bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Late Neogene trend in a venerid bivalve chione cancellata, from the Florida peninsula
Authors: Roopnarine Peter D. 
Published: January 2018

The objective of this project is to understand the long-term relationships, if any, if within-clade bivalve shell morphology to variations in shell growth rate and possible underlying environmental factors. As a preliminary approach to this problem, a study was undertaken to record the history of shell morphology, on the Florida peninsula, of the venerid bivalve Chione cancellata L. (Lower Pliocene - Recent). Samples were obtained from the following formations: Lower Pinecrest (3.5-3.0 mya), Caloosahatchee Fm. (2.5-1.8 mya), Upper Pinecrest Beds (2.4-1.8 mya), Bermont Fm. (1.6-1.1 mya), Anastasia Fm. (0.05 mya), and Recent. The total data set comprised ten samples.Eleven morphometric measurements were selected on their predicted sensitivity to growth rate-caused variations in valve convexity. Comparisons of sample data sets were performed using principal components and canonical variates analyses. Only left-handed valves were analyzed. The results of both the principal component and canonical variates analyses indicate that a disproportionately large amount of the variance in the composite data set is accounted for by one morphometric dimension. This dimension is essentially a summary of contrast between anterior hinge morphology and posterior adductor muscle morphology. The samples form three major clusters; (1) Bermont Fm., Anastasia Fm. and Recent samples, (2) Caloosahatchee Fm. and U. Pinecrest samples, and (3) L. Pinecrest samples. There is some overlap of extremes between clusters (2) and (3), but otherwise the clusters are distinct. The result is a gradual but significant change of morphology during a 3.5 m.y. time span.The next step in the project is to seek an explanation for the above observations. The provinciality of the phenomenon will be tested more extensively with the inclusion of Neogene and Recent samples from the Southern Caribbean and the Atlantic Coastal Plain. Also, considering the dynamism of Florida's oceanographic conditions (temperature, productivity and circulation) during the last 3.5 m.y., correlation of oceanographic conditions with C. cancellata's growth rate and morphology will be examined. The proposed method is a systematic sampling of stable oxygen and carbon isotopes from valves within the samples analyzed.
China and the lost worlds of the dinosaurian era
Authors: Russell Dale A. 
Published: January 2018

What is known of dinosaurian biogeography suggests a centre of evolution first on a fragmenting Pangea-Gondwana and then on a consolidating Laurasia. By Cretaceous time members of Gondwanan low-latitude abelisaur-titanosaur assemblages often bore “back-fans,” while those in polar latitudes were relictual and/or highly derived. The time of last contact between South America and Africa is not well constrained, but links to Antarctica continued beyond the end of the Cretaceous. Many Gondwanan tetrapods appear to have waif-dispersed to Laurasia across southern Europe; few crossed in the opposite direction until the end of the period. Laurasian assemblages were then typically dominated by tyrannosaurids and hadrosaurids.Land masses (“lost worlds”) periodically became isolated from Gondwana-Laurasia. (1) Eastern Asia was isolated between middle Jurassic through Neocomian time, although related temnospondyls and carnosaurs may have co-existed in Austral regions. Mamenchisaurs were the dominant giant terrestrial herbivores, while whip-tailed diplodocids filled the same role in Pangea. Groups of European-North American affinity then replaced many Asian endemics in a manner reminiscent of the Neogene mammalian turnover in South America. (2) In North America. Late Jurassic dinosaur assemblages exhibited Gondwana affinities, but by Late Cretaceous time they were dominated by forms of Asian ancestry. The apparent low diversity of Aptian-Albian dinosaur assemblages and absence of well-marked endemism may have been the result of a brief period of isolation. (3) European archipelagos were a filter bridge between northern lands and Gondwana analogous to the East Indies, which separate comparably different modern biotas in southeast Asia and Australia. (4) During Barremian time India probably hosted an polar dinosaurian assemblage, but low-latitude Gondwana forms (abelisaurids, titanosaurids) were present during at least part of this interval. Isolation ended with the immigration of northern taxa in Maestrichtian time.Underexplored Mesozoic horizons of great biogeographic interest include (1) the Middle Jurassic-Neocomian of China for microvertebrate materials, (2) the pre-Maestrichtian Cretaceous of India, and (3) the post-Cenomanian of Africa, Australia and Antarctica. Paradoxically, the two recently discovered dinosaurian specimens of the latter age in Antarctica, which represent about as much biogeographic information as all described materials of similar age from Africa combined (none are known from Australia), are presently referred to families with Laurasian distributions.
The Upper Devonian fish locality of Miguasha, Quebec, Canada
Authors: Schultze Hans-Peter 
Published: January 2018

At Miguasha, Québec (earlier referred to as Scaumenac Bay), the Escuminac Formation, lowermost Upper Devonian, yields an abundant and diverse fish fauna and flora. Both vertebrates and plant fossils from the locality are reknowned throughout the world. The excellent preservation, including that of endocranial anatomy, enabled Jarvik to describe and illustrate fine anatomical details of the osteolepiform Eusthenopteron. That gives the wrong impression that Miguasha is throughout the Escuminac Formation an outstanding Conservat Fossil-Lagerstätte.The cliffs at Miguasha bear fishes throughout the approximately 120 m thick Escuminac Formation. The lithology of the sediments changes throughout the sequence. Close to the base of the formation, acanthodians and anaspid-like agnathans occur in laminites, sometimes hundreds on one horizon. In these laminites, soft tissue preservation may occur (anapsid-like agnathans), and diagenetic transformations of acanthodians into organic substance led to misinterprations and recognition of the “larval chordate Scaumenella.” Most common within the sequence are limy concretions with different fish fossils, most commonly Bothriolepis. Three-dimensionally preserved fishes occur within the sandstone-siltstones and sometimes within the concretions. In all these cases, dermal bone is preserved, and in few cases chondral bone too, as in Eusthenopteron. One can characterize these fossiliferous sections of the Escuminac Formation as Concentration Fossil-Lagerstätte, whereas the laminites are Conservat Fossil-Lagerstätten.The depositional environment was previously interpreted as an intermontaneous basin, based on tectonic and paleogeographic position. More recent paleogeographic reconstructions show a connection with Scottish deposits and to marine deposits in the present day North Sea. The lack of invertebrates and of marine plant remains, and the occurrence of vertebrates in other localities were used as additional indicators for freshwater deposition.The sedimentological features are ambiguous, the turbidites, such as those found at Miguasha, can occur in marine or large freshwater bodies. Conchostracans occur, sometimes in the thousands on a single plane, in the basal part of the Escuminac Formation. They occur today in freshwater or brackish environments; the same species as the one in the Escuminac Formation is reported from lower Upper Devonian marine deposits in the Baltic (Koknese, Latvia). A detailed comparison of the fish fauna with other lower Upper Devonian fish faunas indicates a coastal marine environment. That is supported by rare trace fossils and by different chemical analyses of the sediments and 87S/86S analysis of Bothriolepis bones.In conclusion, earlier interpretations of the paleogeographic position of the Escuminac Formation at Miguasha and chemical and faunal indicators contradict each other in the interpretation of the paleoenvironment of the formation.
Escalating energy budgets and oligotrophic refugia: winners and drop-outs in the Red Queen's race
Authors: Thayer Charles W. 
Published: January 2018

Preliminary evidence supports a series of predictions and speculations that derive from the hypothesis of evolutionary escalation (Red Queen). If biotic interactions have intensified over geologic time, then:(1) Energy budgets of individuals have increased. This involves both sides of the equation Consumption = Growth + Reproduction + Respiration (includes locomotion & feeding) + Feces + Excreta. Thus living representatives of formerly successful taxa have lower energy budgets than ecologically similar taxa that were successful later, e.g., reptiles vs. mammals, Sphenodon vs. other reptiles, brachiopods vs. bivalves, Nautilus vs. coeleoids, gymnosperms vs. angiosperms.(2) The price of success (cals. per reproducing offspring) has increased. Thus Red Queen evolution leads to energetic inefficiency.(3) Energetic escalation is fueled by increasing plant biomass and turnover, especially on land (angiosperms, including N-fixers such as legumes). The enlarged trophic base pemits diversification without reduction of niche size. Evolution of marine benthos (our primary record of evolution) may be fueled directly by fixed C or indirectly by fixed N (shelf waters are normally N-limited), both increasingly supplied from land as a result of steady state mortality (deciduousness, self-thinning, short life-cycles) or disturbance mortality (fire, wind) of bigger standing crops. The Mesozoic origin of new phytoplankton such as diatoms may be a consequence of terrestrial angiosperms. In turn, diatoms produce lipid, a more energy-dense food than the carbohydrate produced by other phytoplankton. Increased skeletonization of Mesozoic phytoplankton may have diluted the food of Paleozoic-style suspension-feeders, especially brachiopods. Brachiopods have blind guts, which they readily stuff with non-nutritive particles and tight (efficient) energy budgets that might not sustain increased feeding costs.4) Archaic organisms survive in oligotrophic refugia that exclude more recent, high-energy enemies. Marine animals move to deeper water (explaining offshore migration over the Phanerozoic, e.g., Latimeria, Nautilus, Zoophycos.). Other refugia are high latitudes, caves, or dark fiords. Living articulate brachiopods flourish in all of these except the fluvial-influenced Arctic Ocean. Refugia for archaic flora restrict light, water, or N (high latitudes and elevations, forest floor, poor soil).5) Survival in oligotrophic refugia selects for lower energy budgets, including reduction of respiring tissue, so Cope's Rule is reversed (thecideid brachiopods, lycopods, sphenopsids).
Cryptic variation and its manifestation in the Lower Trentonian

Rafinesquina

lineage (Ordovician, New York State)
Authors: Titus Robert 
Published: January 2018

Species populations commonly carry a great deal of genetic variation which is not expressed in individual phenotypes. Cryptic variation can be carried in recessive alleles, in cases of heterosis, or where modifier genes inhibit expression of the hidden trait. Other genetic and ecological factors also allow cryptic variation. Stabilizing selection prevents the expression of hidden traits; normalizing selection weeds out the deviants and canalizing selection suppresses their traits. Together the two keep the species near the top of the adaptive peak. Cryptic variation balances a species' need to be well-adapted to its environment and also for it to maintain a reserve of variation for potential environmental change. Expression of cryptic traits is rare and is usually associated with times of greatly reduced natural selection and rapid population growth, when the lower slopes of the adaptive peak are exposed.A possible example of the manifestation of cryptic traits occurs within the lower Trentonian Rafinesquina lineage of New York State. The two most commonly reported species of the genus have been reappraised in terms of cryptic variation. Extensive collections of Rafinesquina “lennoxensis” reveal far more intergrading morphotypes than had hitherto been recognized. The form which Salmon (1942) described is broadly U-shaped with sulcate margins. It grades into very convex forms as well as sharply-defined or convexly geniculate types. Of great importance, all forms grade into the flat, U-shaped, alate R. trentonensis, which is, by far, the most common and widespread lower Trentonian member of the genus. The R. “lennoxensis” assemblage has a very narrow biostratigraphy, being confined to a few locations in the upper Napanee Limestone. This places it in a quiet, protected, low stress, lagoonal setting behind the barrier shoal facies of the Kings Falls Limestone.The R. “lennoxensis” assemblage does not constitute a natural biologic species; it is reinterpreted as an assemblage of phenodeviants occupying a low stress, low natural selection lagoon facies. All such forms should be included within R. trentonensis. Given the evolutionary plasticity of this genus, extensive cryptic variation is not surprising.
Nuculid bivalves from Surma Group, Mizoram, India
Authors: Tiwari R.P. 
Published: January 2018

The records of nuculid bivalves from the Surma Group sediments of Mizoram, India, are very rare. This paper describes 3 known and 4 new forms of bivalves of the family nuculidae which were collected in the course of field study from Upper Bhuban Formation of Bhuban Subgroup (Surma Group), Mizoram. They are : Nucula alcocki Noetling, Nucula warsarensis Eames, Nucula cf. pulchara Hinds, Nucula agrawali n.sp., Nucula sahnii n.sp., Nucula tewarii n.sp., and Acila (Truncacila) kachharai n.sp. The first three forms, though, known from the other areas of the Indian subcontinent, are reported for the first time from the study area and their synonymy is updated.These forms, together with the other associated vivalves, gastropods and decapod crustacea, indicate a Lower Miocene (Aquitanian-Burdigalian) age and shallow marine enviroment of deposition for the Upper Bhuban Formation.
Economics and evolution
Authors: Vermeij Geerat J. 
Published: January 2018

Individual organisms compete for resources. Among competitive dominants, per-capita energy use has generally increased through time. This increase has had a ripple effect on all other species by increasing the number of competitive and predatory encounters among individuals. Species unable to cope with such biological rigors have become restricted to environments where resource supply is low and where encounters with enemies are few. Among species that hold their own in biologically rigorous habitats, construction materials that are cheap to produce and that enable individuals to grow and respond quickly have generally been favored over those that exact a high cost in energy and time. Extinction interrupts but does not reverse or fundamentally alter these long-term between-clade evolutionary trends. The availability of resources to organisms, as well as the opportunity for evolutionary change, depends on extrinsic events and factors as well as on the competitive abilities of organisms.Those who have raised methodological and theoretical objections against this economic interpretation of the history of life deny the overriding importance of organisms as agents of natural selection, emphasize the random nature of extinction, deny the existence of long-term trends, favor a larger role for mutualistic as opposed to antagonistic interactions, or accord a larger role to species-level attributes in evolution that are not reducible to the properties of individual organisms. These arguments are either unpersuasive or incorrect. The long-term economics of life may have important lessons for our own use of resources.
Fossil mammals from the central Chilean Andes: a new interval in the South American land mammal succession, and implications for Eocene-Oligocene boundary events and Andean tectonics
Authors: Wyss A.R. , Flynn J.J. , Swisher C.C. , Charrier R. , Norell M.A. 
Published: January 2018

Biostratigraphically significant samples have been collected from six localities in post-Neocomian terrestrial deposits of the central Andean Main Range (34° 50 S latitude), Chile. Localities are distributed over an area of 13 km by 5 km, and span more than 2500 m of section.Two eastern localities occurring lowest in the sequence yield a diverse suite of more than 20 taxa indicative of a new biochronologic interval between the Mustersan (?middle Eocene) and Deseadan (?late Oligocene-early Miocene) South American Land Mammal Ages (LMA); speculatively it also is older than the enigmatic Divisideran “LMA”. Noteworthy occurrences include the first South American appearance of rodents, argyrolagoid marsupials, and interatheriine interathere and advanced notohippid Notoungulata, as well as the last appearance of polydolopid marsupials, and notopithicine and notostylopid Notoungulata. Four K-Ar and Ar40-Ar39 analyses on a flow and tuff which directly underlie one locality yield ages between 35.6 ± 0.9 and 37.56 ± 0.14 Ma; the fossiliferous unit itself has produced four Ar40-Ar39 dates between 31.7 ± 0.3 and 31.37 ± 0.08 Ma in one locality. Therefore, the new biochronologic interval appears to be earliest Oligocene in age, and is the oldest sequence representing Simpson's “Second Faunal Stratum”. The “Tinguiririca” assemblage is the oldest South American mammalian fauna dominated by herbivores (in a diversity of taxa) with high-crowned or evergrowing teeth, documenting major changes caused by interaction between a major phase of tectonic uplift in the central Andes and global climatic changes near the Eocene-Oligocene boundary.We recently recovered about one dozen skulls and jaws from several sites some 10 km west of, and 2500 m stratigraphically above, these lowest localities. The fauna from these new western sites appears advanced over the localities to the east, and probably is younger than about 20 Ma, based on stratigraphy and Ar40-Ar39 dates from units overlying the eastern localities. The new faunas should help resolve controversy concerning the younger limit of the Deseadan LMA.Discovery of the mammal faunas has profoundly altered understanding of central Andean geology: 1) we identified an unconformity between Jurassic marine/late Cretaceous clastic units and volcaniclastic mid-Tertiary deposits, indicating that a dramatic episode of volcanism previously attributed to the late Mesozoic is in fact 30 m.y. younger; 2) consequently, the late Cretaceous/early Tertiary is characterized by non-deposition or erosion, rather than by volcanic deposition as had been hypothesized earlier; and 3) our paleomagnetic results also indicate previously unrecognized, but significant post-Miocene clockwise tectonic rotation (up to 20°) of units in this part of the Andes.
Global Jurassic floras and climate
Authors: Yao Jiping 
Published: January 2018

The present day vegetation types on the earth are to a large extent controlled by climatic conditions that are mainly reflected in variations in moisture availability and temperature through the annual cycle. Therefore, fossil plants can be used as a tool to elucidate both spatial and temporal climatic changes. The global climates of the Jurassic can be interpreted with fossil floras because many parts of world have yielded abundant floral localities. Those records not only provide a strong basis for the qualitative depiction of vegetation patterns, but also provide quantitative data for the reconstruction of paleophytogeographic provinces and climatic changes. The computer program known as “Detrended Correspondence Analysis” written by Hill (1979) was used in this study. The floral data for this quantitative approach was assembled at the generic level mainly from the published literature. By definition, it is a method based on ordination scores, that is, the species ordination scores are averages of the sample ordination scores, and vice versa.The scatter diagrams of the first two axes of genera and sample sites derived by detrended correspondence analysis were obtained for the intervals of Early, Middle, and Late Jurassic. The gradient variations of both genera and sample sites are reflected by the scores along axis 1 and 2 because axis 1 and axis 2 maximize the correlation of species and sample sites according to this technique. In the ordination score diagrams, the genera in similar climatic environments and the sample sites in similar paleogeographic regions are relatively close to each other along axis1 and axis2.One of characteristics of the Jurassic vegetation is the taxonomic stability through the period compared with other periods of time. Therefore, the generic scores of axis1 for the Early and Middle, Middle and Late, and Early and Late Jurassic can be plotted against each other. The regression line can be used to assign the scores to the ordered genera. This is the technique used to complement the ordered genera from the gradient score diagrams and to eliminate the effect of some local genera. The genera adjacent to the regression line can be reliably used to reflect climatic gradients. The gradient changes were used to define biomes and to determine phytogeographic patterns on a global scale.The quantitative analysis clearly shows that the use of floral data can achieve fast and satisfactory results in paleoclimatic studies of the Jurassic. For example, the cool-wet temperate climate is reflected by a ginkgophyte dominated deciduous flora, such as Ginkgo, Czekanowskia, Phoenicopsis, and Baiera, whereas the subtropical warm and drier climate is represented by cycad dominated floras, such as Anomozamites, Nilssonia, Pterophylum, Ptilophyllwn, Ctenis, and Otozamites. The general conclusion of earlier workers that Jurassic floras were especially uniform through the earth is true in the relative sense only, and the ordination study allows for the subdivision of the rather shallow gradients that do exist.
Zlichovian–Givetian bivalve fauna from the planktonic facies (Nandan Facies) of Nandan, Guangxi, South China
Authors: Renjie Zhang 
Published: January 2018

A large amount of pteriomorphs of bivalve have been found in the Zlichovian–Givetian black mudstone-siltpelite in the trough in basin facies-zone of Luofu, Nandan, northwest Guangxi, South China. This fauna consists of 20 species, placed in 11 genera and 6 families, of which 1 family, 2 genera and 8 species are new. It has a very low diversity while compared with the contemperaneous fauna of Xiangzhou facies. This fauna is characterized by: a. Only 2 subclasses, the Pteriomorphia and Cryptodonta of 6 subclasses of Bivalvia were presented in the Nandan facies fauna; b. Among the occurred 6 families: Praecardiidae, Antipleuridae, Lunulacardiidae, Pterineidae, Posidoniidae, and Guangxiconchiidae, the Guangxiconchiidae (fam. nov.) is the most falourishing one. About 80% of individuals of bivalves belong to it. In contrast, the Pterineidae which was very flourish in the Xiangzhou facies, is represented by a small amount of specimens. In the generic level, the Guangxiconcha is mostly developed and distributed from Zlichovian to Givetian; c. This is a basically cosmopolitan fauna, and may compare with the contemperaneous bivalve fauna of the same facies of western Europe and North America. Among 11 genera of this fauna, 7 genera: Ptychopteria(Actinopteria), Cheiopteria, Pterochaenia, Posidonia, Lunulacardium and Buchiola are the cosmopolitan or basically cosmopolitan taxa, while Guangxiconcha, Nandannia and Opisthonia are the endemics to South China. 62% of the species are the endemics; d. This fauna is dominated by the small-sized, thin-shalled and fragile taxa. Except for Buchiola and Ptychopteria, most taxa are ornamented by fine concentrical line, or acrossed by very weakly radial line; e. About 54% of taxa and 90% of total individuals of this fauna may be the byssal attached epifauna, most of them may be the pseudoplanktonic bivalves.Seven bivalve zones of Zlichovian–Givetian of Nandan, Guangxi have been recognized, and compared with the associated tentaculitid zones.