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).

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.

Study of the stratigraphic ranges of reef coral species in scattered sequences (Dominican Republic, Bahamas, Costa Rica, Jamaica, and Florida) suggests that a major episode of faunal turnover occurred in the Caribbean region between early Pliocene and mid Pleistocene time. In a data set composed of all reef corals except the families Mussidae and Oculinidae and the genera Cladocora and Madracis, approximately 90% of the Mio-Pliocene fauna, composed of as many as 65–70 species, became extinct during this time interval. Ten of 27 genera became extinct. Despite the high numbers of extinctions, the total number of species in the Caribbean reef coral fauna dropped only slightly over the time interval, due to similar numbers of originations and extinctions in the fauna. With one possible exception, new species arose in surviving genera, and no new genera formed.

Although similar numbers of species became extinct within early Pliocene, late Pliocene, and early Pleistocene time units, shallow water communities experienced higher numbers of extinctions during the late Miocene and early Pliocene. Deeper water communities experienced higher numbers of extinctions during the late Pliocene and early Pleistocene. Species surviving the turnover episode occur in deeper water communities and belong predominantly to the family Agariciidae. Nearshore grass flat communities contain the highest number of early extinctions. No difference in extinction patterns could be detected between taxa which reproduce primarily by fragmentation and those that reproduce primarily by larval recruitment. Although originations appear evenly distributed among community types, a large number occur in Florida along the northern margin of faunal distribution.

The increased extinctions in shallow water communities and increased originations in the north suggest that turnover occurred primarily in response to change in abiotic factors such as temperature and siltation, and not in response to species-area effects associated with sea level change.

'Sirius Passet’ fauna arthropods from the Lower Cambrian Buen Formation of North Greenland form the major component of this exceptionally preserved biota. Early mineralisation of body cavities led to internal anatomy being preserved more readily than external structures such as limbs. Musculature and gut are known in three dimensional form. Many of the taxa present are more easily compared to extant arthropods than to flattened fossil material such as from the Burgess Shale.

The most common arthropod is represented by some 1600 specimens. Although widely differing in preservational style, these specimens may be reconciled to provide a coherent model of the three-dimensional anatomy of the arthropod. The affinities of this arthropod lie with the ‘Cheliceromorph’ rather than the Crustacean biramous-limbed arthropods, and may represent a fairly advanced lineage within the clade.

Recent discussions of the patterns produced by the early metazoan radiations have concentrated on data available from the Burgess Shale. The continuing discovery and description of other Cambrian lagerstätten such as from North Greenland and Chengjiang has highlighted the degree to which the Burgess Shale fauna should be considered to be an aliquot taken from the foment of the ‘Cambrian Explosion’. The discovery of more taxa is tending to flesh out the bare bones of the Burgess fauna. Conclusions about phylogentic patterns drawn from the Burgess Shale alone may thus be premature.

Body patterning in the arthropods, and the validity of the ‘Bauplan’ concept may be investigated by consideration of the actual mechanisms available for profound morphological change. One promising route is provided by the ‘homeotic’ and other hierarchically arranged developmental genes. When the mode of action of these genes is considered in conjunction with phylogenetic methods, it may prove possible to assess evolutionary pathways in terms of the feasibility of the morphological changes required by them rather than relying on what seems inherently reasonable or on marginal advantages in parsimony. Exceptionally preserved biotas also contain the evidence for the evolution of the developmental mechanisms themselves.

Holocene patch-reefs occur throughout the shallow marine platform, to the lee of the barrier reef in northern and southern Belize, Central America. Patch reefs on the northern shelf that occur within an areally extensive patch reef complex (Mexico Rocks) indicate that differences exist between reefs here and well-studied patch reefs on the southern shelf that have been used by workers as a general model for patch reef development throughout Belize. This model proposes that patch reefs on the Belizean shelf are dominated by typical Atlantic-Caribbean, biotically-zoned coral assemblages of Acropora palmata and A. cervicornis that kept up or caught up with Holocene sea level rise during the last 8000 years to form large “keep up” or in some instances “catch up” reefs.

In contrast to those in the south, the northern patch reefs are not biotically zoned, are dominated by Montastrea annularis rather than Acropora spp., and are much younger (400 years old) than those in the south. In addition, northern shelf patch reefs developed predominantly by lateral growth in a milieu of static sea level and are herein called “accretion” type reefs. These differences in biotic and sedimentologic parameters between reefs on the northern and southern shelves imply fundamentally different ecologic and sea level history controls on patch reef formation from north to south. A leading contributor to the variation among the reefs along the Belizean shelf may be species-specific growth rates of the coral species that initiate each patch reef, and response to sea level fluctuation versus stasis through time.

An ecological community, the living part of an ecosystem, can be conceived as a network of interacting organisms. This network specifies the biotic environment influencing the evolution and population dynamics of those organisms. The number and relative strengths of the interactions between an organism and the others in its environment defined by that network (termed network fittedness) are determined in part by heritable morphological and behavioral traits of the organism. This property, fittedness, can be quantified using Levins' (1968) measure of niche breadth applied to the probabilities of interacting with the other species of organisms in the network, i.e., fittedness is a measure of interactive niche breadth. It is hypothesized that organisms optimize fittedness and that the optimum increases with the variability of the environment.

These two hypotheses are combined in a model that predicts the dynamics of interactive structure of ecosystems and the fittednesses of their component organisms, both of which arise from the evolution and coevolution of populations of organisms and their ecological dynamics, including immigration and local extinction. This model applies to interactions of all sorts: predation, competition, mutualisms, etc.

This model leads to predictions on the evolution and stasis of organisms' morphological and behavioural traits and on how the variance in density of individual taxa change through a coherent spatiotemporal interval experiencing relatively undisturbed abiotic environmental conditions. The model predicts that, after an initial period of high turnover of species and dominance by species with high fittedness (generalists), the community will come to comprise an increasing proportion of organisms with narrow interactive niche breadths (specialists), the turnover of generalists will increase as they are replaced by specialists or they evolve specializations reflected in their morphology or behavior, and the turnover of specialist species will decrease. Population densities will fluctuate less as surviving species become more and more likely to interact with fewer species which also fluctuate less. Assuming an inverse relationship between fittedness and the sensitivity of populations to fluctuations in density of the species with which they interact, decreasing fittedness of the species in the community will lead to increasing sensitivity to the inevitable and unpredictable biotic or abiotic environmental perturbations, such as species invasions or increasing sedimentation rates. Moreover, the set of species forming the community will be increasingly sensitive to relatively small perturbations the greater the interval between perturbations, such that the timing of perturbations becomes important in determining the severity of the community's response. These predictions should be testable in the fossil record.

Multicellular organisms must have had a substantial pre-Ediacaran history, but the fossil evidence is sparse and often equivocal. The taxonomic resolution necessary to constrain phylogenetic hypotheses is limited largely to Lagerstätte-grade fossils that retain evidence of diagnostic cell division patterns. Uniseriate and multiseriate filaments in the 1267-723 Ma Hunting Formation, Somerset Island, derive from transverse and longitudinal intercalary cell division programs indistinguishable from those of the modern red alga Bangia, and establish a significantly pre-Ediacaran datum point for the Rhodophyta. Likewise, on the basis of a distinctive “segregative cell division”, three taxa of siphonocladalean green algae (Chlorophyta) are identified in the ca. 750 Ma Svanbergfjellet Formation, Spitsbergen. Process-bearing vesicles in the Svanbergfjellet sequence further compare with the germinating zoospores of the modern chromophyte alga Vaucheria, while convincing Vaucheria-like thalli are reported from ca. 900 Ma deposits in Siberia. The broad co-occurrence of multicellular Rhodophyta, Chlorophyta, and Chromophyta by at least 750 Ma ago accords well with molecular evidence that suggests the three principal algal clades diverged from a common ancestor during a brief but marked radiation relatively late in eukaryote evolution.

Complex multicellularity featuring cellular and tissue(?) differentiation is also encountered in the pre-Ediacaran fossil record. A large ornate form in the Svanbergfjellet succession preserves at least six readily distinguishable cell types and, despite its taxonomic uncertainty, can be characterized as at least as complex as the most complex modern algae or fungi. No cellularity is preserved in the late Proterozoic macrofossil Tawuia; however, SEM and light microscopy of its isolated wall reveal a complex histology suggestive of a relatively advanced grade of multicellularity. Another Svanbergfjellet macrofossil has a distinct wall structure and bears a terminal pair of large reniform structures; if these prove to be truly bilaterally symmetrical, this fossil represents a grade of organization otherwise not recognized until the Ediacaran. Further analysis of these and other pre-Ediacaran ‘problematica’ may clarify their taxonomic relationships and promises to resolve at least some of the ‘Cambrian explosion’ into a meaningful sequence of evolutionary change.

Shell fragments from faeces of the mollusc-eating eider (Somatera mollissima) and shelduck (Tadorna tadorna) were studied in the Dutch Wadden Sea. Both species crush shells internally in their gizzard.

Shelducks feed mainly on the small gastropod Hydrobia ulvae, which they do not always succeed in breaking: in some cases even surviving Hydrobia were collected from the faeces. This indicates that shelduck may help dispersion of Hydrobia and that not only Hydrobia fragments but also intact empty shells are contributed to the sediment by this predator.

Eiders feed mainly on mussels (Mytilus edulis) and cockles (Cerastoderma edule). When these are scarce, they take shorecrabs or the gastropod Littorina littorea. Their crushing method is usually successful; only some Littorina shells were found intact but not alive in their faeces. Shells are crushed to fragments ranging from less than 0.1 to 8 mm, with a peak in the 2 – 4 mm size fraction, 20% was < 1 mm.

Annual shell carbonate production in the Dutch Wadden Sea is ca 150.000 tonnes. The annual average number of eiders is 63.000 with a maximum of up to 200.000 in winter. Annually they consume 3200 tonnes meat (ash-free dryweight). If they fed fifty/fifty on mussels and cockles they would produce ca 75.000 tonnes shell-fragments. As they feed partly on non-molluscan food this is an upper limit, but it implies that they are the main producers of shell-fragments (of all sizes, even the smallest) in the Wadden Sea. The typically square shell-fragments they produce, are easily recognisable in Wadden Sea sediments.

Others predators (shorecrabs, shrimps, flatfish, other mollusc-eating birds like knot and curlew) produce additional shell-fragments. However, some predators e.g. seastars (Asterias rubens) leave intact the shells they consumed.

Shell-fragments in sediments, therefore, may give an indication of predation pressure, but as non-crushed shells may be left over by some predators, total predation pressure on molluscs cannot be estimated in fossil faunas.

Petroleum seeps on the Louisiana continental slope produce luxurious communities based on chemoautotrophic symbiotic bacteria. Petroleum seeps are typical cold seep communities and generate classic autochthonous death assemblages. Fossil cold seep communities are well-known, common and widespread. Most fossil analogues are dominated by lucinids, but petroleum seeps are not. A combination of sample collection and in situ experimentation has been used to determine rates of taphonomy and time averaging in petroleum seep assemblages.

Cores were obtained and sectioned from seep sites in Green Canyon lease blocks 272, 234, and 184 and Garden Banks lease block 386. Lucinids and thyasirids were selected for dating time-since-death to determine the importance of time averaging in these assemblages. Dating was accomplished by measuring the free amino acid content of the shells. Time-since-death became progressively older with depth; accordingly little time averaging had occurred in these autochthonous assemblages. Lucind and mussel shells were placed on the sea floor and recovered 3 yr later. Comparison of each species to the controls left on a laboratory shelf for 3 yr shows that taphonomic alteration was rapid. Mussels were more severely altered than lucinids. Mussels were more heavily dissolved, had more altered edges, were more prone to fragmentation and exhibited greater weight loss than lucinids. The rapid taphonomic loss of the mussels suggests that the preponderance of lucinids in the fossil record is an artifact of preservation. Taphofacies analysis suggests the same; thus verifying an important assumption of taphofacies analysis that taphonomic signatures record biases in preservation by identifying inter-species differences in the rates of important taphonomic processes. Significant variability in taphonomic rates exists between shells from locations 10 m apart indicating significant local variation in the taphonomic process. Local variability in taphonomic and community attributes is characteristic of many autochthonous assemblages.

Early to Middle Triassic marine successions are remarkably lacking in the Southern Hemisphere. It would seem that the best developed and most fossiliferous sequences are preserved in New Zealand. To a lesser extent, successions of Early to Middle Triassic age are known from New Caledonia, New Guinea, the Gympie Basin of Eastern Australia, offshore Western Australia, and western South America (in particular Chile).

Anisian marine faunas were first collected in New Zealand (Etalian local stage) in the 1940s but it was not until 1953 that their age significance was correctly recognised by Marwick. This was later confirmed by Kummel. Since then an unpublished doctoral study has been completed on the paleontology and biostratigraphy of the Anisian succession within the Murihiku terrane of Southland, South Island, New Zealand. A conclusion of this study, based on ammonoid correlations, was that the cosmopolitan halobiid bivalve Daonella appears earlier in New Zealand than it does in North America.

Recent investigations post-date the advent of the tectonostratigraphic terrane concept and suggest that an Anisian fossil record is preserved in at least three terranes in New Zealand (Murihiku, Dun Mountain - Maitai and Torlesse terranes), and two terranes in New Caledonia (probably correlatives of the Murihiku and Torlesse terranes of New Zealand). Analysis of the faunal content of these various terranes suggests that although there are some facies differences (litho and bio), there is little obvious basis for recognition of distinct paleobiogeographic provenance.

A corollary to this research on Anisian faunas is the recognition that the New Zealand ammonoid faunas previously considered to be Early Triassic (Malakovian local stage; Murihiku terrane) by Kummel are almost certainly Anisian. However, this does not imply that there isn't an Early Triassic sedimentary record. Significant thicknesses of apparently unfossiliferous sequence are present in each of the relevant terranes. Two isolated Early Triassic ammonoid faunas are now known from elsewhere in New Zealand but from tectonically complex settings in Brook Street (?) and Dun Mountain - Maitai terranes.

Higher taxonomic ranks typically distinguish morphologically disparate groups whose within-group common ancestry is assumed to be more recent than that between groups. Because in practice this assumption is rarely tested, common wisdom now advocates that the relationship between traditional classifications and phylogenies be made more explicit. Classifications of organisms were established originally to serve a variety of purposes, which may or may not have had an evolutionary rationale. Thus, if named superspecific taxa are to play an interpretable role in macroevolutionary studies, their status as clades should at least be investigated, if not demonstrated unambiguously.

The monophyly of the Brachiopoda is supported by a large number of synapomorphies, both morphological and embryological. Within the Brachiopoda, systematists have focused historically on single character (“key innovation”) definitions of higher taxa (e.g., attitude of the pedicle relative to the valves, nature of articulation between the valves, valve mineralogy); this procedure has resulted in intraphylum divisions whose evolutionary significance is uncertain. For example, monophyly of the Inarticulata continues to be debated vigorously; the position of the calcareous inarticulates (craniaceans) is particularly contentious. The traditional classification, based largely on the presence or absence of teeth and sockets, has been challenged recently by the following arguments: lack of articulation is primitive for brachiopods and, as a symplesiomorphy, cannot define a major clade; valve mineralogy is a more reliable indicator of phylogenetic affinity because phosphatic and calcareous-shelled brachiopods both appear very early in the fossil record.

To test these arguments in the broader context of metazoan phylogeny, I chose to investigate not only relationships among brachiopod higher taxa, but also of brachiopods to other lophophorates and selected protostome and deuterostome taxa. I analyzed (using PAUP 3.0) the phylogenetic relationships among the seven Recent brachiopod superfamilies (assuming each to be monophyletic), using 119 characters of soft and hard anatomy and embryology. Four outgroup taxa were used: Phoronida, Bryozoa, Sipunculida, Pterobranchia. One most parsimonious cladogram of length 219, C.I. = .722, resulted. In this cladogram, Inarticulata and Articulata are each monophyletic, with 9 and 32 synapomorphies, respectively. Calcareous skeletal mineralogy is clearly primitive for metazoans; there is no justification for claiming it as a synapomorphy of a clade within the Brachiopoda. Outgroup analysis has no power, in this instance, to determine the polarity of articulation, since no outgroups possess two valves (molluscs and other animals have evolved the bivalved condition independently, based on numerous other characters); thus, the lack of valve articulation is not unambiguously primitive, by this polarity criterion.

Although many textbooks continue to refer to Lophophorates as a group distinct from other metazoans, presumably by virtue of common ancestry, “lophophorates” do not appear to be monophyletic unless the possession of a lophophore is selectively weighted; among the outgroups in this cladogram, bryozoans cluster with sipunculids, and phoronids with pterobranchs. The notion that lophophorates, as a group, are in some sense “intermediate” between protostomes and deuterostomes must be investigated in greater detail, phylogenetically.

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.

The Upper Triassic spumellarian genus Ferresium Blome ranges from upper Norian to Rhaetian, a relatively short period of geologic time equivalent to three ammonoid zones. During this time Ferresium undergoes rapid evolutionary change on a scale far exceeding the gradual change observed among other radiolarian genera of this age. Evolutionary progression is based on the changing shape of the ferresid cortical shell, a morphological feature easily traced from species to species. By the middle to upper Rhaetian, shell shape changes sufficiently to warrant the establishment of a new genus. In the uppermost Rhaetian, Ferresium is less common and the new genus dominates all assemblages. At the end of the Triassic all members of this lineage are extinct.

The biggest replacement of fauna in the Siwaliks of Pakistan takes place between 7.5 and 7.0 million years (Ma) ago. By 5 Ma, almost the entire fauna that existed at 8 Ma had been replaced by a different fauna. Although other important faunal changes occurred at about 13.5, 12, and 9.5 Ma those changes are small compared to that between 7.5 and 7.0 Ma. What event caused the wholesale local extinction of fauna which was replaced by another?

The stable isotopic composition of paleosol carbonate shows two important “events” in the Siwalik sequence. First, at 8 Ma a big shift in the δ18O of soil carbonate indicates that a major shift in climate occurred. We have found a similar change in Europe and East Africa in soil carbonates on those continents, suggesting a major change in global circulation patterns. The second event is a change in the isotopic composition of carbon-bearing phases which shows that the pre-7.5 Ma vegetation was dominated by C3 plants which were completely replaced by C4 plants between 7 and 6 Ma. This is most likely a replacement of woody plants by tropical (C4) grasses.

The carbon isotopic composition of tooth enamel from Siwalik mammals shows that prior to 7.5 Ma they consumed C3 plants, and by 5 Ma consumed only C4 plants. While it comes as no surprise that animals eat local vegetation, this study shows that isotopic reconstruction of paleo-diets can be traced back into the Tertiary.

Global climatic change in the late Miocene resulted in the invasion of tropical grasslands into the Indian subcontinent. The resulting change in habitat and diet caused the migration of many species of mammals, which is manifested as an almost complete turnover in the fauna fo the Siwaliks.

Caribbean cheilostomes are a highly diverse component of the tropical American marine benthos with an excellent fossil record. Many workers have tended to lump taxa into morphologically variable, geographically widespread species originating in the Miocene, but recent morphometric and genetic analyses have revealed large suites of cryptic species, barely distinguishable morphologically, within several important genera. Most species in such suites have narrow geographic and stratigraphic ranges. In Stylopoma, for example, canonical discriminant and cluster analyses based on skeletal morphology yielded 19 late Neogene to Holocene species, most of which had been previously classified as S. spongites. Seven species were available for genetic analysis, of which six have been confirmed to differ by protein electrophoresis, either by fixed allele differences or significant genetic distances in sympatry. A combination of cladistic and stratophenetic analysis suggests that the most widely distributed and long-lasting species, which originated early in the Miocene, was ancestor to most or all of the other tropical American Stylopoma species. Despite extensive sampling, five species are narrowly distributed, with all known fossil and viving specimens separated by less than 1000 km, and all but three of the 18 descendant species have been restricted throughout their history to relatively limited parts of the tropical western Atlantic. These patterns are consistent with allopatric speciation of peripheral isolates, only a few of which have achieved wide distributions. Cladogenesis was highly episodic, reaching a peak in Late Miocene time, well before final closure of the Panamanian portal, but after formation of the sill that disrupted oceanic circulation patterns throughout the region.

Former workers developed in South America a chronostratigraphic system not essentially different to that of European stage/age system. However, the authors of this paper believe that accurate biostratigraphic studies have to be done in southern South America for establishing the precise boundary stratotypes of most stage/ages. A new South American Upper Cenozoic continental stage/age is recognized. The stratotype is located in the fossiliferous southeastern Buenos Aires Province marine cliffs between Mar del Plata and Miramar. The outcrops in the area are the best continental representation of Plio-Pleistocene times in South America. It is younger than Chapadmalalan and older than Ensenadan and replaces the “Uquian”. We consider that the “Uquian” actually emcopasses Chapadmalalan and Ensenadan times. The Uquía outcrops are here considered inadequate as stratotype especially by the dearth of micromanmals, the relatively poor fossil record and the comparatively inadequate geographic location. The new stage would be correlated with the Gauss Chron and possibly with the lower Matuyama Chron. The lower boundary is tentatively stated. For so doing, a biostratigraphic scheme is proposed. This lower boundary approximately corresponds to the base of the Barranca de los Lobos “Formation” of Kraglievich (1952) and a new (unpublished) unconformity bounded unit (Zárate, 1989). Some taxa that apparently ranges from the base are candidates to define it after a detailed biostratigraphic study.

Additionally, a different timing for the arrival of North American mammals to southern South America is given.

Carcinosomatids are rare among the Silurian eurypterid faunas of northeastern United States. New discoveries, discussed below, extend the geographic and stratigraphic ranges of two important types:

Paracarcinosoma, known primarily from the Bertie Group of western New York, and

Rhinocarcinosoma, known only from the Illion Shale of eastern New York. PENNSYLVANIA: The very distinctive Rhinocarcinosoma was obtained from rocks of the McKenzie Fm., below Bloomsburg redbeds, just east of Lock Haven. Remains consist of a well preserved carapace with characteristic 'shovel’ developed as an extension of the anterior portion of the carapace. This occurrence is analogous to the occurrence in the New York stratigraphic sequence 185 miles (285 km) to the northeast in the type area of the Illion Shale. At the New York localities, the eurypterid-bearing beds are overlain by the redbeds of the Vernon Fm. (Salina Group).

OHIO: The Maumee Quarry east of Toledo has been studied extensively by many geologists. The stratigraphic sequence exposed consists of “Niagaran reefs” overlain by the Greenfield Fm. (Bass Islands Group) but with an impressive array of stromatolitic beds transitionally developed between the two units.

In the transitional beds occur the scattered remains of Paracarcinosoma. Specimens are fragmentary, but a small well preserved carapace was obtained showing the intramarginal position of the compound eyes characteristic of this carcinosomatid. The specimens were obtained from fine-grained dolostone with no evidence of other fossils.

NEW YORK: The original discovery of Rhinocarcinosoma, as described in 1912 by Clarke and Ruedemann, is here supplemented by new finds in the Illion Shale east of the type area and particularly by the discovery of this eurypterid in rocks of the Lockport Group near Sodus Center, N.Y. Exposures of the Sconondoa Fm. in the Sodus Quarry and in the streambed just to the north yielded numerous specimens. Particularly noteworthy is an operculum of the size and structure illustrated by Clarke and Ruedemann. The new occurrences in the Sodus Center area extend the geographic range of Rhinocarcinosoma westward about 100 miles (160 km).

The carcinosomatid occurrences just described are intimately associated with stromatolitic or thrombolitic biostromes or “reefs.” It would appear that both types of eurypterids, Paracarcinosoma and Rhinocarcinosoma, preferred a niche in backreef areas in peculiar algal-lagoonal settings little understood today. Eurypterus, the common form in the Bertie Group, is generally found in rocks having much evidence of hypersalinity (salt hopper structures, etc.), presumably a more supratidal setting.

Prominent growth ridges on the shell of the modern scallop Pecten diegensis are known to form with a daily periodicity. Pecten stearnsii, its direct ancestor, has the same growth ridges and would be expected to form them at the same rate.

Pecten stearnsii specimens collected from the Pliocene Imperial Formation near San Filipe, Baja California, Mexico, have repetitive variations in the spacing of their growth ridges. Harmonic analysis of these variations found three tidal periodicities to be present, tropic (13.7 days), synodic (14.8 days), and anomalistic (27.6 days). This observation also served to confirm the daily nature of the growth ridges.

Tidal patterns at various locations within the present-day Gulf of California are dominated to various degrees by synodic and tropic periodicities. Comparisons of the growth-line records to modern tidal records by cross-correlation found a good match with a tidal station south of the collecting site, where the tropic periodicity dominates but the synodic periodicity is still important.

An important aspect of this match is that a graph of cross-correlations at all possible overlaps shows a cycle of good correlations, with a period of six months between peaks. As this is a reflection of the resonance between tropic and synodic periodicities, the peaks would occur at the same times of year in the Pliocene as today. This makes it possible to relate each specimen's growth record to the calendar, although two alternate interpretations, six months apart, would exist.

Two possible relationships would be of interest. First, if all the specimens had died at the same time of year it could mean a catastrophe, such as a severe storm. This was not the case, which is in itself a useful observation. Second, if all the specimens began their growth line record at the same time of year, it would suggest specific seasons for spawning and for spatfall. Here the evidence was more supportive; most specimens began forming growth ridges in either late March or late September, with perhaps a month's growth prior to the first growth ridge.

If isotopic paleotemperature analysis can be applied to these shells, or to others with similar characteristics, new levels of resolution in both environmental reconstruction and paleopopulation analysis may be achieved.

The study of fossil biomolecules requires not only well preserved fossil samples, but abundant Recent material so that reference points can be established. Ideally it would also be possible to study the in situ decay of organic molecules in samples of different geological ages, and hence determine how degradation proceeds with time. The shells of brachiopods fulfill both these criteria, containing up to 1% organic components entombed within their shells, which are composed of highly stable, low magnesium calcite, that survives well in the fossil record for hundreds of millions of years.

This particular study has concentrated on Plio-Pleistocene brachiopods from New Zealand. These fossils are the ancestors of living species, and hence it is possible to investigate intracrystalline biomolecules in modern day shells, as well as the degradation products of such biomolecules in fossil shells of the same species.

Three of the species investigated have bright red shells in life, and during the study it became clear that this coloration was caused by a carotenoprotein which was embedded within, rather than around, the calcite fibres of the brachiopod shell. Carotenoproteins are composite molecules composed of a protein and a prosthetic carotenoid group. The protein has been characterised by hplc (high performance liquid chromatography) and SDS PAGE (sodium dodecylsulphate polyacrylamide gel electrophoresis), and the amino acids at the N-termini have been sequenced, demonstrating that this is a small protein which has a molecular weight of 6.5 kDa and is identical in all 3 species.

At least two different types of carotenoids were detected after initial purification, and these were characterised using direct probe mass spectra, and hplc/mass spectra. Using these techniques the two carotenoids have been tentatively identified as canthaxanthin and the mono acetylenic analogue of asthaxanthin.

In addition to the carotenoproteins, the calcite crystals of recent brachiopod shells contain lipids (carboxylic acids) and carbohydrates, which were characterised by gas chromatography (GC) and gas chromatography/mass spectrometry analyses (GC/MS).

Fossil brachiopod shells could be distinguished from recent shells due to their lack of unsaturated acids and smaller amounts of carboxylic acids present. However there was no trend of decreasing quantities of fatty acid with increasing age.

The presence of organic molecules such as carotenoproteins, lipids and carbohydrates within calcite crystals poses two questions. Firstly, are these compounds merely wastes metabolic products and are deposited within the shell during growth or, secondly, do they play an important role in the process of biomineralisation? At present these questions remain largely unanswered, because at present only the function of the carotenoprotein has been determined from the spectrum of biomolecules present within the shell (and the carotenoprotein may have other functions apart from coloration).

The currently available fossil record suggests, 1) biogeographic differentiation of the Late Cretaceous terrestrial biota and, 2) distinctly different patterns of evolution of terrestrial faunas and floras across the Cretaceous\Tertiary boundary.

Discovery in Alaska of dinosaurs and mammals that lived at Late Cretaceous northern high latitudes provides evidence that many groups of terrestrial vertebrates had extensive geographic ranges and faunas were biogeographically differentiated. The Alaskan dinosaurs, represented by individuals that range in size from hatchlings to adults, might have been migratory forms living at high latitudes only during the summer months. In contrast, the small mammals probably were not migratory.

Although recent discoveries are expanding our knowledge of the evolution of the terrestrial biota, the fossil record of terrestrial vertebrates during the Cretaceous\Tertiary transition is still heavily biased in favor of the northern Western Interior of North America. Here evolutionary change of the terrestrial fauna did not just involve extinction of lineages, some already decreasing in taxonomic diversity, and survival of many others. Shifts in biogeographic range and immigration of new groups played a significant role in remodeling the terrestrial fauna. The paleobotanical record is more extensive but also is biased with the most detailed record coming from the Western Interior where floral change is characterized as “massive” or “catastrophic” in scope.

These conflicting evolutionary patterns are well founded being based on analysis of substantial fossil records. A new program of research directed toward resolution of the apparent paradox tests the hypothesis that at the end of the Cretaceous the terrestrial biota was biogeographically heterogeneous and evolutionary patterns of faunal and floral change in the Western Interior cannot be taken as globally representative.