two competing hypotheses of relationship: 1) the Diadectomoropha is the sister group of all amniotes, or 2) the Diadectomorpha and Synapsida comprise the most primitive clade within the Amniota. Subsequently more derived groups within the Amniota are: the reptilian family Captorhinidae, and the Protorothyrididae plus the Diapsida. The availability of well preserved atlas-axis complexes for all of the better known genera of diadectomorphs now allow a determination of the primitive condition of the atlas-axis complex for the Amniota. Further, accepted hypotheses of phylogenetic relationships among Late Paleozoic tetrapods allow mapping of features of the atlas-axis complex onto predefined topologies so that the transformations of the complex may be analyzed.

The diadectomorph atlas-axis complex may be characterized in the following manner: paired, well developed proatlases and atlantal neural arches; lack of proatlantal and atlantal neural spines with only posteriorly directed epipophyses present; an extremely robust atlantal intercentrum; tight articulation of the atlantal pleurocentrum with the dorsal aspect of the axial intercentrum preventing exposure of the former on the ventral surface of the vertebral column; a large, anteriorly directed midline projection of the axial intercentrum; a tall and well-developed axial neural spine, presumably for attachment of strong occipital muscles and ligaments. Except for the anterior projection of the axial intercentrum (which is an autapomorphic feature of diadectomorphs), basal amniotes share all of these features with diadectomorphs. Shared, derived features of the atlas-axis complex of diadectomorphs plus other basal amniotes include: 1) fusion of the axial centrum and neural arch, 2) small epipophyses of the atlantal neural arch and, with the exception of Tseajaia, 3) fusion of the atlantal pleurocentrum to the dorsal surface of the axial intercentrum.

The morphology of the atlas-axis complex alone is not sufficient to generate hypotheses of relationship between diadectomorphs and other basal amniotes. However, the atlas-axis complexes of diadectomorphs and other basal amniotes are clearly more similar to one-another than to those of other taxa.
Mid-miocene post-disturbance vegetation dynamics and the emergence of cold desert/steppe vegetation in the northern intermountain region
Authors: Taggart Ralph E. , Cross Aureal T.
Published: January 2018

The mesic broad-leaved and coniferous forests of the Middle Miocene of the northern Intermountain region of the United States contrast strongly with the semi-arid shrub/grassland steppe vegetation that comprises the extant vegetation. This contrast is a consequence of the progressive development of a regional rain shadow, beginning in the Late Miocene, coincident with the uplift of the Cascades to the west. It is generally assumed that the emergence of the extant vegetation was a consequence of a combination of in situ evolution of taxa in response to moisture and thermal stress and the immigration of taxa already adapted to such stressful environments. The study of stratigraphically sequential successional vegetation stages in a number of Middle Miocene floras in the northern Great Basin suggest that many elements of the extant vegetation of the region were already present as taxa adapted to the several characteristic environmental conditions of landscapes affected by volcanic disturbance.

The Middle Miocene “climax” vegetation of southeastern Oregon and southwestern and southcentral Idaho, documented by paleobotanical and palynological data from floras such as Stinking Water (Oregon), Succor Creek (Oregon-Idaho), and Trapper Creek (Idaho), was a complex mosaic of vegetation types comprised of broad-leaved evergreen, mixed mesophytic, and mixed coniferous forest elements. These floras are preserved in volcaniclastic sediments. Palynological analysis of sequential samples from overlying strata indicate that the bulk of the sedimentary record at each of these sites records vegetation in varying stages of recovery following destruction of forests by local volcanism. The earliest seral stages following such events are characterized by taxa, including Artemisia, Sarcobatus, and other Malvaceae, Chenopodiaceae, Amaranthaceae, Compositae, and Gramineae that represent important components of the extant vegetation of the region.

An ash-covered landscape, denuded of forest cover, is a highly stressful environment. Ash forms an edaphically dry and nutrient-poor substrate and such sites would be exposed to a significantly greater range of annual temperatures and much greater exposure than forested sites. Grasses, forbs, and shrubs that evolved in ways that permitted the colonization of such landscapes would be preadapted to the drier and less equable climates that would accompany the development of the Cascadian rain shadow. In addition, such successional areas also supported a mammalian fauna dominated by grazers in contrast to the browsing-dominated fauna of the climax forest mosaic. It would thus appear that the post-disturbance grass/forb/shrub communities provided an evolutionary proving ground for mammalian niches that now dominate the extant cold desert/steppe biome.
A unique taphonomic profile for Lower Carboniferous crinoids of western Canada and possible Recent analogs
Authors: Terry Richard E. , Meyer David L.
Published: January 2018

During diving studies of comatulid crinoids at Lizard Island, Great Barrier Reef, detatched but intact crinoid arms and arm groups were sometimes encountered on the substratum. These arms are thought to originate through autotomy or breakage during attacks of predatory fish that remove the calyx and visceral mass but leave the arms intact. Detached arms remain in a vital condition for several days but soon lose pinnules and fragment as decay ensues.

Occurrence of intact, isolated arms and arm groups in the Banff Formation of western Alberta requires a catastrophic disturbance (not necessarily predation) followed closely, if not coincidently, with burial. The loose arms are preserved mostly as short, straight, distal arm segments (1–2 cm long) or sometimes as long, curved arm segments (2–4.5 cm). The arm groups range from complete arm rays to partial arm rays. If originally present, pinnules are still articulated to the arms and cover plates are preserved on most pinnules. Biserial arms with pinnules, uniserial arms and uniserial arms with pinnules occur in a 2:1 ratio to crinoids having that type of arm structure whereas cuneiform arms with pinnules have a 3:1 ratio of preserved loose arms and arm groups to calyces. Loose, single arms and arm groups account for 33% and 11%, respectively, of the identifiable crinoid remains for the western, deep-water Banff Formation crinoid fauna. Overall, this fauna shows an equitable range from complete articulated crinoid crowns with attached stems to loose isolated plates. The preservation of this fauna has both a time-averaged, accumulation component as well as an instantaneous storm deposited component as represented by both completely articulated crinoids and the high abundance (44%) of loose arms and arm groups. The comparatively anomalous abundance of loose arms and arm groups probably originated through breakage or autotomy coincident with the burial event.

In comparison, the Gilmore City crinoid fauna of Iowa represents an obrution deposit with over 75% of the crinoid specimens preserved as complete articulated crowns with attached stems whereas the eastern Banff Formation crinoid fauna is preserved as a shallow-water, time-averaged accumulation of mainly isolated crinoid calyx plates (54%) and partial calyces (20%). However, both of these faunas have few preserved loose arms or arm groups (<4% for either fauna).
Early metazoan evolution and the concept of progress
Authors: Valentine James W.
Published: January 2018

The number of cell types present in a metazoan body is a reasonable metric of its complexity. If evolutionary progress is defined as increase in complexity, from “lower” to “higher” forms, then progress occurs as cell-type numbers are increased. Using a lumper's definition of cell type, living metazoans range from 4 (placozoans) to over 210 (higher mammals) somatic cell types. The earliest fossil traces may be 580 my old and require an organism of about 30 cell types, while the primitive members of higher invertebrate phyla, appearing near 525 my ago, require about 50 cell types, an increase of about 0.3 cell type/my. Average Phanerozoic cell-type increase was about 0.4 cell type/my. These estimates are indistinguishable considering their crudity, and imply an origin of metazoans between about 645 and 680 my ago. While it may have been episodic rather than gradual, evolutionary progress would seem to have continued throughout metazoan history.

The Cambrian “explosion” occurred chiefly among organisms of 50 or so cell types, but so far as one can judge represented no major leap in the complexity of body plans. Rather it was characterized by a radiation of a number of clades that were at about this same level of complexity, one that permitted the construction of a rich variety of body plans, within a few million years. The diversity of the daughter body types was thus spectacularly broad. Though it may have been only a locus on a sweeping trend of continuing progress, the Cambrian explosion was something special in the history of life.

Concomitant with the rise in cell type numbers during the late Precambrian, the genetic regulatory apparatus that characterizes most metazoans was assembled, involving a cascading, hierarchical system of genes with feedback mechanisms and with informational systems that are not directly encoded. This flexible and open-ended regulatory architecture underlies evolutionary progress in metazoans, and permitted the evolution of cell differentiation. It may prove possible to judge the steps in the assembly of this regulatory system from the early metazoan record of body types, and conversely, it may prove possible to reconstruct the pattern of divergence of clades and the rise of body types as comparative data on pattern-formation systems become available for a variety of major taxa.
Cladistics and the rate of homoplastic morphological evolution
Authors: Wilkinson Mark , Benton Michael J.
Published: January 2018

Estimates of evolutionary rates require measurement of amounts of change and the period of time over which such change has occurred. Many methods of estimating amount of morphological change are available (including phenetic and morphometric measures) but in cladistics the unit of change is the step or transformation.

For a given cladistic data set the length (total number of steps) of the most parsimonious cladogram gives a lower bound estimate of the amount of evolution that has occurred within the clade. This measure is correlated with numbers of characters and taxa (and other internal parameters) in the data sets and so cannot be used to compare amounts of evolution in different clades where data set sizes vary. Further, the number of characters incorporated into cladistic studies varies widely and is likely to be a poor basis for an estimate of overall amounts of change.

One approach to the measurement of amounts of change which avoids some of these problems is to focus upon comparative levels of homoplasy rather than total amounts of morphological evolution. Most parsimonious cladograms provide lower bound estimates of the amount of homoplasy measured as extra steps.

Maximally homoplastic data provides the theoretical upper limit to the amount of homoplasy that can be estimated for a particular data set. Combining this with estimates of group duration derived from the fossil record or from molecular clocks provides an estimate of maximum rates of homoplastic evolution that can be measured using cladistic parsimony and discrete data.

Randomly permuted data provides a measure of the amount of homoplastic evolution that would be reconstructed by parsimony analysis for character data that is independent of phylogeny. Combining this with estimates of group duration provides estimates of rate of homoplastic evolution that would be sufficient to render the application of parsimony to the problems of phylogeny reconstruction inappropriate.

Comparative estimates of the rates of homoplastic evolution in different clades can be used to test macroevolutionary theories.
Comparative taphonomy of Miocene fossil biotas with soft tissues in lake deposits: Clarkia (Idaho, U.S.A.) and Shanwang (Shandong, P.R. China)
Authors: Yang Hong , Smiley Charles J. , Yang Shipu
Published: January 2018

The recent discovery of Tertiary plant fossil DNA from the Clarkia Miocene lacustrine deposits, northern Idaho, has raised concerns of the taphonomic conditions of preservation of fossil biotas with soft tissues and the further prediction of such occurrence in ancient lake deposits. The exceptionally preserved Clarkia fossil biota is compared with the Shanwang biota in Shandong Provence, eastern P.R.China, another example of Miocene conservative fossil lagerstatten. The comparison shows following similarities between the two extraordinarily preserved Miocene fossil biotas: (1) both were deposited under similar age, geological background, and depositional environment; (2) humid, warm-temperate paleoclimate was inferred in both areas; (3) both deposits contain diverse fossil biotas with soft tissues but having limited benthic organisms; (4) higher similarity coefficient exists between fossil diatoms, higher plants and insects at genus or higher taxonomic levels; and (5) overall similar taphofacies exists between the two fossil biotas.

However, following differences appear between the two areas: (1) diverse vertebrate fossils in Shanwang site are sharply contrasted with the Clarkia biota in which terrestrial vertebrates are absent; (2) comparison of taphonomic signatures shows slightly different patterns between the two; (3) the two Miocene lakes originated in different manners, thus differences appear in configuration, stratification, and other paleolimnologic parameters between the two ancient lakes.

The comparison of the two extraordinary fossil biotas, coupled with geologic, sedimentologic, paleoecologic and paleobiochemical studies, demonstrates that the formation and preservation of such fossil biotas with soft tissues in ancient lake deposits were strongly controlled by various paleolimnologic, paleoclimatic, taphonomic and compositional parameters.
Paleobiogeography of Devonian vertebrates
Authors: Young Gavin C.
Published: January 2018

Five distinctive vertebrate faunas characterised by endemic taxa can be recognised for the Early Devonian (Euramerica, Siberia, Tuva, China, and East Gondwana). By Late Devonian time these faunal provinces are obscured by widespread taxa which also inhabited nonmarine aquatic environments, but indicate faunal communication between Gondwana, Euramerica and China. This marked change in pattern between the Early and Late Devonian may be attributed to intrinsic (evolutionary) or extrinsic causal factors. Dispersal capabilities of aquatic vertebrates may have increased during the initial gnathostome radiation of the Devonian, but a predominantly extrinsic cause (e.g. global change in geography or climate) is suggested by the similar pattern for marine invertebrate faunas of Early Devonian endemism and Late Devonian cosmopolitanism. Outstanding problems of Devonian vertebrate biogeography include faunal differentiation on the largest landmass of the time (Gondwana), and the nature of barriers and connections between East and West Gondwana, East Gondwana and South and North China, and West Gondwana and Euramerica. A vertebrate equivalent of the cool-water Malvinokaffric invertebrate faunal realm of the Siluro-Devonian is not clearly identified, but vertebrate data from southern Africa and south America are sparse.

Wide latitudinal distributions for some Late Devonian vertebrate taxa appear anomalous, and could indicate either reduced global climatic gradients, or erroneous paleogeographic base maps. There are difficulties in formulating a hypothesis of global warming and/or major paleogeographic change in a way which clearly distinguishes basic from interpreted data. Three major subdisciplines (paleomagnetism, paleoclimatology, paleobiogeography) contribute to Paleozoic paleogeographic reconstructions. Their data tend to be organised and represented in different ways, but each relies on the same principle of concordance with a general pattern (Young 1990). Degree of consilience of a hypothesis based on one data set (the extent to which it explains patterns within an unrelated set of data) is a primary criterion for accepting or rejecting the hypothesis. Apparent polar wander path representation facilitates testing of paleomagnetic data against those paleoclimatic or paleobiogeographic data which provide evidence of paleolatitude. However, as well as the simple indication of paleolatitude, biogeographic and some other qualitative data sets provide more complex evidence concerning connections or barriers between regions, for which APWP representation is not appropriate. Cladistic analysis of hierarchically organised data sets (Young, 1986, 1987) provides a means of integrating qualitative paleobiogeographic, paleoclimatic, and paleogeographic data such that inconsistencies in the evidence are emphasised, and the hypothesis is exposed to falsification. These ideas are illustrated using Devonian examples.
Migration of exotic species of ammonites during highstands of sea level
Authors: Young Keith
Published: January 2018

In northeastern Chihuahua and Trans-Pecos Texas, in the early Late Albian zone of Hysteroceras varicosum occurs the Boeseites romeri (Haas) fauna with B. romeri (Hass), B. perarmata (Hass), B. aff. barbouri (Haas), B. cf. howelli (Haas), B.proteus (Haas), Prohysteroceras cf. P. hanhaense Haas, Elobiceras sp., and Dipoloceras (?) sp. B. perarmata has also been collected at Cerro Mercado, near Monclova, Coahuila. Haas originally described this fauna from Angola. Now, from rocks in the same zone in the Sierra Mojada, Coahuila, Mexico, there is a form related to if not identical with Hysteroceras famelicum Van Hoepen, also originally described from Angola and also from the zone of Hysteroceras varicosum.

These fossils are known only from southern North America and Angola; they have not been described from the European Tethys. In 1984 I suggested that during the highstand of sea level of the early Late Albian (Hysteroceras varicosum zone) these ammonites migrated from Angola to Mexico and Trans-Pecos Texas via an epeiric seaway extending across the sag between South America and Africa proposed by Kennedy and Cooper. This would be twelve to fifteen million years prior to an oceanic connection between the North and South Atlantic.

I would now ask, can similar epeiric seas and highstands of sea level explain the migration of successive European, Tethyan, Jurassic ammonite faunas down the Mozambique Channel and around the horn of Africa into the Neuquen Basin of Argentina before Africa and Antarctica separated, as proposed by Spath.
Multiplex glycan bead array for high throughput and high content analyses of glycan binding proteins
Authors: Purohit Sharad , Li Tiehai , Guan Wanyi , Song Xuezheng , Song Jing , Tian Yanna , Li Lei , Sharma Ashok , Dun Boying , Mysona David , Ghamande Sharad , Rungruang Bunja , Cummings Richard D. , Wang Peng George , She Jin-Xiong
Published: January 2018

Glycan-binding proteins (GBPs) play critical roles in diverse cellular functions such as cell adhesion, signal transduction and immune response. Studies of the interaction between GBPs and glycans have been hampered by the availability of high throughput and high-content technologies. Here we report multiplex glycan bead array (MGBA) that allows simultaneous analyses of 384 samples and up to 500 glycans in a single assay. The specificity, sensitivity and reproducibility of MGBA are evaluated using 39 plant lectins, 13 recombinant anti-glycan antibodies, and mammalian GBPs. We demonstrate the utility of this platform by the analyses of natural anti-glycan IgM and IgG antibodies in 961 human serum samples and the discovery of anti-glycan antibody biomarkers for ovarian cancer. Our data indicate that the MGBA platform is particularly suited for large population-based studies that require the analyses of large numbers of samples and glycans.
Intermittent C1-Inhibitor Deficiency Associated with Recessive Inheritance: Functional and Structural Insight
Authors: Caccia Sonia , Suffritti Chiara , Carzaniga Thomas , Berardelli Romina , Berra Silvia , Martorana Vincenzo , Fra Annamaria , Drouet Christian , Cicardi Marco
Published: January 2018

C1-inhibitor is a serine protease inhibitor (serpin) controlling complement and contact system activation. Gene mutations result in reduced C1-inhibitor functional plasma level causing hereditary angioedema, a life-threatening disorder. Despite a stable defect, the clinical expression of hereditary angioedema is unpredictable, and the molecular mechanism underlying this variability remains undisclosed. Here we report functional and structural studies on the Arg378Cys C1-inhibitor mutant found in a patient presenting reduced C1-inhibitor levels, episodically undergoing normalization. Expression studies resulted in a drop in mutant C1-innhibitor secretion compared to wild-type. Notwithstanding, the purified proteins had similar features. Thermal denaturation experiments showed a comparable denaturation profile, but the mutant thermal stability decays when tested in conditions reproducing intracellular crowding.Our findings suggest that once correctly folded, the Arg378Cys C1-inhibitor is secreted as an active, although quite unstable, monomer. However, it could bear a folding defect, occasionally promoting protein oligomerization and interfering with the secretion process, thus accounting for its plasma level variability. This defect is exacerbated by the nature of the mutation since the acquired cysteine leads to the formation of non-functional homodimers through inter-molecular disulphide bonding. All the proposed phenomena could be modulated by specific environmental conditions, rendering this mutant exceptionally vulnerable to mild stress.