Fossil Insect Assemblages Research Articles

Reconstruction of the Late Holocene Environment of Central Yakutia Based on Fossil Invertebrates and Plants from a Buried Lake at the Vilyuy River Valley

We present the first record of Holocene fossil insect assemblages from Central Yakutia. A stratigraphic sequence in the locality within the Vilyuy River valley is a buried oxbow. The late Holocene water body inherited an impervious stratum from the late Pleistocene. The organic layer preserved rich fossil assemblages of macrofossils including insects and other invertebrates, plants, and charcoal. The ancient flora and fauna include species that are common in Yakutia as well as those that are rare and absent in the region. The most abundant finds are leech cocoons and bogbean seeds. The macrofossils of some insects were found along with remains of their host plants. Despite the absence of intensive human land use in the area, traces of fires were recorded. The oxbow represents the environment of a floodplain wetland that developed separately from the ecosystem of the adjacent sand dunes.

Relict permafrost preserves megafauna, insects, pollen, soils and pore-ice isotopes of the mammoth steppe and its collapse in central Yukon

In eastern Beringia (unglaciated Alaska and western Yukon), the Pleistocene-Holocene transition was characterised by rapid changes in plant, insect and mammal communities as the mammoth steppe ecosystem was replaced, first by shrub tundra and later boreal forest. These changes indicate a transition from well drained terrain with deep active layers to wetter, cooler soils, to which steppe-tundra vegetation was poorly adapted. The nature and precise timing of these events is not well resolved, particularly in central Yukon where regional climate may have been strongly affected by the retreating Cordilleran-Laurentide ice sheet complex. Resolving this uncertainty is not only important for understanding past ecosystems, but also provides a long-term perspective for contemporary environmental change and shrub expansion that affects large areas of northern high-latitudes today. Here, we report chronology (41 radiocarbon dates), stratigraphy, pore-ice δ2H/δ18O measurements, pollen data, megafauna remains and fossil insect assemblages from a permafrost-preserved loessal sequence in central Yukon, named Lucky Lady. The site spans the interval from ca. 17,000 to 8000 cal yr BP (calibrated years before C.E. 1950) and records the Pleistocene-Holocene transition in exceptional resolution. Full glacial environments (ca. 16,500 cal yr BP) supported elements of steppe-tundra vegetation and an insect fauna dominated by Connatichela artemisiae - an endemic weevil indicating warm soil temperatures. The collapse of the mammoth steppe ecosystem began with slowing of loess accumulation and development of paleosol ca. 13,480 cal yr BP. At this time, C. artemisiae remains become infrequent and Artemisia pollen decline to be replaced by Cyperaceae (ca. 13,220), before mesic, shrub taxa (likely dwarf Betula and Salix) becomes dominant ca. 13,210 cal yr BP. The establishment of shrub tundra is associated with rapid changes in δ2H/δ18O measurements, suggesting that ecological turnover coincided with a shift in atmospheric conditions and moisture availability. Finally, boreal vegetation communities became established ca. 10,680 cal yr BP. The replacement of steppe-tundra vegetation in central Yukon lagged other areas of eastern Beringia by as much as 1000 years and coincided with rapid deglaciation during the Bølling–Allerød time-period (14,600–12,900 cal yr BP). Turnover in insect and vegetation communities took place in ca. 40 years as shrub tundra became dominant. This rapid turnover has parallels with contemporary Arctic greening and re-emphasises the sensitivity of high-latitude environments to climate change.

A very curious larder – Insects from post-medieval Skálholt, Iceland, and their implications for interpreting activity areas

Fossil insect assemblages from post-medieval Skálholt, the oldest episcopal see in Iceland, provide new information about indoor environments and the specific use of a structure which according to historical information was listed as a larder attached to the episcopal school. The assemblages recovered also provide information on the background fauna which comprises of species related to turves, used for building construction and indicating storage of peat. In addition to the introduced Sitophilus granarius, the granary weevil, a new pest, Callosobruchus maculatus which is a pan-tropical and subtropical field and storage pest of legumes, and a rarely introduced species in Iceland even today, were also recovered from the site. In view of the nature of the assemblages, these were probably accidental introductions into the room, perhaps in faeces. The historical record provides information about the life history and events at Skálholt and data about school supplies including imports of stored products to Iceland during this period. In addition, the high numbers of sheep keds, Melophagus ovinus, combined with high numbers of human lice, Pediculus humanus, point to the washing of wool and clothing in urine to get rid of ectoparasites. Intra-site comparisons and a review of all Icelandic archaeological sites suggest a clear correlation between the presence of ectoparasites and wool preparation and cleaning. The results from Skálholt clearly show that rooms and specific spaces in post-medieval buildings could have multiple functions, not only the one assigned to them in the historical record.

Environmental interpretation of fossil insect assemblages from MIS 5 at Ziegler Reservoir, Snowmass Village, Colorado

Organic-rich lake sediments from a trench exposed at the Ziegler Reservoir fossil site near Snowmass Village, Colorado yielded a sequence of 27 insect fossil assemblages, spanning the time interval from about 125 to 77ka. The assemblages appear to represent MIS 5e, 5c, 5b, and 5a. A total of 99 taxa were identified, mostly beetles. The fossils represent the oldest known Pleistocene insect faunas from high elevation in the Rocky Mountains, and document a series of climatic oscillations from full interglacial to stadial and interstadial environments, accompanied by changes in regional biological communities. The MIS 5e fauna indicates summer temperatures similar to modern values, with winter temperatures 5–7°C cooler than today. Regional climates cooled somewhat by MIS 5c, and during MIS 5b summer temperatures were 5–6°C colder than modern values. Summer temperatures recovered to near-modern levels during early MIS 5a, and cooled by 1–2°C at its end, although winter temperatures were apparently above modern levels. The indication of milder but wetter winters, strengthened by the inclusion of species found today only in the Pacific Northwest region, suggests conditions that may have led to increased snowpack at high elevations in this part of the Rocky Mountains, linked with the onset of MIS 4 glaciation.

The paleoenvironment of the Olympia beds based on fossil beetles from Discovery Park, Seattle, Washington, U.S.A.

Two fossil insect assemblages with ages of 17,959 and 19,786 cal BP are reported from cross-laminated silts and sands within the Olympia beds at Magnolia Bluff, Discovery Park, Seattle, Washington (N 47° 39′, W 122° 25′). The silts accumulated during MIS 2 at a time when the Puget Lobe of the Cordilleran Ice Sheet was advancing southward. Eventually the Olympia beds were buried sequentially by lacustrine beds, outwash sands and gravels and finally till. The depositional environment based on paleoecology and sedimentary facies was a floodplain of a large braided river. The fossils are disarticulated skeletal parts representing a diverse fauna of 132 beetle species, all extant. The habitats represented by fossils include sparsely vegetated sand and gravel bars (Opisthius richardsoni), open muddy areas (Elaphrus californicus), and vegetation-shaded banks (Elaphrus clairvillei and Elaphrus purpurans). Outside of the floodplain, the habitat was grassland (Carabus taedatus) with occasional stands of coniferous trees indicated by scolytids (bark beetles). Large mammals probably used the river as a watering hole, based on the abundance of dung-feeding Aphodiinae (scarabs) and staphylinid beetles (Tachinus). Most of the beetle species have modern geographic ranges which include northern Washington State. Notably, however, species characteristic of the temperate rainforest of the Pacific Northwest are absent. For the older of the two fossil assemblages, mean summer temperature is estimated to be 17 °C, or similar to Seattle today. The climate was more continental and winters would have been colder than at Seattle today. The occurrence of the northern species Pelophila borealis and Olophrum boreale in the younger of the two assemblages indicates a colder climate estimated to represent a lowering of mean summer temperature by 1–2° C. The climatic cooling is possibly associated with the advance of the Puget Lobe. Both pollen and fossil beetle evidence are in agreement that there was less available moisture, possibly one half of today's precipitation. Palynologists have referred to the MIS 2 vegetation as tundra, cold steppe, or subarctic parkland. None of the Discovery Park fossils are obligate tundra species, and because the majority of taxa have ranges which overlap in northern Washington State today, we prefer to use the term prairie for the temperate to cold-temperate MIS 2 grassland.

Middle Pleistocene (MIS 7) to Holocene fossil insect assemblages from the Old Crow basin, northern Yukon, Canada

The Old Crow basin, northern Yukon, provides a key record of environmental change in northwestern North America from the late-Middle Pleistocene through the Early Holocene. Site chronologies are based on the presence of the Old Crow tephra (OCt: 124 ± 10 ka) at three sites, and provide a stratigraphic framework for observations. Ecological affinities of fossil insects indicate that Pleistocene environments were dominated by dry tundra and steppe-tundra. Forest insect species are relatively rare even during the last interglaciation (MIS 5e), and it is only by considering the total insect assemblages that interglacial beds can be recognized. Last interglacial insects from these sites indicate a relatively wet and warm tundra environment with evidence for sparse forest vegetation. Rare taxa with strong affinities to warmer temperatures are present and could suggest a warmer than modern climate. Early Holocene deposits yield a greater abundance of forest insects relative to MIS 5 or 7 interglacial deposits. Fossil insect assemblages reflect the position of the sites above the Arctic Circle, and in contrast to central Yukon sites, steppe insects are less common during cold stages and forest insects are less common during warm stages. These data suggest overall that the contrast between cold and warm stages was less pronounced than in other regions of Yukon and Alaska, and may indicate influence of persistent large regional lakes during the Pleistocene.

New approach to the Quaternary studies: QINSIB – The database of Siberian fossil insects

The QUINSIB database is a part of growing network of computerised insect data. It was created on the foundation of more than 30 years of research of the Quaternary insects (mostly beetles) in northwest Siberia. The main goal of the database is to gather the information about numerous studied insect samples: site, age, species list, number of fossils; with short notes about ecology and distribution of each species and their pictures. This should be a good working tool for the international research which collects data from many sources in one place including little-known ones published in Russian. QUINSIB includes over 13,400 records, more than 600 fossil insect assemblages, and modern distribution and ecology of more than 400 insect taxa (mostly beetles, Coleoptera).

Late Holocene environmental change in southwest Greenland – fossil insect assemblages from Tasiusaq

Palaeoecological research based on insect remains from the vicinity of a Norse farm at Tasiusaq in southwest Greenland provides information on the area surrounding the farm and new information on extirpations attributed to human impact. Anthropochorous species (spread by people) from the farm faunas are lacking in the assemblages, and the natural faunas provide evidence of moderate exploitation of the landscape as a result of activities related to livestock. The gaps in the stratigraphic sequence of the site are interpreted to be the result of peat‐cutting for structural turfs or fuel, and the implications of this activity are discussed. Insect assemblages from Tasiusaq, and studies from Norse sites in Greenland, do not provide clear evidence for any distinct climatic event during the medieval period. In contrast to what happened on other islands of the North Atlantic, insects introduced to Greenland by the Norse did not find suitable natural habitats and did not survive after the demise of the farms. However, the landscape did not return entirely to its pre‐Landnám biota after the human colonizers disappeared from it. Our findings provide new evidence for the consequences of the Norse and their agricultural practices on the Greenlandic environment and additional information on the fate of insect introductions in the area during the late Holocene.

A Method for Comparison of Northern Fossil Insect Assemblages

The paleoenvironmental resolving power of late CenozoicColeoptera fossils from arctic and subarctic sites is hindered by the fact that the fossil assemblages often differgreatly in taxonomic diversity and minimum number of individuals represented. In order to compare faunas of different age and from different sites, the fossil insect assemblages must first be normalized. One method of doing this is to group the fossils according to the ecological requirements of the taxa that they represent and then compare assemblages on the basis of the percentage of individual insects in each group. Eight such groups are defined in this paper and then used to compare fossil assemblages from the Yukon Territory, Alaska and eastern Siberia. Such comparisons reveal differences related to local site-of-deposition conditions but they also reflect the character of the regional late Pleistocene beetle fauna. The grouping procedure supports conclusions based on other information, such as taxonomic content, but it masks certain assemblage characteristics that may also be of paleoenvironmental significance. Thus grouping insect fossils as a means of normalizing the dataf or purposes of comparison should not be used in lieu of other analytical approaches.

Taphonomy and Paleoecology of Fossil Insect Assemblages from Old Crow River (CRH-15) Northern Yukon Territory, Canada

The paleoenvironmental message delivered by any fossil assemblage is nearly always filtered to some degree by taphonomic and preservational biases. This paper discusses some of the types of biases that affect the composition of fossil Coleoptera (beetles) assemblages. Eight samples from a single site in the northern Yukon provide the raw data for the analysis. They represent different types of host sediments — ranging from autochthonous peats to organic rich alluvial sands. For each assemblage the authors noted the state of preservation of the fossils, counted the individual anatomical parts (pronota, heads, elytra) referred to each taxon and the number of articulated or partially articulated specimens, and sorted the fossils on the basis of predefined ecological groups. The resulting data were then examined statistically, and compared with paleoenvironmental conclusions derived by examination of the present distribution of the taxa in each assemblage. The content of the insect assemblages varies with the type of host sediment. Insect fossils from autochthonous sediments deliver a reliable local environmental signal. Allochthonous sediments, such as alluvium, might be expected to contain fossils that provide an integrated picture of the regional environment, but in the Yukon such samples are seriously overrep resented by Lepidophorus lineaticollis, a weevil that lives on or near sandy floodplains. Deviations in the representation of particular anatomical elements of L. lineaticollis from one sample to another warn of other more subtle taphonomic biases that may also skew the content of northern fossil insect assemblages.

Sciaridae in lake sediments: indicators of catchment and stream contribution to fossil insect assemblages

The larval head capsules of Sciaridae (black fungus gnats) are transported into lakes from terrestrial habitats, in most cases via streams or rivers, and preserve well in lake sediments. The abundance of sciarid remains can provide information on the importance of terrestrial and running-water input into fossil insect assemblages in lake sediments if examined in relation to the number of fossils of aquatic insects such as the Chironomidae, Thaumaleidae, Ceratopogonidae, or Simuliidae. Here we describe fossil head capsules of sciarid larvae and provide an example of how these remains can be used to constrain past changes in taphonomic processes that influence fossil chironomid records.

Using pre-Quaternary Diptera as indicators of paleoclimate

Many researchers have used fossilized insects to determine Quaternary climates with great success. However, pre-Quaternary insect fossils have not been utilized as indicators of climate with the same frequency, despite levels of preservation that are often equal to that of Quaternary fossils. In this study we use the Mutual Climate Range (MCR) approach with fossil Diptera from the Florissant Formation to examine the accuracy with which pre-Quaternary insect fossils can be used to determine paleoclimate. A database of extant Dipteran climate ranges was compiled and MCR analyses were performed on all fossil Dipteran genera from Florissant with extant representatives. The analyses were performed using all fossil Dipteran genera and then again with only non-host-specific taxa. The estimates of paleoclimate from our analyses were then compared to previous estimates obtained from various paleobotanical studies of the Florissant Formation. The paleobotanical studies utilize a variety of methods to determine paleoclimate, including nearest living relative (NLR), modern analogues, CLAMP, palynalysis, and leaf margin analysis. We found that using a MCR approach with fossil Diptera can provide an estimate of paleoclimate for pre-Quaternary assemblages that is consistent with estimates made by paleobotanists. The analysis that included all Diptera gave a less precise climate estimate (12–18 °C) than the analysis in which host-dependent taxa were omitted. Our climate estimate, based on only non-host-specific taxa, was 12–14 °C, which is well within the range of estimates for Florissant derived from floral material. Although approaches that use modern analogs are sometimes viewed with concern because of the necessary assumption that fossil taxa share the same environmental tolerances as their modern counterparts, we believe that fossil insect assemblages, especially when used in MCR analyses, can be quite informative in estimating pre-Quaternary paleoclimate.

Taphonomy of insects in carbonates and amber

The major taphonomic processes that control insect preservation in carbonate rocks (limestones, travertines and nodules) are biological: insect size and wingspan, degree of decomposition, presence of microbial mats, predation and scavenging; environmental: water surface tension, water temperature, density and salinity, current activity; and diagenetic: authigenic mineralisation, flattening, deformation, carbonisation. The major taphonomic processes that control the preservation of insects in fossil resins (amber and copal) are different, but can be considered under the same headings – biological: presence of resin producers, size and behaviour of insects; environmental: latitude, climate, seasonality, resin viscosity, effects of storms and fires, soil composition; and diagenetic: resin composition, insect dehydration, pressure, carbonisation, thermal maturation, reworking, oxidation. These taphonomic processes are geographically and temporally restricted, and generate biases in the fossil record. Nevertheless, where insects occur they may be abundant and very diverse. Taphonomic processes may impact on phylogenetic and palaeobiogeographic studies, in determining the timing of the origin and extinction of insect groups, and in identifying radiations and major extinctions. Taphonomic studies are an essential prerequisite to the reconstruction of fossil insect assemblages, to interpreting the sedimentary and environmental conditions where insects lived and died, and to the investigation of interactions between insects and other organisms.

Changes in the Thermal Climate in Northwestern Europe during Marine Oxygen Isotope Stage 3, Estimated from Fossil Insect assemblages

More than 30 fossil coleopteran (beetle) assemblages have been recorded from oxygen isotope stage 3 in northern Europe, comprising several hundred identified species. Using the mutual climatic range method for quantifying palaeotemperatures, these assemblages show that the climates of the times can be divided into two distinct interstadial types. One, a short phase of temperate/oceanic climate occurred between 43,000 and 42,000 14C yr B.P. when conditions were not much different from those of the present day. In spite of the temperate climate, trees did not colonize northwestern Europe at this time. Two, both before and after this temperate interlude there were phases of cold/continental climate during which summers were too cold for trees to grow and winters were of Siberian intensity. It is possible that periods of even colder conditions intervened from time to time between the interstadial but, because of the intensity of the cold, biological systems were so inhibited that no fossil evidence for them can be found in northern Europe. Evidence for them must be sought in the fossil records from the warmer parts of southern Europe or in the physical evidence in the Greenland ice cores.

Late‐glacial and Holocene high‐altitude environmental changes in Vallée des Merveilles (Alpes–Maritimes, France): insect evidence

AbstractA series of sedimentary profiles derived from the Lac Long Inférieur peat‐bog (2090 m altitude, southern Alps) enabled the tracing of the evolution of successive fossil insect assemblages (Coleoptera, Hymenoptera Formicidae, Diptera Bibionidae, Trichoptera, Megaloptera and Nevroptera) from the Würm deglaciation to the present in this part of Vallée des Merveilles. This evolution reflects the climatic changes and hence the vegetation changes, as well as the human impact on the environment since neolithic times. During deglaciation, an episode marked by very poor fossil insect assemblages was followed by one with abundant boreo‐alpine Coleoptera dependent on melting snow and steppe Coleoptera. This episode corresponds to the Younger Dryas climatic deterioration (10 970 ± 210yr BP; 10 430 ± 210yr BP) during which a steppe vegetation prevailed. The sudden fall in the number of insects belonging to cold environments marks the beginning of the Holocene warming. During the Preboreal and the Boreal period (8801 ± 54 yr BP; 8692 ± 53 yr BP) these insects disappear almost totally. On the other hand, Coleoptera mostly living at the tree‐line and at forest margins increase and reach a maximum at the end of the Boreal. Thereafter (Atlantic, 8087 ± 58yr BP; 5678 ± 50yr BP) they decrease to the benefit of forest insects. This development corresponds to an elevation of the tree‐line during the Atlantic and the Sub‐boreal (4770 ± 300yr BP; 3740 ± 160yr BP) and to a thicker forest cover. Coleoptera dependent on Abies and Larix appear at this time. The final entomological event occurs at the end of the Sub‐boreal and in the Subatlantic (2660 ± 190yr BP): it is characterised by a regular decrease of tree‐dependent taxa. This development is attributed to human action. Copyright © 2001 John Wiley & Sons, Ltd.

Late Quaternary Beetle Faunas of Southwestern Alaska: Evidence of a Refugium for Mesic and Hygrophilous Species

Recent investigations of fossil insect assemblages from 11 late Quaternary sites in the southwestern Alaska region of Eastern Beringia demonstrate the survival of an abundant mesic to hygrophilous beetle fauna in this refugium before, during, and after the last glacial interval. These faunas contrast sharply with late Quaternary fossil insect assemblages described from interior and northern sites in Eastern Beringia, where xeric and steppe-tundra species dominated regional faunas. Proximity of southwestern Alaskan to maritime sources of moisture may have played a role in the development of a refugium for mesic and hygrophilous species by maintaining wet habitats even through the last glaciation.

A rapid climatic change at the end of the Younger Dryas in south Sweden — palaeoclimatic and palaeoenvironmental reconstructions based on fossil insect assemblages

The Late Weichselian deposits of an ancient lake at Toppeladugård, S Sweden, were analysed in detail using litho-, and pollen-stratigraphy, macroscopic plant remains, and insect fossils. The chronology is mainly based on the pollen stratigraphy, and the studied sequence covers the time span c. 10,000–11,800 yr B.P. This paper is concerned mainly with the lithostratigraphy and insect studies. The period investigated in characterized by major changes in the insect fauna, reflecting changes in the climate at the site. The Mutual Climatic Range Reconstruction Package (MCRRP) was used to interpret the thermal environment based on the beetle record. At the beginning of the period, temperate conditions prevailed, with average summer temperatures of 15–18°C. At c. 11,600 yr B.P., a gradual climatic deterioration started, and at c.10,800 yr B.P., arctic conditions became established in the area, with average summer temperatures of 10–13°C. A marked amelioration is indicated at c. 10,200 yr B.P., when average summer temperatures rapidly reached 14–16°C.

Observations on the Taphonomy of Late Quaternary Insect Fossil Remains in Packrat Middens of the Chihuahuan Desert

The approach included a comparison of the composition of fossil insect faunas to the modern regional faunas, and a preliminary analysis of living packrat diet preferences. As in other Quaternary insect fossil assemblages, hard-bodied (well-sclerotized) taxa, especially predatory and scavenging beetles, are dominant. The ecological composition of fossil insect assemblages is skewed in comparison with the modern regional fauna, but the abundance and diversity of the fossil faunas is sufficient to allow paleoenvironmental reconstructions to be made

Late Pleistocene environmental changes indicated by fossil insect faunas of the English Midlands

Twenty‐five fossil insect assemblages are described from discrete lenses of or‐ganic material in a gravel sequence at Four Ashes. The youngest date of 30,500 years B.P. obtained on the organic materialhas confirmed that the till overlying the gravels is Late Devensian (Weichselian) in age. The analyses of the insect faunas have shown conclusively for the first time the existence of climatic changes in one geographic area during the Early and Middle Devensian in Britain. Some of the earliest insect faunas can be correlated with the Brorup Interstadial, when boreal forests existed in the English Midlands. It is suggested that a cold period prior to 43,000 years ago (but post‐Brorup) may have caused the elimination of the trees, because around 40,000 years ago the insects indicate that there was a rapid climatic amelioration when it was warm enough for trees to grow again in that area. Around 36,000 years ago there was another climatic deterioration when the thermophilous insect species were replaced by a large number of arctic stenotherms and a tundra type of environment. This cold period lasted for at least 6,000 years and probably became increasingly severe with the approach of the main Devensian ice advance sometime after 30,500 years B.P.

An insect fauna from Mid-Weichselian deposits at Brandon, Warwickshire

An insect fauna of 172 taxa, chiefly of coleoptera, is described from Mid-Weichselian deposits at Brandon, Warwickshire. This fauna includes two species that are now believed to be extinct and thirty-three that are no longer found living in Britain. All but one of these species live today in Arctic or sub-Arctic regions of north-east Europe and northern Sibera—the single exception being an insect of decidedly steppe environments. The fauna as a whole indicates an open treeless habitat closely analogous to the northern tundras of the present day to which several of the recorded species are exclusively confined. Details of the local environment of the times are inferred from the fossil insect fauna. An interpretation of the climatic regime based on the northern requirements of the species in this fauna, suggests that conditions were more severe than for any other entomologically investigated site. A moderate degree of continentality is inferred and an attempt is made to give a range of average monthly temperatures through the year. A comparison of this fauna with other known fossil insect assemblages suggests that these may be of value in correlation of Quaternary deposits.