Tooth morphology elucidates shark evolution across the end-Cretaceous mass extinction

Abstract: Sharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their prolific fossil record is represented mainly by isolated shed teeth, which provide the basis for reconstructing deep time diversity changes affecting different selachimorph clades. By contrast, corresponding shifts in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine tooth morphologies in multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction—this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades across the Cretaceous–Paleogene interval. Nevertheless, selective extinctions did impact apex predator species characterized by triangular blade-like teeth. This is particularly evident among lamniforms, which included the dominant Cretaceous anacoracids. Conversely, other groups, such as carcharhiniforms and orectolobiforms, experienced disparity modifications, while heterodontiforms, hexanchiforms, squaliforms, squatiniforms, and †synechodontiforms were not overtly affected. Finally, while some lamniform lineages disappeared, others underwent postextinction disparity increases, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. Notably, this increase coincides with the early Paleogene radiation of teleosts as a possible prey source, and the geographic relocation of disparity sampling “hotspots,” perhaps indicating a regionally disjunct extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction and highlights an event that influenced the evolution of modern sharks.

shark
end-cretaceous mass extinction
tooth morphology


Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

Abstract: Lipid biomarker assemblages preserved within the bitumen and kerogen phases of sedimentary rocks from the ca. 780–729 Ma Chuar and Visingsö Groups facilitate paleoenvironmental reconstructions and reveal fundamental aspects of emerging mid‐Neoproterozoic marine communities. The Chuar and Visingsö Groups were deposited offshore of two distinct paleocontinents (Laurentia and Baltica, respectively) during the Tonian Period, and the rock samples used had not undergone excessive metamorphism. The major polycyclic alkane biomarkers detected in the rock bitumens and kerogen hydropyrolysates consist of tricyclic terpanes, hopanes, methylhopanes, and steranes. Major features of the biomarker assemblages include detectable and significant contribution from eukaryotes, encompassing the first robust occurrences of kerogen‐bound regular steranes from Tonian rocks, including 21‐norcholestane, 27‐norcholestane, cholestane, ergostane, and cryostane, along with a novel unidentified C30 sterane series from our least thermally mature Chuar Group samples. Appreciable values for the sterane/hopane (S/H) ratio are found for both the free and kerogen‐bound biomarker pools for both the Chuar Group rocks (S/H between 0.09 and 1.26) and the Visingsö Group samples (S/H between 0.03 and 0.37). The more organic‐rich rock samples generally yield higher S/H ratios than for organic‐lean substrates, which suggests a marine nutrient control on eukaryotic abundance relative to bacteria. A C27 sterane (cholestane) predominance among total C26–C30 steranes is a common feature found for all samples investigated, with lower amounts of C28 steranes (ergostane and crysotane) also present. No traces of known ancient C30 sterane compounds; including 24‐isopropylcholestanes, 24‐n‐propylcholestanes, or 26‐methylstigmastanes, are detectable in any of these pre‐Sturtian rocks. These biomarker characteristics support the view that the Tonian Period was a key interval in the history of life on our planet since it marked the transition from a bacterially dominated marine biosphere to an ocean system which became progressively enriched with eukaryotes. The eukaryotic source organisms likely encompassed photosynthetic primary producers, marking a rise in red algae, and consumers in a revamped trophic structure predating the Sturtian glaciation.

sedimentary rock
eukaryote
mid‐neoproterozoic marine community
tonian period


Nonuniform response of the major surface currents in the Nordic Seas to insolation forcing: Implications for the Holocene climate variability

Abstract: [1] High-resolution sediment cores from the Voring Plateau, the North Iceland shelf, and the East Greenland shelf have been studied to investigate the stability of major surface currents in the Nordic Seas during the Holocene. Results from diatom assemblages and reconstructed sea-surface temperatures (SSTs) indicate a division of the Holocene into three periods: the Holocene Climate Optimum (9500–6500 calendar (cal) years BP), the Holocene Transition Period (6500–3000 cal years BP) and the Cool Late Holocene Period (3000–0 cal years BP). The overall climate development is in step with the decreasing insolation on the Northern Hemisphere, but regional differences occur regarding both timing and magnitude of SST changes. Sites under the direct influence of the Norwegian Atlantic Current and the Irminger Current indicate SST cooling of 4–5°C from early Holocene to present, compared to 2°C recorded under the East Greenland Current. Superimposed on the general Holocene cooling trend, there is a high-frequency SST variability, which is in the order of 1–1.5°C for the Voring Plateau and the East Greenland shelf and 2.5–3°C on the North Iceland shelf.

major surface current
nordic seas
insolation


Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history

Abstract: The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem–gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates.


Late Cretaceous (Maastrichtian) crocodyliforms from north-eastern Iberia: a first attempt to explain the crocodyliform diversity based on tooth qualitative traits

Abstract: During recent years, knowledge about crocodyliform diversity of the uppermost Cretaceous from Europe has been substantially improved. Palaeontological efforts have also been focused on microvertebrate diversity and its palaeoecological implications. Isolated crocodylomorph teeth are, by far, one of the most frequently recovered elements in microvertebrate samples. In the present paper, morphological features of crocodylomorph teeth collected throughout the complete Maastrichtian series of the southern Pyrenean basin (north-eastern Spain), together with several mandibular remains, are described and analysed. Teeth were grouped in morphotypes and their taxonomic significance is discussed. The results highlight a diverse crocodylomorph assemblage in this area throughout the Maastrichtian. In addition, feeding habits and environmental preferences are inferred for the identified taxa according to dental features, occurrences and taphonomy.

maastrichtian
crocodyliform diversity
tooth


A new eomysticetid from the Oligocene Kokoamu Greensand of New Zealand and a review of the Eomysticetidae (Mammalia, Cetacea)

Abstract: Eomysticetids represent a worldwide, short-lived radiation of archaic baleen-bearing mysticetes that elucidate morphofunctional shifts and ontogenetic change amongst early Neoceti. Fossils of eomysticetids are now recorded from Oligocene marine rocks along the margins of the North Pacific (Japan), North Atlantic (South Carolina), and the Southern Ocean (New Zealand). The assemblage from New Zealand is diverse, with five species in three genera present during the Duntroonian stage (Chattian, 27.3–25.2 Ma). A new genus and species of eomysticetid from the lower Kokoamu Greensand of New Zealand, Matapa waihao gen. et sp. nov., increases the known diversity of Southern Hemisphere eomysticetids. Matapa uniquely exhibits a rounded margin of the occipital shield, and shares a mosaic of features seen in Northern Hemisphere eomysticetids such as a large squamosal prominence, an inflated and posteriorly rounded paroccipital process, and a double-faced posterior bullar facet with longitudinal ridges. The holotype specimen of Matapa waihao is ontogenetically immature, but ontogenetically static tympanoperiotic characters that diagnose this new species are shared by referred adult specimens. Matapa is uppermost Whaingaroan (28.1–27.3 Ma) in age, the oldest eomysticetid from New Zealand. Fossils of Matapa are recovered from both the modern west and east coast of New Zealand which, during the Oligocene, were on the margin of the Southern Ocean. Inclusion of Matapa within an earlier published cladistic analysis recovers Matapa as the earliest diverging member of the New Zealand eomysticetid clade, and confirms eomysticetid monophyly. The taxonomy, morphology and geochronological age of all known eomysticetids are reviewed. http://zoobank.org/urn:lsid:zoobank.org:pub:EE1CB5CC-618B-4ABA-9D97-5B9DEDD3470E


Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events

Abstract: Periods of globally distributed extreme oxygen depletion, so-called oceanic anoxic events (OAEs), have been recognized in the Mesozoic geological record and appear to be characteristic of episodes of extreme warmth. Here we explore the application of iodine/calcium ratios (I/Ca) in marine carbonate as a new geochemical proxy to constrain seawater redox change, and provide additional insights into the response of ocean chemistry to ancient climatic warming. Iodine has long been known as a redox-sensitive and biophilic element, mainly present as iodate and iodide in seawater, iodate converting to iodide under anoxic conditions. Laboratory experiments growing calcite crystals from solutions spiked with iodate show that this is the ionic species incorporated into the carbonate structure, likely substituting for the CO 3 2− ion. A fall in the I/Ca ratio measured in carbonates formed in shallow water by marine calcifiers during the early Toarcian and Cenomanian-Turonian OAEs is interpreted both as a response to a decrease in the iodate/iodide ratio in ocean waters and the drawdown of the global iodine inventory under conditions of accelerated organic-matter burial. The results suggest that I/Ca ratios in carbonates may be used to monitor seawater oxidation levels throughout Earth history.

calcium ratio
marine carbonate
oceanic anoxic event
iodine


Tarsals of Sespedectinae (?Lipotyphla) from the Middle Eocene of Southern California, and the Affinities of Eocene ‘Erinaceomorphs’

Abstract: ABSTRACT Postcranial morphology of Paleogene lipotyphlans (Mammalia: Laurasiatheria) is poorly known relative to dental morphology. When these elements can be referred, they have proven to be a rich source of data for phylogenetic and ecological inferences. In particular, tarsal morphology has challenged hypothesized relationships of several taxa. We refer isolated tarsals from several early and late Uintan (middle Eocene) localities in the San Diego area to three genera of sespedectine erinaceomorph lipotyphlan, Crypholestes, Proterixoides, and Sespedectes, based on patterns of size, morphology, and abundance. Astragali and calcanei are confidently referred to all three genera, whereas naviculars are more tentatively referred to Proterixoides and Sespedectes, and cuboids to Sespedectes. Tarsals of the three genera are morphologically nearly uniform, supporting their hypothesized close relationship. The most significant difference is a relatively longer calcaneal tuber in Proterixoides. The tarsal morphology of Sespedectinae is most consistent with an unspecialized terrestrial locomotor repertoire. Some distinctive features of the sespedectine tarsus, such as ‘S’-shaped ectal facets and a prominent tuber tibialis on the navicular, are potentially indicative of lipotyphlan affinities. However, there is no support for an exclusive relationship to extant erinaceids (or any other lipotyphlan family) or to other Paleogene erinaceomorphs (Macrocranion, Zionodon). Phylogenetic analysis confirms that sespedectines are most likely relatively basal lipotyphlans and that Erinaceomorpha is not a natural group.


HIGHLY DIVERSIFIED LATE CRETACEOUS FISH ASSEMBLAGE REVEALED BY OTOLITHS (RIPLEY FORMATION AND OWL CREEK FORMATION, NORTHEAST MISSISSIPPI, USA)

Abstract: Bulk sampling and extensive, systematic surface collecting of the Coon Creek Member of the Ripley Formation (early Maastrichtian) at the Blue Springs locality and primarily bulk sampling of the Owl Creek Formation (late Maastrichtian) at the Owl Creek type locality, both in northeast Mississippi, USA, have produced the largest and most highly diversified actinopterygian otolith (ear stone) assemblage described from the Mesozoic of North America. The 3,802 otoliths represent 30 taxa of bony fishes representing at least 22 families. In addition, there were two different morphological types of lapilli, which were not identifiable to species level. The large number of otolith specimens as well as the preservation contributed to the recognition of 4 new genera and 13 new species. The otoliths supplied information regarding the presence of bony fishes not available solely on the basis of osteological remains, and the Late Cretaceous bony fish assemblage at the sites would be underestimated and misinterpreted without an examination of the otoliths. The otoliths also contributed evidence on the evolutionary development of teleosts in North America, especially the diversity of the beryciforms in the Late Cretaceous, and provided indications of the paleoecology during the Maastrichtian. The Ripley Formation (Coon Creek Member) otolith assemblage, which accounted for 3,718 of the specimens, is compared to other Cretaceous otolith assemblages in North America that meet certain criteria (employed bulk-sampling techniques, had well-preserved specimens, and possessed a substantial number of specimens and taxa for analysis). These sites were in Alabama, Maryland, Mississippi (two localities), New Jersey, North Carolina, North Dakota, Tennessee, and Texas. Systematic surface collecting at the Blue Springs locality proved to be very beneficial in supplying otoliths specimens from maturer fishes. Many of the surface-collected otoliths represent older adult fishes that assist with the identification of several forms with greater specificity.

otolith
ripley formation
owl creek formation
north america
cretaceous otolith assemblage


Gastropods from the Jurassic neptunian sills of Rocca Busambra (north‐western Sicily, Italy): Patellogastropoda, Pleurotomarioidea, Scissurelloidea, Fissurelloidea and Eucycloidea

Abstract: The gastropods from Jurassic neptunian sills of Rocca Busambra (Sicily, Italy) represent an extraordinary assemblage for richness and extremely high degree of novelty, consisting of about 250 species (two‐thirds of which are new) of 20 superfamilies. A total of 38 species and 18 genera of Lottioidea, Pleurotomarioidea, Scissurelloidea, Fissurelloidea and Eucycloidea are described. Of these, 30 species and 9 genera are new, namely Ramusatomaria nuda gen. et sp. nov., Trapanimaria gattoi gen. et sp. nov., Trapanimaria nicolosiensis gen. et sp. nov., Trapanimaria? pallinii gen. et sp. nov., Trochotomaria conoidea sp. nov., Trochotomaria polymorpha sp. nov., Laevitomaria babalusciae sp. nov., Pyrgotrochus vorosi sp. nov., Auritoma lenticula gen. et sp. nov., Busambrella fasciata gen. et sp. nov., Emarginula (Emarginula) burgioi sp. nov., Emarginula (Tauschia) acutidens sp. nov., Propeucyclus sicanus gen. et sp. nov., Propeucyclus obesus gen. et sp. nov., Propeucyclus? semireticulatus gen. et sp. nov., Eucyclomphalus? marenostrum sp. nov., Toronyella lineata gen. et sp. nov., Toronyella margaritata gen. et sp. nov., Zarnglaffia polygonalis sp. nov., Zarnglaffia palermitana sp. nov., Ambercyclus cratisculptus sp. nov., Elymicyclus alternatus gen. et sp. nov., Elymicyclus ietumensis gen. et sp. nov., Elymicyclus martae gen. et sp. nov., Elymicyclus garibaldii gen. et sp. nov., Jurassiscala sturanii gen. et sp. nov., Jurassiscala? tenuiretis gen. et sp. nov., Fischeriella sicula sp. nov., Retimusina poseidoni gen. et sp. nov. and Retimusina? tritoni sp. nov. The new scissurelloidean family Auritomidae fam. nov. is erected. A palaeobiogeographical analysis indicates close relationships with coeval faunas from condensed pelagic carbonates of the central region of western Tethys.


A new species of Azendohsaurus (Diapsida: Archosauromorpha) from the Triassic Isalo Group of southwestern Madagascar: cranium and mandible

Abstract: Abstract:  Here, we describe a new species of Azendohsaurus from the Middle–Late Triassic of Madagascar, extending the geographical range of a taxon known otherwise only by a single species from Morocco. Although Azendohsaurus has consistently been regarded as an early dinosaur (based on various advanced dental and gnathic features resembling those characterizing certain dinosaur subgroups), the relatively complete skeletal material, now available from Madagascar, argues strongly against its dinosaurian affinities. Rather, the retention of numerous primitive cranial and postcranial features indicates a surprisingly early divergence of Azendohsaurus within Archosauromorpha and an unusual mosaic of characters in this taxon. Features considered diagnostic of Sauropodomorpha thus are inferred to occur homoplastically in at least one clade of nondinosaurian archosauromorphs, indicating a complex evolution and distribution of features traditionally thought to be derived within archosaurs. Azendohsaurus has teeth resembling those of both early sauropodomorph and ornithischian dinosaurs, yet also possesses numerous inarguable basal archosauromorph cranial and postcranial attributes. This highlights the risk of uncritically referring isolated, Middle–Late Triassic (or even later), ‘leaf‐shaped’ teeth with denticles to the Dinosauria. Similarly, the occurrence of such teeth in an early diverging archosauromorph indicates that specializations for herbivory originated more frequently within this clade than conventionally assumed. For example, Azendohsaurus and numerous basal sauropodomorph dinosaur taxa share an array of convergently acquired features associated with herbivory, including tooth denticles, expanded tooth crowns, a downturned dentary and the articular located at the ventral margin of the mandible. Some of these features (denticles, expanded crowns and the ventrally deflected articular) are even more widespread among archosauromorphs, including aetosaurs, silesaurs and ornithischian dinosaurs. A downturned dentary also occurs in Trilophosaurus, a taxon further marked by unique specializations for herbivory, including transversely lophate, tricuspid teeth. An array of features associated with herbivory also occurs in rhynchosaurs and certain crocodilians (e.g. Simosuchus). This distribution suggests that craniodental features associated with herbivory were much more pervasive across the archosauromorph clade than previously recognized, possibly evolving at least six to eight times independently.


X-ray micro-tomography of Carboniferous stem-Dictyoptera: new insights into early insects

Abstract: Computer reconstructions of Archimylacris eggintoni, a Carboniferous stem-group dictyopteran (‘roachoid’), are presented. A siderite-hosted specimen was scanned using high-resolution X-ray microtomography (µCT), and a ‘virtual fossil’ was created with a resolution of 17.7 µm. This has revealed the morphology in great detail, including adhesive limb structures indicative of climbing and specializations for rapid movement. The antennae are filiform, and the mandibles are comparable to those of certain extant cockroaches, suggesting a similar generalist, saprophagous diet. The reconstruction reveals a high degree of specialization, and provides insights into the mode of life of these common Palaeozoic insects. Further µCT study of insect fossils has the potential to supplement wing venation with new characters, and hence improve fossil insect phylogenies.

insect
x-ray micro-tomography
coal measures fossil
powerful tool


Squatiniformes (Chondrichthyes, Neoselachii) from the Late Cretaceous of southern England and northern France with redescription of the holotype of Squatina cranei Woodward, 1888

Abstract: Abstract:  Bulk sampling of phosphate‐rich horizons within the Late Cretaceous of the Anglo‐Paris Basin yielded numerous teeth of members of the Squatiniformes. Along with isolated tooth remains, two museum specimens comprising partial articulated encoskeletal remains including the holotype of the species Squatina cranei Woodward, 1888a are described, and a new subgenus Cretascyllium is proposed for species of the genus Squatina with high degree of heterodonty and triangular anterior teeth. The species Squatina (Cretascyllium) cranei comb. nov. and Squatina (Cretascyllium) hassei comb. nov. are referred to this subgenus. The genus Parasquatina Herman, 1982 previously erected on a single tooth is valid, and two new species P. justinensis sp. nov. and P. jarvisi sp. nov. are described along with a third taxon Parasquatina sp. An enigmatic tooth referred to ?Neoselachii incertae sedis is also reported. The palaeoecology of these taxa is discussed.


The osteology and phylogenetic position of the loricatan (Archosauria: Pseudosuchia) Heptasuchus clarki, from the ?Mid-Upper Triassic, southeastern Big Horn Mountains, Central Wyoming (USA)

Abstract: Loricatan pseudosuchians (known as “rauisuchians”) typically consist of poorly understood fragmentary remains known worldwide from the Middle Triassic to the end of the Triassic Period. Renewed interest and the discovery of more complete specimens recently revolutionized our understanding of the relationships of archosaurs, the origin of Crocodylomorpha, and the paleobiology of these animals. However, there are still few loricatans known from the Middle to early portion of the Late Triassic and the forms that occur during this time are largely known from southern Pangea or Europe. Heptasuchus clarki was the first formally recognized North American “rauisuchian” and was collected from a poorly sampled and disparately fossiliferous sequence of Triassic strata in North America. Exposed along the trend of the Casper Arch flanking the southeastern Big Horn Mountains, the type locality of Heptasuchus clarki occurs within a sequence of red beds above the Alcova Limestone and Crow Mountain formations within the Chugwater Group. The age of the type locality is poorly constrained to the Middle—early Late Triassic and is likely similar to or just older than that of the Popo Agie Formation assemblage from the western portion of Wyoming. The holotype consists of associated cranial elements found in situ, and the referred specimens consist of crania and postcrania. Thus, about 30% of the osteology of the taxon is preserved. All of the pseudosuchian elements collected at the locality appear to belong to Heptasuchus clarki and the taxon is not a chimera as previously hypothesized. Heptasuchus clarki is distinct from all other archosaurs by the presence of large, posteriorly directed flanges on the parabasisphenoid and a distinct, orbit-overhanging postfrontal. Our phylogenetic hypothesis posits a sister-taxon relationship between Heptasuchus clarki and the Ladinian-aged Batrachotomus kupferzellensis from current-day Germany within Loricata. These two taxa share a number of apomorphies from across the skull and their phylogenetic position further supports ‘rauisuchian’ paraphyly. A minimum of three individuals of Heptasuchus are present at the type locality suggesting that a group of individuals died together, similar to other aggregations of loricatans (e.g., Heptasuchus, Batrachotomus, Decuriasuchus, Postosuchus).

osteology
phylogenetic position
big horn mountains


Cutting the first ‘teeth’: a new approach to functional analysis of conodont elements

Abstract: The morphological disparity of conodont elements rivals the dentition of all other vertebrates, yet relatively little is known about their functional diversity. Nevertheless, conodonts are an invaluable resource for testing the generality of functional principles derived from vertebrate teeth, and for exploring convergence in a range of food-processing structures. In a few derived conodont taxa, occlusal patterns have been used to derive functional models. However, conodont elements commonly and primitively exhibit comparatively simple coniform morphologies, functional analysis of which has not progressed much beyond speculation based on analogy. We have generated high-resolution tomographic data for each morphotype of the coniform conodont Panderodus acostatus. Using virtual cross sections, it has been possible to characterize changes in physical properties associated with individual element morphology. Subtle changes in cross-sectional profile have profound implications for the functional performance of individual elements and the apparatus as a whole. This study has implications beyond the ecology of a single conodont taxon. It provides a basis for reinterpreting coniform conodont taxonomy (which is based heavily on cross-sectional profiles), in terms of functional performance and ecology, shedding new light on the conodont fossil record. This technique can also be applied to more derived conodont morphologies, as well as analogous dentitions in other vertebrates and invertebrates.

functional analysis
conodont element
vertebrate
tooth


The palaeogeography of Sundaland and Wallacea since the Late Jurassic

Abstract: The continental core of Southeast (SE) Asia, Sundaland, was assembled from Gondwana fragments by the Early Mesozoic. Continental blocks rifted from Australia in the Jurassic [South West (SW) Borneo, East Java-West Sulawesi-Sumba], and the Woyla intraoceanic arc of Sumatra, were added to Sundaland in the Cretaceous. These fragments probably included emergent areas and could have carried a terrestrial flora and fauna. Sarawak, the offshore Luconia-Dangerous Grounds areas, and Palawan include Asian continental material. These probably represent a wide accretionary zone at the Asia-Pacific boundary, which was an active continental margin until the mid Cretaceous. Subduction ceased around Sundaland in the Late Cretaceous, and from about 80 Ma most of Sundaland was emergent, physically connected to Asia, but separated by deep oceans from India and Australia. India moved rapidly north during the Late Cretaceous and Early Cenozoic but there is no evidence that it made contact with SE Asia prior to collision with Asia. One or more arc-India collisions during the Eocene may have preceded India-Asia collision. The arcs could have provided dispersal pathways from India into SE Asia before final suturing of the two continents. During the Late Cretaceous and Early Cenozoic there was no significant subduction beneath Sumatra, Java and Borneo. At about 45 Ma Australia began to move north, subduction resumed and there was widespread rifting within Sundaland. During the Paleogene east and north Borneo were largely submerged, the Makassar Straits became a wide marine barrier within Sundaland, and West Sulawesi was separated from Sundaland but included land. By the Early Miocene the proto-South China Sea had been eliminated by subduction leading to emergence of land in central Borneo, Sabah and Palawan. Australia-SE Asia collision began, eliminating the former deep ocean separating the two continents, and forming the region now known as Wallacea. The microplate or terrane concept of slicing fragments from New Guinea followed by multiple collisions in Wallacea is implausible. Neogene subduction drove extension and fragmentation of Wallacea that caused both subsidence of deep marine basins and elevation of land; bathymetry changed very rapidly, especially during the Pliocene, but the detailed palaeogeography of this region remains uncertain.

palaeogeography sundaland wallacea emergence


Leishmaniasis in Ancient Egypt and Upper Nubia

Abstract:
To the Editor: Leishmaniasis is a disease caused by parasites of the genus Leishmania. The infection is transmitted to humans through the bites of female sandflies and manifests mainly in 3 forms: visceral, cutaneous, and mucocutaneous. Visceral leishmaniasis or kala-azar, the often fatal form of the disease, is caused by species of the Leishmania donovani complex. These parasites were responsible for severe recent outbreaks in Sudan and other countries and are thought to originate in East Africa (1–4).

In this report, we describe the successful amplification of L. donovani DNA in ancient Egyptian and Christian Nubian mummies dating back 4,000 years. Besides the first proof for visceral leishmaniasis in paleopathology, we provide evidence that leishmaniasis was present in Nubia in the early Christian period and that the organism also infected ancient Egyptians, probably because of close trading contacts to Nubia, during the Middle Kingdom. We analyzed 91 bone tissue samples from ancient Egyptian mummies and skeletons and 70 bone marrow samples from naturally mummified human remains from Upper Nubia. The Egyptian material derived from the Pre- to Early Dynastic site of Abydos (n = 7; 3500–2800 BC), a Middle Kingdom tomb in Thebes West (42; 2050–1650 BC), and different tomb complexes in Thebes West, which were built and used between the Middle and New Kingdom until the Late Period (42; c. 2050–500 BC). The Nubian samples were taken before the flooding caused by the Aswan Dam from 2 early Christian burial sites at Kulubnarti, between the second and third cataracts of the Nile River in northern Sudan. One site was on an island in the Nile and dated from 550 to 750 AD. The other was on the western bank of the Nile and was in use from c.750 to 1500 AD. All samples were tested for Leishmania spp. DNA and further characterized by direct sequencing.

In 4 of the 91 Egyptian and 9 of the 70 Nubian samples, a 120-bp fragment of a conserved region of the minicircle molecule of kinetoplastid mitochondrial DNA of the parasite (5,6) could be successfully amplified and, with the first primer pair, unambiguously related to L. donovani species after sequencing (Figure). The positive samples from ancient Egypt exclusively originated from the Middle Kingdom tomb, while no molecular evidence for ancient Leishmania DNA was found in the Pre- to Early Dynastic and the New Kingdom to Late Period specimens.

Figure

PCR amplification of a 120-bp fragment of kinetoplastid mitochondrial DNA of Leishmania spp. in Egyptian and Nubian mummies. Lane 1, 50-bp ladder lanes 2–8, mummy samples; lanes 9,10, extraction controls; lane 11, PCR controls. Lane 6 provides ...

In the Middle Kingdom, the Egyptians extended trade relationships and military expeditions to Nubia, the modern Sudan, with particular interest in the gold resources of the country and in obtaining slaves to serve as servants or soldiers in the pharaoh’s army. Today, the Sudan is one of the highly endemic countries for visceral leishmaniasis or kala-azar, which is thought to have originated in East Africa and later spread to the Indian subcontinent and the New World (4). Therefore, the high incidence of Leishmania DNA in the Middle Kingdom samples (4 [9.5%] of 42) and the lack of findings in earlier or later time periods, may indicate that leishmaniasis was introduced into Egypt at this time. Leishmaniasis did not likely become endemic in the Egyptian Nile Valley because the disease is closely linked to its vector, the phlebotomine sandfly, and the distribution of Acacia-Balanites woodland (7). That ancient Egyptians became infected because of close trade contacts and associated travel with Nubia during the Middle Kingdom seems more plausible. The high frequency of Leishmania DNA–positive samples in the Nubian mummies (12.9%) suggests that leishmaniasis was endemic in Nubia during the Early Christian period and, in light of the data on the ancient Egyptian mummies, probably already several thousand years before. Taken together, our results support the theory that Sudan could have been indeed the original focus of visceral leishmaniasis (4).

Our study shows a completely new aspect of molecular paleopathology. The detection of ancient pathogen DNA is not only used to identify a certain disease and gain information on its frequency and evolutionary origin but also to trace back cultural contacts and their role in the transmission and spread of infectious diseases.


Polycotylus latipinnis Cope (Plesiosauria, Polycotylidae), a Nearly Complete Skeleton from the Niobrara Formation (Early Campanian) of Southwestern South Dakota

Abstract:
ABSTRACT
 A nearly complete skeleton of Polycotylus latipinnis (SDSM 23020) from the upper Niobrara Formation (early Campanian) of South Dakota (U.S.A) greatly improves information for this formerly poorly known taxon. Specimens SDSM 23020 and YPM 1125 (paratype P. latipinnis) exhibit numerous postcranial characters that distinguish Polycotylus, in particular presacral vertebral count, nature of chevron facets, unique ilia, and highly derived paddles including five epipodial ossifications and increased hyperphalangy. Greater vertebral and phalangeal counts of Polycotylus are accompanied by exceptional foreshortening; thus, the relative body and limb proportions are likely similar to less derived polycotylids, with fewer, more elongate vertebrae and phalanges. The complete skull, derived among polycotylids, has short temporal fenestrae, elongate frontals, exceptionally slender parasphenoid with prominent cultriform process, and exceptionally long extensions of the angulars and splenials within the mandibular symphysis. Cladistic analysis indicates that Polycotylus nests firmly within derived Polycotylidae as a potential sister taxon to Dolichorhynchops osborni and Trinacromerum, despite a ‘primitive’ presacral vertebral count. Future improvements in available data, in particular better information regarding basal polycotylids, and refinement of character selection to nullify homoplasy could significantly alter the tree structure to show distinct subgroups within Polycotylidae. North American polycotylids with elongate temporal fenestrae, elongate podials, and relatively long vertebrae are confined to occurrences of late Cenomanian and earliest Turonian age, whereas polycotylids distinctly foreshortened in these respects are restricted to post-Turonian occurrences. Ilium morphology is highly variable among polycotylids and, in addition to taxonomic utility, may be in part attributable to sexual dimorphism.

polycotylidae
complete skeleton
early campanian


The systematics and paleobiogeographic significance of Sub-Boreal and Boreal ammonites (Aulacostephanidae and Cardioceratidae) from the Upper Jurassic of the Bohemian Massif

Abstract: Abstract Upper Jurassic marine deposits are either rarely preserved due to erosion or buried under younger sediments in the Bohemian Massif. However, fossil assemblages from a few successions exposed in northern Bohemia and Saxony and preserved in museum collections document the regional composition of macro-invertebrate assemblages and thus provide unique insights into broad-scale distribution and migration pathways of ammonites during the Late Jurassic. In this paper, we focus on the systematic revision of ammonites from the Upper Oxfordian and Lower Kimmeridgian deposits of northern Bohemia and Saxony. The ammonites belong to two families (Aulacostephanidae and Cardioceratidae) of high paleobiogeographic and stratigraphic significance. Six genera belong to the family Aulacostephanidae (Prorasenia, Rasenia, Eurasenia, Rasenioides, Aulacostephanus, Aulacostephanoides) and one genus belongs to the family Cardioceratidae (Amoeboceras). They show that the Upper Jurassic deposits of the northern Bohemian Massif belong to the Upper Oxfordian and Lower Kimmeridgian and paleobiogeographically correspond to the German-Polish ammonite branch with the geographical extent from the Polish Jura Chain to the Swabian and Franconian Alb. Therefore, the occurrences of ammonites described here imply that migration pathway connecting the Polish Jura Chain with habitats in southern Germany was located during the Late Oxfordian and Early Kimmeridgian in the Bohemian Massif.


Resolving the relationships of Paleocene placental mammals

Abstract: The ‘Age of Mammals’ began in the Paleocene epoch, the 10 million year interval immediately following the Cretaceous–Palaeogene mass extinction. The apparently rapid shift in mammalian ecomorphs from small, largely insectivorous forms to many small‐to‐large‐bodied, diverse taxa has driven a hypothesis that the end‐Cretaceous heralded an adaptive radiation in placental mammal evolution. However, the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters. We improve the resolution of the relationships of several enigmatic Paleocene clades, including families of ‘condylarths’. Protungulatum is resolved as a stem eutherian, meaning that no crown‐placental mammal unambiguously pre‐dates the Cretaceous–Palaeogene boundary. Our results support an Atlantogenata–Boreoeutheria split at the root of crown Placentalia, the presence of phenacodontids as closest relatives of Perissodactyla, the validity of Euungulata, and the placement of Arctocyonidae close to Carnivora. Periptychidae and Pantodonta are resolved as sister taxa, Leptictida and Cimolestidae are found to be stem eutherians, and Hyopsodontidae is highly polyphyletic. The inclusion of Paleocene taxa in a placental phylogeny alters interpretations of relationships and key events in mammalian evolutionary history. Paleocene mammals are an essential source of data for understanding fully the biotic dynamics associated with the end‐Cretaceous mass extinction. The relationships presented here mark a critical first step towards accurate reconstruction of this important interval in the evolution of the modern fauna.

paleocene
placental mammal
protungulatum
hyopsodontidae
phylogenetic analysis


A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources

Abstract: Radiodonts, a clade of Cambro-Devonian stem group euarthropods, have classically been regarded as nektonic apex predators. However, many aspects of radiodont morphology and ecology have remained unclear because of the typically fragmentary nature of fossil material. Here, we describe a new hurdiid radiodont based on abundant and exceptionally well-preserved fossils from the Burgess Shale (Marble Canyon area, British Columbia, Canada). Cambroraster falcatus gen. et sp. nov. is characterized by an extra-large horseshoe-shaped head carapace, bearing conspicuous posterolateral spinous processes, and partially covering a short trunk with eight pairs of lateral flaps. Each of the pair of frontal appendages possess five mesially curving rake-like endites equipped with a series of anteriorly directed hooked spines, altogether surrounding the oral cone. This feeding apparatus suggests a micro to macrophagous sediment-sifting feeding ecology. Cambroraster illuminates the evolution of Hurdiidae and evinces the exploitation of the diversifying infauna by these large and specialized nektobenthic carnivores in the aftermath of the Cambrian explosion.

new hurdiid radiodont
burgess shale
exploitation
appendage
rake-like endite


Alkenone paleothermometry in the North Atlantic: A review and synthesis of surface sediment data and calibrations

Abstract: Despite a clear correlation of alkenone unsaturation and sea surface temperatures (SST) throughout most parts of the ocean, scatter of the regression for various calibration equations has been shown to increase significantly at low SSTs. In this study, we combine previously published (n = 101) and new (n = 51) surface sediment data from the northern North Atlantic to constrain uncertainties of alkenone paleothermometry at low SSTs and to discuss possible sources of the increased scatter in the regression. The correlation between alkenone unsaturation and SSTs is strongest, in particular at the cold end (SSTs < 10°C), when the tetra‐unsaturated alkenones (C37:4) are included in the unsaturation index (expressed as U37K ) and regressed against spring‐summer temperature. Surface ocean salinity and sea ice cover are not correlated with U37K per se. However, samples located in regions of permanent winter sea ice cover exhibit a significant warm bias. Deviation from the linear regression is posited to be related to a number of additional non‐exclusive factors, such as advection of allochthonous material, local temperature stratification, and uncertainty in the absolute age of surface sediment samples assumed to be equivalent to modern conditions. We conclude that alkenone unsaturation allows accurate reconstruction of SST records from many regions of the North Atlantic if the factors confounding alkenone paleothermometry detailed here can be excluded.

north atlantic
surface sediment data
sst
alkenone paleothermometry


Dental microwear textures: reconstructing diets of fossil mammals

Abstract: Dietary information of fossil mammals can be revealed via the analysis of tooth morphology, tooth wear, tooth geochemistry, and the microscopic wear patterns on tooth surfaces resulting from food processing. Although dental microwear has long been used by anthropologists and paleontologists to clarify diets in a diversity of mammals, until recently these methods focused on the counting of wear features (e.g., pits and scratches) from two-dimensional surfaces (typically via scanning electron microscopes or low-magnification light microscopes). The analysis of dental microwear textures can instead reveal dietary information in a broad range of herbivorous, omnivorous, and carnivorous mammals by characterizing microscopic tooth surfaces in three-dimensions, without the counting of individual surface features. To date, dental microwear textures in ungulates, xenarthrans, marsupials, carnivorans, and primates (including humans and their ancestors) are correlated with known dietary behavior in extant taxa and reconstruct ancient diets in a diversity of prehistoric mammals. For example, tough versus hard object feeding can be characterized across disparate phylogenetic groups and can distinguish grazers, folivorous, and flesh consumers (tougher food consumers) from woody browsers, frugivores, and bone consumers (harder object feeders). This paper reviews how dental microwear textures can be useful to reconstructing diets in a broad array of living and extinct mammals, with commentary on areas of future research.

fossil mammal
dental microwear texture
dmta


A Gondwanan perspective on the Ordovician Radiation constrains its temporal duration and suggests first wave of speciation, fuelled by Cambrian clades

Abstract: This study presents a Cambrian–Ordovician (Cambrian, ‘Series 3’ – Katian, Ka4) brachiopod α-diversity curve for the Iberian terrane. Three diversity pulses characterized the northern Gondwanan margin through the studied interval; an initial increase in linguliformean diversity that culminated during the Tremadocian (Tr3); a second, Darriwilian (Dw2) pulse caused primarily by a rise in orthid species; and a third pulse during Katian times (Ka3–4) marking the most diverse and phylogenetically complex faunas recorded in this study. Each of the three diversity pulses is phylogenetically distinct and characterized by large turnover rates. The first pulse consists almost exclusively of remnants of the Cambrian Evolutionary Fauna, whereas the second pulse shows a sudden rise of clades typical of the Paleozoic Evolutionary Fauna. The fact that otherwise typical Cambrian clades also radiated at the dawn of the Ordovician suggests that whatever facilitated the emerging Ordovician Radiation, also benefitted these ancient lineages. However, eventually the succeeding Paleozoic Evolutionary Fauna came to dominate during the second diversity pulse. This pulse represents a high-latitude correlative to the main pulse of the Ordovician Radiation. Although it coincides with a globally occurring transgression of eustatic nature, our analysis shows that the generic composition remained overwhelmingly endemic up through the Darriwilian–Sandbian interval. Opposed to this, the third pulse coincides with the globally occurring Boda warming event, which also marks a time of global dispersal. In Iberia, this is reflected by almost entirely cosmopolitan brachiopod faunas, suggesting that the phases of rapid speciation which characterize the Ordovician Radiation had ceased by the mid-Katian.

ordovician radiation
speciation
cambrian clade
dispersal


Purgatorius, an Early Paromomyid Primate (Mammalia)

Abstract: Fragmentary mandibles of Purgatorius unio Van Valen and Sloan from the Puercan (approximately early Paleocene), Garbani Locality, Montana, preserve associated postcanines. Their morphology indicates that this mammal was an early paromomyid primate and suggests that primate ancestry does not include currently known members of the palaeoryctid and leptictid Insectivora or of the Condylarthra.

early paromomyid primate
montana
purgatorius


Eptingiacea and Saturnaliacea (Radiolaria) from the middle Carnian of Turkey and some late Ladinian to early Norian samples from Oman and Alaska

Abstract: This article is a taxonomic study of the radiolarian species of the superfamilies Eptingiacea and Saturnaliacea occurring in the middle Carnian fauna from the Ko ¨seyahya section, near the town of Elbistan, southeastern Turkey. This fauna is characteristic of the Tetraporobrachia haeckeli Radiolarian Zone as defined in Austria and later found also in Turkey and Oman. It comes from an 8 m thick succession of clayey/cherty limestones from the lower part of the section. In addition, a few species from the late Ladinian and Carnian from Oman and the early Norian from Alaska have also been included in this study, in order to improve some generic diagnoses and to show the diversity and evolutionary trends of some genera. 32 radiolarian species of which 22 are new are described and illustrated, and assigned to 16 genera of which three are new (Capnuchospyris, Veleptingium, and Triassolaguncula). The diagnoses of some species, genera, subfamilies and families have been revised, and the family Eptingiidae has been raised to the rank of superfamily.

saturnaliacea
turkey
carnian fauna
succession
triassic spumellaria


Scale-dependence of Cope's rule in body size evolution of Paleozoic brachiopods

Abstract: The average body size of brachiopods from a single habitat type increased gradually by more than two orders of magnitude during their initial Cambrian–Devonian radiation. This increase occurred nearly in parallel across all major brachiopod clades (classes and orders) and is consistent with Cope's rule: the tendency for size to increase over geological time. The increase is not observed within small, constituent clades (represented here by families), which underwent random, unbiased size changes. This scale-dependence is caused by the preferential origination of new families possessing initially larger body sizes. However, this increased family body size does not confer advantages in terms of greater geological duration or genus richness over families possessing smaller body sizes. We suggest that the combination of size-biased origination of families and parallel size increases among major, more inclusive brachiopod clades from a single habitat type is best explained by long-term, secular environmental changes during the Paleozoic that provided opportunities for body size increases associated with major morphological evolution.


How many Pleistocene species of Lestodon (Mammalia, Xenarthra, Tardigrada)?

Abstract: Among the Tardigrada (Mammalia, Xenarthra), terrestrial sloths were very abundant in the South American fauna during the Cenozoic and were especially well represented in the Lujanian (late Pleistocene–early Holocene) fauna. The last systematic revision of the Pleistocene genus Lestodon from Argentina, Bolivia and Uruguay recognized two species: L. armatus Gervais, 1855 and L. australis Kraglievich, 1934. In this paper we revise the species of Lestodon and assess the possibility of sexual dimorphism in body size. The results obtained from a morphological study and morphometrical analysis of the skull do not support a distinction between the two species. Estimations of body mass based on tibial measurements did not support the case for size sexual dimorphism in Lestodon. Nor can this be observed in cranial dimensions. Consequently, it is proposed that the only valid species of the genus is L. armatus, the type species. We provide an emended diagnosis for L. armatus taking into account features found in specimens previously assigned to L. australis. Although the largest specimens of the genus Lestodon are from the current territory of Argentina, the average size of specimens from Uruguay is marginally larger. http://zoobank.org/urn:lsid:zoobank.org:pub:


Redescription of Dapedium pholidotum (Agassiz, 1832) (Actinopterygii, Neopterygii) from the Lower Jurassic Posidonia Shale, with comments on the phylogenetic position of Dapedium Leach, 1822

Abstract: Dapedium pholidotum (Agassiz, 1832) (Actinopterygii, Neopterygii) is redescribed based on new material from the Posidonia Shale (Early Jurassic: Early Toarcian) of Germany. Dapediiformes ord. nov. is introduced for Dapedium Leach, 1822 and other deep-bodied Mesozoic neopterygians. The species diagnosis of D. pholidotum is amended. Comparison with D. stollorum Thies & Hauff, 2011 and D. caelatum Quenstedt, 1858, also from the Lower Jurassic Posidonia Shale, shows that D. pholidotum is unique in having: (1) a length/height ratio of the operculum of c. 0.73, whereas in D. stollorum and D. caelatum this value reaches only c. 0.58; (2) a length/width ratio of the gular plate of c. 1.6, whereas in D. stollorum and D. caelatum this value is 1.3; (3) 27 or more caudal fin lepidotrichia, whereas in D. stollorum and D. caelatum there are 24 and 25 lepidotrichia, respectively; (4) at least 26 dorsal fin lepidotrichia, whereas D. stollorum and D. caelatum possess only 24 dorsal fin lepidotrichia each; and (5) a length/height ratio of the flank scales immediately behind the operculum of 0.37, whereas in D. stollorum and D. caelatum this ratio ranges around 0.31 and 0.5, respectively. A cladistic analysis based on modification of a previously published taxon–character matrix shows that Dapedium is the sister group of the ginglymodian fishes [Semionotiformes + Lepisosteiformes]. The generic diagnosis of Dapedium Leach, 1822 is amended.

dapedium pholidotum
actinopterygii
neopterygii


New late Paleocene (late middle Tiffanian) mammals from the Roche Percée local fauna, south-eastern Saskatchewan, Canada

Abstract: An exceptionally large and diverse assemblage of mammals from the early late Paleocene (about 58 million years ago) has been collected from the Ravenscrag Formation near Roche Percée, south-eastern Saskatchewan, Canada. Previous research of the Roche Percée local fauna has examined only a small portion of the mammals, with the vast majority of taxa remaining unstudied. Identification and descriptions of these latter taxa are provided here. With these new additions, the assemblage is now known to include 44 mammalian species. Notable among these findings is the substantial collection of the erinaceomorph lipotyphlan Litocherus lacunatus, the remarkable diversity of viverravid carnivorans, and the recovery of some of the first known elements of the upper dentition of the pantolestid Besseocetor pilodontus. A complete description of the mammalian fauna supports previous assignments of a late middle Tiffanian North American Land Mammal Age (Ti4 lineage zone) to the Roche Percée local fauna. Faunal comparisons further suggest a close similarity of the Roche Percée assemblage to the near contemporaneous Divide Quarry local fauna from the Bighorn Basin, northern Wyoming, but also reveal some similarities to slightly older middle Tiffanian local faunas (Ti3 lineage zone) at localities in the Paskapoo Formation of central Alberta. The specimens from the Roche Percée local fauna represent the largest and most taxonomically diverse assemblage of late middle Tiffanian mammals yet known, offering a unique perspective on mammalian evolution and diversity in North America during this time interval.

paleocene
local fauna
south-eastern saskatchewan


The chronology of abrupt climate change and Late Upper Palaeolithic human adaptation in Europe

Abstract: This paper addresses the possible connections between the onset of human expansion in Europe following the Last Glacial Maximum, and the timing of abrupt climate warming at the onset of the Lateglacial (Bölling/Allerød) Interstadial. There are opposing views as to whether or not human populations and activities were directly ‘forced’ by climate change, based on different comparisons between archaeological and environmental data. We review the geochronological assumptions and approaches on which data comparisons have been attempted in the past, and argue that the uncertainties presently associated with age models based on calibrated radiocarbon dates preclude robust testing of the competing models, particularly when comparing the data to non‐radiocarbon‐based timescales such as the Greenland ice core records. The paper concludes with some suggestions as to the steps that will be necessary if more robust tests of the models are to be developed in the future. Copyright © 2006 John Wiley & Sons, Ltd.

climate change
europe
last glacial maximum


Secondary Cartilage Revealed in a Non-Avian Dinosaur Embryo

Abstract: The skull and jaws of extant birds possess secondary cartilage, a tissue that arises after bone formation during embryonic development at articulations, ligamentous and muscular insertions. Using histological analysis, we discovered secondary cartilage in a non-avian dinosaur embryo, Hypacrosaurus stebingeri (Ornithischia, Lambeosaurinae). This finding extends our previous report of secondary cartilage in post-hatching specimens of the same dinosaur species. It provides the first information on the ontogeny of avian and dinosaurian secondary cartilages, and further stresses their developmental similarities. Secondary cartilage was found in an embryonic dentary within a tooth socket where it is hypothesized to have arisen due to mechanical stresses generated during tooth formation. Two patterns were discerned: secondary cartilage is more restricted in location in this Hypacrosaurus embryo, than it is in Hypacrosaurus post-hatchlings; secondary cartilage occurs at far more sites in bird embryos and nestlings than in Hypacrosaurus. This suggests an increase in the number of sites of secondary cartilage during the evolution of birds. We hypothesize that secondary cartilage provided advantages in the fine manipulation of food and was selected over other types of tissues/articulations during the evolution of the highly specialized avian beak from the jaws of their dinosaurian ancestors.

non-avian dinosaur embryo
nestling
secondary cartilage


A new species of glyptodontine (Mammalia, Xenarthra, Glyptodontidae) from the Quaternary of the Eastern Cordillera, Bolivia: phylogeny and palaeobiogeography

Abstract: Xenarthrans constitute a relict clade of endemic South American placental mammals with a long evolutionary history starting, at least, in the early Eocene. Within Xenarthra, Glyptodontidae (late Eocene–earliest Holocene) was a conspicuous group of large-sized armoured herbivores. During the Pleistocene (ca. 2.6–0.001 Ma) several genera (e.g. Panochthus and Glyptodon) achieved a remarkable latitudinal distribution in South America, as members of one of the xenarthran groups that participated in the Great American Biotic Interchange. Knowledge of the evolutionary history of this clade in some areas remains poorly known, especially in the high elevation Andean and sub-Andean regions of South America. Here we describe a new species, Glyptodon jatunkhirkhi sp. nov., from several localities of the Eastern Cordillera in Bolivia (ca. 2500–4100 m above sea level). From a phylogenetic viewpoint this new taxon appears as the sister group of the two lowland species recorded in southern South America (Glyptodon munizi + G. reticulatus), and this is congruent with the morphological differences observed between both clades, mainly with respect to the general morphology of the dorsal carapace and the skull. This new species expands the complex biogeographical scenario for Pleistocene glyptodonts and highlights the importance of Andean areas as key in understanding the evolutionary history of this clade. According to this revision, the diversity of Glyptodon is limited to G. munizi and G. reticulatus (two chronologically successive lowland species) plus this new species. The genera Panochthus (P. hipsilis) and Glyptodon seem to be the only Pleistocene glyptodonts to have been adapted to high elevation environments. http://zoobank.org/urn:lsid:zoobank.org:pub:7B5EFC11-626A-4BB5-8A00-DF657741698C

xenarthra
glyptodontidae
eastern cordillera


Phylogeny and Biogeography of Pholadid Bivalve Barnea (Anchomasa) with Considerations on the Phylogeny of Pholadoidea

Abstract: The paper examines the systematics, phylogeny and biogeographical history of Barnea (Anchomasa), which is one of the most abundant and diversified of modern pholadid bivalves. The range of morphology of its distinctive characters and comparisons with other pholadoidean taxa are described in detail. An extensive cladistic analysis based on morphological characters at genus and subgenus levels allowed the inclusion of B. (Anchomasa) into the phylogeny of Pholadoidea and the establishment of its most appropriate taxonomic position. The analysis confirms that Barnea s.s. and B. (Umitakea) are its closest relatives and that the morphological similarities to other taxa are mainly due to plesiomorphies. The fossil record and the data on the present-day distribution contributed to trace the biogeographical history of B. (Anchomasa). The present-day biogeography is marked by the disjunct distribution of species. Species are distributed mainly either along the Atlantic and Pacific coasts of the American continent (American group) or in the Indo-West Pacific region (Indo-West Pacific group). Both these groups have distinct morphological features and biogeographical structures. The fossil record and the known geodynamic scenario suggest a relationship of direct derivation between the Indo-West Pacific group and a stock of north-eastern Atlantic to Paratethyan species. This reflects a vicariant event related to the closure of the connection between western Tethys and the Indian Ocean in the middle Miocene. The American group presumably arose from the European stock during the Late Pliocene by dispersal towards the eastern coasts of North America and rapid southward diffusion. A relative differentiation within the American group is probably related to the last phases of emergence of the Panama Isthmus. The cladistic analysis also gives suggestions for the reconstruction of the phylogeny of the superfamily Pholadoidea. It confirms the interpretation of several characters sustained by previous authors. However, it also shows remarkable differences to the previous taxonomic arrangements. Pholadinae includes only taxa having the protoplax and it appears to be the sister-group of a major clade composed mainly of two groups, namely Martesiinae-Jouannetiinae and Xylophagainae—Teredinidae. The Martesiinae are paraphyletic whereas the obligate wood-boring Xylophagainae and Teredinidae form a well-supported monophyletic group.


Global gridded data set of the oxygen isotopic composition in seawater

Abstract: We present a new 3‐dimensional 1° × 1° gridded data set for the annual mean seawater oxygen isotope ratio (δ18O) to use in oceanographic and paleoceanographic applications. It is constructed from a large set of observations made over the last 50 years combined with estimates from regional δ18O to salinity relationships in areas of sparse data. We use ocean fronts and water mass tracer concentrations to help define distinct water masses over which consistent local relationships are valid. The resulting data set compares well to the GEOSECS data (where available); however, in certain regions, particularly where sea ice is present, significant seasonality may bias the results. As an example application of this data set, we use the resulting surface δ18O as a boundary condition for isotope‐enabled GISS ModelE to yield a more realistic comparison to the isotopic composition of precipitation data, thus quantifying the ‘source effect’ of δ18O on the isotopic composition of precipitation.

data set
isotopic composition
seawater
precipitation


Bizarre fossil beaked whales (Odontoceti, Ziphiidae) fished from the Atlantic Ocean floor off the Iberian Peninsula

Abstract: ABSTRACT Forty partial fossil skulls belonging to beaked whales (Cetacea, Odontoceti, Ziphiidae) were collected by trawling and long-line fishing on Neogene (probably Late Early to Middle Miocene) layers of the Atlantic floor off the coasts of Portugal and Spain (Asturias and Galicia). The systematic study of the most diagnostic Iberian specimens, those preserving the rostrum and the dorsal part of the cranium, led to the recognition of two new genera (Globicetus n. gen. and Imocetus n. gen.) and four new species (Choneziphius leidyi n. sp., G. hiberus n. gen., n. sp., I. piscatus n. gen., n. sp., and Tusciziphius atlanticus n. sp.). Based on the matrix of a previous work, the phylogenetic analysis places all the new taxa in the subfamily Ziphiinae Gray, 1850. More fragmentary specimens are tentatively referred to the genera Caviziphius Bianucci & Post, 2005 and Ziphirostrum du Bus, 1868. Among these new ziphiids, extremely bizarre skull morphologies are observed. In G. hiberus n. gen., n. sp. the proximal portion of the rostrum bears a voluminous premaxillary spheroid. In T. atlanticus n. sp. a medial premaxillary bulge is present on the rostrum; together with asymmetric rostral maxillary eminences at the rostrum base, this bulge displays various degrees of elevation in different specimens, which may be interpreted as sexual dimorphism. Specimens of I. piscatus n. gen., n. sp. bear two sets of even crests: spur-like rostral maxillary crests and longitudinal maxillary crests laterally bordering a wide and long facial basin. A preliminary macroscopic observation of these elements indicates very dense bones, with a compactness comparable with that of cetacean ear bones. Questioning their function, the high medial rostral elements (the premaxillary spheroid of G. hiberus n. gen., n. sp. and the medial bulge of T. atlanticus n. sp.) remind the huge rostral maxillary crests of adult males of the extant Hyperoodon ampullatus (Forster, 1770). In the latter, the crests are very likely related to head-butting. However, they are made of much more spongy bone than in the fossil taxa studied here, and therefore possibly better mechanically suited for facing impacts. Other interpretations of these unusual bone specializations, related to deep-diving (ballast) and echolocation (sound reflection), fail to explain the diversity of shapes and the hypothetical sexual dimorphism observed in at least part of the taxa. The spur-like rostral maxillary crests and long maxillary crests limiting the large facial basin in I. piscatus n. gen., n. sp. and the excrescences on the maxilla at the rostrum base in Choneziphius spp. are instead interpreted as areas of origin for rostral and facial muscles, acting on the nasal passages, blowhole, and melon. From a palaeobiogeographic point of view, the newly described taxa further emphasize the differences in the North Atlantic (including Iberian Peninsula) and South African Neogene ziphiid faunal lists. Even if the stratigraphic context is poorly understood, leaving open the question of the geological age for most of the dredged specimens, these differences in the composition of cold to temperate northern and southern hemisphere fossil ziphiid faunas may be explained by a warm-water equatorial barrier.


Constraining uncertainty in the timescale of angiosperm evolution and the veracity of a Cretaceous Terrestrial Revolution

Abstract: Summary Through the lens of the fossil record, angiosperm diversification precipitated a Cretaceous Terrestrial Revolution (KTR) in which pollinators, herbivores and predators underwent explosive co‐diversification. Molecular dating studies imply that early angiosperm evolution is not documented in the fossil record. This mismatch remains controversial. We used a Bayesian molecular dating method to analyse a dataset of 83 genes from 644 taxa and 52 fossil calibrations to explore the effect of different interpretations of the fossil record, molecular clock models, data partitioning, among other factors, on angiosperm divergence time estimation. Controlling for different sources of uncertainty indicates that the timescale of angiosperm diversification is much less certain than previous molecular dating studies have suggested. Discord between molecular clock and purely fossil‐based interpretations of angiosperm diversification may be a consequence of false precision on both sides. We reject a post‐Jurassic origin of angiosperms, supporting the notion of a cryptic early history of angiosperms, but this history may be as much as 121 Myr, or as little as 23 Myr. These conclusions remain compatible with palaeobotanical evidence and a more general KTR in which major groups of angiosperms diverged later within the Cretaceous, alongside the diversification of pollinators, herbivores and their predators.

timescale
angiosperm evolution
cretaceous terrestrial revolution
diversification


From bone to fossil: A review of the diagenesis of bioapatite

Abstract: Abstract The preservation of bone or bioapatite over geologic time has presented paleobiologists with long-standing and formidable questions. Namely, to elucidate the mechanisms, processes, rates, and depositional conditions responsible for the formation of a fossil from a once living tissue. Approaches integrating geochemistry, mineralogy, physics, hydrology, sedimentology, and taphonomy have all furthered insights into fossilization, but several fundamental gaps still remain. Notably, our limited understanding of: (1) the timing of processes during diagenesis (e.g., early and/or late), (2) the rate of bioapatite transformation into thermodynamically more stable phases, (3) the controls imparted by depositional environment, and (4) the role of (micro)biology in determining the fate of bone bioapatite (dissolution or preservation). The versatility of fossil bioapatite to provide information on the biology of extinct vertebrates rests on our ability to identify and characterize the changes that occurred to bioapatite during diagenesis. This review will evaluate our current understanding of bioapatite diagenesis and fossilization, focusing on the biogeochemical transformations that occur during diagenesis to the mineral and organic components of bone (excluding teeth and enamel), the analytical approaches applied to evaluate fossilization processes, and outline some suggestions for future promising directions.

review
diagenesis
bioapatite
fossilization process


Marine mammals through time: when less is more in studying palaeodiversity

Abstract: The validity of biological explanations of patterns of palaeodiversity has been called into question owing to an apparent correlation of diversity with the amount of sedimentary rock preserved. However, this claim has largely been based on comprehensive estimates of global marine Phanerozoic diversity, thus raising the question of whether a similar bias applies to the records of smaller, well-defined taxonomic groups. Here, new data on European Caenozoic marine sedimentary rock outcrop area are presented and compared with European occurrences of three groups of marine mammals (cetaceans, pinnipedimorphs and sirenians). Limited evidence was found for a correlation of outcrop area with marine mammal palaeodiversity. In addition, similar patterns were identified in the cetacean and pinnipedimorph diversity data. This may point to the preservation of a genuine biological signal not overwhelmed by geological biases in the marine mammal diversity data, and opens the door to further analyses of both marine mammal evolution and geological bias in other small and well-defined groups of taxa.


Strong middepth warming and weak radiocarbon imprints in the equatorial Atlantic during Heinrich 1 and Younger Dryas

Abstract: We present a benthic foraminiferal multiproxy record of eastern equatorial Atlantic (EEA) middepth water (1295m) covering the last deglacial. We show that EEA middepth water temperatures were elevated by 3.90.5 degrees C and 5.21.2 degrees C during Heinrich event 1 (H1) and Younger Dryas (YD), respectively. The radiocarbon content of the EEA middepth during H1 and YD is relatively low and comparable to the values of the pre-H1 episode and BOlling-AllerOd, respectively. A transient Earth system model simulation, which mimics the observed deglacial Atlantic Meridional Overturning Circulation (AMOC) history, qualitatively reproduces the major features of the EEA proxy records. The simulation results suggest that fresh water-induced weakening of the AMOC leads to a vertical shift of the horizon of Southern Ocean-sourced water and a stronger influence of EEA sea surface temperatures via mixing. Our findings reaffirm the lack of a distinctive signature of radiocarbon depletion and therefore do not support the notion of interhemispheric exchanges of strongly radiocarbon-depleted middepth water across the tropical Atlantic during H1 and YD. Our temperature reconstruction presents a critical zonal and water depth extension of existing tropical Atlantic data and documents a large-scale and basin-wide warming across the thermocline and middepth of the tropical Atlantic during H1 and YD. Significant difference in the timing and pace of H1 middepth warming between tropical Atlantic and North Atlantic likely points to a limited role of the tropical Atlantic middepth warming in the rapid heat buildup in the North Atlantic middepth.

middepth warming
equatorial atlantic
younger dryas


The skull and neck of the basal theropod Herrerasaurus ischigualastensis

Abstract: ABSTRACT We describe the skull and neck of Herrerasaurus ischigualastensis from specimens discovered recently in the Upper Triassic Ischigualasto Formation of northwestern Argentina. The skull has a rectangular profile and a transversely narrow snout. Marked supratemporal depressions for jaw adductor musculature on the skull roof and a well-developed, sliding intra-mandibular joint suggest that Herrerasaurus ischigualastensis was an active predator. The neck is relatively slender with prominent epipophyses on all of the cervical vertebrae. Diagnostic features of the species include the semicircular shape of the antorbital fossa and the long, slender posterodorsal process of the dentary. Other features of the skull, such as the loss of the postfrontal and small post-temporal opening, constitute dinosaurian synapomorphies. These synapomorphies, however, remain equivocal at the level of Dinosauria because they cannot be evaluated in immediate dinosaurian outgroups for which cranial information is lacking. Co...

skull
neck
herrerasaurus ischigualastensis


The mammal localities of Grand Daoui Quarries, Ouled Abdoun Basin, Morocco, Ypresian : A first survey

Abstract:
The unexpected discovery of mammals such as the earliest known proboscidean Phosphatherium escuilliei in the Ouled Abdoun phosphate Basin (Morocco), which is otherwise renowned for its very rich marine vertebrate fauna, has opened major new perspectives on the early African placental fauna. It was the impetus for several field parties by us between 1997 and 2001 which has allowed this survey of the geological, stratigraphic and paleontological context of Phosphatherium localities. This is the first important paleontological field work dealing with higher vertebrates in the Ouled Abdoun Basin since the work of C. Arambourg.

Most of the material of Phosphatherium and other Ouled Abdoun mammals was found by local people searching for fossils for dealing, in an area where the economy is widely dominated by the mining development, in addition to more traditional but very poor agricultural resources. All Phosphatherium remains were found in the northeasternmost quarries of the Ouled Abdoun Basin, from a restricted quarrying area called Grand Daoui (fig. 3). In all Grand Daoui recognized localities (8), the mammals come from the lowermost Eocene level. The stratigraphically re-situated mammalian material was found in a bone-bed of the level called "Intercalaire Couches II/I" which is dated as early(iest) Ypresian on the basis of its relative stratigraphic position and its selachian fauna. At present, the occurrence of several mammal horizons in the "Intercalaire Couches II/I" (and Couche I ?) cannot be excluded, but their age difference seems not significant according to both the associated selachian taxa and the mammalian material, in present data. The bone-bed is very rich in macro-vertebrates. It includes especially large teeth of the shark Otodus obliquus which are the subject of very active research for dealing, and which explains the recent discovery of mammals such as Phosphatherium

The level "Intercalaire Couches II/I" is made of a hardened phosphatic bioclastic limestone which is separated from underlying Paleocene levels by a major discontinuity. It is the first deposit of the Eocene sequence (megasequence C) in the Ouled Abdoun phosphate series. Deposition of this new sequence partly reworked the underlying Thanetian levels in the lowermost horizons of the level "Intercalaire Couches II/I", such as the mammals bearing bone-bed. This explains the recovery of Thanetian selachians in the matrix of the holotype of P. escuilliei and its initial allocation to the Thanetian by Gheerbrant et al. [1996, 1998]. These Thanetian selachian species are now clearly recognized as reworked. Studies of new samples of selachians associated with the newly recovered remains of P. escuilliei and other Grand Daoui mammals have confirmed our field observations owing to the identification of typical early Ypresian species which are listed in table I. P. escuilliei and other mammals from Grand Daoui quarries are confidently dated here as early(iest) Ypresian.

As a general rule, there is no known concentration of fossil remains of species of terrestrial origin in the Ouled Abdoun epicontinental Basin. The mammals are exceedingly rare, documented by very few occurrences in contrast to the associated very rich marine vertebrate remains in the phosphate deposits. The occurrence of several rare mammals in these marine facies is related to a peculiar taphonomy characterized by a transport from near shores and continental hinterland under conditions of low hydrodynamic energy such as floated bodies. This is consistent with both the scattered nature of the material in the basin and with its well preserved state (e.g., dental rows, skulls) with respect to other early African mammal localities such as the Ouarzazate basin sites.

Up to now, the Grand Daoui sites have yielded 7 species of mammals, which is not an inconsiderable diversity. The provisional faunal list includes a new hyaenodontid creodont, a small (P. escuilliei) and a large (Daouitherium rebouli) proboscidean, the two "condylarths" Abdounodus hamdii (cf. Mioclaneidae) and Ocepeia daouiensis (cf. Phenacodonta), and two indeterminate species which are described here. One of these, known only by a broken bilophodont lower molar, might belong to a new "condylarth" or a new ungulate. It has a reduced one-rooted M/3. An isolated M/3 belongs to another new species close to the genus Seggeurius. It is the oldest known hyracoidean along with an indeterminate species from the Ypresian of N'Tagourt 2 (Morocco).

In the mammalian Ouled Abdoun « fauna », P. escuilliei is largely predominant. As a whole this "fauna" shows typical endemic African affinities. It provides new insight into the origin and initial radiation of major endemic African placental taxa. Despite their scarcity, the well preserved Ouled Abdoun mammal remains provide new data especially on the earliest known African ungulates. This is indeed the only known locality bearing large mammals in the Paleocene and early Eocene of Africa, probably in connection to the peculiar taphonomy of continental vertebrates in the phosphatic facies.

The vertebrates associated with the Grand Daoui mammals include selachians, osteichthyans, marine reptiles (crocodilians, turtles, and the snakes Palaeophis) and also marine birds which are here reported for the first time in the Ouled Abdoun and other African phosphate basins. The Ouled Abdoun birds are diversified and much less rare than the mammals. They are the oldest known birds in Africa and among the oldest representatives of modern marine groups. Preliminary identifications indicate the occurrence of Procellariiformes (cf. Diomedeidae, cf. Procellariidae), Pelecaniformes (cf. Phaethontidae, cf. Prophaethontidae, cf. Fregatidae, cf. Pelagornithidae), and Anseriformes (cf. Presbyornithidae).

mammal locality
ouled abdoun basin
morocco


Abstract: In total, less than 50 specimens of the Passeriformes are known from the Paleogene, which contrasts with the fact that now it is the largest and most diverse order of birds. The so far described fossils include only three nearly complete specimens, an articulated wing and legs, and a handful of isolated bones. This paper describes a new species and genus of a passerine bird the size of the extant Parus major, imprinted on a slab and a counter slab of the siliceous clayey shales of the Outer Carpathians in southeastern Poland, and dated to the Rupelian, early Oligocene (ca. 31 m.y.a.). It is one of the very few passerine specimens from the Paleogene with bones in articulation, and thus provides a window into the ancestral osteology of passeriforms, which is characterized by a mosaic of characters typical for extant Oscines and Suboscines. The bird shows a unique manus, with a relatively short carpometacarpus and cleavershaped phalanx proximalis digiti majoris. Besides bones, fragmentary feathers are also imprinted on both slabs. Zbigniew M. Bochenski. Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31-016 Krakow, Poland. (corresponding author) bochenski@isez.pan.krakow.pl Teresa Tomek. Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31-016 Krakow, Poland. tomek@isez.pan.krakow.pl Krzysztof Wertz. Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31-016 Krakow, Poland. wertz@isez.pan.krakow.pl Johannes Happ. Department of Palaeontology, Faculty of Earth Sciences, University of Vienna, Vienna, Austria. johanneshapp@yahoo.de Małgorzata Bujoczek. Department of Forest Biodiversity, Faculty of Forestry, University of Agriculture, al. 29 Listopada 46, 31-425 Krakow, Poland. malgorzata.bujoczek@urk.edu.pl Ewa Swidnicka. Department of Palaeozoology, Institute of Environmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland. gama@biol.uni.wroc.pl http://zoobank.org/DDC682C0-D2BD-44FF-B8F2-E48B940DC7D4 Bochenski, Zbigniew M., Tomek, Teresa, Wertz, Krzysztof, Happ, Johannes, Bujoczek, Małgorzata, and Swidnicka, Ewa. 2018. Articulated avian remains from the early Oligocene of Poland adds to our understanding of Passerine evolution. Palaeontologia Electronica 21.2.32A 1-12. https://doi.org/10.26879/843 palaeo-electronica.org/content/2018/2300-passerine-bird-from-oligocene Copyright: August 2018 Paleontology Society. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ BOCHENSKI: PASSERINE BIRD FROM OLIGOCENE

avian
early oligocene
passerine evolution


Scheenstia bernissartensis (Actinopterygii: Ginglymodi) from the Early Cretaceous of Bernissart, Belgium, with an appraisal of ginglymodian evolutionary history

Abstract: Lepidotes bernissartensis is a species of holostean ray-finned fish from the Barremian–Aptian of Bernissart, Belgium, described by Traquair in 1911. We provide here a revision of its anatomy, which led us to include this species in the genus Scheenstia, and to consider L. brevifulcratus and L. arcuatus, both from the same site, synonymous with S. bernissartensis. We performed two cladistic analyses in order to assess the phylogenetic position of S. bernissartensis and to do an updated appraisal of the evolutionary history of the ginglymodians. Scheenstia is included in the Lepidotidae, and placed in a pectinated position between the basal genus Lepidotes and the more derived members of the family (other species of Scheenstia, Isanichthys and Camerichthys). The nodes within the lepidotids are weakly supported. Although S. bernissartensis is not directly related to S. mantelli from the Wealden of Europe, the two species have similar palaeoenvironments and stratigraphical ranges. Taken as a whole, the ginglymodians experienced several episodes of diversification that are spatially and temporally restricted. The oldest episode involved basal ginglymodians and occurred in the Middle Triassic, in marine environments along the northern margin of the Tethys. A second episode affected the Semionotidae and occurred in freshwater environments of North America and Europe in the Late Triassic and Early Jurassic. The remaining Semionotiformes, Macrosemiidae and Callipurbeckidae, ranged from the Triassic to the Early Cretaceous and were mostly marine. Among the Lepisosteiformes, two clades, the Lepidotidae and the Lepisosteoidi, show episodes of diversification, first in marine and then in freshwater environments.

early cretaceous
evolutionary history
scheenstia bernissartensis


Sutural pattern and shell stress in Baculites with implications for other cephalopod shell morphologies

Abstract: In Baculites, a straight shelled ammonite, the constructional limits on shell shape resulting from the limited strength of nacre in tension are circumvented by a system of vaults in the phragmocone. Vaults bridge between regions of the phragmocone supported by the complex ammonite septal suture, and maintain the shell wall in compression when hydrostatic load induces bending moments. To determine how these vaults interact in the phragmocone to resist hydrostatic loading, measurements were made on a suite of Baculites specimens. In Baculites there is a statistically significant inverse relationship between circumferential curvature (radius of curvature) of the vaulted shell surface and the size of vaults spanning between sutural elements supporting the phragmocone. The inverse relationship between radius of curvature and the sizes of spans in this system of vaults results in the generation of comparable reactive forces at the ends of the vault spans where adjacent vaults interact. The equivalence of these reactive forces prevents the lateral displacement of the vault ends. Consequently, compressive stresses from adjacent vaults are superimposed on, and reduce, the tensional stress component of bending. Limiting tensile stress is of utmost importance in a lightweight shell composed of a brittle material such as nacre, which is strong in compression but weak in tension. Baculites is particularly appropriate for this study because its straight shell is curved only in the circumferential direction, thus simplifying the problem. However, sutural patterns in coiled ammonites appear to be similarly constrained to produce vaults in the phragmocone which vary inversely in curvature and span size.


Phylogenetic affinities of the enigmatic avian taxon zygodactylus based on new material from the early oligocene of France

Abstract: Synopsis Until now, the avian taxon Zygodactylus has been known only from distal tibiotarsi and tarsometatarsi from the early Miocene of Europe. Although the tarsometatarsus exhibits derived similarities to that of extant Pici (barbets, toucans, woodpeckers and their allies), it differs in many aspects and the phylogenetic affinities of Zygodactylus were uncertain. Here, a well‐preserved skeleton with a tentatively referred skull is described from the early Oligocene of the Luberon, southern France, as a new species, Z. luberonensis. It is about 10 million years older than previously assigned species and exhibits derived characters which support a clade comprising Zygodactylus and Eocene zygodactyl birds that were assigned to the taxon ‘Primoscenidae’. Primoscenidae Harrison & Walker, 1977 is synonymised with Zygodactylidae Brodkorb, 1971. Zygodactylus lacks derived features of crown group Piciformes and the derived similarities in the distal tarsometatarsi of Zygodactylus and the Pici are thus a striking example of convergence. Instead, the analysis results in a sister group relationship between Zygodactylidae and Passeriformes (passerines), and morphological characters are listed which support this hypothesis. Recognition of Zygodactylidae as the possible sister taxon of the Passeriformes implies that stem group representatives of passerines already existed by the early Eocene.

avian taxon zygodactylus
early oligocene
passeriformes
phylogenetic affinity


Partial Skeleton of a Bony-Toothed Bird from the Late Oligocene/Early Miocene of Oregon (USA) and the Systematics of Neogene Pelagornithidae

Abstract: Abstract A partial skeleton of a pelagornithid bird found in latest Oligocene or earliest Miocene marine strata in Oregon consists of a pelvis fragment, thoracic vertebrae, and leg bones of a single individual. It is the most completely preserved pelagornithid from the late Oligocene/early Miocene, and one of the few bony-toothed birds from this time period in general. The new fossil is from the Nye Mudstone and shows some previously unknown features that contribute to a better understanding of the osteology of pelagornithids. Because Paleogene and late Neogene pelagornithids differ in several osteological features and the temporally intermediate forms are poorly known, it further bridges a gap in our knowledge of character evolution in pelagornithids. The interrelationships within Pelagornithidae are still poorly resolved, but we detail that a clade of Neogene species, which the Oregon pelagornithid is not part of, can be supported by a derived morphology of the femur. To ease description of Neogene pelagornithids, we synonymize Palaeochenoides Shufeldt, 1916 and Tympanonesiotes Hopson, 1964 with Pelagornis Lartet, 1857, and suggest classification of all Neogene pelagornithids in the latter taxon.

bony-toothed bird
early miocene
partial skeleton


Rautangaroa, a new genus of feather star (Echinodermata, Crinoidea) from the Oligocene of New Zealand

Abstract: Abstract. We describe a nearly complete, and thus extremely rare, feather star (Crinoidea, Comatulida) from Oligocene strata of North Otago/South Canterbury, New Zealand. A detailed analysis of this specimen, as well as newly recovered material and previously described fragmentary remains from nearby contemporaneous sedimentary units, in addition to relevant historical specimens, lead us to conclude that it cannot be placed in any currently established genus. A new genus, Rautangaroa, is proposed to accommodate it. This intact specimen of Rautangaroa aotearoa (Eagle, 2007), provides rare data on the morphology of arms and cirri. It represents the first example of arm autotomy and regeneration in a fossil feather star and thus has bearing on the importance of predation to the evolutionary history of this group.


Tetrapod postural shift estimated from Permian and Triassic trackways

Abstract: Abstract:  The end‐Permian mass extinction, 252 million years (myr) ago, marks a major shift in the posture of tetrapods. Before the mass extinction, terrestrial tetrapods were sprawlers, walking with their limbs extended to the sides; after the event, most large tetrapods had adopted an erect posture with their limbs tucked under the body. This shift had been suspected from the study of skeletal fossils, but had been documented as a long process that occupied some 15–20 myr of the Triassic. This study reads posture directly from fossil tracks, using a clear criterion for sprawling vs erect posture. The track record is richer than the skeletal record, especially for the Early and Middle Triassic intervals, the critical 20 myr during which period the postural shift occurred. The shift to erect posture was completed within the 6 myr of the Early Triassic and affected both lineages of medium to large tetrapods of the time, the diapsids and synapsids.


THE CENOZOIC DEEP SEA MICROFOSSIL RECORD: EXPLORATIONS OF THE DSDP/ODP SAMPLE SET USING THE NEPTUNE DATABASE

Abstract:
For 30 years the Deep Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP) have been drilling the ocean floors and retrieving sediment cores. This study presents a relational micropaleontological and stratigraphic database, Neptune, where a selection of the published studies made on these sediments is available. The selected sites and their stratigraphic extent represent a statistically reproducible subset of the whole DSDP and ODP data set as of 1995 (up to Leg 135). Cenozoic sediments from 165 globally distributed holes were dated with age/depth plots using biochronology of four marine plankton groups (diatoms, nannofossils, foraminifera, and radiolarians). Each hole's location is available with paleogeographic coordinates. A taxonomic revision of the 8000+ reported species names was also made. The database is searchable and a variety of routines are available. Data can be exported to produce age range charts, geographic distribution maps, and occurrence charts.
A rigorous evaluation of the database potentials and limitations is presented together with a summary of the published studies that have been carried on with the data. These include stratigraphic studies (diachrony of Neogene plankton, hiati distribution in Cenozoic sediments) and evolution studies (cladogenesis and evolution of one foraminiferal lineage). Unpublished data on macroevolutionary patterns (species longevity and richness, speciation and extinction rates) are presented as example of Neptune's potential for paleobiological research. Finally, some suggestions are presented as to how Neptune can be more fully exploited through the addition of sedimentologic and isotopic data. A variety of critical sedimentologic and paleoceanographic questions could be addressed with this extended database.

cenozoic dsdp neptune nannofossil foraminifera


Are palaeoscolecids ancestral ecdysozoans?

Abstract: SUMMARY The reconstruction of ancestors is a central aim of comparative anatomy and evolutionary developmental biology, not least in attempts to understand the relationship between developmental and organismal evolution. Inferences based on living taxa can and should be tested against the fossil record, which provides an independent and direct view onto historical character combinations. Here, we consider the nature of the last common ancestor of living ecdysozoans through a detailed analysis of palaeoscolecids, an early and extinct group of introvert‐bearing worms that have been proposed to be ancestral ecdysozoans. In a review of palaeoscolecid anatomy, including newly resolved details of the internal and external cuticle structure, we identify specific characters shared with various living nematoid and scalidophoran worms, but not with panarthropods. Considered within a formal cladistic context, these characters provide most overall support for a stem‐priapulid affinity, meaning that palaeoscolecids are far‐removed from the ecdysozoan ancestor. We conclude that previous interpretations in which palaeoscolecids occupy a deeper position in the ecdysozoan tree lack particular morphological support and rely instead on a paucity of preserved characters. This bears out a more general point that fossil taxa may appear plesiomorphic merely because they preserve only plesiomorphies, rather than the mélange of primitive and derived characters anticipated of organisms properly allocated to a position deep within animal phylogeny.

palaeoscolecid
ancestral ecdysozoan
scalidophoran


Compilation and Network Analyses of Cambrian Food Webs

Abstract: A rich body of empirically grounded theory has developed about food webs—the networks of feeding relationships among species within habitats. However, detailed food-web data and analyses are lacking for ancient ecosystems, largely because of the low resolution of taxa coupled with uncertain and incomplete information about feeding interactions. These impediments appear insurmountable for most fossil assemblages; however, a few assemblages with excellent soft-body preservation across trophic levels are candidates for food-web data compilation and topological analysis. Here we present plausible, detailed food webs for the Chengjiang and Burgess Shale assemblages from the Cambrian Period. Analyses of degree distributions and other structural network properties, including sensitivity analyses of the effects of uncertainty associated with Cambrian diet designations, suggest that these early Paleozoic communities share remarkably similar topology with modern food webs. Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web. Most aspects of Cambrian food-web structure are well-characterized by a simple “niche model,” which was developed for modern food webs and takes into account this scale dependence. However, a few aspects of topology differ between the ancient and recent webs: longer path lengths between species and more species in feeding loops in the earlier Chengjiang web, and higher variability in the number of links per species for both Cambrian webs. Our results are relatively insensitive to the exclusion of low-certainty or random links. The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions among metazoan species. The few differences could reflect a transition to more strongly integrated and constrained trophic organization within ecosystems following the rapid diversification of species, body plans, and trophic roles during the Cambrian radiation. More research is needed to explore the generality of food-web structure through deep time and across habitats, especially to investigate potential mechanisms that could give rise to similar structure, as well as any differences.

food webs
burgess shale
diversification
complex marine ecosystem
cambrian explosion