A trackway and burrows of a small rodent-sized bounding mammal (attributed to the Cape gerbil, Gerbilliscus afra) and a traceway of a large arachnid (spider) from the Pleistocene Waenhuiskrans Formation represent two biological groups not previously reported from this track-rich dune facies, which is widely distributed along the Cape south coast of South Africa. This may be due to biases against the preservation of small tracks. Trackways of hopping or bounding rodent-sized mammals are rare in the fossil record, occurring at only two known Mesozoic sites and three Cenozoic sites. Where these occur in dune facies, they are commonly associated with arachnid and other arthropod surface trails. The arachnid trace fossils commonly include the spider traceway Octopodichnus, known from the Permian to Recent, which is also the temporal range of the eponymous Octopodichnus ichnofacies. The abundance of small-mammal tracks associated with dune ichnofaunas led to the naming of the late Palaeozoic and Mesozoic Chelichnus ichnofacies, which is largely co-extensive with the Octopodichnus ichnofacies at this time. However, the recognition of similar mammal–arthropod dune facies assemblages in the Cenozoic requires adjusting our understanding of their distribution in space and time, and extends the known distribution of dune ichnofacies.

The is insufficient knowledge of arthropod communities occurring in specific microhabitats. In this study, we characterize the arthropod assemblages inhabiting burrows of the common hamster (Cricetus cricetus L.) and factors that determine their diversity and abundance. We tested the following hypotheses: (1) arthropod assemblages are associated with a particular dominant vegetation occurring in the vicinity of burrows; (2) a correlation exists between fine-scale geographic distances among burrows and assemblage dissimilarity; and (3) the type of trap influences the sampling success of captured arthropods. We found 73 morphospecies belonging to 16 families in 109 burrows, most of which were in the families Staphylinidae (Coleoptera) and Parasitidae (Arachnida: Acari: Mesostigmata). The most abundant families were Staphylinidae, Cryptophagidae (Coleoptera), Parasitidae, and Macrochelidae (Mesostigmata) (78.89%). Among the identified species, we found Aleochara irmgardis (Staphylinidae) and Poecilochirus sexclavatus (Parasitidae) which had not yet been reported in Poland, and several other rare species. Meat-baited traps captured 64.34% more individuals, which were more diverse and species-rich than the non-baited control traps, but the former was more selective for saprophages, necrophages, and coprophages. The burrows located in areas overgrown by triticale (a hybrid of wheat and rye) were inhabited by 69.86% of the identified arthropod species, and these also had the highest abundance (64.07%) in comparison with other habitats. However, differences in sample size biased our results toward and overestimate arthropods associated with this vegetation. This study underlines that the species composition detected in burrows was affected by the methods used and hamster preferences for a specific habitat rather than the geographic proximity of the burrows. More extensive sampling across multiple habitats will be necessary to confirm our findings.

The Georgia, USA, kaolins contain three major occurrences of Fe-sulphide minerals, namely (1) in burrow structures, (2) as nodules associated with lignite and (3) as finely disseminated material. We have used sulphur isotope analysis and X-ray powder diffraction to understand these three occurrences in order to gain insight into the diagenetic conditions and microbial influences affecting the kaolin mineralogy. Burrows and nodules are dominated by corroded marcasite with thin pyrite overgrowths. The δ34S composition of each sulphide sample has internal fractionations (δ34Shigh – δ34Slow) ranging from 22‰ to 67‰. The secondary pyrite phase tends to be the most 34S depleted, with a low δ34S value of –47‰, whereas marcasite displays a δ34S range from 30‰ to +33‰. Early acidic environments from organic acids could have facilitated the initial marcasite crystallization, with a pH increase during later diagenesis producing pyrite overgrowths. Sulphide formation would have continued until burial restricted the diffusion of sea-water sulphate. At this point, the metabolism of sulphate-reducing bacteria would have been retarded, producing δ34S values ranging from –30‰ (open sulphate supply) to +40‰ (highly restricted sulphate supply). Under the nutrient-starved conditions of later-diagenesis, disproportionate sulphur-reducing bacteria would likely have become more dominant, yielding additional δ34Ssulphide fractionation and producing the observed fractionation (δ34Ssulphate – δ34Ssulphide) values of +67‰.

New specimens described herein add to our knowledge of uncommon parataxa (embedment structures, borings and a certain type of burrow) from the type area of the Maastrichtian Stage, the material originating from the ENCI-HeidelbergCement Group (Maastricht), Ankerpoort-'t Rooth (Bemelen) and former Blom (Berg en Terblijt) quarries in southern Limburg (the Netherlands), and from the CBR-Romontbos (Eben Emael) and CPL SA (Haccourt) chalk pits in the province of Liège (northeast Belgium). Although Centrichnus eccentricus Bromley & Martinell has previously been recorded from this area, it has not received formal description; the specimen documented herein shares a test of the echinoid Echinocorys gr. conoidea with numerous other episkeletozoans. Podichnus cf. centrifugalis Bromley & Surlyk occurs both on echinocorythid echinoid tests and guards of belemnitellid coleoids; two out of seven specimens display radial discontinuous channels, indicative of the extreme penetration of filaments from the attached brachiopod's pedicle. Renichnus arcuatus Mayoral shows a range of morphologies, from the embedment structure sensu stricto through to specimens retaining internal moulds of the producing, embedded vermetid gastropod to free shells of Vermetus binkhorsti Cossmann. Burrows packed with bioclastic debris, particularly primary spines and a few test plates of phymosomatid echinoids, present a systematic conundrum, although appearing comparable to the ichnogenera Nummipera Hölder and Baronichnus Breton in several respects.

Relationships between sediment characteristics and the spatial organization of biogenic structures remain poorly understood, albeit important for characterizing bioturbation impacts and small-scale ecological patterns. Using axial tomodensitometry (CT-scan) and core sectioning, we studied the spatial distribution of Alitta virens burrows in sediment cores from two mudflats with different degrees of exposure along the St Lawrence Estuary, Canada. A variety of burrow morphologies was observed at both sites, with most being I-shaped. Most values measured (organic matter content, mean tomographic intensity, the number and diameter of burrow shafts and the percentage of space they occupy per transverse section) covaried with depth. The more sheltered site had higher organic matter and mud contents, and lower average tomographic intensity values. The spatial distribution of burrow shafts also differed between sites, with the more sheltered site having a higher number of burrow shafts and percentage of biogenic space in the upper sediment column, as well as a greater volume of biogenic structures that were connected to the surface (although intra-site variability was great). Along the horizontal plane and at various depths within sediments, burrow shafts were more randomly distributed at the exposed site, compared to a more even, maximal spacing at the sheltered site. In addition to finding differences in burrow organization at two spatial scales, we found significant correlations between tomographic intensity and (1) the number of burrow shafts, (2) biogenic space and (3) organic matter content. CT-scan data, including tomographic intensity, are useful for examining and comparing biogenic structures in sediment cores.

The aim of the present study was to characterize the external morphology and the orientation of burrows constructed by the mangrove crab Ucides cordatus. Data were obtained from two mangrove forests of similar vegetation dominance (Laguncularia racemosa) but differing in flooding heights. These mangroves were located near Barra de Icapara, Iguape City (SP), Brazil, (24°50′36″S–47°59′53′W). A total of 221 burrows were examined (120 on the high mangrove and 101 on the low mangrove). External morphology of the burrows was recorded by photographs for categorization and description. The directions of the burrow openings were recorded using a geological compass and the declivities of the ducts were measured with a clinometer. Females constructed 70.8% at Site A and 69.4% at Site B of the occupied burrows with the opening facing the margin of the river (P < 0.001), whilst males showed no significant difference in the burrow orientation (P > 0.05) at either site. In females, the tendency for burrow orientation possibly has a reproductive connotation as larval dispersal may be favoured and enhanced by the tides. Four groups of distinct tracks related to the morphotypes and developmental stages of U. cordatus were observed. No sediment constructions associated with the burrows were recorded for this species. Declivity of the burrows from juveniles was lower than from adults (P < 0.05), probably caused by the differential growth of the chelipeds in this species.

Tsetse flies Glossina pallidipes Austen and G. morsitans morsitans Westwood deposit their larvae in warthog burrows, in August–November, at Rekomitjie Research Station, Zambezi Valley, Zimbabwe. Artificial burrows, made from 200–l steel drums, were used to sample these flies and to collect their puparia. Sand-filled plastic trays in the burrows served as a substrate for larval deposition. The sand was covered with c. 2 cm of leaf litter after it was shown that only 3% of larvae were deposited on bare sand if both substrates were available. Other burrow modifications – artificially shading the burrow entrance, increasing the relative humidity inside the burrow, or reducing the size of the burrow entrance – significantly decreased deposition rates. The use of burrows in the hot season results in a reduction in the temperature experienced by the puparium towards an assumed optimum level of 26°C. Artificial burrows maintained a mean temperature of 28.5°C during October-November 1998, c. 2.5°C cooler than ambient; earlier work has shown that natural burrows can be c. 5°C cooler than ambient at these times. This may explain why natural burrows in full sunlight were used for larviposition, whereas artificial burrows were used only when they were in deep shade, and why significantly higher proportions of G. pallidipes were found in natural (66%) than in artificial burrows (34%). Better-insulated artificial burrows might produce more puparia with higher proportions of G. pallidipes. Burrows become waterlogged during the rains and may be too cool for optimum puparial development during the rest of the year. The percentages of G. m. morsitans in catches of females from artificial burrows, refuges and odour-baited traps were 34, 26 and < 10% respectively. Traps are biased in favour of G. pallidipes; artificial burrows may show a bias in favour of G. m. morsitans that is a function of temperature. Artificial warthog burrows provide a convenient way of studying the puparial stage in tsetse and for the first time facilitate the capture of females as they deposit their larvae.

The allometric relationship between body mass and burrow cross-sectional area for burrowing animals holds across greater than six orders of magnitude variation in body mass, and includes species separated by >500 million years of evolution from two phyla (Arthropoda and Chordata), seven classes (Arachnida, Insecta, Malacostraca, Osteichthyes, Amphibia, Reptilia, and Mammalia) and both terrestrial and marine habitats. Only birds, which construct relatively large burrows, and vermiform animals, which construct relatively narrow burrows, are separated from the remaining burrowing species. No difference is found between fossorial (burrowing animals that forage beneath the soil surface) and semi-fossorial (burrowing animals that forage terrestrially) mammals, suggesting that subterranean foragers do not modify burrow cross-sectional area to increase energy yields. However, solitary fossorial mammals do construct significantly larger nest chambers than semi-fossorial and colonial fossorial mammals. These large nest chambers probably assist in maintaining body temperature by providing a better thermally insulated microenvironment. This offsets the thermoregulatory problems faced by these animals, which are characterized by low, labile body temperatures and poor thermoregulatory ability. Colonial fossorial mammals, on the other hand, construct nest chambers that are the same relative size as those constructed by semi-fossorial mammals and probably maintain homeothermy by huddling with endothermic nest-mates.

Eight aardvarks Orycteropus afer were fitted with radio-transmitters at Tussen die Riviere Nature Reserve between June 1996 and December 1997. Two became habituated and could be approached to a distance of 1 m. Activity patterns, home ranges and burrow use were investigated using telemetry and direct observations. In winter, aardvarks emerged above ground earlier, returned to burrows earlier and were active for shorter periods than in summer. They were nocturnal except occasionally in winter when some individuals foraged above ground before sunset. Home ranges varied between 133 ha and 302 ha and range overlap occurred within and between both sexes. Densities were c. eight animals per 1000 ha. Aardvarks used steep slopes (>15°) less than would have been expected according to availability. Average lengths of consecutive burrow use for three aardvarks were 4.9, 6.9 and 8.6 days, with some burrows being abandoned after only 1 day and one burrow being used for 38 days.

Temperature and respiratory gas (CO2 and O2) concentrations were measured in the foraging tunnels of burrows naturally inhabited by two species of southern African mole-rats, the Cape mole-rat Georhychus capensis and the Damaraland mole-rat Cryptomys damarensis. Both species are completely fossorial and inhabit closed burrow systems. Tunnels of G. capensis burrows had a mean diameter of 8.7 cm and a depth, measured to the roof of the tunnel, of 6.2 cm; those of C. damarensis had a mean diameter of 6.5 cm and depth of 40 cm. In both species, the mean concentration of CO2 was higher, and mean concentration of O2 lower, in burrows than in the surrounding soil or in ambient air. Mean and minimum values of O2 were 20.4% and 19.8%, respectively, in G. capensis and 20.4% and 19.9% in C. damarensis; mean and maximum values of CO2 were 0.4% and 1.2% in G. capensis and 0.4% and 6.0% in C. damarensis. Temperature varied between 18.5 and 24.2 °C in burrows of G. capensis by comparison with an ambient range of 16.9 to 26.8 °C; and from 19.6 to 29.3 °C in burrows of C. damarensis by comparison with an ambient range of 8.6 to 30.8 °C. Thus a burrowing habit seems to offer both species protection from extremes of temperature without entailing the cost of a grossly abnormal respiratory environment. From a review of the relevant literature, we conclude that average concentrations of CO2 and O2 in mammalian burrows often do not differ greatly from ambient values. However, more work is needed to determine the respiratory gas concentrations in the immediate vicinity of active, burrowing animals.

The fossil record of unquestionable decapod remains dates back to Permo Triassic times. Evaluation of all available data from the fossil record, trace fossils and facies reveals various trends within the evolution of Mesozoic decapods, and its relation to their ecology. One of these trends is the protection of the long vulnerable abdomen. The most successful method, gradual reduction and inflection of the abdomen against the ventral cephalothorax, led to the Brachyura. Brachyurans exhibit the broadest spectrum of habitat adaptions.