Faunal Changes Research Articles

A new crocodylid from the middle Miocene of Kenya and the timing of crocodylian faunal change in the late Cenozoic of Africa

AbstractBrochuchusis a small crocodylid originally based on specimens from the early Miocene of Rusinga Island, Lake Victoria, Kenya. Here, we report occurrences ofBrochuchusfrom several early and middle Miocene sites. Some are from the Lake Victoria region, and others are in the Lake Turkana Basin. Specimens from the middle Miocene Maboko locality form the basis of a new species,Brochuchus parvidens, which has comparatively smaller maxillary alveoli. Because of the smaller alveoli, the teeth appear to be more widely spaced in the new species. We also provide a revised diagnosis forBrochuchusand its type species,B.pigotti. A phylogenetic analysis supports a close relationship betweenBrochuchusand tube-snoutedEuthecodon, but although relationships among crocodylids appear poorly resolved in the set of optimal trees, this is becauseBrochuchusandEuthecodon, along with early Miocene “Crocodylus”gariepensisfrom the early Miocene of Namibia, jointly adopt two distinct positions—either closely related to the living sharp-nosed crocodile (Mecistops) or to a group including the living dwarf crocodiles (Osteolaemus). Character support for a close relationship withMecistopsis problematic, and we suspect a closer relationship toOsteolaemuswill be recovered with improved sampling, but the results here are ambiguous. In either case,Brochuchusis more closely related to living groups not currently found in East Africa. This material helps constrain the timing of crocodylian faunal turnover in the East African Rift Valley System, with endemic lineages largely being replaced byCrocodylusin the middle or late Miocene possibly in response to regional xerification and the replacement of continuous rainforest cover with open grasslands and savannas.UUID:http://zoobank.org/e6f0b219-5f3e-44e5-bdb9-60a4fae8d126

Signals of changes in the ichthyofauna composition of Galician waters (NW Iberian Peninsula)

Evidences of changes in the fish fauna of Galician waters is documented based on the occurrence of 24 specimens belonging to eight warm affinity fishes. Information about the morphology and new findings of Desmodema polystictum (Trachipteridae), Halobatrachus didactylus (Batrachoididae), Dactylopterus volitans (Dactylopteridae) Anthias anthias (Serranidae), Callanthias ruber (Callanthiidae), Seriola rivoliana (Carangidae), Uranoscopus scaber (Uranoscopidae) and Sphyraena sphyraena (Sphyraenidae), is reported from Galician waters, where they are unusual or rare. Morphometric and meristic parameters confirmed the identification to species level of each specimen, which was also supported by DNA barcoding. In addition, sex identification by histology and oocyte measurements of several specimens were carried out. The record of D. polystictum supposes the first occurrence for Atlantic European waters and a new northernmost record of the distribution in the Eastern Atlantic. A Neighbour-Joining comparison of COI mitochondrial DNA sequences of D. volitans suggests the possible occurrence of an undescribed cryptic species or the existence of a species that could be resurrected from one of its many catalogued synonyms. According to the obtained rate, S. rivoliana is the species more commonly recorded. The gonad histological analysis proposes A. anthias and C. ruber as protogynous hermaphrodite species.

Development of the zooplankton community in the growing ponds of the Novosibirsk region when growing carp fingerlings using the probiotic “Sibmos-PRO”

Quantitative characteristics of the zooplankton community in cyprinid growth ponds were studied. As a method of stimulating the growth and development of hydrobionts, the introduction of probiotic into water and feed was used. It was taken into account that zooplankton is the main and significant part of the natural food base for young carp grown in ponds. At the early stages of ontogenesis, the activity of digestive enzymes in carp is extremely low, the larva practically does not assimilate high-molecular compounds [7]. At the same time, zooplankton is a secondary link in the food chain of aquatic ecosystems, and plays an important role in their functioning and structure. Changes in plankton fauna can lead to modification of the aquatic ecosystem [18]. The development and existence of zooplankton pond communities during the growing season is influenced by a combination of abiotic and biotic factors, in particular: the composition and abundance of ichthyofauna, fluctuations in the water level in the reservoir, temperature, «flowering» of water, etc. Due to a set of indicators, and the strengthening or weakening of certain factors, it is possible to observe changes in the seasonal dynamics of zooplankton communities, which are more uneven than progressive. In the conducted research on the use of the probiotic Sibmos-Pro-antimicrobial feed concentrate based on mananoligosaccharides (obtained from yeast cell walls) in combination with the bacteria Bacillus Subtilis and Bacillus Licheniformis. Its introduction was carried out both in feed and in feed and water. Studies have shown that, judging by the productivity of carp and zooplankton biomass, the probiotic is absorbed by hydrobionts and affects the increase in the number and productivity of crustaceans. The level of development of the natural food supply increases, which ensures an increase in fish production. The structure of the zooplankton community changes under the influence of probiotics.

Investigating the exploitation pattern of a newly established species, the case of the Late-Glacial roe deer (Capreolus capreolus) at La Fru (Savoie, France)

The Late-Glacial period offers a key window into the expansion of temperate species from southern refugia towards northern areas and the impact of faunal change on hunting strategies. In the Jura and in the Alps, the arrival of red deer and the withdrawal of reindeer are coeval with the warming of the GI-1e. Very little is known about roe deer, however. A high-resolution study of the rich archaeofauna from the Early Azilian occupation at the Northern Alpine site of La Fru provides data on the habitat and exploitation of roe deer. Roe deer populations were already established in the region in the early Bolling (~GI-1e), as is shown by the earliest radiocarbon date of roe deer bones (14.7–14.3 ky cal BP, 1σ). This is the earliest post-Last Glacial Maximum evidence of this species in northern France. The specimens from the site show the highest δ15N values among the deer species present in the areas. This is probably linked to the roe deer’s selective foraging of highly nutritious vegetation already available in the open habitat at that time. Our zooarchaeological study shows that roe deer was a key resource at La Fru and was intensively hunted between May and September. The mortality profile indicates a “deliberate” targeting of inexperienced subadults and weaker older animals. These new data provide further evidence that there was both a reorganization of the animal environment and a reorientation of hunting on red deer and roe deer associated with the Early Azilian culture during the Bolling chronozone.

Mercury anomalies within the lower Cambrian (stage 2–3) in South China: Links between volcanic events and paleoecology

The early Cambrian period is characterized by not only the explosive radiation of metazoans, but also several mass extinction events. Mercury (Hg) enrichment is now widely used as a proxy for volcanic input, with implications for the CO2 and temperature to which the biosphere was subject during these events. Here, we report the oldest mercury anomaly records from organic matter in the Phanerozoic, taken from two wells (Xa1 and Xb1), which represent early Cambrian slope to basin sections in South China. The first mercury anomaly coincided with both a negative carbon isotope excursion (Shiyantou Carbon isotope Excursion, SHICE) recorded in Cambrian Stage 2, and the disappearance of small shelly fossil assemblages (SSFs). The above events may have been closely related to an unknown large igneous province (LIP) in Earth's history. Two subsequent mercury anomalies occur in conjunction with phases of hydrothermal (submarine volcanic) events. In addition, we find evidence for photic zone euxinia (PZE) in some parts of the depositional environment, with iron-speciation data suggestive of dissolved H2S concentrations close to 10 mM in the basin environment, along with hyper-enrichment of V and Zn in shale suggesting the presence of dissolved H2S in the photic zone. We interpret our results as providing potential evidence for links between volcanism, widespread euxinia, and early Cambrian faunal changes.

ZOONOTIC HELMINTHOSIS OF DOMESTIC AND WILD CARNIVORES IN THE EPIZOOTIOLOGIC TERRITORY OF SERBIA

In the last decade, as the result of climate changes, there have been considerable changes in the parasitofauna of domestic and wild carnivores. The prevalence of the existing parasitic species has varied significantly, showing an increasing tendency, and some parasitic species not present before in this epizootiologic territory have been diagnosed as well. It is thought that the reason for such an epizootiological situation is increased presence of owners with their pet animals in the regions endemic for particular zoonotic helminthoses during summer holidays and touristic visits. This tendency has become especially conspicuous in the last several years characterized by warm winters and very hot summers due to global warming effects, with abundant atmospheric precipitation. Oral vaccination of foxes against rabies, regulated in Serbia by appropriate laws since 2010, has led to an increased number of foxes and rise of prevalence of the parasitic diseases for which foxes represent the infection source/reservoir. Continued urbanization of Serbian cities, with the extension of urban belts into the suburbia and recreational (“weekend”) settlements, lead to a closer contact of street dogs and owned dogs with foxes, which results in a significant change in the parasitic fauna of dogs. It is an additional factor, which in the chain fox - street dog - owned dog - human increases the risk and tendency for the occurrence of human infections with zoonotic endoparasites of wild and domestic carnivores. In order to reliably predict the degree of spread of particular zoonotic helminthoses in particular regions in Serbia, for which wild carnivores represent the infection source, it is necessary to institute continued monitoring of the parasitic fauna in this type of wild animals.

The trends of human dirofilariasis in Croatia: Yesterday – Today – Tomorrow

IntroductionHuman dirofilariasis is a disease historically linked to the Mediterranean area. For the last few decades, however, Dirofilaria nematodes have been spreading, both in terms of prevalence and the geographical expansion in non-endemic areas. Currently, cases of human dirofilariasis are recorded in more than 40 countries worldwide. Croatia is considered an endemic area of the Adriatic basin. MethodsIn a nationwide investigation, new and previously published cases of human dirofilariasis in Croatia were analyzed. ResultsSince 1996, 30 cases of human dirofilariosis were reported in Croatia. A total of 14 (46,67%) cases were from the coastal and 16 (53,33%) from continental regions of the country. Based on anatomical location, 13 (43,33%) cases were subcutaneous, 12 (40%) were ocular and five (16,67%) occurred in the reproductive organs. In all 30 cases, Dirofilaria repens was identified as the causative agent. ConclusionsAn increase in air temperature as climate change, changes in mosquito fauna, high prevalence of D. repens in dogs and limited use of chemoprophylaxis are possible risk factors for Dirofilaria infection in the Croatian population. Since reporting to epidemiological services is not mandatory in this country, the real number of human dirofilariasis cases is probably significantly higher than published. This emphasizes the need for mandatory reporting of human cases and surveillance of Dirofilaria infection in dogs and mosquitoes in Croatia, following the “One Health” concept.

Ancient DNA of northern China Hystricidae sub-fossils reveals the evolutionary history of old world porcupines in the Late Pleistocene

BackgroundOld World porcupines (Family: Hystricidae) are the third-largest rodents and inhabit southern Europe, Asia, and most regions of Africa. They are a typical indicator of warm climate and their distribution is restricted to tropical and subtropical zones. In China, porcupines are widely distributed in southern areas of the Yangtze River. However, fossil remains have been identified in a few sites in northern China, among which Tianyuan Cave—near Zhoukoudian site—represents the latest known porcupine fossil record. So far, studies have focused mainly on porcupines’ husbandry and domestication but little is known about their intrafamilial phylogenetic relationships and evolutionary history.ResultsIn this study, we sequence partial mitochondrial 12S rRNA and cyt b genes for seven Late Pleistocene porcupine individuals from Northern, Southern and Central China. Phylogenetic analyses show that the Tianyuan Cave porcupines, which had been morphologically identified as Hystrix subcristata, have a closer relationship to Hystrix brachyura.ConclusionTogether with morphological adaptation characteristics, associated fauna, and climate change evidence, the molecular results reveal that a Late Quaternary extirpation has occurred during the evolutionary history of porcupines.

Evidence for three successive upper Barremian–lower Aptian rudist faunas in the Urgonian-type deposits of southeastern France and their stratigraphic value

The stratigraphic reappraisal of the Urgonian-type carbonate platform series of southeastern France, based on new ammonite discoveries, supports a precise dating of the Brouzet-les-Alès, Orgon and Rustrel upper Barremian–lower Aptian rudist faunas. The Brouzet-les-Alès fauna consists of an assemblage dominated by Homopleura and Agriopleura species spanning the Toxancyloceras vandenheckii Zone and the two lower subzones of the Gerhardtia sartousiana Zone (Gerhardtia sartousiana and Gerhardtia provincialis subzones). The Orgon fauna is characterised by an impoverished requieniid–monopleurid assemblage (missing Agriopleura) restricted to the upper part of the Gerhardtia sartousiana Zone (= Hemihoplites feraudianus Subzone). The Rustrel fauna records the outbreak of caprinid rudists, ascribed to the Martelites sarasini Subzone of the Martelites sarasini Zone, though some its key taxa locally extend into the lower Aptian. The definition of these rudist faunas is based on the combined First Occurrence (FO) or Last Occurrence (LO) of cardinal species and the co-occurrence of subordinate taxa. Two main faunal changes are recognized, viz. the regional disappearance of Agriopleura (collapse of the Bouzet-lès-Alès fauna) and the beginning of the family Caprinidae (Rustrel fauna). Both faunal changes have a widespread records along the western European Tethys margins and coincide with large-scale environmental perturbations.

The extinction of the Pleistocene megafauna in the Pampa of southern Brazil

The Late Pleistocene-early Holocene faunal turnover in South America was characterized by the extinction of all mammals with body mass >300 kg and several smaller taxa, but the driving mechanisms behind it are still poorly understood. Here is presented an analysis of the extinction in the Pampa of southern Brazil (Rio Grande do Sul state), based on fossil assemblages found in the coastal plain (CPRS) and western area of the state (WRS). The comparison between fossil and extant mastofaunas show that 90% of the mammals represented in fossil assemblages went extinct, and allowed distinguishing three groups: 1) taxa that underwent local extinction, i.e., disappeared locally but survived in other regions until becoming extinct later (including all megamammals); 2) pseudoextinct taxa that disappeared locally but survive until today in other areas, and 3) taxa that disappeared locally but returned during the Holocene. The faunal changes recorded along stratigraphic successions and available numerical ages indicate two phases of extinction, the first around 30 ka b2k in the CPRS (apparently also recorded in Argentina and Uruguay) would have been related to the onset of the cold and dry conditions of the stadial MIS 2, predating the arrival of humans to the region by about 25 kyrs. The second phase eliminated taxa that survived until about 12.7 ka BP in WRS in reduced suitable environments (‘refugia’) associated with perennial rivers; it coincides with the transition from glacial to interglacial conditions, but pollen data suggest that humans may have contributed for environmental modifications through fire. The results show that the Pleistocene xenarthran-dominated mastofauna was replaced by a Holocene fauna dominated by small rodents and carnivores, and indicate that climate-driven environmental changes, also influenced by sea-level oscillations, were a major agent in the Late Pleistocene mammalian extinctions in the Brazilian Pampa.

Is there a common threshold to subfossil chironomid assemblages at 16 m water depth? Evidence from the Tibetan Plateau

Fluctuating lake levels are an important driver of ecosystem change, and changes in the precipitation/evaporation balance of a region can lead to undesirable changes in ecosystem functioning. Large-scale changes in hydrology will become increasingly more likely as a result of ongoing climate change in the coming century. This is especially true for the Tibetan Plateau, which plays a crucial role as the “Asian water tower” for the surrounding densely populated regions. Chironomids (Diptera: Chironomidae) have proven to be one of the most valuable bioindicators for monitoring and reconstructing the development of aquatic ecosystems. Besides temperature, water depth and salinity are two of the most important environmental factors affecting chironomids. To study the relationship between chironomids and water depth, we analyzed surface sediment samples of two large Tibetan lakes, Selin Co and Taro Co. These lakes have similar environmental conditions (e.g. elevation, temperature and oxygenation) but show strong differences in salinity (7–10 and 0.5 ppt, respectively). Our results show that the chironomid assemblages in both lakes have similar water depths at which the fauna abruptly changes in composition, despite different faunal assemblages. The most important boundaries were identified at 0.8 and 16 m water depth. While the uppermost meter, the “splash zone”, is characterized by distinctly different conditions, resulting from waves and changing water levels, the cause of the lower zone boundary remains enigmatic. Even though none of the measured water depth-related factors, such as water temperature, oxygen content, sediment properties, light intensity or macrophyte vegetation, show a distinct change at 16 m water depth, comparison to other records show that a similar change in the chironomid fauna occurs at 16 m water depth in large, deep lakes around the world. We propose that this boundary might be connected to water pressure influencing the living conditions of the larvae or the absolute distance to the surface that has to be covered for the chironomid larvae to hatch. We conclude that water depth either directly or indirectly exerts a strong control on the chironomid assemblages even under different salinities, resulting in distribution patterns that can be used to reconstruct past fluctuations in water depths.

Crustacea Decapoda from the Rhodes Island Area (Eastern Mediterranean): New Records and an Updated Checklist

Decapod crustaceans are ecologically and commercially important members of marine communities. Faunal surveys constitute essential tools for the understanding of local diversity, especially in areas subjected to significant alterations of community composition due to climate changes, anthropogenic impacts, and biological invasions. Following a literature review and the study of new samples, we hereby update on the Crustacea Decapoda from the Rhodes Island area (Greece), situated in a key position in the eastern Mediterranean Sea. Published data yielded records of 120 species, whereas 28 taxa are recorded here for the first time from the study area. Among them, the collection of Liocarcinus bolivari widens its distribution to the eastern Mediterranean. Details on material examined and distributional/faunal remarks are provided for the species newly recorded and for some other native and alien species rarely reported from Rhodes. The present paper raises the local decapod biodiversity to 148 species, accounting for ~50% of the Hellenic Aegean decapod fauna and provides a useful baseline for analysing the long-term changes in the local fauna and the westward spreading of Lessepsian species. Despite present advances, the lack of records of many common Mediterranean species may be still due to limited fieldwork in some habitats rather than a true absence.

Ecosystem shifts at two mid-Holocene tipping points in the alpine Lake Son Kol (Kyrgyzstan, Central Asia)

Tipping points can be defined as critical ecosystem thresholds that start self-enforced dynamics pushing systems into new stable states. Many lake ecosystems of arid Central Asia are sensitive to hydrological changes as they are located at the intersection of the influence of the dry Siberian Anticyclone and the relatively humid mid-latitude Westerlies, and their sediment records can be used to study past tipping points. We studied subfossil chironomid remains preserved in a ca. 6000-year-long sediment record from the Central Asian lake Son Kol (Central Kyrgyzstan) to reconstruct past ecosystem dynamics. Our results show abrupt transitions from a chironomid fauna dominated by macrophyte-associated, salinity-indicating taxa, to a vegetation-independent fauna, and subsequently to a macrophyte-associated, freshwater-indicating fauna. A comparison of the chironomid-based environmental reconstruction to other proxy indicators from the same record suggests a phase of increased Westerly strength starting about 4900 cal. yr BP. This increase led to enhanced precipitation and sediment fluxes into the lake, which in turn led to high turbidity levels and consequently to a macrophyte collapse causing abrupt changes in the chironomid fauna. At 4300 cal. yr BP, a weakening of the Westerlies in combination with higher lake levels led to lower turbidity and ultimately to the recovery of the macrophyte population and associated changes in the chironomid assemblage. These two sequences of events show how the occurrence of a gradual change in an external trigger (Westerlies) can trigger a cascade of within-lake processes (turbidity, macrophyte density) and may ultimately lead to an abrupt reorganization of the ecosystem (chironomid fauna), providing models for tipping points.

Living in a time of change: Late Pleistocene/Holocene transitional vertebrate fauna of Grot Skeliastyi (Crimea, Ukraine)

ABSTRACT The paper presents the results of the study of vertebrate fossil assemblages recovered from the Grot Skeliastyi rock shelter in south-western Crimea (Ukraine). The deposition of its fossil-bearing layers covers the time span from the Late Glacial to the early Holocene. The studied sample consists of 2,736 bones belonging to 52 species of vertebrates (including 3 fishes, 1 amphibian, 12 reptiles, 10 birds, 26 small and large mammals). Among them, the past presence of the Aesculapian snake, four-lined ratsnake, squacco heron, tree pipit, and water pipit in the region is here documented for the first time. Extinct taxa in the faunal assemblage of Grot Skeliastyi were represented by wild horse, European ass, steppe bison, and woolly mammoth. Remains of small animals were accumulated due to the feeding activity of the eagle owl, while bones of large mammals could have been a part of the prey of carnivores but mostly are associated with the hunting activity of ancient people who inhabited the rock shelter. Most of the species persisted from the Pleistocene to the Holocene without losses. Our results indicate that the Pleistocene/Holocene transition in Crimea was not characterised by drastic faunal changes unlike those in other parts of Eastern Europe.Not StartedCompletedRejected

Geochemistry of the new Permian-Triassic boundary section at Sitarička Glavica, Jadar block, Serbia

The new Permian-Triassic boundary section at Sitarička Glavica is unusual for the Alpine-Dinaride area, in that it is dominantly detrital in the early Triassic. It shows a change from late Permian limestones and shales with a diverse algal-brachiopod-echinoid-molluscan biota deposited in quieter normal marine water (unit 1), into similar sediments, with coarser calcisiltites and a reduced fauna (unit 2), into a post-extinction early Triassic calcareous micaceous siltstones and silty limestones (unit 3) with only molluscan fossils. The major element ratios to Al, reported previously, change little through the section, but with slightly higher ratios just above the extinction horizon (except for K) at the top of unit 2, and show moderate chemical weathering, and change to slightly less mature sediments above. Trace element ratios to Al show little consistent change, except for higher values of most ratios at the contact of units 1 and 2, where slight but temporary increases in TOC, δ13Corg and δ15Norg, and C/N, and decrease in δ34Spyrite occur. Low HFSE (Zr, Nb, REE, Th, U, Ta) values and ratios to other elements indicate that the resistant mineral containing these elements were somehow removed prior to deposition in residual lags by preferential wind erosion. Paleoredox indicators are inconsistent but anoxia seems present in unit 1 and 2 with mostly oxic conditions in unit 3 above. The geochemistry of this section does not show the concentrations of Ni and other elements attributed to Siberian Trap sources and evidence of volcanic input to the sediments is confined to below and above the extinction horizon. The main geochemical changes occur at the top of unit 1, corresponding with a faunal diversity decrease, but not extinction, and at the +5 metre horizon, which seems to- have no faunal changes associated with it. The carbon and other organic-related elements and isotopes indicate a terrestrial input of freshwater and organic matter just before the main negative spike in carbon isotopes, which greatly reduced the diversity of the fauna, and was shorty followed by an input of intermediate volcanic ash. The actual extinction and paleontological Permian-Triassic boundary occurred at the top of unit 2, and has little geochemical changes associated with it. These events can be recognized in other Alpine-Dinaride sections -. All Alpine-Dinaride sections also show a latest Permian ostracod-dominated horizon with a negative spike in organic carbon and sulphur isotopes that indicate an input of freshwater and land plant material, reducing the surface waters to almost brackish, followed by a return to normal salinities with the return of a reduced latest Permian fauna, accompanied by a gradual negative shift in carbonate carbon isotopes accompanied by input of intermediate volcanic material. The main extinction is accompanied by a drop in the difference between carbon and organic carbon isotopes, indicating less land plant input; but otherwise there is little geochemical change at this horizon.

Amphi-American Neogene teleostean tropical fishes

During the last 20 years of paleontological expeditions in different sedimentary basins of Brazil, Colombia, Costa Rica, Ecuador, Jamaica, Trinidad, Panama, the Dominican Republic and Venezuela, teleost otoliths have been found along the tropical western central Atlantic (TWCA) and the tropical eastern central Pacific (TECP); these otoliths relate to the amphi-American distribution of fishes and the paleoceanographic and paleoenvironmental changes in the region during the Cenozoic. This study analyzes of the marine fish fossil based on comprehensive species records belonging to the Neogene period and listed at the generic level. Joint classification and ordination techniques were used to identify and analyze data comprising 169 genera belonging to 56 families and 20 orders, which were mostly represented by the demersal species that inhabit shallow waters. Analyses of principal components were used to calculate the covariance and the variance between formations, countries, basins, and age. The results showed that the main faunistic changes along the geochronological sequence in the Neogene basins of tropical America were a consequence of paleoenvironmental changes.

Bathyal cumacean assemblages from the southern margin of the Cap Ferret Canyon (SE Bay of Biscay)

The structure of the cumacean assemblages from the southern margin of the Cap Ferret Canyon was studied at 13 stations ranging from 346 to 1099 m depth with a modified Macer-GIROQ suprabenthic sledge (four superimposed nets; 0.5 mm mesh size). A total of 1885 specimens were collected and classified into 5 families and 42 species. The total abundances fluctuated between 2.8 ind./100 m2 (station TS04; 484-485 m) and 55.8 ind./100 m2 (station TS08; 714-708 m). The highest values of species richness and diversity were recorded at station TS13 (1097-1099 m): S=25 species; H’(log2)=4.05. The near-bottom vertical distribution of the cumacean fauna showed the same pattern at all stations: at least 60% of the individu­als were sampled by the lower net of the sledge and a drastic abundance decrease occurred between the two lowermost water layers sampled by the sledge. The multivariate analysis carried out on abundance data discriminated three main groups of stations distributed across depth (TS09 excluded): group Ia (346-485 m) characterized by the dominance of Nannastacidae (57.2%) at family level and Campylaspis sulcata, Leptostylis macrura at species level; group Ib (522-714 m) characterized by the dominance of Nannastacidae (66.1%) at family level and Campylaspis squamifera, C. laevigata and Leptostylis ma­crura at species level; and group II (790-1099 m) characterized by the dominance of Diastylidae (40.3%) at family level and Makrokylindrus (Adiastylis) josephinae, Leucon (Epileucon) pusillus and Diastyloides serratus at species level. According to this analysis, the main faunal change occurs between group I and II between 714 and 790 m, in relation to changes in the texture of surficial sediments. Although bathyal cumacean assemblages appear to be less abundant than those studied on continental shelves, they are significantly more diverse. However, such results could be in part related to the use of different sampling methods.

Faunal change in Cretaceous endemic shallow-marine bivalve genera/subgenera of the northeast Pacific

Endemic shallow-marine Cretaceous bivalves in the northeast Pacific region (NEP), extending from southwestern Alaska to the northern part of Baja California Sur, Mexico, are tabulated and discussed in detail for the first time. Twenty-three genera/subgenera are recognized. Their first appearance was in the Valanginian, and their biodiversity continued to be very low during the rest of the Early Cretaceous. The bivalves of the middle Albian Alisitos Formation in northern Baja California are excluded because they did not live in the NEP. The highest number (13) of NEP endemic bivalve genera/subgenera occurred during the Turonian, which was the warmest time of the Cretaceous. At the Turonian/Coniacian boundary, when cooler waters migrated southward, there was a moderate dropoff in endemics that persisted until an origination event near the beginning of the early Maastrichtian, when 11 were present. Five of the 11 were present also during the Turonian, but the others were newcomers. Only three survived the turnover associated with the “Middle Maastrichtian Event” (MME), and none survived the K/Pg boundary mass-extinction event.

Fossils from Mille-Logya, Afar, Ethiopia, elucidate the link between Pliocene environmental changes and Homo origins

Several hypotheses posit a link between the origin of Homo and climatic and environmental shifts between 3 and 2.5 Ma. Here we report on new results that shed light on the interplay between tectonics, basin migration and faunal change on the one hand and the fate of Australopithecus afarensis and the evolution of Homo on the other. Fieldwork at the new Mille-Logya site in the Afar, Ethiopia, dated to between 2.914 and 2.443 Ma, provides geological evidence for the northeast migration of the Hadar Basin, extending the record of this lacustrine basin to Mille-Logya. We have identified three new fossiliferous units, suggesting in situ faunal change within this interval. While the fauna in the older unit is comparable to that at Hadar and Dikika, the younger units contain species that indicate more open conditions along with remains of Homo. This suggests that Homo either emerged from Australopithecus during this interval or dispersed into the region as part of a fauna adapted to more open habitats.

New material of fossil rodents (Mammalia) from the Eocene (Bridgerian-Uintan) Washakie Formation, southcentral Wyoming

Eight species of rodents are described based on previously unreported fossil material from the early Eocene Adobe Town Member of the Washakie Formation of Wyoming. Among these are two new species: the sciuravid Pauromys turnbulli and the cylindrodont Pareumys flynni. The overall rodent fauna consists of twelve species. The greatest change in the rodent fauna is between the lower and middle units of the Adobe Town Member; six species having their last occurrence in the lower unit and three species having their first occurrence in the middle unit. This coincides with the boundary of the Bridgerian and Uintan North American Land Mammal Ages.