Diverse Plant-Insect Associations from the Latest Cretaceous and Early Paleocene of Patagonia, Argentina

Abstract:
Abstract.
 Little is known about the recovery of terrestrial ecosystems after the end-Cretaceous extinction outside of the Western Interior of North America, relatively close to the 66 Ma bolide impact crater in Chicxulub, Mexico. A previous report showed that in Patagonia, Argentina, insect damage on fossil leaves decreased from the latest Cretaceous to early Paleocene but recovered to pre-extinction levels within ca. four million years. Here, we present the first detailed study of these Patagonian plant-insect associations, key components of terrestrial food webs, during the latest Cretaceous and three time slices from the early Paleocene recovery. The lithologic units studied are the uppermost Cretaceous portion of the Lefipán Formation and the Danian Salamanca and Peñas Coloradas formations in Chubut, Argentina. Seven functional feeding groups are present throughout: hole feeding, margin feeding, skeletonization, surface feeding, piercing and sucking, mining, and galling. Fifty damage types (DTs) were present at Maastrichtian localities, and 39–48 were found at Danian localities. Plant-insect associations that apparently went locally extinct at the end of the Cretaceous include several gall, mine, and piercingand-sucking DTs. Based on our preliminary leaf morphotypes, host plants did not provide refuge for specialized insect herbivores across the K/Pg boundary. Despite a decrease in insect damage diversity after the bolide impact, Danian floras hosted a rich array of DTs, including specialized damage such as mines and galls. Many of these early Paleocene DTs were not found in the terminal Cretaceous, providing evidence for a rapid recovery of plant-insect associations regionally.


Jaw movement in fossil mammals: analysis, description and visualization

Abstract: A terminology for and visualizations of different mammalian mastication paths are provided, resulting from orientation of attritional and abrasional facets and striation on fossil (and extant) teeth. The occlusal motion of the left lower jaw is considered, and a moderate wear stage (IDAS 3) is used as standard. In contrast to conventional terminologies, the proposed nomenclature differentiates between the inclination and the direction of the lower jaw movement as projected onto a horizontal plane for each phase of the power stroke. The proposed mastication compass attempts to combine three aspects of the power stroke: (1) the number of phases, (2) the occlusal direction, and (3) the inclination of each phase. Descriptions and visualizations are given for several taxa in order to demonstrate its general applicability. The proposed new terminology and the mastication compass simplify comparisons of different modes of mastication in different mammalian taxa.

visualization
inclination
power stroke
jaw movement
cycle


Graptolite (Hemichordata, Pterobranchia) preservation and identification in the Cambrian Series 3

Abstract: Due to inadequate preservation, pterobranchs are often difficult to identify in the fossil record, and a better understanding of preservational modes and diagenetic and metamorphic effects is needed for their recognition. Pterobranch hemichordates are common in Cambrian Stage 5 and younger sedimentary rocks, but are frequently overlooked. Often, pterobranch hemichordate colonies have been considered to be algal remains or hydroids. Re‐examination of Cambrian Burgess Shale algae reveals that the genera Yuknessia and Dalyia can be recognized as putative early representatives of pterobranch hemichordates. Distinct fusellar construction of the individual zooidal tubes and branching of the creeping proximal part of the colonies are found in the morphologically similar rhabdopleurid pterobranch genus Sphenoecium. The erect tubes of Sphenoecium do not branch and can reach a length of several centimetres. The development of the fusellar construction in this taxon shows a highly irregular development of the suture patterns, but a fairly consistent height of the individual fuselli. The taxon is widely distributed in the Cambrian Series 3, but has regularly been identified as a hydroid or an alga. Sphenoecium wheelerensis from the Cambrian Wheeler Shale of Utah is described as new.

cambrian series
fusellar construction
original organic material
tubaria
clay template


Abstract: Li, L.-Y., Zhang, X.-L., Yun, H. & Li, G.-X., October 2015. New occurrence of Cambroclavus absonus from the lowermost Cambrian of North China and its stratigraphical importance. Alcheringa 40, xxx–xxx. ISSN 0311-5518. The problematic Small Shelly Fossil Cambroclavus absonus is described from the Xinji Formation in the Longxian area, which is located near the southwestern margin of the North China Platform. The Xinji Formation, the basal rock unit of the Cambrian in the studied area, yields an assemblage of skeletal fossils that share many common elements with contemporary faunas from South Australia. Sclerites of C. absonus reported herein represent the first occurrence of the species outside Australia, thus extending the palaeogeographic range of the taxon to northern China. To date, palaeogeographic occurrences of Cambroclavus sclerites are restricted to the Peri-Gondwana realm, including South China, Australia, Tarim, Kazakhstan, North China and Western Europe. These occurrences are divided into a Southern Group realm and Northern Group realm. Stratigraphically, Cambroclavus occurs mostly in Cambrian Stage 3 and has three occurrences in Stage 5, separated by Stage 4 in which Cambroclavus has not yet been found. The first appearance datum of Cambroclavus in Cambrian Stage 3 is of importance for regional and inter-regional correlations. In particular, the presence of Cambroclavus absonus in North China allows species-level correlation between North China and South Australia. Luoyang Li [lly@stumail.nwu.edu.cn], Xingliang Zhang [xzhang69@nwu.edu.cn], Hao Yun [yunhao@stumail.nwu.edu.cn], Early Life Institute and State Key Laboratory Of Continental Dynamics, Department of Geology, Northwest University, Xian 710069, PR China; Guoxiang Li [gxli@nigpas.ac.cn], Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, PR China.

cambroclavus absonus
stratigraphical importance
cambrian stage


Rapid Pliocene adaptive radiation of modern kangaroos

Abstract: Secrets revealed by kangaroo teeth The teeth of mammals display complex adaptations to diet and can thus provide a window into the environments of extinct species. Couzens and Prideaux used such a window to examine the expansion and diversification of kangaroos, Australia's largest herbivores (see the Perspective by Polly). True kangaroos diversified not in response to drying in the Miocene, as suggested by molecular results, but rather as grasslands expanded during the Pliocene. Furthermore, the now-extinct short-faced kangaroos were not declining because of increases in aridity at the end of the Pleistocene but instead were experiencing an increase in dietary divergence. Science, this issue p. 72; see also p. 25 Kangaroos show unexpected patterns of diversification in response to past changes in climate. Differentiating between ancient and younger, more rapidly evolved clades is important for determining paleoenvironmental drivers of diversification. Australia possesses many aridity-adapted lineages, the origins of which have been closely linked to late Miocene continental aridification. Using dental macrowear and molar crown height measurements, spanning the past 25 million years, we show that the most iconic Australian terrestrial mammals, “true” kangaroos (Macropodini), adaptively radiated in response to mid-Pliocene grassland expansion rather than Miocene aridity. In contrast, low-crowned, short-faced kangaroos radiated into predominantly browsing niches as the late Cenozoic became more arid, contradicting the view that this was an interval of global browser decline. Our results implicate warm-to-cool climatic oscillations as a trigger for adaptive radiation and refute arguments attributing Pleistocene megafaunal extinction to aridity-forced dietary change.

pliocene
adaptive radiation
late miocene


Periodic Vesicle Formation in Tectonic Fault Zones—an Ideal Scenario for Molecular Evolution

Abstract: Tectonic fault systems in the continental crust offer huge networks of interconnected channels and cavities. Filled mainly with water and carbon dioxide (CO2), containing a wide variety of hydrothermal chemistry and numerous catalytic surfaces, they may offer ideal reaction conditions for prebiotic chemistry. In these systems, an accumulation zone for organic compounds will develop at a depth of approximately 1 km where CO2 turns sub-critical and dissolved components precipitate. At this point, periodic pressure changes caused for example by tidal influences or geyser activity may generate a cyclic process involving repeated phase transitions of carbon dioxide. In the presence of amphiphilic compounds, this will necessarily lead to the transient formation of coated water droplets in the gas phase and corresponding vesicular structures in the aqueous environment. During this process, the concentration of organic components inside the droplets and vesicles would be drastically increased, allowing for favorable reaction conditions and, in case of the vesicles generated, large trans-membrane concentration gradients. Altogether, the process of periodic formation and destruction of vesicles could offer a perfect environment for molecular evolution in small compartments and for the generation of protocells. The basic process of vesicle formation is reproduced experimentally with a lipid in a water/CO2 system.

vesicle formation
molecular evolution
continental crust
prebiotic chemistry
protocell


Early Eudicot flower and fruit: Dakotanthus gen. nov. from the Cretaceous Dakota Formation of Kansas and Nebraska, USA

Abstract: Abstract An extinct plant that populated the eastern margin of the Cretaceous Midcontinental Seaway of North America about 100 million years ago has attracted interest as one of the earliest known bisexual flowers in the fossil record. Reexamination of the type specimen of Carpites cordiformis Lesq., and corresponding specimens from sandstones and clays of the Dakota Formation of Kansas and Nebraska and the correlative Woodbine Sandstone of Texas, with both light microscopy and micro CT scanning, leads to a revised concept of the morphology and affinities of the “Rose Creek flower”. The moderately large flowers (22–30 mm diameter) have two perianth whorls: five basally fused sepals and five free spatulate petals. The gynoecium is pentacarpellate with five styles. A crescent-shaped nectariferous pad occurs at the base of the gynoecium aligned with each sepal. Ten stamens are inserted at the level of the nectaries, one whorl organized opposite the sepals and another opposite the petals. In situ pollen is oblate, brevitricolporate and finely verrucate. The fruits are loculicidal capsules with persistent calyx and disk. Comparing the full suite of observed characters with those of extant angiosperms indicates particularly close similarity to the monogeneric fabalean family Quillajaceae, with shared features of perianth number and morphology, nectary position and morphology, stamen number and morphology, and gynoecium merosity, although the fossil differs from extant Quillaja in fruit type (capsule vs basally syncarpous follicles) and especially in pollen morphology (10 μm oblate, microverrucate, vs 30–40 μm prolate, striate).

fruit
cretaceous dakota formation
bisexual flower


Developmental paleobiology of the vertebrate skeleton

Abstract: Abstract Studies of the development of organisms can reveal crucial information on homology of structures. Developmental data are not peculiar to living organisms, and they are routinely preserved in the mineralized tissues that comprise the vertebrate skeleton, allowing us to obtain direct insight into the developmental evolution of this most formative of vertebrate innovations. The pattern of developmental processes is recorded in fossils as successive stages inferred from the gross morphology of multiple specimens and, more reliably and routinely, through the ontogenetic stages of development seen in the skeletal histology of individuals. Traditional techniques are destructive and restricted to a 2-D plane with the third dimension inferred. Effective non-invasive methods of visualizing paleohistology to reconstruct developmental stages of the skeleton are necessary. In a brief survey of paleohistological techniques we discuss the pros and cons of these methods. The use of tomographic methods to reconstruct development of organs is exemplified by the study of the placoderm dentition. Testing evidence for the presence of teeth in placoderms, the first jawed vertebrates, we compare the methods that have been used. These include inferring development from morphology, and using serial sectioning, microCT or synchrotron X-ray tomographic microscopy (SRXTM), to reconstruct growth stages and directions of growth. The ensuing developmental interpretations are biased by the methods and degree of inference. The most direct and reliable method is using SRXTM data to trace sclerochronology. The resulting developmental data can be used to resolve homology and test hypotheses on the origin of evolutionary novelties.


Osteology and phylogeny of Zalmoxes (n. g.), an unusual Euornithopod dinosaur from the latest Cretaceous of Romania

Abstract: Synopsis The dinosaurs of the Hateg Basin of Transylvania (late Maastrichtian; western Romania) include Theropoda, Sauropoda, Ornithopoda and Ankylosauria. Of these, one of the most enigmatic taxa is the ornithopod that Franz Baron Nopcsa originally described as Mochlodon suessi and M. robustus in 1902. These two species have come to be regarded as a single species of Rhabdodon, R. robustus, which is distinct from R. priscus from the Late Cretaceous of southern France and northern Spain. This study provides a detailed anatomical revision of the Rhabdodon material that was described originally by Nopcsa during the early decades of the 20th century. It also adds information on material discovered in the Hateg area of Romania since the 1930s. A phylogenetic analysis of basal euornithopods indicates that the non‐hadrosaurid material from Hateg comprises two distinct, but congeneric, species. These two species can be distinguished unambiguously from R. priscus. A new genus Zalmoxes is established for the Romanian ornithopod, comprising Z. robustus comb. nov. (the type‐species of the genus) and Z. shqiperorum sp. nov. Phylogenetic analysis indicates that the two species of Zalmoxes and R. priscus are united in the monophyletic clade Rhabdodontidae (nov.). Rhabdodontidae constitutes the sibling clade to Iguanodontia. R. septimanicus, M. suessi, and the Villeveyrac Rhabdodon also appear to be members of Rhabdodontidae. The evolutionary implications of this phylogenetic analysis include the recognition of a ghost lineage, extending from the most recent common ancestor of Rhabdodontidae and Iguanodontia, which extends for 73 million years. This extraordinarily long ghost lineage duration may reflect considerable gaps in the history of this group or the geographical isolation of Rhabdodontidae in Europe during much of the Cretaceous period. The area of origin of the Rhabdodontidae + Iguanodontia clade may be North America, while the common ancestor of Rhabdodontidae dispersed to Europe, at that time a marine‐dominated region with tectonically‐active terrestrial habitats. Adult individuals of Z. robustus are smaller than either of its two closest relatives, Z. shqiperorum and R. priscus, within the Rhabdodontidae, or with many species of Iguanodontia and, therefore, is considered a possible paedomorphic dwarf.

zalmoxes
romania
new genus zalmoxes
rhabdodontidae


EVOLUTION OF THE WORLD FAUNA OF AQUATIC FREE‐LIVING ARTHROPODS

Abstract: Is there a grand pattern to the evolution of global biota and ecological systems? This question, which has lately attracted much thought, can rather more easily be approached through considering the relative microcosm of a major taxonomic group evolving within a major adaptive zone. This paper examines the evolution of aquatic free-living arthropods, the occupants of one such adaptive zone, from the Cambrian to the present. Combining established ideas on arthropod evolution with new ideas on measurement, it first develops a quantitative measure of the morphological complexity of arthropod limb mechanisms which in turn provides a rough measure of ecological specialization for the respective animals. This measure is then applied to study of the evolution of the world fauna of aquatic free-living arthropods as reflected in the fossil record. The paper analyzes evolutionary patterns thus revealed, and tests the idea that, within an adaptive zone, the specialization of its occupants increases with their taxonomic diversity. Upshots from the study are surprising estimates for rates of taxonomic diversification and rough quantitative estimates for the percentage completeness of the fossil record through geologic time for taxa of different ranks. Simpson (1969) and May (1973) both wondered whether certain regularities in taxonomic diversity data from the fossil record might not reflect some grand strategy in the evolution of global ecological systems. Paleontologists have begun to further examine such patterns in the evolution of world biota and to interpret them in terms of the evolution of the ecological systems those biota may represent (e.g., Simpson, 1969; Valentine, 1969a,b, 1971, 1973a,b; Valentine and Moores, 1970, 1972; Flessa and Imbrie, 1971, 1973; Raup, 1972). The essence of the approach taken by Valentine and others are the beliefs that a biota is constituted as a hierarchy of taxonomically and ecologically structured systems, that taxonomic structure in some way reflects ecological structure, and that the history of a biota as a system can reliably be interpreted through analysis of data from the fossil record (Valentine, 1968). The kinds and number of kinds of organisms comprising a biota constitute its taxonomic structure. The functional relationships among organisms which, if strong enough, may unite populations, communities, and perhaps an entire biota


REDESCRIPTION OF PLATYCRANIELLUS ELEGANS (THERAPSIDA, CYNODONTIA) FROM THE LOWER TRIASSIC OF SOUTH AFRICA, AND THE CLADISTIC RELATIONSHIPS OF EUTHERIODONTS

Abstract: Abstract:  Platycraniellus elegans is an enigmatic Triassic cynodont from South Africa that has only been briefly described previously. New preparation of the holotype and additional unpublished material allows a detailed redescription and comparison with different cynodonts. Platycraniellus elegans is recognized as a valid species of basal cynodont. The distinct suborbital angulation of the zygomatic process, previously considered as a diagnostic character in chiniquodontid cynodonts, and more recently observed in some galesaurids, is also present in P. elegans. A larger, second specimen was initially referred to P. elegans, but most recently considered to belong to Galesaurus planiceps. Close comparison of this specimen with the holotype of P. elegans and with galesaurid specimens allows a tentative allocation to G. planiceps. A cladistic analysis of 32 taxa (two gorgonopsians, seven therocephalians and 23 cynodonts) and 96 craniodental characters places P. elegans as sister taxon of Eucynodontia. Results from the analysis favour a dichotomy between (1) Cynognathia, including the sectorial‐toothed cynodonts Ecteninion, Cynognathus and the gomphodont cynodonts, and (2) Probainognathia, including most sectorial‐toothed eucynodonts (e.g. Lumkuia, Probainognathus, Chiniquodon), tritheledontids, tritylodontids and mammaliaforms. The Late Triassic sectorial‐toothed Ecteninion is the most basal member of Cynognathia, whereas the Middle Triassic Lumkuia is the basal representative of Probainognathia. Tritylodontids (Oligokyphus and Kayentatherium) are placed among Probainognathia, forming a monophyletic group with the tritheledontid Pachygenelus, whereas Brasilitherium is the sister taxon of Mammaliaformes. The cladistic analysis also indicates paraphyly for Therocephalia, with the whaitsiid Theriognathus identified as sister taxon of Cynodontia.

cynodontia
triassic
sister taxon
mammaliaformes
redescription


Contributions to the diversity in cryptogamic covers in the mid-Palaeozoic: 'Nematothallus' revisited

Abstract: Compression fossils from the Silurian and Devonian of southern Britain, composed of cuticles and tubes, were described by W. H. Lang as the genus Nematothallus and placed, with Prototaxites, in Nematophytales, related neither to algae nor tracheophytes. Dispersed cuticles of Nematothallus and perforated forms assigned to Cosmochlaina were frequently recovered in macerates, their affinities being unresolved. New collections from a Lochkovian locality in the Welsh Borderland permitted the reconstruction of the stratified thalli of these nematophytes; they comprise a superficial cortex (which produced the cuticles) overlying a palisade zone composed of septate, parallel tubes, presumed to be hyphae, and a basal zone comprising wefts of randomly interwoven hyphae. Excellent three dimensional preservation allows the erection of a new species of Nematothallus, N. williamii. A similar anatomy is seen in a new group of fossils with either circular incisions in the cortex or complete separation of thickened cortical cells, presumably comprising a developmental sequence. By their stratified organization the nematophytes differ from extant and extinct algae and bryophytes and the enigmatic Spongiophyton. A complex anatomy and septate tubes suggest affinity with lichenized fungi. Limited data support a fungal rather than embryophyte chemistry, but a photobiont is missing. Nematophytes, globally widespread in cryptogamic covers from mid-Ordovician times, added to the biodiversity in early terrestrial ecosystems and enhanced chemical weathering.

cryptogamic cover
nematothallus
silurian
palisade zone
parallel tube


Rarefaction analysis of morphological and taxonomic diversity

Abstract: Our assessment of morphological diversity is influenced by morphological extremes and therefore depends on sample size (taxonomic richness). Rarefaction predicts the morphological diversity that would probably be observed in a sample of reduced size, thereby allowing both compensation for differences in sample size that may be strictly preservational, and analysis of diversity structure, that is, the relationship between morphological and taxonomic diversity. Middle and Late Cambrian trilobites exhibit a diversity structure characterized by many variations on a few morphological themes. In contrast, Middle and Late Ordovician trilobites occupy a larger range of morphospace per unit of species richness. Diversity structure in the Devonian is similar to that in the Middle and Late Ordovician, but the magnitude of morphological diversity is lower in the Devonian, as many fewer species are observed. For blastoids, different aspects of morphological diversity (range of morphospace occupied, number of character states possessed, and number of different regions in morphospace occupied) exhibit different relationships to taxonomic richness. In all cases Permian blastoids are characterized by a diversity structure in which morphological diversity per unit of taxonomic richness is greater than for Devonian blastoids. Changes in morphological diversity in fissiculate blastoids appear to reflect evolution of continuous variation in thecal morphology more than changes in the number of character states. Saunders and Swan's data on Namurian ammonoids illustrate some significant differences in diversity structure among stratigraphic levels, but many apparent differences in morphological diversity are consistent with the possibility that they reflect the sampling of different numbers of species from the same underlying diversity structure. Rarefaction curves are also presented for idealized increases and decreases in diversity, and these are compared to some of the observed changes in trilobites, blastoids, and ammonoids.

taxonomic diversity
sample size
morphospace
sum


Shell Orientation Terminology among the Bivalvia (Mollusca): Problems and Proposed Solutions

Abstract: TRADITIONAL TERMS used to describe shell orientation in bivalves are unsatisfactory in three important ways: 1) for poorly known bivalve taxa, unbiased and directionally neutral terms are sometimes needed to replace anterior and posterior where data are incomplete; 2) there is a striking absence of simple terms to apply to the long and short ends of the shell; and 3) the term lateral is either incorrectly or inconsistently applied. In the following discussion, I shall explore each of these issues and suggest remediation. Although application of terminology describing shell orientation is unlikely to be an issue among extant bivalve taxa, identifying anterior and posterior ends of the shell can sometimes be a speculative business when dealing either with juveniles of living bivalves (Hoggarth, 1987) or, more commonly, with poorly studied or specialized fossil groups, especially where the internal morphology of the shell is either ambiguous, weakly impressed, or limited by preservation. The prevalence of posterior elongation among the Bivalvia has nurtured a disconcerting bias either: 1) to intuitively assume the long end of the shell to be posterior within published descriptions; or 2) to confuse right and left valves in figure captions and typological registers. In passing, it should be noted that the problem of distinguishing ‘‘head-from-tail’’ is not unique to the study of bivalves, but has been a significant issue in other molluscan studies, for example, sorting out the several univalve groups within the polyphyletic ‘‘Class’’ Monoplacophora (see Peel, 1991). Among bivalves, beaks and umbones are rarely central in position; instead, they are placed either in front of or behind the center. Bivalves are thus described as either posteriorly elongate or anteriorly elongate, implying an a priori understanding of the orientation of the soft anatomy within the shell. Whereas the greatest diversity of bivalves favors the posteriorly elongate condition, there are nevertheless significant numbers of bivalve taxa where the condition is reversed, even though the direction of elongation may not be immediately apparent from the shell morphology. For example, among the Palaeotaxodonta, nuculids and solemyids are anteriorly elongate, whereas nuculanids and mallettiids are often posteriorly elongate, yet many shell characters are otherwise broadly shared (Bradshaw and Bradshaw, 1971; Bailey, 1983). Despite their directional ambiguity, the terms equilateral and inequilateral are currently accepted in reference to relative beak placement along the anteroposterior axis. Currently, the shell is called equilateral if the beaks are placed centrally, or inequilateral if beak placement is either in front of or behind the midpoint of the anteroposterior axis, despite the fact that the shell inequality is essentially anteroposterior, not lateral. Conventional usage is problematic on etymological grounds because the original Latin root later-, refers to the sides (sideways or flanks) that is, to the left and right of the plane of commissure, perpendicular to the anteroposterior axis. A similar usage is applied to denticles called lateral teeth, which are not truly ‘‘lateral,’’ but placed either behind or in front of the cardinal teeth. To confuse matters further, the term lateral is simultaneously applied in its proper sense to locations either left or right of the commissure. For example, left and right valves are lateral in placement relative to the commissure. Thus, lateral, when applied to bivalve morphology has a twofold meaning. I therefore recommend that, at least for poorly known bivalves (or perhaps other molluscan groups where applicable), it is desirable in formal descriptions to avoid subjective terms like anterior and posterior where they potentially represent an interpretive bias in favor of directionally neutral terms that are purely descriptive. Obviously, anterior and posterior should (and must) be freely applied once an unequivocal understanding of the anatomy is attained. I further recommend that terms such as equilateral and inequilateral be abandoned with respect to beak placement. Accordingly, I therefore offer the following revisions of orientation terms used in the description of bivalves with reference to shell axes, shell extremities, and shell dorsum and ligamental placement (Fig. 1).

orientation
bivalvia
problem
neutral term


Geometric morphometrics to interpret the endophytic egg-laying behavior of Odonata (Insecta) from the Eocene of Patagonia, Argentina

Abstract: Abstract. Although the order Odonata has a rich fossil record, many questions about its reproductive biology remain unanswered. There are two strategies of egg laying among odonates, exophytic and endophytic, the latter being one of the most revealing vestiges of plant–insect association in the fossil record. We assessed whether geometric morphometrics based on elliptical series of Fourier allow expression of variability of shape in traces of Odonata eggs within a leaf of Eucalyptus chubutensis (Berry) González (in part), González, 2009 (Myrtaceae) from Laguna del Hunco (Chubut, Argentina) (early Eocene) and whether this variability is consistent with the ichnotaxonomy of this material. We found that the largest variation corresponds to the compression of the shape while the remaining two components reflect variations in the apex position and its curvature, which changed according to the relative position of the traces in the leaf. There was no evidence that the hardness of the leaf would affect the shape of the egg trace. We postulate that these traces could have been produced by one single female: Variations in the pattern observable in the fossil of an originally three-dimensional structure are consistent with differences in the position of the eggs inserted by a single female who has flexed her abdomen to insert the eggs as she approaches the apex of the leaf (behavior observed also in extant dragonflies). For the first time, endophytic egg traces are analyzed with geometrical morphometrics, and this allows us to make inferences on the oviposition behavior of a female that lived around 52 million years ago.

behavior
eocene
trace
female
geometric morphometric


Unravelling the identity of the platanistoid Notocetus vanbenedeni Moreno, 1892 (Cetacea, Odontoceti) from the early Miocene of Patagonia (Argentina)

Abstract: Platanistoidea remains one of the most evolutionarily intriguing lineages of toothed whales (Odontoceti). The clade comprises mostly extinct species from the late Oligocene–early Miocene onward and a single extant riverine genus (Platanista). There is an ongoing debate as to the membership of Platanistoidea and the causes of their near extinction. In Patagonia (Argentina), the most abundant platanistoid recorded in the lower Miocene Gaiman Formation is Notocetus vanbenedeni, first described by Moreno in 1892 based on two individuals. The goal of the present contribution is to conduct an updated anatomical, palaeobiological and phylogenetic analyses of Notocetus vanbenedeni and hence contribute to an understanding of the evolutionary history of the Platanistoidea. Our analyses, including at least 26 individuals (12 undescribed), show that Notocetus vanbenedeni is a valid platanistoid taxon, recovered as part of a new clade. Among its most outstanding features, this taxon has an elevated dorsal tubercular supraorbital crest formed mainly by the frontal, the precursor of the pneumatized crest of the extant Platanista. Notocetus vanbenedeni also shows initial stages of the plesiomorphic bony connection between the earbones and skull as in Platanista, although the functional implications for hearing remain elusive. The nasal sac system, pterygoid sinus system and morphology of the earbones suggest that this species was able to hear high-frequency sounds and echolocate underwater, similar to extant odontocetes. Thus, Notocetus vanbenedeni presents a mosaic of features that suggest an intermediate platanistoid morphotype. Anatomical differences and phylogenetic analyses suggest that Peruvian specimens could not be referred to this species. The feeding apparatus of Notocetus vanbenedeni makes it the only combination suction-feeder recorded in the early Miocene of Patagonia and among the smallest odontocetes. Finally, the abundant records of Notocetus vanbenedeni in an inner shelf environment with freshwater influence suggest a possible early preference for such protected habitats.


Caught in the act? Distraction sinking in ammonoid cephalopods

Abstract: Two specimens of the Late Mississippian ammonoid cephalopod Metadimorphoceras sp. were recovered from the Bear Gulch Limestone in Montana. This unit was deposited in the lowest part of the Big Snowy Basin, where the bottom waters are thought to have been strongly oxygen deficient. The two nearly equally sized specimens are impressions with soft tissues preserved as brown carbonaceous smears. Diagenetic processes destroyed their aragonitic shells. The preserved soft tissues are interpreted as mandibles, remains of food in the crop, and, possibly, ovaries and eyes. The specimens are on their sides, aperture-to-aperture, and probably the male is on the left and the female is on the right. The specimens are thought to have been in the process of copulation when they died. Copulation by most (all?) externally shelled cephalopods (extinct ammonoids and fossil and extant nautiloids) was probably in a head-to-head, aperture-to-aperture position. This was probably governed in part by restricted accessibility to the female reproductive organs due to the presence of the shell and the ability of both animals to partly withdraw into their shells during copulation. The shell protected them from predators during copulation. In coleoids, which lack an external shell, copulation is a more rapid affair due to the greater vulnerability from predators including other coleoids. We suggest that the fossils from the Bear Gulch Limestone and similar finds of paired ammonoids preserved together with interlocking apertures, and including soft parts in the body chamber, represent examples of ammonoid behavior frozen in time. The two ammonoids were probably too pre-occupied with copulation to notice that they were sinking into the hypoxic bottom waters of the basin and facing suffocation (distraction sinking).


The origin of modern amphibians: a re-evaluation

Abstract: There are currently three competing hypotheses seeking to explain the evolutionary origins of modern amphibians. The lepospondyl hypothesis holds that the lysorophian lepospondyls constitute the sister taxon to all lissamphibians. The temnospondyl hypothesis suggests that modern amphibians are most closely related to the dissorophoid temnospondyls. Finally, the polyphyletic hypothesis posits that the modern amphibian orders have separate evolutionary origins from among different groups of Palaeozoic tetrapods. Here, we review the character matrices used in previous studies. These data sets differ significantly in choice of characters. Therefore, we built a matrix based on data from all three hypotheses and analysed key taxa phylogenetically using both Bayesian inference and parsimony. Uncorrected, the supermatrix yielded inconclusive results, demonstrating the presence of at least two phylogenetic optima. When the data were corrected according to new observations on Doleserpeton, Eocaecilia, and other fossil forms, the phylogeny supported the temnospondyl hypothesis of lissamphibian origins. This conclusion is also supported by a careful study of character changes in the individual lineages.

modern amphibian
temnospondyls
dissorophoid temnospondyls


Discrepancy between Cranial and DNA Data of Early Americans: Implications for American Peopling

Abstract: Currently, one of the major debates about the American peopling focuses on the number of populations that originated the biological diversity found in the continent during the Holocene. The studies of craniometric variation in American human remains dating from that period have shown morphological differences between the earliest settlers of the continent and some of the later Amerindian populations. This led some investigators to suggest that these groups—known as Paleomericans and Amerindians respectively—may have arisen from two biologically different populations. On the other hand, most DNA studies performed over extant and ancient populations suggest a single migration of a population from Northeast Asia. Comparing craniometric and mtDNA data of diachronic samples from East Central Argentina dated from 8,000 to 400 years BP, we show here that even when the oldest individuals display traits attributable to Paleoamerican crania, they present the same mtDNA haplogroups as later populations with Amerindian morphology. A possible explanation for these results could be that the craniofacial differentiation was a local phenomenon resulting from random (i.e. genetic drift) and non-random factors (e.g. selection and plasticity). Local processes of morphological differentiation in America are a probable scenario if we take into consideration the rapid peopling and the great ecological diversity of this continent; nevertheless we will discuss alternative explanations as well.

american peopling
holocene
craniometric variation


Sponge grade body fossil with cellular resolution dating 60 Myr before the Cambrian

Abstract: Significance Phylogenomic extrapolations indicate the last common ancestor of sponges and eumetazoans existed deep in the Cryogenian, perhaps 200 million years (Myr) before the Cambrian (541 Ma). This inference implies a long Precambrian history of animals phylogenetically allied with sponges. However, there is yet little unequivocal paleontological evidence of Precambrian sponges. Here, we present a newly discovered 600-Myr-old fossil preserved at cellular resolution, displaying multiple poriferan features. The animal was covered with a dense layer of flattened cells resembling sponge pinacocytes, displaying a hollow tubular structure with apparent water inflow and outflow orifices. Although requiring additional specimens of similar form for confirmation, this finding is consistent with phylogenomic inference, and implies the presence of eumetazoan ancestors by 60 Myr before the Cambrian. An extraordinarily well preserved, 600-million-year (Myr)-old, three-dimensionally phosphatized fossil displaying multiple independent characters of modern adult sponges has been analyzed by SEM and synchrotron X-ray tomography. The fossilized animal (Eocyathispongia qiania gen. et sp. nov.) is slightly more than 1.2 mm wide and 1.1 mm tall, is composed of hundreds of thousands of cells, and has a gross structure consisting of three adjacent hollow tubes sharing a common base. The main tube is crowned with a large open funnel, and the others end in osculum-like openings to the exterior. The external surface is densely covered with flat tile-like cells closely resembling sponge pinacocytes, and this layer is punctuated with smaller pores. A dense patch of external structures that display the form of a lawn of sponge papillae has also survived. Within the main funnel, an area where features of the inner surface are preserved displays a regular pattern of uniform pits. Many of them are surrounded individually by distinct collars, mounted in a supporting reticulum. The possibility cannot be excluded that these pits are the remains of a field of choanocytes. The character set evinced by this specimen, ranging from general anatomy to cell type, uniquely indicates that this specimen is a fossil of probable poriferan affinity. So far, we have only this single specimen, and although its organized and complex cellular structure precludes any reasonable interpretation that its origin is abiogenic, confirmation that it is indeed a fossilized sponge will clearly require discovery of additional specimens.


How to find a dinosaur, and the role of synonymy in biodiversity studies

Abstract: Abstract Taxon discovery underlies many studies in evolutionary biology, including biodiversity and conservation biology. Synonymy has been recognized as an issue, and as many as 30–60% of named species later turn out to be invalid as a result of synonymy or other errors in taxonomic practice. This error level cannot be ignored, because users of taxon lists do not know whether their data sets are clean or riddled with erroneous taxa. A year-by-year study of a large clade, Dinosauria, comprising over 1000 taxa, reveals how systematists have worked. The group has been subject to heavy review and revision over the decades, and the error rate is about 40% at generic level and 50% at species level. The naming of new species and genera of dinosaurs is proportional to the number of people at work in the field. But the number of valid new dinosaurian taxa depends mainly on the discovery of new territory, particularly new sedimentary basins, as well as the number of paleontologists. Error rates are highest (>50%) for dinosaurs from Europe; less well studied continents show lower totals of taxa, exponential discovery curves, and lower synonymy rates. The most prolific author of new dinosaur names was Othniel Marsh, who named 80 species, closely followed by Friedrich von Huene (71) and Edward Cope (64), but the “success rate” (proportion of dinosaurs named that are still regarded as valid) was low (0.14–0.29) for these earlier authors, and it appears to improve through time, partly a reflection of reduction in revision time, but mainly because modern workers base their new taxa on more complete specimens. If only 50% of species are valid, evolutionary biologists and conservationists must exercise care in their use of unrevised taxon lists.


A new upper Middle Ordovician–Lower Silurian drillcore standard succession from Borenshult in Östergötland, southern Sweden: 1. Stratigraphical review with regional comparisons

Abstract: A recent drilling at Borenshult near Motala resulted in discovery of the stratigraphically most complete succession through the upper Darriwilian–Rhuddanian interval known in Östergötland. The approximately 70 m long drillcore succession is subdivided into eight formations, the oldest being the late Darriwilian Furudal Limestone and the youngest being the Rhuddanian Motala Formation. Conodonts are used for a detailed biostratigraphic classification of the Borenshult drillcore into three subzones of the Pygodus serra Zone, two subzones of the Pygodus anserinus Zone, and three subzones of the Amorphognathus tvaerensis Zone. The base of the Amorphognathus superbus Zone is taken to be ∼10 m above the Kinnekulle K-bentonite, that of the Amorphognathus ordovicicus just below the Fjäcka Shale, and that of the Ozarkodina hassi Zone at the base of the Middle Member of the Loka Formation. Because of its unique lithology and paleontology and its wide geographic occurrence, this member is formally named herein the Skultorp Member. The previously uncertain stratigraphical position of the internationally known “Borenshult fauna” is shown to correlate with the Skultorp Member. A regional comparison of the Borenshult drillcore succession shows it to be most similar to coeval successions in Västergötland and Dalarna but there are some significant regional differences. The average rate of net rock accumulation during late Darriwilian and Sandbian time is calculated to be ∼3–4 mm/ka.

succession
östergötland
kinnekulle k-bentonite


Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain

Abstract: Significance The middle Pleistocene Sima de los Huesos (SH) fossil collection provides the rare opportunity to thoroughly characterize the postcranial skeleton in a fossil population, comparable only to that obtained in the study of the Neandertal hypodigm and recent (and fossil) modern humans. The SH paleodeme can be characterized as relatively tall, wide, and muscular individuals, who are less encephalized than both Neandertals and modern humans. Some (but not all) Neandertal derived traits are present, which phylogenetically links this population with Neandertals. Thus, the full suite of Neandertal features did not arise all at once, and the evolution of the postcranial skeleton could be characterized as following a mosaic pattern. Current knowledge of the evolution of the postcranial skeleton in the genus Homo is hampered by a geographically and chronologically scattered fossil record. Here we present a complete characterization of the postcranium of the middle Pleistocene paleodeme from the Sima de los Huesos (SH) and its paleobiological implications. The SH hominins show the following: (i) wide bodies, a plesiomorphic character in the genus Homo inherited from their early hominin ancestors; (ii) statures that can be found in modern human middle-latitude populations that first appeared 1.6–1.5 Mya; and (iii) large femoral heads in some individuals, a trait that first appeared during the middle Pleistocene in Africa and Europe. The intrapopulational size variation in SH shows that the level of dimorphism was similar to modern humans (MH), but the SH hominins were less encephalized than Neandertals. SH shares many postcranial anatomical features with Neandertals. Although most of these features appear to be either plesiomorphic retentions or are of uncertain phylogenetic polarity, a few represent Neandertal apomorphies. Nevertheless, the full suite of Neandertal-derived features is not yet present in the SH population. The postcranial evidence is consistent with the hypothesis based on the cranial morphology that the SH hominins are a sister group to the later Neandertals. Comparison of the SH postcranial skeleton to other hominins suggests that the evolution of the postcranium occurred in a mosaic mode, both at a general and at a detailed level.


Rise of the Earliest Tetrapods: An Early Devonian Origin from Marine Environment

Abstract: Tetrapod fossil tracks are known from the Middle Devonian (Eifelian at ca. 397 million years ago - MYA), and their earliest bony remains from the Upper Devonian (Frasnian at 375–385 MYA). Tetrapods are now generally considered to have colonized land during the Carboniferous (i.e., after 359 MYA), which is considered to be one of the major events in the history of life. Our analysis on tetrapod evolution was performed using molecular data consisting of 13 proteins from 17 species and different paleontological data. The analysis on the molecular data was performed with the program TreeSAAP and the results were analyzed to see if they had implications on the paleontological data collected. The results have shown that tetrapods evolved from marine environments during times of higher oxygen levels. The change in environmental conditions played a major role in their evolution. According to our analysis this evolution occurred at about 397–416 MYA during the Early Devonian unlike previously thought. This idea is supported by various environmental factors such as sea levels and oxygen rate, and biotic factors such as biodiversity of arthropods and coral reefs. The molecular data also strongly supports lungfish as tetrapod's closest living relative.

tetrapod
early devonian
marine environment


A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora

Abstract: Significance Paleozoic lobopodians constitute a diverse assemblage of worm-like organisms that are known from various exceptional fossil deposits and were among the earliest animals to develop skeletonized body parts for protection. Here, we describe Collinsium ciliosum gen. et sp. nov., an armored lobopodian from the early Cambrian Xiaoshiba Lagerstätte (South China). Collinsium belongs to an extinct clade of superarmored lobopodians characterized by supernumerary dorsal spines, and specialized limbs for filter feeding; collectively, these fossil taxa represent a well-defined group within the lineage leading to extant velvet worms (Onychophora). Despite their greater morphological variety and appendage complexity compared with other lobopodians and extant velvet worms, Collinsium and its close relatives embodied a unique, yet ultimately failed, autoecology during the Cambrian explosion. We describe Collinsium ciliosum from the early Cambrian Xiaoshiba Lagerstätte in South China, an armored lobopodian with a remarkable degree of limb differentiation including a pair of antenna-like appendages, six pairs of elongate setiferous limbs for suspension feeding, and nine pairs of clawed annulated legs with an anchoring function. Collinsium belongs to a highly derived clade of lobopodians within stem group Onychophora, distinguished by a substantial dorsal armature of supernumerary and biomineralized spines (Family Luolishaniidae). As demonstrated here, luolishaniids display the highest degree of limb specialization among Paleozoic lobopodians, constitute more than one-third of the overall morphological disparity of stem group Onychophora, and are substantially more disparate than crown group representatives. Despite having higher disparity and appendage complexity than other lobopodians and extant velvet worms, the specialized mode of life embodied by luolishaniids became extinct during the Early Paleozoic. Collinsium and other superarmored lobopodians exploited a unique paleoecological niche during the Cambrian explosion.

lobopodian
onychophora
xiaoshiba lagerstätte
south china
tardigrade


Utility of Marine Benthic Associations as a Multivariate Proxy of Paleobathymetry: A Direct Test from Recent Coastal Ecosystems of North Carolina

Abstract: Benthic marine fossil associations have been used in paleontological studies as multivariate environmental proxies, with particular focus on their utility as water depth estimators. To test this approach directly, we evaluated modern marine invertebrate communities along an onshore-offshore gradient to determine the relationship between community composition and bathymetry, compare the performance of various ordination techniques, and assess whether restricting community datasets to preservable taxa (a proxy for paleontological data) and finer spatial scales diminishes the applicability of multivariate community data as an environmental proxy. Different indirect (unconstrained) ordination techniques (PCoA, CA, DCA, and NMDS) yielded consistent outcomes: locality Axis 1 scores correlated with actual locality depths, and taxon Axis 1 scores correlated with actual preferred taxon depths, indicating that changes in faunal associations primarily reflect bathymetry, or its environmental correlatives. For datasets restricted to taxa with preservable hard parts, heavily biomineralized mollusks, open ocean habitats, and a single onshore-offshore gradient, the significant correlation between water depth and Axis 1 was still observed. However, for these restricted datasets, the correlation between Axis 1 and bathymetry was reduced and, in most cases, notably weaker than estimates produced by subsampling models. Consistent with multiple paleontological studies, the direct tests carried out here for a modern habitat using known bathymetry suggests that multivariate proxies derived from marine benthic associations may serve as a viable proxy of water depth. The general applicability of multivariate paleocommunity data as an indirect proxy of bathymetry is dependent on habitat type, intrinsic ecological characteristics of dominant faunas, taxonomic scope, and spatial and temporal scales of analysis, highlighting the need for continued testing in present-day depositional settings.

multivariate proxy
community composition
bathymetry
utility


A dynamic explanation for the origin of the western Mediterranean organic‐rich layers

Abstract: The eastern Mediterranean sapropels are among the most intensively investigated phenomena in the paleoceanographic record, but relatively little has been written regarding the origin of the equivalent of the sapropels in the western Mediterranean, the organic‐rich layers (ORLs). ORLs are recognized as sediment layers containing enhanced total organic carbon that extend throughout the deep basins of the western Mediterranean and are associated with enhanced total barium concentration and a reduced diversity (dysoxic but not anoxic) benthic foraminiferal assemblage. Consequently, it has been suggested that ORLs represent periods of enhanced productivity coupled with reduced deep ventilation, presumably related to increased continental runoff, in close analogy to the sapropels. We demonstrate that despite their superficial similarity, the timing of the deposition of the most recent ORL in the Alboran Sea is different than that of the approximately coincident sapropel, indicating that there are important differences between their modes of formation. We go on to demonstrate, through physical arguments, that a likely explanation for the origin of the Alboran ORLs lies in the response of the western Mediterranean basin to a strong reduction in surface water density and a shoaling of the interface between intermediate and deep water during the deglacial period. Furthermore, we provide evidence that deep convection had already slowed by the time of Heinrich Event 1 and explore this event as a potential agent for preconditioning deep convection collapse. Important differences between Heinrich‐like and deglacial‐like influences are highlighted, giving new insights into the response of the western Mediterranean system to external forcing.


Astronomical calibration of the geological timescale: closing the middle Eocene gap

Abstract: Abstract. To explore cause and consequences of past climate change, very accurate age models such as those provided by the astronomical timescale (ATS) are needed. Beyond 40 million years the accuracy of the ATS critically depends on the correctness of orbital models and radioisotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical timescale and confirms the intercalibration of radioisotopic and astronomical dating methods back through the Paleocene–Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous–Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the ATS into the Mesozoic.


A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae) from the Early Triassic of South Africa

Abstract: A new species of the erythrosuchid archosauriform reptile Garjainia Ochev, 1958 is described on the basis of disarticulated but abundant and well-preserved cranial and postcranial material from the late Early Triassic (late Olenekian) Subzone A of the Cynognathus Assemblage Zone of the Burgersdorp Formation (Beaufort Group) of the Karoo Basin of South Africa. The new species, G. madiba, differs from its unique congener, G. prima from the late Olenekian of European Russia, most notably in having large bony bosses on the lateral surfaces of the jugals and postorbitals. The new species also has more teeth and a proportionately longer postacetabular process of the ilium than G. prima. Analysis of G. madiba bone histology reveals thick compact cortices comprised of highly vascularized, rapidly forming fibro-lamellar bone tissue, similar to Erythrosuchus africanus from Subzone B of the Cynognathus Assemblage Zone. The most notable differences between the two taxa are the predominance of a radiating vascular network and presence of annuli in the limb bones of G. madiba. These features indicate rapid growth rates, consistent with data for many other Triassic archosauriforms, but also a high degree of developmental plasticity as growth remained flexible. The diagnoses of Garjainia and of Erythrosuchidae are addressed and revised. Garjainia madiba is the geologically oldest erythrosuchid known from the Southern Hemisphere, and demonstrates that erythrosuchids achieved a cosmopolitan biogeographical distribution by the end of the Early Triassic, within five million years of the end-Permian mass extinction event. It provides new insights into the diversity of the Subzone A vertebrate assemblage, which partially fills a major gap between classic ‘faunal’ assemblages from the older Lystrosaurus Assemblage Zone (earliest Triassic) and the younger Subzone B of the Cynognathus Assemblage Zone (early Middle Triassic).

erythrosuchidae
early triassic
garjainia madiba


Early Paleocene Paleoceanography and Export Productivity in the Chicxulub Crater

Abstract: The Chicxulub impact caused a crash in productivity in the world's oceans which contributed to the extinction of ∼75% of marine species. In the immediate aftermath of the extinction, export productivity was locally highly variable, with some sites, including the Chicxulub crater, recording elevated export production. The long‐term transition back to more stable export productivity regimes has been poorly documented. Here, we present elemental abundances, foraminifer and calcareous nannoplankton assemblage counts, total organic carbon, and bulk carbonate carbon isotope data from the Chicxulub crater to reconstruct changes in export productivity during the first 3 Myr of the Paleocene. We show that export production was elevated for the first 320 kyr of the Paleocene, declined from 320 kyr to 1.2 Myr, and then remained low thereafter. A key interval in this long decline occurred 900 kyr to 1.2 Myr post impact, as calcareous nannoplankton assemblages began to diversify. This interval is associated with fluctuations in water column stratification and terrigenous flux, but these variables are uncorrelated to export productivity. Instead, we postulate that the turnover in the phytoplankton community from a post‐extinction assemblage dominated by picoplankton (which promoted nutrient recycling in the euphotic zone) to a Paleocene pelagic community dominated by relatively larger primary producers like calcareous nannoplankton (which more efficiently removed nutrients from surface waters, leading to oligotrophy) is responsible for the decline in export production in the southern Gulf of Mexico.

paleocene
export productivity
chicxulub crater
nannoplankton


A new lophocyonid, Izmirictis cani gen. et sp. nov. (Carnivora: Mammalia), from the lower Miocene of Turkey

Abstract: Lophocyonids are one of the more enigmatic groups of Carnivora in the European Miocene fossil record. Lophocyonids are clearly distinguished from other Feliformia by their peculiar lophodont dental morphology. For this reason, the systematic relationships of the family have been controversial. Here we describe and interpret dental remains from the early Miocene of Sabuncubeli, Turkey, which we attribute to a new genus and species: Izmirictis cani. The phylogenetic analysis allows us to include Izmirictis within a monophyletic group, Lophocyonidae new rank, characterized by the molarization of the anterior premolars (P3 and p4), the lophodont adaptation of the molar dentition and the complex morphology of the incisors. The phylogenetic analysis shows a close relationship between Izmirictis and primitive hyaenids (represented herein by Protictitherium). The divergence between Lophocyonidae and Hyaenidae is estimated by biochronological data to have occurred during the early Miocene (MN2). Dental microwear analysis, although limited by poor dental enamel preservation, indicates that the pronounced lophodonty in Izmirictis cani could be connected to a herbivorous feeding habit. http://zoobank.org/urn:lsid:zoobank.org:pub:8D75382D-6C22-41C1-A47F-BA3EAF766881

izmirictis cani
carnivora
miocene
turkey


A 3D anatomical atlas of appendage musculature in the chelicerate arthropod Limulus polyphemus

Abstract: Limulus polyphemus, an archetypal chelicerate taxon, has interested both biological and paleontological researchers due to its unique suite of anatomical features and as a useful modern analogue for fossil arthropod groups. To assist the study and documentation of this iconic taxon, we present a 3D atlas on the appendage musculature, with specific focus on the muscles of the cephalothoracic appendages. As L. polyphemus appendage musculature has been the focus of extensive study, depicting the muscles in 3D will facilitate a more complete understanding thereof for future researchers. A large museum specimen was CT scanned to illustrate the major exoskeletal features of L. polyphemus. Micro-CT scans of iodine-stained appendages from fresh, non-museum specimens were digitally dissected to interactively depict appendage sections and muscles. This study has revealed the presence of two new muscles: one within the pushing leg, located dorsally relative to all other patella muscles, and the other within the male pedipalp, located in the modified tibiotarsus. This atlas increases accessibility to important internal and external morphological features of L. polyphemus and reduces the need for destructive fresh tissue dissection of specimens. Scanning, digitally dissecting, and documenting taxa in 3D is a pivotal step towards creating permanent digital records of life on Earth.

atlas
appendage musculature
limulus polyphemus
cephalothoracic appendage


Isotopic variation in fossils and matrix of the Cretaceous Red Chalk at Speeton and South Ferriby, Yorkshire, England

Abstract: SUMMARY Macro- and micro-fossils (belemnites, planktonic and benthonic foraminifera) and coccolithic matrix from the middle Cretaceous Red Chalk of Yorkshire, UK, have been examined using petrographic, isotopic, and chemical methods to investigate the conditions within which they were formed or altered. Only the belemnites ( Neohibilites sp.) attain the petrographic and geochemical criteria for being well preserved. In contrast, the foraminifera and matrix reveal evidence of diagenetic alteration. Mean belemnite δ 18 O values are −0.97‰ (PDB) from South Ferriby and −1.28‰ (PDB) from Speeton. Assuming a sea water SMOW value of −1.0‰, mean palaeotemperatures calculated from the oxygen isotopic compositions are 15.9°C and 16.8°C respectively. The range of isotopic values provided by the belemnites in this study suggests that the isotopic values obtained from early studies of the Chalk, that used only petrographic and/or hand specimen descriptions to screen for diagenetic alteration, could largely represent unaltered values. The palaeotemperatures interpreted from the belemnites are comparable to recent estimates of middle Cretaceous temperature from general circulation model predictions.

cretaceous red chalk
south ferriby
palaeotemperature


Teisseirei barattinia Roselli 1939: the first sphinx moth trace fossil from palaeosols, and its distinct type of wall

Abstract: The trace fossil Teisseirei barattinia, found in Cenozoic formations of Uruguay and Argentina, is an elongated chamber recognizable by its depressed cross-section, antechamber, and its multi-layered lining with an inner surface texture composed of densely packed sub-rectangular to sub-triangular pits. Our recent behavioural observations on larval and pupal stages of Sphingidae (Lepidoptera), particularly on Manduca rustica, suggest that Teisseirei barattinia is the pupation chamber of a sphinx moth. Last instar larvae of Manduca rustica, Eumorpha anchemolus and E. labruscae were placed in terraria to observe their burrowing behaviour and to recover pupation chambers. Chambers show depressed or plane convex cross-sections as T. barattinia. The internal surface texture of walls is also similar to that of T. barattinia. The same pattern could be obtained experimentally by pressing the true legs of Manduca rustica larva against plasticine. The multi-layered wall structure, shown by T. barattinia, is a new type of lining for insect trace fossils in palaeosols that result from soil packing combined with discharges of abundant liquid excretion by soft-bodied larvae, as in the case of Manduca rustica. T. barattinia is the first trace fossil documented in palaeosols attributed to sphinx moths and supported by macro and micromorphological comparisons with extant pupation chambers. The shallow emplacement of moth pupation chambers in soils suggests that T. barattinia would be a good indicator of palaeosol upper horizons.


Early Origin for Human-Like Precision Grasping: A Comparative Study of Pollical Distal Phalanges in Fossil Hominins

Abstract:
BACKGROUND
The morphology of human pollical distal phalanges (PDP) closely reflects the adaptation of human hands for refined precision grip with pad-to-pad contact. The presence of these precision grip-related traits in the PDP of fossil hominins has been related to human-like hand proportions (i.e. short hands with a long thumb) enabling the thumb and finger pads to contact. Although this has been traditionally linked to the appearance of stone tool-making, the alternative hypothesis of an earlier origin--related to the freeing of the hands thanks to the advent of terrestrial bipedalism--is also possible given the human-like intrinsic hand proportion found in australopiths.

METHODOLOGY/PRINCIPAL FINDINGS
We perform morphofunctional and morphometric (bivariate and multivariate) analyses of most available hominin pollical distal phalanges, including Orrorin, Australopithecus, Paranthropous and fossil Homo, in order to investigate their morphological affinities. Our results indicate that the thumb morphology of the early biped Orrorin is more human-like than that of australopiths, in spite of its ancient chronology (ca. 6 Ma). Moreover, Orrorin already displays typical human-like features related to precision grasping.

CONCLUSIONS
These results reinforce previous hypotheses relating the origin of refined manipulation of natural objects--not stone tool-making--with the relaxation of locomotor selection pressures on the forelimbs. This suggests that human hand length proportions are largely plesiomorphic, in the sense that they more closely resemble the relatively short-handed Miocene apes than the elongated hand pattern of extant hominoids. With the advent of terrestrial bipedalism, these hand proportions may have been co-opted by early hominins for enhanced manipulative capabilities that, in turn, would have been later co-opted for stone tool-making in the genus Homo, more encephalized than the previous australopiths. This hypothesis remains may be further tested by the finding of more complete hands of unequivocally biped early hominins.

precision grasping
hominin
advent
bipedalism
pollical distal phalanx


Fossilization transforms vertebrate hard tissue proteins into N-heterocyclic polymers

Abstract: Vertebrate hard tissues consist of mineral crystallites within a proteinaceous scaffold that normally degrades post-mortem. Here we show, however, that decalcification of Mesozoic hard tissues preserved in oxidative settings releases brownish stained extracellular matrix, cells, blood vessels, and nerve projections. Raman Microspectroscopy shows that these fossil soft tissues are a product of diagenetic transformation to Advanced Glycoxidation and Lipoxidation End Products, a class of N-heterocyclic polymers generated via oxidative crosslinking of proteinaceous scaffolds. Hard tissues in reducing environments, in contrast, lack soft tissue preservation. Comparison of fossil soft tissues with modern and experimentally matured samples reveals how proteinaceous tissues undergo diagenesis and explains biases in their preservation in the rock record. This provides a target, focused on oxidative depositional environments, for finding cellular-to-subcellular soft tissue morphology in fossils and validates its use in phylogenetic and other evolutionary studies.

tissue
n-heterocyclic polymer
product
soft tissue preservation
diagenesis


Dermal Armor Histology of Saltasaurus loricatus, an Upper Cretaceous Sauropod Dinosaur from Northwest Argentina

Abstract: The first unambiguous evidence of the presence of osteoderms in sauropod dinosaurs came from the discovery of Saltasaurus loricatus, a titanosaur from the Upper Cretaceous of Argentina. The dermal armor of Saltasaurus is composed of bony plates and small dermal ossicles. Here, we analyze the bone microstructure of these elements and provide information regarding its origin and development. The bony plates are composed almost entirely of reconstructed cancellous bone. Remains of primary bone consist of coarse bundles of mineralized collagenous fibers towards the external surface. Also, woven fibered bone tissue appears in the basal and lateral regions. Dermal ossicles lack secondary remodeling, and their matrix is formed by three orthogonal systems of collagenous fiber bundles. Growth lines are present in both bony plates and ossicles. Bone histology reveals that osteoderms mainly originated through direct mineralization (metaplasia) of the dermis, although other mechanisms are also involved (at least in the origin of dermal plates). The common features of development and integumental location of the osteoderms of Saltasaurus and other non-related vertebrates (e.g., lepidosaurs, crocodylomorphs) are linked to the intrinsic skeletogenic properties of the dermis.

saltasaurus loricatus
sauropod dinosaur
osteoderm
titanosaur
secondary remodeling


The diplacanthid fishes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian of Scotland

Abstract: The Diplacanthiformes are a clade of acanthodian fishes which were widespread during the Middle and early Late Devonian. They are best represented in the Middle Devonian, by articulated fossils, fin spines, and abundant scales, the latter particularly from northern Europe. Three species of diplacanthid diplacanthiforms, Diplacanthus crassisimus, Diplacanthus tenuistriatus, and Rhadinacanthus longispinus, are found in Middle Devonian (Eifelian-Givetian) assemblages of articulated fish in northern Scotland. Our detailed study of the dermal structures and endoskeletal shoulder girdles in these fish supports the validity of Rhadinacanthus as a separate genus from Diplacanthus, with the two being differentiated by spine morphology, scale morphology, and histology, and shape and form of the pectoral girdle. In Orkney and Caithness, D. crassisimus first occurs in the Thursius macrolepidotus vertebrate biozone and disappears by the Millerosteus minor + Thursius pholidotus vertebrate biozone. Diplacanthus tenuistriatus and R. longispinus range from the Coccosteus cuspidatus biozone to the end of the Millerosteus minor + Thursius pholidotus biozone. Through comparing the results of our detailed work on the morphology and histology of fin spines and scales from the articulated fish with diplacanthid taxa based on isolated scales and fin spines from the Baltic region, Belarus, and Severnaya Zemlya, we recognize many of the latter taxa from contemporary deposits as junior synonyms of the Scottish species. Phylogenetic analysis of selected gnathostome genera shows the diplacanthiforms Diplacanthus, Rhadinacanthus, Uraniacanthus, and Culmacanthus form a well-supported clade within a larger clade comprising all acanthodian taxa plus a monophyletic Chondrichthyes.

diplacanthiformes
middle devonian
phylogenetic analysis
chondrichthyan


Life habits and evolutionary biology of new two-winged long-proboscid scorpionflies from mid-Cretaceous Myanmar amber

Abstract: Long-proboscid scorpionflies are enigmatic, mid-Mesozoic insects associated with gymnosperm pollination. One major lineage, Aneuretopsychina, consists of four families plus two haustellate clades, Diptera and Siphonaptera. One clade, Pseudopolycentropodidae, from mid-Cretaceous Myanmar amber, contains Parapolycentropus. Here, we newly establish Dualula, assigned to Dualulidae, constituting the fifth lineage. Parapolycentropus and Dualula lineages are small, two-winged, with unique siphonate mouthparts for imbibing pollination drops. A cibarial pump provides siphonal food inflow; in Dualula, the siphon base surrounds a hypopharynx housing a small, valved pump constricted to a narrow salivary duct supplying outgoing enzymes for food fluidization. Indirect evidence links long-proboscid mouthpart structure with contemporaneous tubulate ovulate organs. Direct evidence of gymnospermous Cycadopites pollen is associated with one Parapolycentropus specimen. Parapolycentropus and Dualula exhibit hind-wing reduction that would precede haltere formation, likely caused by Ultrabithorax. Distinctive, male Aneuretopsychina genitalia are evident from specimens in copulo, supplemented by mixed-sex individuals of likely male mating swarms.

long-proboscid scorpionflie
mid-cretaceous myanmar amber
pseudopolycentropodidae
dualulidae


Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates

Abstract: The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates.

mesozoic marine reptile
evolutionary rate
emergence
ichthyosauromorpha
early triassic


Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution

Abstract: Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs—a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet.

ecology
herbivorous ecomorphology
cranial diversity
evolutionary process


Cranial Anatomy of Morturneria seymourensis from Antarctica, and the Evolution of Filter Feeding in Plesiosaurs of the Austral Late Cretaceous

Abstract:
ABSTRACT
 This paper redescribes the holotype skull of the aristonectine elasmosaur Morturneria seymourensis from the upper Maastrichtian of Seymour Island, Antarctica. This description supports the validity of the genus Morturneria, distinct from the genus Aristonectes from Chile and Argentina. The paroccipital process of Morturneria is plesiomorphic, similar to Alexandronectes and unlike the autapomorphic occiput of Aristonectes. The palate of Morturneria is autapomorphic in possessing a strongly developed midline keel. The cranium of Morturneria is about 60% complete and preserves the anterior skull roof and palate; both regions were previously unknown in any aristonectine. The combination of the Morturneria holotype and recent research on other aristonectines allows the first confident cranial reconstruction of an aristonectine elasmosaur. The cranial anatomy of both Morturneria and its close relatives is derived relative to all other plesiosaurs, possessing a novel suite of dental and oral cavity adaptions. The suspensorium extends far behind the occipital condyle, and the jaw is long and hoop-like; together these features allowed a large gape and oral cavity volume. The palate of Morturneria is strongly keeled, forming arched lateral oral chambers that further increased oral cavity volume. The dentition of Morturneria is similar to that of Aristonectes, and all share autapomorphic interlocking combs of needle-like teeth that occluded outside the mouth and did not meet tip to tip. The upper and lower dentition formed an oral battery that may have functioned like a sieve in straining food particles from substrate ejected from the oral cavity. We theorize that this highly derived suite of adaptations is convergent with extant gray whales and archaic mysticetes and hypothesize that it functioned similarly in sieve feeding following suction. This is the first identification of whale-like filter feeding in any marine reptile, a condition once claimed to be anatomically impossible.

antarctica
plesiosaur
oral cavity
cranial anatomy


Evaluating Devonian bioregionalization: quantifying biogeographic areas

Abstract: Abstract. The work of Arthur J. Boucot (vale, 1924–2017) is foundational to Devonian biogeography. Cited more than 1000 times and mentioned in excess of 105,000 times, his classification of the Old World, Eastern Americas, and Malvinokaffric realms has become the framework for Devonian biogeographic and faunal studies. This study is the first to test and quantify the biotic area classification using the distributional data of trilobite, brachiopod, and fish taxa across the Lower, Middle, and Late Devonian. The biotic similarity analysis of 676 genera (ca. 30,000 occurrences) of late Silurian (Ludlow–Pridoli) and Devonian taxa represents the largest quantification of distributional data undertaken in Devonian biogeography. The temporal area approach (TAAp), applied here for the first time, failed to recover in the area phenogram many of the realms and regions used by Devonian biogeographers, excepting the Malvinokaffric realm, across the entirety of the Devonian. The Old World and Western Gondwana realms are found to be artificial and in need of revision. Without natural areas, bioregionalizations (area classifications) become unstable and unusable, resulting in authors creating further artificial regions and provinces. This study offers a better solution, namely, to identify artificial areas in existing area classifications using TAAp and biotic similarity analysis and revise them. Area classifications are modeled on taxonomic process (Wilson and Brown 1953; Starrett 1958) and the movement toward revision is necessary to break the cycle of reinvention of realms and regions within bioregionalization.

bioregionalization
devonian biogeography
malvinokaffric realm


Taxonomic Implications of the Residual Colour Patterns of Ampullinid Gastropods and Their Contribution to the Discrimination from Naticids

Abstract: Caze, B., Merle, D., Le Meur, M., Pacaud, J.-M., Ledon, D., and Saint Martin, J.-P. 2011. Taxonomic implications of the residual colour patterns of ampullinid gastropods and their contribution to the discrimination from naticids. Acta Palaeontologica Polonica 56 (2): 329–347. The diversity of residual colour patterns is revealed for the first time in the European fossil Ampullinidae. The colour patterns were studied under Ultraviolet (UV) light in approximately 3100 specimens belonging to 83 species, 12 genera (Ampullina, Globularia, Crommium, Amaurellina, Pachycrommium, Amauropsina, Ampullonatica, Eocernina, Ampullinopsis, Vanikoropsis, Pictavia, and Ampullospira) and three subgenera (Globularia, Deshayesia, and Cernina within the genus Globularia). Forty-six Cainozoic species revealed residual colour patterns and 29 of them, belonging to six genera (Ampullina, Globularia, Crommium, Amaurellina, Pachycrommium, Amauropsina), are described herein as examples representing the entire diversity of the encountered colour patterns. These patterns are most diverse during the Middle Eocene coincident with the period of highest taxonomic diversity of the Ampullinidae. Four basic classes, regarded as containing possible homologous colour patterns in terms of pigments incorporation modalities, are proposed. Class I, a fluorescent wide diffuse area or spiral stripes, occurs in most of the species, while the three others are more peculiar. Class II, fluorescent axial zigzagging stripes, Class III, fluorescent axial to slightly opisthocline stripes or segments, and Class IV, fluorescent patches forming axial segments by coalescence, allow an easy distinction between the genera Globularia, Pachycrommium, and three peculiar species of Ampullina. The bauplan of the colour patterns revealed in Globularia is very similar to that of the single extant species, Globularia (Cernina) fluctuata. This supports the view of previous authors who classified them in the same genus. Furthermore, at the family level, the peculiar residual patterns belonging to classes II, III, and IV have not been observed in naticid gastropods. Thus our results for the Cainozoic fossil record are consistent with the conclusions based on anatomy and feeding habits, namely that ampullinid gastropods, regarded for a long time as belonging to the family Naticidae, constitute a family apart.

colour pattern
ampullinid gastropod
contribution
naticid


The evolution of a single toe in horses: causes, consequences, and the way forward.

Abstract: Horses are a classic example of macroevolution in three major traits-large body size, tall-crowned teeth (hypsodonty), and a single toe (monodactyly)-but how and why monodactyly evolved is still poorly understood. Existing hypotheses usually connect digit reduction in horses to the spread and eventual dominance of open-habitat grasslands, which took over from forests during the Cenozoic; digit reduction has been argued to be an adaptation for speed, locomotor economy, stability, and/or increased body size. In this review, we assess the evidence for these (not necessarily mutually exclusive) hypotheses from a variety of related fields, including paleoecology, phylogenetic comparative methods, and biomechanics. Convergent evolution of digit reduction, including in litopterns and artiodactyls, is also considered. We find it unlikely that a single evolutionary driver was responsible for the evolution of monodactyly, because changes in body size, foot posture, habitat, and substrate are frequently found to influence one another (and to connect to broader potential drivers, such as changing climate). We conclude with suggestions for future research to help untangle the complex dynamics of this remarkable morphological change in extinct horses. A path forward should combine regional paleoecology studies, quantitative biomechanical work, and make use of convergence and modern analogs to estimate the relative contributions of potential evolutionary drivers for digit reduction.

single toe
horse
macroevolution
digit reduction


Mating moths (Tineidae, Ditrysia, Lepidoptera) preserved as frozen behavior inclusion in Baltic Amber (Eocene)

Abstract: The investigation of amber inclusions provides a unique insight into the biology of animals living millions of years ago, due to their exceptional preservation in nearly lifelike conditions. This is not only true for morphological aspects, aspects of behavior can also be deduced from these fossils. Here, Microlepidoptera are reported from Eocene Baltic amber most likely as a first occurrence of fossil Lepidoptera found in copula. The moths belong to Tineidae (tineid moths includes clothes moths) and are described as a new species and new genus, Forcepsites michalskii. The clasping organ of the male is quite uncommon for moths from Baltic amber, with a ventral and dorsal part, each ending in two parallel, thorn-like protuberances, and seemingly not being formed by the valvae. The co-occurrence of male and female, most likely in copula, allowed studying their sexual dimorphism directly, and there is evidence that the habitat of this species is the site of resin production in the Baltic amber forest. From sexual dimorphism of the antennae and eye morphology it is interpreted that the female was the calling sex for mating in this species. Thilo C. Fischer. Förderverein der Bayerischen Staatssammlung für Paläontologie und Historische Geologie München Richard-Wagner-Straße 10, D-80333 München, Germany. thilo.fischer@tum.de Marie K. Hörnig. University of Greifswald, Zoological Institute and Museum, Cytology and Evolutionary Biology, Soldmannstr. 23, D-17489 Greifswald, Germany. marie.hoernig@palaeo-evo-devo.info


Palaeo-trajectories of forest savannization in the southern Congo

Abstract: Tropical savannah and forest are thought to represent alternative stable states in ecosystem structure in some climates. The implication is that biomes are maintained by positive feedbacks, e.g. with fire, and that historical distributions could play a role in determining modern ones. In this context, climate alone does not govern transitions between biomes, and understanding the causes and pathways of such transitions becomes crucial. Here, we use a multi-proxy analysis of a 2000-year core to evaluate modes of transition in vegetation structure and fire regimes. We demonstrate a first transition ca 1540 BP, when a cyclic fire regime entered a forested landscape, eventually resulting, by ca 1060 BP, in a transition to a more open savannah-like or mosaicked structure. This pattern may parallel currently accelerating fire regimes in tropical forests suggesting that fires can savannize forests, but perhaps more slowly than feared. Finally, ca 540 BP, a drought combined with anthropogenic influences resulted in a conclusive transition to savannah, probably resembling the modern landscape in the region. We show here that fire interacted with drought to transition forest to savannah, suggesting that disturbance by fire can be a major driver of biome change.


A genetic record of population isolation in pocket gophers during Holocene climatic change.

Abstract: A long-standing question in Quaternary paleontology is whether climate-induced, population-level phenotypic change is a result of large-scale migration or evolution in isolation. To directly measure genetic variation through time, ancient DNA and morphologic variation was measured over 2,400 years in a Holocene sequence of pocket gophers (Thomomys talpoides) from Lamar Cave, Yellowstone National Park, Wyoming. Ancient specimens and modern samples collected near Lamar Cave share mitochondrial cytochrome b sequences that are absent from adjacent localities, suggesting that the population was isolated for the entire period. In contrast, diastemal length, a morphologic character correlated with body size and nutritional level, changed predictably in response to climatic change. Our results demonstrate that small mammal populations can experience the long-term isolation assumed by many theoretical models of microevolutionary change.

pocket gopher
climatic change
lamar cave


Insights into the timing, intensity and natural setting of Neanderthal occupation from the geoarchaeological study of combustion structures: A micromorphological and biomarker investigation of El Salt, unit Xb, Alcoy, Spain

Abstract: Middle Paleolithic lithic and faunal assemblages throughout Eurasia reflect short-term Neanderthal occupations, which suggest high group mobility. However, the timing of these short-term occupations, a key factor to assess group mobility and territorial range, remains unresolved. Anthropogenic combustion structures are prominent in the Middle Paleolithic record and conceal information on the timing and intensity and natural setting of their associated human occupations. This paper examines a concentration of eleven combustion structures from unit Xb of El Salt, a Middle Paleolithic site in Spain through a geoarchaeological approach, in search of temporal, human impact and paleoenvironmental indicators to assess the timing, intensity and natural setting of the associated human occupations. The study was conducted using micromorphology, lipid biomarker analysis and compound specific isotope analysis. Results show in situ hearths built on different diachronic topsoils rich in herbivore excrements and angiosperm plant residues with rare anthropogenic remains. These data are suggestive of low impact, short-term human occupations separated by relatively long periods of time, with possible indicators of seasonality. Results also show an absence of conifer biomarkers in the mentioned topsoils and presence of conifer charcoal among the fuel residues (ash), indicating that fire wood was brought to the site from elsewhere. A microscopic and molecular approach in the study of combustion structures allows us to narrow down the timescale of archaeological analysis and contributes valuable information towards an understanding of Neanderthal group mobility and settlement patterns.

neanderthal occupation
combustion structure
spain
high group mobility
long period


Dating primate divergences through an integrated analysis of palaeontological and molecular data.

Abstract: Estimation of divergence times is usually done using either the fossil record or sequence data from modern species. We provide an integrated analysis of palaeontological and molecular data to give estimates of primate divergence times that utilize both sources of information. The number of preserved primate species discovered in the fossil record, along with their geological age distribution, is combined with the number of extant primate species to provide initial estimates of the primate and anthropoid divergence times. This is done by using a stochastic forwards-modeling approach where speciation and fossil preservation and discovery are simulated forward in time. We use the posterior distribution from the fossil analysis as a prior distribution on node ages in a molecular analysis. Sequence data from two genomic regions (CFTR on human chromosome 7 and the CYP7A1 region on chromosome 8) from 15 primate species are used with the birth-death model implemented in mcmctree in PAML to infer the posterior distribution of the ages of 14 nodes in the primate tree. We find that these age estimates are older than previously reported dates for all but one of these nodes. To perform the inference, a new approximate Bayesian computation (ABC) algorithm is introduced, where the structure of the model can be exploited in an ABC-within-Gibbs algorithm to provide a more efficient analysis.

molecular data
fossil preservation
posterior distribution
molecular clock analysis


Amphilagus plicadentis (Lagomorpha, Mammalia) from the Tagay locality (Olkhon Island, Baikal region, Eastern Siberia)

Abstract: New excavations in the Tagay locality have revealed the presence of Amphilagus plicadentis Erbajeva, 2013, which belongs to the palaeolagine Lagomorpha rather than leporids, previously referred to Procaprolagus sp. (Logachev et al., 1964) . Herein, we report a comprehensive morphological description of this species and compare it with the other known species of the genus Amphilagus. The Tagay lagomorph is conspecific with the Early Miocene species Amphilagus plicadentis found at locality Unkheltseg (UNCH-A) (biozone D; Early Miocene) in the Valley of Lakes, Central Mongolia. The Tagay specimens suggest a more advanced evolutionary stage of A. plicadentis and an age around Early/Middle Miocene transition.

lagomorpha
palaeolagidae
small mammal tooth
fossil collection
turtle


Human intestinal parasites in the past: new findings and a review.

Abstract: Almost all known human specific parasites have been found in ancient feces. A review of the paleoparasitological helminth and intestinal protozoa findings available in the literature is presented. We also report the new paleoparasitologic findings from the examination performed in samples collected in New and Old World archaeological sites. New finds of ancylostomid, Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Trichostrongylus spp., Diphyllobothrium latum, Hymenolepis nana and Acantocephalan eggs are reported. According to the findings, it is probable that A. lumbricoides was originally a human parasite. Human ancylostomids, A. lumbricoides and T. trichiura, found in the New World in pre-Columbian times, have not been introduced into the Americas by land via Beringia. These parasites could not supported the cold climate of the region. Nomadic prehistoric humans that have crossed the Bering Land Bridge from Asia to the Americas in the last glaciation, probably during generations, would have lost these parasites, which life cycles need warm temperatures in the soil to be transmitted from host to host. Alternative routes are discussed for human parasite introduction into the Americas.


‘Nedoceratops’: An Example of a Transitional Morphology

Abstract: Background The holotype and only specimen of the chasmosaurine ceratopsid dinosaur ‘Nedoceratops hatcheri’ has been the source of considerable taxonomic debate since its initial description. At times it has been referred to its own genus while at others it has been considered synonymous with the contemporaneous chasmosaurine Triceratops. Most recently, the debate has focused on whether the specimen represents an intermediate ontogenetic stage between typical young adult Triceratops and the proposed mature morphology, which was previously considered to represent a distinct genus, ‘Torosaurus’. Methodology/Principal Findings The only specimen of ‘Nedoceratops hatcheri’ was examined and the proposed diagnostic features of this taxon were compared with other chasmosaurine ceratopsids. Every suggested autapomorphy of ‘Nedoceratops’ is found in specimens of Triceratops. In this study, Triceratops includes the adult ‘Torosaurus’ morphology. The small parietal fenestra and elongate squamosals of Nedoceratops are consistent with a transition from a short, solid parietal-squamosal frill to an expanded, fenestrated condition. Objections to this hypothesis regarding the number of epiossifications of the frill and alternations of bone surface texture were explored through a combination of comparative osteology and osteohistology. The synonymy of the three taxa was further supported by these investigations. Conclusions/Significance The Triceratops, ‘Torosaurus’, and ‘Nedoceratops’ morphologies represent ontogenetic variation within a single genus of chasmosaurine: Triceratops. This study highlights how interpretations of dinosaur paleobiology, biodiversity, and systematics may be affected by ascribing ontogenetic and other intraspecific variation a taxonomic significance.

nedoceratop
nedoceratops hatcheri
ontogenetic stage
torosaurus
single genus


Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic

Abstract: The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 ± 0.5 million years of massive volcanism in East Greenland, are coeval. The relative age of Danish Ash-17 thus places the PETM onset after the beginning of massive flood basalt volcanism at 56.1 ± 0.4 million years ago but within error of the estimated continental breakup time of 55.5 ± 0.3 million years ago, marked by the eruption of mid-ocean ridge basalt–like flows. These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe.

northeast atlantic
eruption
paleocene-eocene thermal maximum
ash layer
radiometric dating