bluuebunny/crossref_metadata_2025 huggingface dataset:
Oligocene carbonate platform evolution and reef development in the eastern Gulf Coastal Plain
Authors: Bryan Jonathan R.
Published: January 2018

Throughout the Early Oligocene, the eastern Gulf Coast was characterized by three paleogeographic/carbonate facies provinces: (1) Shelf Province (Alabama/NW Florida), with foramol/bryomol limestones and local red algal pavements; (2) Gulf Trough/Apalachicola Embayment Province (N Florida/SW Georgia), a deep, current-swept structure with shallow, flanking coralgal reefs; and (3) Florida Platform Province (peninsular Florida/SE Georgia), a miliolid, peloidal, chlorozoan limestone with local patch reefs and coral thickets.

During the mid-Oligocene highstand (TO1.2 depositional sequence), the Shelf Province became a drowned ramp with a shelf margin condensed section (Glendon LS). This carbonate system was unable to keep-up with sealevel rise because of the slow-growing, temperate water character of its fauna (30 °N paleolatitude). Around the Gulf Trough, however, coralgal reefs (Bridgeboro LS) kept pace with sealevel rise and formed a rimmed platform. Despite their comparatively high paleolatitude (29–32°N), the tropical fauna of these carbonates thrived because of the influence of warm Gulf Trough waters originating in the Caribbean. The Florida Platform also kept pace with sealevel rise, and was partially emergent (so-called “Orange Island”).

This mosaic of adjacent tropical and temperate water carbonates, developed on rimmed platform and ramp settings, is comparable to the modern shelf margin from south Florida (Florida Reef Tract), westward to the west Florida carbonate ramp slope. A good modern analog for the Gulf Trough-Florida Platform Facies Provinces is the Florida Reef Tract-Florida Straits-Bahama Bank system.

During the 30 Ma eustatic sealevel fall, coralgal reefs moved from the flanks of the Gulf Trough (Bridgeboro LS) into the Trough (Okapilco Member, Suwannee Limestone). This time-transgressive shift in reef development continued to step down the bathymetric gradient (tracking sealevel fall) until by the Late Oligocene, reefs were growing along the northern Gulf shelf margin in southern Mississippi and Alabama (Heterostegina Zone) as a rimmed shelf. Isolated, time-equivalent reefs grew on the shoals produced by emerging salt domes in Texas and Louisiana (e.g., Damon Mound).
Morphometric species recognition and phylogeny reconstruction in scleractinian reef corals
Authors: Budd Ann F. , Johnson Kenneth G.
Published: January 2018

Scleractinian reef corals have a number of properties that are somewhat unique in morphometrics and therefore require methodologies different from those used in more structurally complex, non-colonial organisms with determinate growth. Most importantly, characters used in species recognition occur at two levels: (1) within modules and (2) among modules within colonies. Due to structural constraints imposed by radial symmetry and to the fact that growth is accomplished primarily by continuous accretion along the upper skeletal surface, most characters at the first level are continuous and consist either of architectural features related to coral lite size or to the upward growth of vertical structures forming the septa and columella. Because of high environmental variability, these features are best described using landmark based methods. Patterns of distribution of modules across colonies are best estimated using spatial statistics that can be related to underlying rules of budding and overall colony shape.

Here we demonstrate how traditional multivariate statistical procedures can be applied to these two different levels of data to recognize species in the common branching and massive coral Porites, and to derive characters useful in phylogeny reconstruction. Discrete morphologic units are first identified by subdividing modules from the same colony into two groups of so-called “colony halves”, running cluster analysis on distances among halves, and using the relative positions of halves from the same colony and a modified jackknife procedure to establish cutoffs on the dendrogram for group recognition. The resulting clusters are tested using crossvalidation procedures in discriminant analysis which compare classification results for corallite level and colony level data sets, and similar results for different portions of the same colonies. Iterative procedures are then used to maximize the probability of correct group assignment for each colony. Using multiple comparisons among the resulting species, a set of independent characters that maximize group separation are selected for use in phylogeny reconstruction. Comparison with electrophoretic analyses on the same material shows high correspondence in both species assignments and phylogenetic trees based on the morphometric and allozyme approaches.
Benthonic foraminifera of the northern Monagas area, in the eastern Venezuelan basin: its implications in hydrocarbon exploration
Authors: Carrillo Marta , Intevep S.A.
Published: January 2018

An association of benthonic foraminifera, Late Oligocene to Early Miocene in age, characteristic of the Monagas area, Eastern Venezuelan Basin, is presented in this paper.

The identified assemblage could indicate a sequence boundary between a lowstand wedge and a transgressive system tract; this assemblage overlies the Naricual Formation oil sand reservoirs; therefore it is very important to have it well described.

The studied assemblage has been picked out of samples analyzed from ten wells in the El Carito - El Furrial area. A total of one hundred species were identified, including twenty species turned out to be unidentifiable. Four new taxa have been described in this age interval.

The fauna exhibits strong dominance, being the main species: Nonionella opima, Nonion atlanticus, Textularia cf. T. grenadana, Textularia sp., Textularia panamensis, Valvulineria sp., Ammonia beccarii, Nonionella sp., and Trochammina sp. All these species correspond to a transitional to inner neritic environment.

The detailed identification of this fauna assemblage will contribute to a better understanding of the stratigraphy in the area, and in consequence to optimize hydrocarbon exploration.
Quaternary forcing of diversity in neotropical forests
Authors: Colinvaux P.A.
Published: January 2018

The climate of the Amazon during the last northern glaciation may be taken to represent the normal climate of the basin throughout the Quaternary, since boundary conditions for Amazon and neotropical environments had not otherwise changed since the Andean orogeny and emplacment of the Isthmus of Panama late in the Teritary.

The few radiocarbon dated data describing the climate of the ice age Amazon suggest that the principal climatic forcing was cooling in excess of 6 o C, associated with modest reductions in precipitation. Unlike Africa, the New World tropics were not noticeably arid. The evidence for cooling comes from paleoecological data at the foot of the Equatorial Andes, where temperature sensitive taxa had descended 1500 m into elevations that now support rain forest. Pollen data from all elevations of the Andes show that climates continued moist throughout glacial cycles, thus making appropriate the application of moist air lapse rates to substantial evidence for cooling in the high Andes also. Evidence that reductions in precipitation were modest in the lowlands come from new pollen records from 2-300 m elevation in the central Amazon of Brazil.

A long record of lake sediments from lowland Panama possibly represents a complete glacial cycle. Pollen, phytolith, and other paleoecological data show both cooling and modest reductions in precipitation, in parallel with the Amazon records.

At all stages in glacial cycles, neotropical forests have been subjected to intermediate disturbance tending to prevent competitive exclusion. But the forests have never been fragmented or displaced into “refugia”. Vicariance has always been provided by the scales of geography and local disturbance. The forests are dynamic systems of species whose adaptive norms are appropriate to climates of the ice age earth, but which are able to form temporary accomodations in response to climatic change.

The modern Amazon rain forest was formed as an ephemeral response to the short-lived warm episode of the Holocene. Local concentrations of species, like those noted on elevated regions surrounding the Amazon basin by refugial theorists, can best be explained because occupying regions of greatest environmental change, with the consequent pattern of invasion and reinvasion necessary with each climatic shift.
Whither

Anomalocaris

? The search in the Burgess Shale continues
Authors: Collins Desmond
Published: January 2018

A hundred years ago, Anomalocaris canadensis Whiteaves, 1892, was described as the body of a Phyllopod Crustacean. At NAPC III in Montreal in 1982, Whittington and Briggs showed that Anomalocaris canadensis was a claw, one of a pair at the front of an extraordinary predatory animal, whose jaws had previously been described as a jellyfish (Peytoia). The search to understand Anomalocaris and its relatives continues. So does the mistaken allocation of separated parts.

In 1991, the first complete Anomalocaris canadensis was collected. It has a fan tail, much like the tail of another Burgess Shale conundrum, Opabinia. Another new specimen shows that its head and claws were more flexible than previously realized, and its eyes were on stalks.

The large feeding claw, Appendage F, was allocated first to the arthropod, Sidneyia, by Walcott, then to the other Anomalocaris species, A. nathorsti, by Whittington and Briggs. The small size and lack of strong cross spines on the claws of A. nathorsti suggest that Appendage F probably came from another anomalocarid. Another puzzling feature on A. nathorsti is the thin, segmented structure running across the abdomen, one per body segment, ending in a club-shaped extremity on each side.

A third anomalocarid is now recognized in the Burgess Shale. Its front half is composed of 3 or 4 carapace like parts previously named Hurdia and Proboscicaris. Two small sheathed claws on stalks are attached at the rear of the “carapaces”. Hanging below the rear of the “carapaces” is a grasping, feeding organ composed of a pair of claws and Peytoia jaws with an inner set of teeth. It is connected to the body which has 11 segments and a tail. The two “oblique compressions” and the Peytoia jaws with the extra group of “spines” within the mouth allocated by Whittington and Briggs (1985) to Anomalocaris nathorsti almost certainly belong to the Hurdia anomalocarid.

It is evident that attempting to allocate anomalocarid parts to a particular anomalocarid is much like a Pin-the-Tail-on-the-Donkey game. In both cases the players are operating in the dark. The differences are that there is an unknown number of anomalocarids in the Burgess Shale and not only do they disarticulate easily, but they often have similar parts. As a consequence, our understanding of the anomalocarids is almost completely dependent on finding articulated specimens with the parts in place. This in turn depends on the success of field excavation. It took 100 years and 12 seasons of excavation to get the first complete Anomalocaris canadensis.
Timing of environmental change in Caribbean shallow waters relative to the closure of the Tropical American Seaway: evidence from benthic foraminifera
Authors: Collins Laurel S.
Published: January 2018

The most significant change in Pliocene oceanic circulation resulted from closure of the Tropical American Seaway between the Caribbean Sea and Eastern Pacific Ocean around 3 Ma. Faunal changes in Caribbean shallow-water marine organisms such as mollusks and corals have been attributed to possible environmental changes associated with this event, including cyclical cooling, initiation of a carbonate regime in the southern Caribbean, and upwelling of deeper waters on the continental shelf, but their occurrences and timing have been unclear.

This study uses the ecological and evolutionary record of benthic foraminifera of the upper continental slope to inner continental shelf to investigate environmental change in Caribbean shallow waters with respect to final closure of the interoceanic seaway. Benthic foraminifera are useful as environmental indicators so periods of increased taxonomic turnover should correspond to times of environmental change. Over 100 species commonly occurring in deposits of Caribbean Panama and Costa Rica dated from 6.5 to 1.6 m.y. were taxonomically standardized with existing literature and collections to produce stratigraphic ranges within the Caribbean region.

Although an average common species has lived from Early Miocene times until today, an increase in first appearances suggests that an interval of ecological restructuring occurred on the continental shelf to upper slope in latest Miocene time. The last 15 m.y. includes about 45% of the first and last appearances, 70% of which are comparably dated in other Caribbean strata. For the period from 15 to 3 Ma, about 75% of first appearances occurred between 7 and 3 Ma, and more than twice as many occurred between 7 and 5 Ma as occurred before or after that interval. Comparable numbers of continental shelf and slope taxa have first occurrences between 7 and 5 Ma, indicating a general change on the continental shelf to upper slope in the latest Miocene which preceded closure of the interoceanic seaway by 2 to 4 m.y. Few extinctions occurred in the last 7 m.y.; 86% of the common taxa less than 7 m.y. old in Panama and Costa Rica have survived to the present. The appearance of carbonate-loving species in Panama to Costa Rica at 4.6–5.0 Ma and northern Colombia by 5.0 Ma indicates a well established carbonate regime in the southern Caribbean by earliest Pliocene time. Benthic foraminiferal assemblages show no evidence of upwelling in the Panama-Costa Rican region through the Pliocene.

The Late Miocene environmental changes in shallow Caribbean waters preceded isotopic changes in open-ocean surface waters that occurred 4 to 3 Ma. Ecological restructuring took place in the latest Miocene, several m.y. before the seaway closed, and any subsequent environmental changes had little effect on benthic foraminifera of the Caribbean continental shelf.
Biostratigraphic investigations help evaluation of the ground-water-flow system near the Savannah River Site, Georgia and South Carolina
Authors: Edwards Lucy E. , Clarke John S.
Published: January 2018

The Savannah River Site (SRS) has produced and disposed of a variety of potentially hazardous materials since the early 1950's; as a result, ground water is contaminated at several locations on the site. In 1991, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy and the Georgia Department of Natural Resources, began a 6-year study to determine if ground water is flowing from aquifers in South Carolina beneath the Savannah River and into aquifers in Georgia and, if not, under what conditions such flow could occur. A conceptual model based on physical data and a digital ground-water-flow model will be developed to better understand the ground-water-flow system in the study area. Biostratigraphic interpretations will be used to help define the hydrogeologic framework for the conceptual and digital models.

The SRS is located in the South Carolina Coastal Plain on the eastern side of the Savannah River, approximately 100 miles upriver from the Atlantic Ocean. In this area, aquifers of Late Cretaceous and Tertiary age are recharged by precipitation. The age and stratigraphic correlation of sediments in the study area have been controversial because existing fossil evidence is sparse, lithologies of adjacent units are commonly similar, and facies changes occur in relatively short distances. These three factors have also complicated understanding of the ground-water-flow system, because clay and silt confining units are more discontinuous updip; therefore identification of ground-water flow paths and delineation of aquifers and confining units are difficult. Detailed biostratigraphy, using marine and nonmarine fossils, is essential to understanding the depositional history of the region and to determining the complex three-dimensional relations of stratigraphic and hydrogeologic units needed for accurate conceptual and ground-water-flow models.

Development of the hydrogeologic framework will require data on the geologic, hydrologic, and water-quality characteristics of coastal plain sediments. To provide these data, clusters of seven to ten wells will be constructed at each of seven sites. At each site, a continuous core will be collected from land surface to basement rock, and monitor wells will be installed in each water-bearing zone. The first three cluster sites are located in Georgia along an updip-downdip transect parallel to the Savannah River. The southernmost of the three sites will serve as a biostratigraphic and lithostratigraphic reference section because it will have the thickest section of sediments and will contain marine facies in which a greater abundance of fossil evidence can be expected. Paleoenvironmental data will help predict the continuity of confining units between cluster sites.
Paleoecological affinities of selected Miocene megafossil taxa from the northern intermountain region based on palynological modeling
Authors: Fields Patrick F. , Taggart Ralph E.
Published: January 2018

Palynological analysis of stratigraphically-controlled samples from a number of localities in the Succor Creek area of the Oregon-Idaho boundary, the Stinking Water flora of eastern Oregon, and the Trapper Creek flora of southern Idaho has proved to be a valuable interpretive tool in the study of these mid-Miocene plant assemblages. Models derived from analysis of the Succor Creek data suggest: 1) paleotopographic trends, 2) patterns of distribution of major forest elements, 3) the role of disturbance and succession, and 4) limits for paleoclimatic reconstruction. These have proved consistent with patterns of megafossil representation at Succor Creek and both megafossil and palynological data at Stinking Water and Trapper Creek. Such models also appear useful in the refinement of ecological affinities of a number of megafossil taxa which occur in these and other Neogene assemblages throughout the northern Intermountain region.

Some taxa are quite specific in their affinities, both in terms of vegetational maturity and elevational zonation. Species of Abies, Picea, Pseudotsuga, Thuja and Tsuga appear characteristic of ecologically mature forests at somewhat higher elevations. Such forests are rare at Stinking Water, are best developed in the southern part of the Succor Creek region, and represent the “climax” forests at Trapper Creek. In contrast, broad-leaved taxa, including species of Castanea, Castanopsis, Nyssa, and most Quercus, are reliable indicators of ecologically mature, lower elevation forests.

The ecological significance of a number of mixed-mesophytic taxa, including species of Carya, Juglans, Liquidambar, Pterocarya, Sassafras, Tilia, Ulmus, and Zelkova, is ambiguous. Broad-leaved deciduous assemblages dominated by these plants occur as mid-seral recovery stages over a wide range of elevation from lowlands to higher slopes. Ecologically mature forests of these trees tend to be found only at intermediate elevations. At lower elevations they are largely, but not exclusively, replaced in later seral stages by the ecologically mature, low-elevation taxa noted previously; while at higher elevations they are replaced by conifers.

Some taxa, most notably Equisetum, Glyptostrobus, Osmunda, and Typha are restricted to very wet habitats, irrespective of elevation. The shade-intolerant Typha forms ephemeral marshes that are rapidly replaced by Glyptostrobus swamps. Lake margins (and riparian settings), over a wide elevational gradient, are characterized by thickets of Acer, Alnus, Arbutus, Populus, Quercus simulata, “Quercus” eoprinus, and Salix. Locally Sequoia occurs in upland settings (i.e. at Payette, Idaho), while Glyptostrobus is more common in lowlands (Stinking Water and northern Succor Creek localities), but can occur in lower frequencies at any paleoelevation. Some taxa, such as Acer medianum appear to be characteristic of mid-seral recovery stages in these wet habitats.
Early morphological diversity in blastozoan echinoderms
Authors: Foote Mike
Published: January 2018

Morphological diversity (MD) is important for understanding a clade's evolution and for comparing clades to discover evolutionary laws. As the scale of analysis (taxonomic rank) increases, defining a morphological space becomes less tractable, and assessing MD becomes more difficult. Continuous morphometric variables are hard to define for very disparate species, but morphological dissimilarity can be assessed by discrete characters. I use this approach to document the history of MD in the echinoderm subphlylum Blastozoa.

About 60 discrete characters were defined, relating to: arrangement and number of thecal plates; shape and symmetry of theca; number, arrangement, form, and plating of ambulacra; arrangement, form, and plating of brachioles; form and plating of attachment structure; nature of respiratory structures; and position of mouth and anus. Character difference for binary and unordered multistate characters is 0 for matches and 1 for mismatches. Ordered multistate characters were scaled so that the maximum character difference was unity. Pairwise dissimilarity between species was measured by the mean character difference. MD in a stratigraphic interval was measured by the mean pairwise dissimilarity among species. Over half of all described genera were represented. MD involves not only the origin of new character states but also the maintenance of primitive states in a clade; therefore, assessment of MD was deliberately not restricted to analysis of novelties! The figures below compare MD to generic diversity based on the Treatise and post-Treatise monographs.

Debate persists about the nature and extent of early echinoderm diversification. Most pertinent to this debate, MD in the Cambrian and Lower Ordovician is extremely high compared to taxonomic diversity; there are few taxa sparsely occupying much morphospace. Analysis of clade-shape statistics indicates that the blastozoan clade is bottom-heavy in both aspects of diversity, but more so with respect to MD. The results overall are not sensitive to the details of the time scale, the inclusion of problematic forms, or the number of characters used. The general picture agrees with that advocated by Sprinkle (among others) for the echinoderms as a whole.
The origins and Paleogene history of modern plant communities
Authors: Greenwood David R. , Collinson Margaret E.
Published: January 2018

Modern plant communities define global Biomes by their structure, floristics and physiognomy. The modern distribution and character of plant communities is determined by climate, large-scale biotic interactions and abiotic factors such as fire and other disturbance history. Biogeographic patterns also reflect past continental movements, dispersal, extinction and speciation events. The past distribution and history of the principal modern plant communities can be traced using key taxa and associations of taxa, and the foliar physiognomy of the biomal communities.

The antecedents of many modern types of vegetation can be found in the mixed plant communities of the Cretaceous and earlier. Late Cretaceous angiosperm radiation and K/T extinctions substantially altered these plant communities, setting preconditions for subsequent evolution and the floristic character of terrestrial plant communities. Paleocene vegetation appears intermediate, and the main phase of floristic modernisation appears to have been during the Eocene.

Tropical rainforests and deciduous forests of a modern aspect are well represented in Eocene macrofloras at middle and higher palaeolatitudes respectively, in North America, Europe and Australia. These forests partly reflected present day phytogeographic provincialism but many taxa exhibited past cosmopolitanism, having much reduced modern ranges. The presence of “tropical” forests at middle latitudes, well outside their present day latitudinal extent, reflects the Early to Middle Eocene thermal maximum with widespread equable, humid and subhumid climates. At higher latitudes macrofloras reflect deciduous angiosperm vegetation of lower diversity than the middle latitude rainforests. Deciduousness in these forests was probably an adaptation to seasonal darkness beyond the palaeo-Arctic circle, but at intermediate latitudes may have reflected adaptation to greater temperature seasonality. Coniferous forests are represented in Eocene macrofloras from high latitudes and from uplands in the middle latitudes. Grasses are present in some Eocene macrofloras, but grasslands do not appear in the fossil record until the Oligocene or later. They seem to be a response to climatic deterioration and an evolving mammalian biota. Forested and herbaceous wetland communities may have been more diverse and latitudinally more uniform in the Palaeogene than today, but are otherwise quite modern. Post Oligocene history of most plant communities is that of climate altered distribution and floristic extinction.
Comparative paleoecology of Paleogene and Neogene mammalian faunas: guild structure and diversity
Authors: Gunnell Gregg F. , Gingerich Philip D. , Morgan Michele E. , Maas Mary
Published: January 2018

We examined guild structure and diversity in the mammalian biota of the Paleogene of Wyoming and Montana and the Neogene of Pakistan. Trophic structure was measured as frequency of generic diversity in each of the following trophic categories: insectivore, omnivore, frugivore, herbivore, and carnivore. Trophic categories were inferred from dental morphology.

Results are summarized below (see graphs). In Wyoming/Montana, the Paleocene is dominated by herbivores (from the orders Condylarthra, Multituberculata, and Pantodonta) and insectivores (“Proteutheria” and Proprimates). In the early Eocene, herbivores (Perissodactyla, Artiodactyla, and Rodentia), carnivores (Carnivora, Creodonta, and Mesonychia), and insectivores (“Proteutheria,” Proprimates, and Primates) dominate. At the beginning of the Eocene, carnivores and insectivores are more diverse than herbivores, but later, herbivores are more diverse. Adapid primates become an important frugivore element in the early Eocene. Herbivores are the most common group throughout the sequence, ranging from 30% to 75% of all specimens.

In the Siwaliks, herbivores (from Proboscidea, Rodentia, Perissodactyla, and Artiodactyla) dominate in generic diversity (70–80%), with artiodactyls consistently representing about 50% of herbivore genera. Circa 16 Ma, rodents appear and become an important herbivore group. At 14 Ma, bovid diversity increases dramatically. Specialized browsers (tragulids, giraffids) and grazers (suids) represent 25% to 35% of herbivore diversity throughout the sequence. Carnivores, represented by creodonts and true carnivores, range from 5% to 20% of generic diversity in the Siwaliks. At 11 Ma, carnivores increase in generic diversity with amphicyonid and hyaenid carnivores dominating the guild. Carnivores and insectivores are never as diverse in the Siwaliks as they are in the early Eocene of North America.
Devonian bryozoan extinction and diversification
Authors: Horowitz Alan S. , Pachut Joseph F.
Published: January 2018

The names proposed world-wide for Devonian bryozoans have been evaluated with respect to replaced names, synonyms, and nomina dubia [Horowitz and Pachut (1993), Journal of Paleontology, in press]. The resulting list contains 1738 specific names assigned to 199 genera in 45 families. Approximately 75% of Devonian bryozoan species are reported from a single stage. Not more than 10%, and usually 4–6%, of the species reported in any Devonian stage are also reported in the succeeding stage.

The largest decrease in observed bryozoan diversity occurs between the Givetian and Frasnian stages, reducing the number of species by 77%, genera by 64%, and families by 42%. These values are less than those reported for the range-through method for the entire fauna of the Permian mass extinction (Raup, 1979) but larger than percentage extinctions (presumably based on range-though data) for four other Phanerozoic mass extinctions tabulated by Valentine and Walker (1987).

The range-through method dampens the observed differences in taxonomic diversity among Devonian stages at all taxonomic levels. The range-through number of species/stage is based upon both direct applications of the range-through method and on the assignment of ranges known only to early, middle and late Devonian to include appropriate Devonian stages. Generic and familial diversity increases monotonically from Lochkovian through Givetian stages. Thereafter (Givetian to Frasnian), range-through values for specific (69%), generic (31%), and familial diversity (10%) decrease. Specific and familial decreases across the Givetian-Frasnian boundary are comparable to those reported for non-Permian mass extinctions by Valentine and Walker, but the generic decrease is not as great. These results are consistent with Valentine and Walker's random mass extinction model.

Observed bryozoan diversity across the Frasnian-Famennian boundary increases while values calculated using the range-through method decrease by approximately 5–15%. This does not suggest a major bryozoan extinction event. Conversely, the decrease in bryozoan diversity across the Givetian-Frasnian interval is similar to an important Devonian extinction among rugose corals. The reason(s) for these extinctions is not yet clear. With respect to Devonian bryozoans, our inadequate understanding of the cause(s) of mass extinctions and the relatively coarse resolution of the stadial timescale does not permit differentiating between gradual or catastrophic scenarios.
Nothing new under the sun? Tropical vs. temperate patterns in the biogeography of evolutionary innovation
Authors: Jablonski David
Published: January 2018

Evolutionary novelties do not originate randomly in time and space, but geographic patterns have not been investigated systematically. The present-day latitudinal diversity gradient, manifest at many taxonomic levels, has been taken to suggest that most evolutionary novelties originate in the tropics, but differential extinction could have been as important as differential origination in the accumulation of taxa at low latitudes. Further, a clade's Recent diversity pattern need not reflect its initial geographic distribution. For example, several marine genera that are widespread or mainly tropical today have their oldest representatives recorded as fossils in high paleolatitudes. Are the tropics, in Stenseth's words, a cradle or a museum?

The question requires an empirical analysis of the fossil record, but preservation and sampling are highly uneven across the globe over the Phanerozoic. As a first attempt to detect robust patterns, I compared the geographic distribution of the 26 post-Paleozoic marine invertebrate orders having high preservation potential to two datasets likely to reflect preservation and sampling bias (Jablonski and Bottjer 1991): (a) first occurrences of poorly preserved orders (having flimsy or easily disarticulated skeletons, e.g. notaspidean gastropods and comatulid crinoids, n = 16), and (b) all published records of Triassic-Bajocian echinoids (n = 887, first third of Paleozoic-time, with most ordinal originations). First occurrences of well-preserved orders were evenly distributed above and below 30° absolute paleolatitude, contrasting significantly with the poorly preserved orders, which are predominantly extra-tropical in first occurrences (p 0.001, G test). Despite the much more intense collecting and description of fossils at higher paleolatitudes, the Triassic-Bajocian peak in the first occurrence of well-preserved orders falls below 30° paleolatitude, significantly different from the contemporaneous echinoid records, which do appear to reflect collecting intensity (p< 0.005, G test; p < 0.05 for frequency distributions using 10° blocks, Kolmogorov-Smirnov test). The difference increases if the echinoid superorder Microstomata (which contains primitive taxa bearing novelties related to an important shift to deposit-feeding, but not assignable to any presently recognized order) is used instead of its oldest named order, the Cassiduloida; and remains significant if the Lower Triassic is ignored owing to especially poor sampling (p < 0.02). Low paleolatitudes, then, contain significantly more first occurrences of marine invertebrate orders than would be expected from a null hypothesis of sampling and preservation: major novelties appear to have originated preferentially in the tropics. Still unknown is whether the tropics have a higher per-taxon rate of novelty production, but the apparent discordance between within-habitat diversity and ordinal origination along bathymetric gradients sugqests that a simple probabilistic explanation may be inappropriate.
Isotopic and molecular characterization of modern and fossil proteins in ostrich eggshell
Authors: Johnson Beverly J. , Fogel Marilyn L. , Miller Gifford H. , Tuross Noreen
Published: January 2018

Stable carbon and nitrogen isotopes in fossil ostrich eggshell (OES) proteins have the potential to provide paleodietary information on ostriches through the Late Pleistocene in arid and semiarid regions of the Old World. Carbon isotopes may be used as a monitor for floral composition (C3 vs. C4 plant abundance), for example. The stable isotope composition of the organic matter in modern OES and Middle Holocene fossil OES samples from Bir Tarfawi (an archaeological site in southern Egypt) are presented, as well as the nature of modern proteins in OES and the degree to which they are preserved in the fossil samples.

The organic fraction was extracted from OES samples and subsequently desalted by (1) decalcification in 0.5 N EDTA, followed by dialysis against water in >6-8,000 molecular weight cut off (MWCO) tubing, or (2) hydrolysis in 6N HCl for 20 minutes at 153°, followed by the addition of concentrated HF to facilitate the precipitation of CaF2. There is good agreement between the stable isotope results of the two organic fractions from modern OES samples (δ13C = −23.51±±0.76 and −23.53±±0.39, and δ15N = +6.23±±0.15 and +6.42±±0.33 for the >6-8,000 MWCO and HF preparations, respectively). A 2± and 4± enrichment between ostrich diets and the organic fraction was found for carbon and nitrogen, respectively. These relationships support a vegetarian diet comprised almost exclusively of C3 plants. Result from the HF preparation show higher variability in both the δ13C and δ15N values in the fossil samples than in the modern. This increased variability may be due to isotopic fractionation accompanying protein degradation or to inadequate methodologies for isolating the bulk organic matter. These effects could be minimized by analyzing individual molecules throughout the study.

The >6-8,000 MWCO fraction of the modern and fossil OES samples were electrophoresed on SDS polyacrylamide gels. The modern sample shows predominant bands corresponding to apparent molecular weights of 14 kilodaltons (kD), 28 kD, and 35 kD, and a light smear at the top of the gel. Preliminary results of the fossil sample show a pronounced band corresponding to an apparent molecular weight of 80 kD, and a light smear over the whole gel. Results of an enzyme linked immunosorbent assay (ELISA) on the modern material demonstrate a positive antibody-antigen reaction between the >6-8,000 MWCO fraction and osteocalcin, osteonectin, and albumin.

Due to the “closed-system” nature of the ostrich eggshell matrix and the ease with which it can be accurately dated through the Late Pleistocene, it provides an ideal medium for studying protein diagenesis. Subsequent isotopic analyses, using the newly developed technologies of GC/IRMS, offer an alternative method for using the paleodiets of ostriches as a tool for paleoenvironmental reconstructions in Africa and Asia.
Biological patterns in sequence stratigraphy; Cretaceous of the Western Interior Basin, North America
Authors: Kauffman Erle G. , Sageman Bradley B
Published: January 2018

High-resolution stratigraphic analysis of Cretaceous strata in the Western Interior Basin (WIB) of North America has allowed definition of numerous disconformity-bounded, eustatically and/or tectonically driven sequences and their systems tracts at 2nd- through 4th-order scale, as well as 5th- to 7th-order climate-induced cycles. Integrated event chronostratigraphy and biostratigraphy allow detailed regional tracing and facies analysis of these sequences, leading to three-dimensional modeling of facies evolution. Whether driven by relative sealevel changes or smaller scale climate cycles, Cretaceous sequences and their bounding disconformities reflect dynamic changes in many factors which moderate biological systems (e.g. sealevel and paleobathymetric changes, changes in current velocity and in erosion/sedimentation rates and patterns, watermass temperature and chemistry, etc). Predictable biological responses (patterns) to varying environmental conditions and different systems tracts are expected in sequence stratigraphy. Once defined within well-studied systems, these patterns can then be used as an independent tool for sequence stratigraphic analysis. To date, our research has focused on the development of paleobiological criteria which aid in the recognition of sequence stratigraphic frameworks, especially in basinal facies where sequence boundaries and systems tracts may be subtly defined in the physical stratigraphy. Such criteria may include the identification of sequence boundaries and other omission surfaces by punctuated character displacement in evolutionary series, by condensation or omission of biostratigraphic zones, by mixed or time-averaged community elements and biozones, and by selective colonization by firm substrate-dependent benthic communities. Gradients within and between systems are characterized by different community composition, biofacies, taxonomic and community diversity patterns, adaptive bauplans among resident taxa, taphonomic signatures, and bioevents that allow predictive biological characterization in sequence stratigraphy. Once established and correlated, sequence stratigraphic systems among different basins provide a chronostratigaphic and environmental framework within which the regional dynamics of ancient populations and communities can be evaluated, leading to the analysis and modeling of relationships between sealevel changes and biogeographic migration patterns, and the rates and patterns of evolution and extinction.
The isotopic record of oxygen in phosphates of fossil fish - Devonian to Recent
Authors: Kolodny Yehoshua , Luz Boaz
Published: January 2018

The isotopic composition of oxygen in the phosphate (δ18Op)was determined in 159 fish bones and teeth from museum collections throughout the world. The fossils were both marine and fresh-water ranging in age from the Devonian to the Recent. In 45 of those we also determined the isotopic composition of oxygen and carbon of the lattice carbonate in apatite (δ18Oc and δ13C). In most cases the isotopic results are compatible with previously available geological information: the difference between marine and fresh water, the indication of previously known warm and cold time periods, and the ranking of fishes from warm to cold according to their inferred life habitat.

Three fish specimen from the Devonian of the Orcadian Basin in Scotland yield results which are compatible with the thermal structure of a stratified lake. The isotopic analysis of Inocentrus vulgaris, a fish found inside Cretaceous inoceramids, yields normal marine δ18Op. Hence we favor the suggestion of Tourtelot and Rye (1969) that 18O depleted inoceramids did not deposit their shells in isotopic equilibrium with sea water.

The relationship between δ18Op and δ18Oc suggests early diagenetic replacement of an originally phosphatic phase by carbonate fluor apatite (CFA). This conclusion is in accord with REE studies of fish fossils. The correlated latitudinal variation in δ18O of meteoric water and temperature should result in a small variation of δ18Op in fresh water fish. The large range in δ18Op of Recent fish is the outcome the “altitude effect” (Dansgaard, 1964) i.e. of the existence of Recent high altitudes, and sharp morphological gradients.
Late Wenlock-Ludlow graptolite extinction and evolution: perspectives from Arctic Canada
Authors: Lenz Alfred C.
Published: January 2018

An abrupt change in the composition of graptolite faunas just below, and at, the Wenlock-Ludlow boundary has recently been demonstrated in southeastern Germany and Kirgizistan. JAEGER (1991) terms that changeover the “Big Crisis”.

On a global scale, throughout all but the uppermost Wenlock, Monograptus (s.s.), Cyrtograptus, and plectograptine retiolitids are moderately diverse and very abundant. This fauna is abruptly replaced in the uppermost Wenlock by an acme of simply thecate Pristiograptus dubius types and “pristiograptids”, and a marked increase in the diversity of the plectograptines. The succeeding earliest Ludlow fauna, which too appears abruptly, is marked by a mostly new fauna of plectograptines and new forms of monograptids the earliest of which include Lobograptus, Neodiversograptus and Bohemograptus. Two “crises” are therefore manifest, the earlier one being more profound.

The Cape Phillips Formation of the Arctic Islands, Canada, yields a superb late Wenlock and early Ludlow graptolite, fauna. The late Wenlock lundgreni-testis Biozone has yielded isolated specimens of about 15 species of monograptids (including Monograptus (s.s.); especially M. testis), Cyrtograptus (several species), and at least seven species of plectograptines. About half of the fauna continues from the underlying zone. The overlying uppermost Wenlock ludensis Biozone is markedly different. Pristiograptus (of the P. dubius type) and “Pristiograptus” (Pseudomonoclimacis?) with novel thecal and sicular development (four or five species) are very abundant, and ten species plectograptines, only two of which continue from the underlying zone, appear abruptly. Cyrtograptus and Monograptus (s.s.) are totally absent.

The succeeding earliest Ludlow is also characterized by rather abrupt appearances, again of several or more species of plectograptines, most very small, as well as monograptids with new thecal/rhabdosomal styles; these include Lobograptus. Neodiversograptus, Bohemograptus and Colonograptus, and slightly later, Saetograptus and the reappearance of Monograptus (s.s.). Plectograptines apparently become totally extinct by about mid Ludlow.
Ruedemann's Gasport Channel revisited: investigation of a Silurian (Ludlovian) Konservat-Lagerstätte
Authors: Lo Duca Steven
Published: January 2018

In 1925 Rudolf Ruedemann described a remarkable Silurian biota dominated by noncalcified plants and animals from the Lockport Dolomite of western New York State. Ruedemann stated that the biota was confined to a single lens of interreef strata exposed at a Gasport, New York quarry; hence, he referred to the deposit as the Gasport Channel. Apart from a brief taxonomic treatment of the biota, this deposit remained largely unstudied, principally due to the destruction of the fossil site (by quarrying activity) shortly after the publication of Ruedemann's report. Recently, several new exposures of this fossil-bearing interval were discovered, prompting renewed interest in this unusual occurrence.

The stratigraphic relations of this fossil occurrence reveal that it is not a lenticular interreef channel deposit, as indicated by Ruedemann, but is instead a thin (10 cm on average), laterally continuous unit that overlies the bioherms. Based on the great lateral extent of this unit (over 100 km), and the abundance of the noncalcified dasyclad alga Medusaegraptus mirabilis within, this interval has been termed the Medusaegraptus epibole.

The biota of the Medusaegraptus epibole is dominated by dendroid graptolites and noncalcified algae. Several well preserved worms (Protoscolex) have been recovered, as well as fragments of probable terrestrial plants. A typical Silurian shelly marine biota of brachiopods, bryozoa, corals, trilobites and crinoids is almost completely absent, although shelly material is represented by rare internal and external molds. Apparently, the Medusaegraptus epibole does not present a taphonomically biased view of a “typical” Silurian community, but instead presents a picture of an entirely different kind of Silurian association.

Based on the sedimentology and paleontology of the Medusaegraptus epibole, this unit was likely deposited in rather shallow (10–20 m), stagnant marine water. The fossil-bearing beds represent a series of tempestites with sharp, slightly erosional bases and distinct internal grading; fossil material is concentrated near the tops of these graded beds.

Other, quite similar Ludlovian Konservat-Lagerstätten from North America (basal Mississinewa Shale, Lecthaylus Shale) apparently were deposited concomitant with the Medusaegraptus epibole. Synchronous deposition of these widespread units suggests that a large-scale mechanism, such as the emplacement of dysaerobic water on the craton, may be at least partly responsible for the formation of these Silurian Konservat-Lagerstätten.
Relative importance of molecular, morphological and paleontological data in understanding evolutionary innovations
Authors: Marshall Charles R.
Published: January 2018

Recently there have been increasing efforts to integrate morphological, molecular and paleontological data in assessing evolutionary relationships. In some instances molecules appear more reliable than morphology. For example, a DNA-DNA hybridization phylogeny of clypeasteroid echinoids appears superior to conflicting morphological phylogenies, because: 1) Of all the nodes on the morphological tree, the one drawn into question by the DNA data is the least supported (the characters are few and of relatively low quality; character quality was judged using Remane's a priori homology recognition criteria). 2) A case can be made for the conflicting characters being functional correlates. 3) The morphological tree only finds support in 1% of 500 bootstrap analyses of the DNA data. 4) On the DNA tree sister groups occupy the same paleobiogeographic realm while on the morphological tree sister groups occupy completely disparate paleobiogeographic realms.

However, in other instances morphology appears more reliable than molecules. For example, a recent 18S rRNA phylogeny of amniotes unites birds and mammals to the exclusion of crocodiles. Paleontologically this result seemed highly unlikely and it was suspected that some sort of substitution bias was responsible for the 18S rRNA result. Not only were pronounced substitution biases found, but when the 18S rRNA sequences were analyzed with an algorithm designed to deal with substitution biases a paleontologically more ‘reasonable’ tree resulted (birds were closer to crocodiles, not mammals).

By comparing independent data sets, it appears that both morphological features and molecules may evolve less than parsimoniously. More significantly, in these cases the unanticipated parallel evolution has an identifiable biological 'signature’. It is perhaps disappointing that the evolutionary process may produce more parallel evolution than is implied by most-parsimonious trees. But when analyzed carefully there appears to be a coherency to the unanticipated parallel evolution, a coherency that may help us understand the structure of the adaptive landscapes within which evolutionary innovation arises.