Paleobiochemistry of North American fossil Liriodendron sp.

Organic geochemical analyses are presented for a fossil Liriodendron sp. from the Miocene, Clarkia Flora of Northern Idaho. Flavonoid profiles determined for the fossil and two extent species of Liriodendron (L. chinense and L. tulipifera) confirm the generic status of the fossil material, but owing to a generic uniformity in flavonoid composition, fail to resolve taxonomic affinities at the species level. Steroid and other cycloalkane-alkene profiles indicate that the fossil taxon has a greater chemical similarity with L. chinense than L. tulipifera, despite the general leaf outline similarity between the fossil species and extent L. tulipifera. The morphologic and chemical data are interpreted as evidence for mosaic evolution within the genus, and the non-canalization of character states in some Miocene species.     

Structural behaviour and strain distribution of the long bones of the human lower limbs

Although stiffness and strength of lower limb bones have been investigated in the past, information is not complete. While the femur has been extensively investigated, little information is available about the strain distribution in the tibia, and the fibula has not been tested in vitro. This study aimed at improving the understanding of the biomechanics of lower limb bones by: (i) measuring the stiffness and strain distributions of the different low limb bones; (ii) assessing the effect of viscoelasticity in whole bones within a physiological range of strain-rates; (iii) assessing the difference in the behaviour in relation to opposite directions of bending and torsion. The structural stiffness and strain distribution of paired femurs, tibias and fibulas from two donors were measured. Each region investigated of each bone was instrumented with 8–16 triaxial strain gauges (over 600 grids in total). Each bone was subjected to 6–12 different loading configurations. Tests were replicated at two different loading speeds covering the physiological range of strain-rates. Viscoelasticity did not have any pronounced effect on the structural stiffness and strain distribution, in the physiological range of loading rates explored in this study. The stiffness and strain distribution varied greatly between bone segments, but also between directions of loading. Different stiffness and strain distributions were observed when opposite directions of torque or opposite directions of bending (in the same plane) were applied. To our knowledge, this study represents the most extensive collection of whole-bone biomechanical properties of lower limb bones.     

A Mass Burial of Fossil Lions (Carnivora,Felidae, <Emphasis Type="Italic">Panthera</Emphasis> (<Emphasis Type="Italic">Leo</Emphasis>) <Emphasis Type="Italic">ex gr. fossilis-spelaea</Emphasis>) from Eurasia

The vertebrate fauna from the cave deposits in Imanai Cave in the Southern Urals (53°02′ N, 56°26′E) has been studied. It contains 715 bones that belonged to at least 11 individuals of fossil lion (Panthera (Leo) ex gr. fossilis-spelaea). It has been established that this is one of the largest Eurasian burial sites of fossil lions. The bones were accumulated due to the natural death of animals inside the cave. The age and sex estimations have shown that at least six adult males and five adult females died there. According to the accompanying fauna, radiocarbon, geochemical, and mineralogical analyses and archaeological finds, the interval of the lion bone accumulation is determined as the first half to middle of Late Pleistocene (OIS 5–3).     

A Three-Dimensional Skeletal Reconstruction of the Stem Amniote Orobates pabsti (Diadectidae): Analyses of Body Mass,Centre of Mass Position,and Joint Mobility

Orobates pabsti, a basal diadectid from the lower Permian, is a key fossil for the understanding of early amniote evolution. Quantitative analysis of anatomical information suffers from fragmentation of fossil bones, plastic deformation due to diagenetic processes and fragile preservation within surrounding rock matrix, preventing further biomechanical investigation. Here we describe the steps taken to digitally reconstruct MNG 10181, the holotype specimen of Orobates pabsti, and subsequently use the digital reconstruction to assess body mass, position of the centre of mass in individual segments as well as the whole animal, and study joint mobility in the shoulder and hip joints. The shape of most fossil bone fragments could be recovered from micro-focus computed tomography scans. This also revealed structures that were hitherto hidden within the rock matrix. However, parts of the axial skeleton had to be modelled using relevant isolated bones from the same locality as templates. Based on the digital fossil, mass of MNG 10181 was estimated using a model of body shape that was varied within a plausible range to account for uncertainties of the dimension. In the mean estimate model the specimen had an estimated mass of circa 4 kg. Varying of the mass distribution amongst body segments further revealed that Orobates carried most of its weight on the hind limbs. Mostly unrestricted joint morphology further suggested that MNG 10181 was able to effectively generate propulsion with the pelvic limbs. The digital reconstruction is made available for future biomechanical studies.     

An updated review of the middle Eocene avifauna from the Geiseltal (Germany), with comments on the unusual taphonomy of some bird remains

The brown coal mines of the Geiseltal in Germany were among the most important middle Eocene fossil localities and constitute the reference sites for the Geiseltalian stage of the European Land Mammal Mega Zones. Here, an updated review of the Geiseltal avifauna is given. Thirteen species are represented by diagnostic bones and can be referred to avian higher-level taxa, but various indeterminable albeit distinct fossils indicate a higher diversity of the Geiseltal avifauna. The majority of the Geiseltal fossils belong to taxa, which are well known from early to mid-Ypresian fossil sites of Europe and North America. Some of the species from the Geiseltal are larger than their early Eocene relatives, but it remains elusive whether this indicates an evolutionary size increase in some avian lineages or reflects different palaeohabitats of the involved fossil sites. The Geiseltal avifauna exhibits some taphonomic peculiarities that have not yet been addressed. Most bird fossils consist of isolated bones or partial skeletons and here it is hypothesized that at least some of the fragmentary specimens represent feeding remains of crocodilians. For the first time, medullary bone, which is indicative of breeding females, is reported for birds from the Geiseltal. The comparative abundance of the coliiform species Eoglaucidium pallas is remarkable, and either this species was extremely abundant in the Geiseltal ecosystem or it had ecological preferences, which favored its preservation.     

Frasnian vertebrate taphonomy and sedimentology of macrofossil concentrations from the Langsēde Cliff,Latvia

Luk?evi?s, E., Ahlberg, P.E., Stinkulis, ?., Vasi?kova, J. & Zupi??, I. 2011: Frasnian vertebrate taphonomy and sedimentology of macrofossil concentrations from the Langsēde Cliff, Latvia. Lethaia, Vol. 45, pp. 356–370. The siliciclastic sequence of the Upper Devonian of Kurzeme, Western Latvia, is renowned for abundant vertebrate fossils, including the stem tetrapods Obruchevichthys gracilis and Ventastega curonica. During the first detailed taphonomic study of the vertebrate assemblage from the Ogre Formation cropping out at the Langsēde Cliff, Imula River, abundant vertebrate remains have been examined and identified as belonging to one psammosteid, two acanthodian and three sarcopterygian genera; the placoderm Bothriolepis maxima dominates the assemblage. Besides fully disarticulated placoderm and psammosteid plates, separate sarcopterygian scales and teeth, and acanthodian spines, partly articulated specimens including complete distal segments of Bothriolepis pectoral fins, Bothriolepis head shields and sarcopterygian lower jaws have been found. The size distribution of the placoderm bones demonstrates that the individuals within the assemblage are of approximately uniform age. Distinct zones have been traced within the horizontal distribution of the bones. These linear zones are almost perpendicular to the dominant dip azimuth of the cross‐beds and ripple‐laminae and most probably correspond to the depressions between subaqueous dunes. Concavity ratio varies significantly within the excavation area. The degree of fragmentation of the bones and disarticulation of the skeletons suggest that the carcasses were reworked and slightly transported before burial. Sedimentological data suggest deposition in a shallow marine environment under the influence of rapid currents. The fossiliferous bed consists of a basal bone conglomerate covered by a cross‐stratified sandstone with mud drapes, which is in turn overlain by ripple laminated sandstone, indicating the bones were buried by the gradual infilling of a tidal channel. All the Middle–Upper Devonian vertebrate bone‐beds from Latvia are associated with sandy to clayey deposits and have been formed in a sea‐coastal zone during rapid sedimentation episodes, but differ in fossil abundance and degree of preservation. □Agnathans, Devonian, facies analysis, fish, fossil assemblage, palaeoenvironment.     

Quantifying the relative contribution of ante- and post-mortem factors to the variability in beef texture

This study aims to investigate the relative contribution of ante- and post-mortem factors to the final quality of beef. In all, 112 steers (four breed-crosses) were arranged in a 2 × 2 × 2 factorial experimental including production system, growth implant and β-adrenergic agonist strategies. Carcasses were suspended by the Achilles tendon or the aitch bone and meat was aged for 2/6/13/21/27 days (longissimus muscle) or 2/27 days (semimembranosus muscle). Meat quality traits related to beef texture were measured. Statistical analyses were developed including ante- and post-mortem factors and their relative contribution to the variability observed for each measured trait was calculated. The main factor responsible for the variability in sarcomere length was the suspension method (91.1%), which also influenced drip-loss (44.3%). Increasing the percentage of British breeds increased (P < 0.05) the intramuscular fat content in longissimus muscle, but only when implants were not used. Thus, the breed-cross, implant strategy and their interaction were responsible for >58% of the variability in this trait. The variability in instrumental and sensory tenderness was mainly affected by post-mortem factors (carcass suspension, ageing time and their interaction), explaining generally ∼70% of the variability in these traits. Breed-cross was the second most important effect (∼15%) when carcass suspension was not considered in the model, but still ageing time was responsible for a much larger proportion of the variability in tenderness (>45%). In conclusion, post-mortem handling of the carcasses may be much more effective in controlling beef tenderness than pre-mortem strategies.     

Taphonomy of the south Brazilian Triassic herpetofauna: fossilization mode and implications for morphological studies

Skulls and limb bones of reptiles from Mid-Triassic rocks in southern Brazil show striking morphological and volumetric differences among specimens from the same taxonomic group; this is caused by early calcite cementation. Petrographic analysis of 40 thin sections of selected fossil bones demonstrates that the main agent of fossilization was precipitation of calcite and minor hematite in the pores of bones during early burial mineralization. The framework of the bones has been broken and replaced by calcite (and hematite), beginning in the spongy inner part of the bone (the cancellous bone) and gradually extending into the compact external layers. Three taphonomic groups of fossil bones are recognized: I – those almost entirely retaining their original structure and shape; II – those whose internal structure is destroyed, but which still have solid outer 'bone surface', and III – those composed of fragments of bone apatite 'floating' in a carbonate matrix. Destruction of the bone structure was caused by the displacive force of calcite crystallization, which typically occurs at shallow burial, during early diagenesis. This process occurs in the vadose zone and requires markedly alternating wet and dry seasons, which indicates a semi-arid paleoclimate for the south Brazilian Mid-Triassic, an inference consistent with other paleoclimatic data. Diagenesis can significantly alter the shape and size of bones and cause considerable morphological variation within the same fossil group, possibly leading to taxonomic misinterpretation.     

Analysis of fossil bone organic matrix by transmission electron microscopy

A transmission electron microscope (TEM) study was initiated on samples of geological ages ranging from Devonian to Jurassic to analyse the ultrastructure of the organic matrix in fossil bones that have preserved a histological structure after demineralisation. All samples show a network of variably well-preserved fibrils. Within the sampling, the best results were obtained in two specimens: the scales of the Devonian sarcopterygian tetrapodomorph Eustenopteron foordi, and the humerus of Jurassic dinosaur Lappentosaurus madagascariensis. Despite an extended time difference between both specimens, their fossil bone is composed of a plywood-like structure in which the fibrils are very closely packed. These observations support the hypothesis that dense initial packing of collagen fibrils favours the preservation of the fossil bone.     

A new morphometric analysis of the hominid pelvic bone

This study is based upon a new morphometric technique providing both size and shape variables. It has been applied to 189 pelvic bones of extant humans and African apes as well as to 13 hominid pelvic bones of various taxonomic status. The main aim of this work is to include such fossil bones in the same study in order to set a synthetic comparison of their shape in the light of the yardstick given by the African ape/human pelvic bone comparison. To do so, ratio diagrams are chosen because they are simple and very expressive tools with which to present such comparisons. Shape differences are very well illustrated and quantified by this technique. The ilium appears to be the most different of the three parts of the pelvic bone. Compared to these differences, discrepancies between fossil hominid and extant human bones are of a totally different scale. This shows the architectural unity related to the acquisition of bipedalism by hominids. It is nonetheless possible to detect two levels of difference. The first separates Australopithecus from Homo and could be seen as reflecting locomotor differences between both genera. The second splits both Homo erectus and Neanderthal from modern human pelvic bones. It appears from the hominid fossil record of pelvic bones that two periods of stasis exist and are separated by a period of very rapid evolution corresponding to the emergence of the genus Homo. We are of the opinion that the same could be true for the split between African ape and hominid lineages at the end of the Miocene.     

The influence of mass,volume and density on the frequency of recovery of fossil hominid hand and wrist bones

A study of the mass, volume and density of each of the wrist and hand bones of male and female human skeletons was undertaken. It was found that the mass and volume (i.e. size) of the bones are well correlated with the relative frequencies of preservation ofAustralopithecus and earlyHomo wrist and hand bones from fossil hominid sites in Africa. In general, the larger the bone, the greater its preservation frequency. In contrast to findings on bovid bones, the density of hand and wrist bones is not well correlated with the frequency of such bones recovered from these sites. These findings may be explained in terms of the agents of deposition of the bones, the physical nature of the deposit, and the methods of extraction of the fossils from the deposit.     

Lateral line morphology and cranial osteology of the Rubynose Brotula,Cataetyx rubrirostris

Cranial osteology, canal neuromast distribution, superficial neuromast distribution and innervation, and cephalic pore structure were studied in cleared and stained specimens of the deep sea brotulid Cataetyx rubrirostris. The cranial bone structure of C. rubrirostris is similar to other brotulids (Dicrolene sp.) and zoarcids (Zoarces sp.), except for an unusual amount of overlapping of the bones surrounding the cranial vault. The superficial neuromasts are innervated by the anterodorsal, anteroventral, middle and posterior lateral line nerves and are organized similarly to those of the blind ophidioid cave fish Typhliasina pearsei. The cephalic pores open into a widened lateral line canal system. The canal is compartmentalized into a series of neuromast‐containing chambers that probably amplify signals received by the system. J. Morphol. 241:265–274, 1999. © 1999 Wiley‐Liss, Inc.     

Serpulids and other calcareous tube-dwelling encrusting polychaetes from the Early Cretaceous Agrio Formation (Neuquén Basin,Argentina)

Serpulids and other related tube-dwelling polychaetes are often ignored when found as fossil remains. They are, however, a widespread and important group today, and abundant literature has been published on them. Knowledge of fossil serpulids is centered on European material, and little has already been done on South American fossil calcareous tubes. In this paper, seven serpulid and sabellid morphotypes are described from the Early Cretaceous marine Agrio Formation of Argentina, revealing a diversity of worms recorded as encrusters on bivalves, ammonites and corals. Sabellids are represented by Glomerula cf. serpentina. Serpulids are represented by two subfamilies: “Serpulinae” includes Mucroserpula mucroserpula, Parsimonia antiquata, Placostegus cf. conchophilus, Propomatoceros semicostatus and P. sulcicarinatus; Spirorbinae is represented by heavily worn tiny coiled tubes assigned to ?Neomicrorbis. Serpulids and sabellids are one of the main components of the mollusk-encrusting fauna recorded in the Agrio Formation, along with small oysters but much more diverse. They are most commonly found as post-mortem encrusters, but some cases of unquestionable living interaction are also found, such as serpulid tubes embedded on coral branches. They are often overgrown by bryozoans, and sometimes by oysters; they frequently occur aggregated.     

A new tool for determining degrees of mineralization in fossil amphibian skeletons: The example of the Late Palaeozoic branchiosaurid Apateon from the Autun Basin,France

Studying ontogenetic features of fossil tetrapods is of major interest for investigating the adaptive strategies of early tetrapods to their palaeoenvironments. To determine the degree of calcification of skeletal elements, biologists have until now relied on X-ray radiographs of organisms or isolated bones, or on thin sections. An X-ray tomographic scan of Apateon, a Carboniferous – Permian branchiosaurid from the Autun Basin, France, reveals distinct density properties related to different mineralized tissues (calcified cartilage versus bone). The rendering of Apateon as a “test individual” provides a 3D map of the degrees of ossification of the axial and cranial elements. The combination of these anatomical observations with histological information from classical thin sections made in limb bones of several other specimens of the same locality allows the detailed determination of their ontogenetic stage. A comparison with the well-known specimens of the Saar-Nahe Basin, Germany, makes it possible to investigate the influence of different palaeoenvironments on ontogenetic features.     

Dynamics of the TOM Complex of Mitochondria during Binding and Translocation of Preproteins

Translocation of preproteins across the mitochondrial outer membrane is mediated by the TOM complex. This complex consists of receptor components for the initial contact with preproteins at the mitochondrial surface and membrane-embedded proteins which promote transport and form the translocation pore. In order to understand the interplay between the translocating preprotein and the constituents of the TOM complex, we analyzed the dynamics of the TOM complex of Neurospora crassa and Saccharomyces cerevisiae mitochondria by following the structural alterations of the essential pore component Tom40 during the translocation of preproteins. Tom40 exists in a homo-oligomeric assembly and dynamically interacts with Tom6. The Tom40 assembly is influenced by a block of negatively charged amino acid residues in the cytosolic domain of Tom22, indicating a cross-talk between preprotein receptors and the translocation pore. Preprotein binding to specific sites on either side of the outer membrane (cis and trans sites) induces distinct structural alterations of Tom40. To a large extent, these changes are mediated by interaction with the mitochondrial targeting sequence. We propose that such targeting sequence-induced adaptations are a critical feature of translocases in order to facilitate the movement of preproteins across cellular membranes.     

Bone structure and the patterns of force transmission in the cat skull (Felis catus)

Projection microradiography was used to determine the density and orientation of the force transmitting structures, i.e., trabeculae and bone lying between approximately parallel vascular canals, within the bones of cat skulls. The organisation in the skulls was confirmed statistically for a total of ten cats. The results of the observations showed that within specific areas of the skull a high degree of structural orientation and an increased density of osseous structures was present. The distribution of these characters corresponded in contiguous bones such that a continuum of structural organisation was established between the alveolar region and the site of attachment of the temporalis and masseter muscles and the glenoid region. The patterns of force transmission during jaw closure were determined when a resistance was placed initially between the canines and then the carnassials. An analysis was first carried out on dry skulls using colophonium resin to determine the direction of the force distribution. The nature and the approximate magnitude of the forces were ascertained by replacing the resin with strain gauges. The basic similarities in the strain patterns recorded from the dry skulls and those from the ten anaesthetised cats in which strain gauges had been intra-vitally implanted, substantiated the recordings made on the dry skulls. Combination of the results from the three sets of experiments defined the patterns of force distribution in the cat skull during the closure of the mandible against a resistance. The results showed that: (1) the combined action of the temporalis and masseter muscles tended to reduce the overall strain in the skull bones, and that the deformations produced by the action of the masseter were greater than that exerted by the temporalis muscles; (2) during biting, whether the resistance was placed between the canines or carnassials, compressive forces predominated in the facial bones; (3) small movements observed between facial bones indicated the presence of a flexible component within the skull, thus allowing large forces to be exerted during biting without overstressing the facial bones; (4) the glenoid fossa is part of a force bearing joint; (5) forces generated during biting were resisted within the skull by forces of an opposite nature generated within the system, the incompressible nature of bone and by the effect of the soft tissues; (6) the nature and the magnitude of the strain altered when a resistance was placed at the canines and then at the carnassials; however, the pattern of force distribution within the skull remained the same; (7) there was a direct correspondence between the detailed structural organisation of the bones and the patterns of force distribution. This conclusion would appear to apply in general to mammalian skulls. The study also emphasises the importance, neglected hitherto, of carrying out a variety of experiments to determine the patterns of force distribution in bones. The Trajectorial Theory of bone organisation is discussed and, on the basis of the results obtained, a modified theory is proposed. This states that: the structural continuum is common to the compact and cancellous bone and comprises bony bars which are aligned in the optimum direction for the transmission of force to a region in the bone or bones where it is effectively resisted.     

Taphonomic analysis of the early Pleistocene (2.4 Ma) faunal assemblage from A.L. 894 (Hadar, Ethiopia)

The A.L. 894 site (Hadar, Ethiopia) is, together with OGS 7 (Gona, Ethiopia), one of the oldest archaeological sites documenting a spatial association of stone tools and bones retrieved from an in situ excavation. In contrast with OGS 7, the better preservation of the bone assemblage at A.L. 894 allows the identification of taphonomic processes of bone breakage, thanks to abundant green bone fractures. The presence of tooth marks and the lack of hominin-produced bone modifications together argue against hominins as the responsible agents for bone accumulation and modification. This taphonomic study of A.L. 894 shows lack of evidence for functional associations between stone tools and bones, a pattern documented in several other early Pleistocene sites. Such a pattern underscores the complex phenomena involved in site formation processes, especially in the earliest archaeological assemblages     

Recognizing hominoid-modified bones: the taphonomy of colobus bones partially digested by free-ranging chimpanzees in the Kibale Forest, Uganda

We present a taphonomic study of bones that have passed though the digestive tracts of free-ranging chimpanzees from the Kibale Forest in Uganda. The bone assemblage can be characterized as having a very low species diversity; low number of identifiable specimens (NISP) per scat; bones extremely broken up (very small size range); skeletal part frequencies similar in some ways to those resulting from carnivore partial digestion; and sometimes articulated specimens. Modifications to the bones include corrosion, tiny tooth scores and pits, cracking, and fraying of bone edges. Together, these characteristics suggest that hominoid bone digestion may be recognizable, despite some similarities with leopard-, canid-, and eagle-modified bone. Chimpanzees are well-documented hunters of medium-sized vertebrates such as monkeys. This is significant in the study of human evolution if, as it seems, the last common ancestor of chimpanzees and humans was chimpanzee-like. It suggests there was a pre-stone-tool-using hunting phase in human evolution, perhaps by australopiths or the last common ancestor. Taphonomically, pre-stone tool meat eating has been very difficult to detect in the fossil record. However, if chimpanzees leave a recognizable taphonomic signature on the bones of their prey, we will be able to look for analogous signatures in fossil bones associated with fossil hominoids and hominids.     

Where to Dig for Fossils: Combining Climate-Envelope,Taphonomy and Discovery Models

Fossils represent invaluable data to reconstruct the past history of life, yet fossil-rich sites are often rare and difficult to find. The traditional fossil-hunting approach focuses on small areas and has not yet taken advantage of modelling techniques commonly used in ecology to account for an organism’s past distributions. We propose a new method to assist finding fossils at continental scales based on modelling the past distribution of species, the geological suitability of fossil preservation and the likelihood of fossil discovery in the field, and apply it to several genera of Australian megafauna that went extinct in the Late Quaternary. Our models predicted higher fossil potentials for independent sites than for randomly selected locations (mean Kolmogorov-Smirnov statistic = 0.66). We demonstrate the utility of accounting for the distribution history of fossil taxa when trying to find the most suitable areas to look for fossils. For some genera, the probability of finding fossils based on simple climate-envelope models was higher than the probability based on models incorporating current conditions associated with fossil preservation and discovery as predictors. However, combining the outputs from climate-envelope, preservation, and discovery models resulted in the most accurate predictions of potential fossil sites at a continental scale. We proposed potential areas to discover new fossils of Diprotodon, Zygomaturus, Protemnodon, Thylacoleo, and Genyornis, and provide guidelines on how to apply our approach to assist fossil hunting in other continents and geological settings.     

Biometric study of ruminant carpal bones and implications for phylogenetic relationships

The mammalian Carpus is a complex of several small bones with multiple interactions during walking. Therefore, it is highly probable that different mammalian families developed distinctive constellations in their Carpi, which could be useful for biometric identification of phylogenetic groupings. The carpal bones of nineteen extant ruminant species (nine bovid, nine cervid, and one moschid) have been investigated to search for biometric traits which are diagnostic for the three families. Additionally, we searched for diverging functional adaptations in the carpal constellations. Therefore, measurements have been taken from the five main carpals, which are carrying the body weight. As a sesamoid bone, Os carpi accessorium was excluded. After transformation of the data into their natural logarithms, multivariate methods of factor analyses and discriminant analyses were performed for each bone. Bivariate plots of the factor scores allowed a clear separation of bovids and cervids. The only one species of the Moschidae (Moschus moschiferus) lies closer to the cervids than to the bovids. The grouping is due to phylogenetic relationships and not due to functional differences in the groups or differing habitat preferences. Generally, the carpals of cervids are more slender and higher in contrast to the bulky and flat carpals in bovids. This approach could be used to assign isolated carpal bones found in fossil sites to their ruminant family.