OLIGOCENE TERRESTRIAL STRATA OF NORTHWESTERN ETHIOPIA: A PRELIMINARY REPORT ON PALEOENVIRONMENTS AND PALEONTOLOGY

Abstract: The Paleogene record of Afro-Arabia is represented by few fossil localities, most of which are coastal. Here we report sedimentological and paleontological data from continental Oligocene strata in northwestern Ethiopia. These have produced abundant plant fossils and unique assemblages of vertebrates, thus filling a gap in what is known of Paleogene interior Afro-Arabia. The study area is approximately 60 km west of Gondar, Chilga Woreda; covers about 100 km 2 ; and represents as few as 1 Myr based on radiometric dates and paleomagnetic chronostratigraphy. The sedimentary strata are 150 m thick, and dominated by kaolinitic and smectitic mudstones and airfall tuff deposits. Five main paleosol types are interpreted as representing Protosols (gleyed or ferric), Histosols, Gleysols, Vertisols, and Argillisols. Varied, poor drainage conditions produced lateral variation in paleosols, and stratigraphic variation probably resulted from lateral changes in drainage conditions through time. Vertebrate fossils occur in sediments associated with ferric Protosols and occur with fruits, seeds, and leaf impressions. Plant fossils also occur as in situ forests on interfluves, leaf and flower compressions associated with in situ carbonized trees in overbank deposits (Gleyed Protosols), and compressions of leaves, twigs and seeds in tuffs. Plant fossil assemblages document diverse forests, from 20-35 m tall, of locally heterogeneous composition, and representing families occurring commonly (legumes) or uncommonly (palms) in forests today. Sedimentological and paleobotanical data are consistent with a nearly flat landscape where a meandering river and ample rainfall supported lush vegetation. Over time, the region was subject to intermittent ashfalls. A unique fauna of archaic mammalian endemics, such as arsinoitheres and primitive hyracoids, lived here with the earliest deinotheres.

northwestern ethiopia
oligocene strata
paleosol


Ancient collagen reveals evolutionary history of the endemic South American ‘ungulates’

Abstract: Since the late eighteenth century, fossils of bizarre extinct creatures have been described from the Americas, revealing a previously unimagined chapter in the history of mammals. The most bizarre of these are the ‘native’ South American ungulates thought to represent a group of mammals that evolved in relative isolation on South America, but with an uncertain affinity to any particular placental lineage. Many authors have considered them descended from Laurasian ‘condylarths’, which also includes the probable ancestors of perissodactyls and artiodactyls, whereas others have placed them either closer to the uniquely South American xenarthrans (anteaters, armadillos and sloths) or the basal afrotherians (e.g. elephants and hyraxes). These hypotheses have been debated owing to conflicting morphological characteristics and the hitherto inability to retrieve molecular information. Of the ‘native’ South American mammals, only the toxodonts and litopterns persisted until the Late Pleistocene–Early Holocene. Owing to known difficulties in retrieving ancient DNA (aDNA) from specimens from warm climates, this research presents a molecular phylogeny for both Macrauchenia patachonica (Litopterna) and Toxodon platensis (Notoungulata) recovered using proteomics-based (liquid chromatography–tandem mass spectrometry) sequencing analyses of bone collagen. The results place both taxa in a clade that is monophyletic with the perissodactyls, which today are represented by horses, rhinoceroses and tapirs.


Ordovician edrioasteroids from Morocco: faunal exchanges across the Rheic Ocean

Abstract: A new edrioasteroid fauna from the Ordovician of Morocco, North Africa includes eight new isorophid species placed in six genera of which three are new. A phylogenetic analysis of Moroccan genera and other taxa places these new edrioasteroids into a phylogenetic framework. Pyrgocystidae is redefined to include plesiomorphic isorophids with hood plates underlying the cover plates. New pyrgocystid taxa include Streptaster nodosus sp. nov., Belochthus? chauveli sp. nov., Argodiscus espilezorum sp. nov. and Moroccopyrgus matacarros gen. et sp. nov. Isorophinid taxa include Isorophus africanus sp. nov., Isorophusella gutii sp. nov., Euryeschatia reboulorum gen. et sp. nov. and the morphological aberrant Anedriophus moroccoensis gen. et sp. nov. These taxa are attached either epibiotically on conulariids or echinosphaeritid rhombiferans, or encrust large bioclasts such as cephalopods and trilobites in a siliciclastic environment that is otherwise devoid of suitable hard substrates. The presence of close relatives of North American taxa in this Perigondwanan section indicates a high degree of communication between North America and North Africa in Ordovician time. Also described are two species of an unusual eocrinoid? Hexedriocystis gen. nov., the type species H. inexpectatus sp. nov. and H. mimus sp. nov., that is a close mimic of isorophid taxa.

edrioasteroid
morocco
phylogenetic analysis


Coryphodon, the northernmost Holarctic Paleogene pantodont (Mammalia), and its global wanderings

Abstract: The pantodont Coryphodon is a frequently found component of early Eocene terrestrial faunas in North America, distributed widely from the Arctic to the Gulf Coast. The most northerly member of this genus of large herbivore is a new species that appears to be closest to the oldest known mid-latitude species, Coryphodon proterus from the Clarkforkian (Cf-2), late Paleocene, of Montana. Coryphodon is widely distributed during the early Eocene across the Holarctic, occurring also in England, Belgium, and France (MP7-9, early Eocene) on the one hand and Kazakhstan, Mongolia, and China (Gashatan-Bumbanian, late Paleocene-early Eocene, Xinjiang, Shandong, and Shanxi) on the other. Although other genera of Coryphodontidae, as well as of other pantodont families, appear to have had more sedentary habits, Coryphodon is noted for its wide distribution. Adaptations to a warm temperate northern climate, including its northern light regime, may be postulated for this genus of pantodont as well as a pattern of dispersal leading to its wide range across the Holarctic.


The skull of the basal stegosaur Huayangosaurus taibaii and a cladistic diagnosis of stegosauria

Abstract: ABSTRACT The recent discovery of the Middle Jurassic stegosaur, Huayangosaurus taibaii has shed new light on the early phylogeny of Stegosauria. The skull of this taxon is described in detail and compared to those of other thyreophorans. Cranial and postcranial autapomorphies of Huayangosaurus include high premaxillary and maxillary tooth counts (7 and 25–30, respectively), small postorbital horn, intercostal articular flanges, and a carpus composed of a single coossified block. Nineteen synapomorphies unite Huayangosaurus and other stegosaurs and constitute a revised cladistic diagnosis for Stegosauria. Huayangosaurus is the sister-taxon to all other stegosaurs, which have lost premaxillary teeth, reduced the size of the antorbital fossa, increased the length of the prepubic process of the pubis, and lost lateral scute rows along the trunk.

skull
huayangosaurus
cladistic diagnosis
stegosauria
other thyreophoran


Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution

Abstract: The independent evolution of gigantism among dinosaurs has been a topic of long-standing interest, but it remains unclear if gigantic theropods, the largest bipeds in the fossil record, all achieved massive sizes in the same manner, or through different strategies. We perform multi-element histological analyses on a phylogenetically broad dataset sampled from eight theropod families, with a focus on gigantic tyrannosaurids and carcharodontosaurids, to reconstruct the growth strategies of these lineages and test if particular bones consistently preserve the most complete growth record. We find that in skeletally mature gigantic theropods, weight-bearing bones consistently preserve extensive growth records, whereas non-weight-bearing bones are remodelled and less useful for growth reconstruction, contrary to the pattern observed in smaller theropods and some other dinosaur clades. We find a heterochronic pattern of growth fitting an acceleration model in tyrannosaurids, with allosauroid carcharodontosaurids better fitting a model of hypermorphosis. These divergent growth patterns appear phylogenetically constrained, representing extreme versions of the growth patterns present in smaller coelurosaurs and allosauroids, respectively. This provides the first evidence of a lack of strong mechanistic or physiological constraints on size evolution in the largest bipeds in the fossil record and evidence of one of the longest-living individual dinosaurs ever documented.


New records of the dolphin Albertocetus meffordorum (Odontoceti: Xenorophidae) from the lower Oligocene of South Carolina: Encephalization, sensory anatomy, postcranial morphology, and ontogeny of early odontocetes

Abstract: We report five new specimens of xenorophid dolphins from North and South Carolina. Four of the specimens represent the xenorophid Albertocetus meffordorum, previously only known from the holotype skull. The other is a fragmentary petrosal from the upper Oligocene Belgrade Formation that we refer to Echovenator sp, indicating at least two xenorophids from that unit. Two of the Albertocetus meffordorum specimens are from the lower Oligocene Ashley Formation: 1) a partial skeleton with neurocranium, fragmentary mandible, ribs, vertebrae, and chevrons, and 2) an isolated braincase. The partial vertebral column indicates that Albertocetus retained the ancestral morphology and locomotory capabilities of basilosaurid archaeocetes, toothed mysticetes, and physeteroids, and caudal vertebrae that are as wide as tall suggest that the caudal peduncle, which occurs in all extant Cetacea, was either wide or lacking. CT data from the isolated braincase were used to generate a digital endocast of the cranial cavity. The estimated EQ of this specimen is relatively high for an Oligocene odontocete, and other aspects of the brain, such as its anteroposterior length and relative size of the temporal lobe, are intermediate in morphology between those of extant cetaceans and terrestrial artiodactyls. Ethmoturbinals are also preserved, and are similar in morphology and number to those described for the Miocene odontocete Squalodon. These fossils extend the temporal range of Albertocetus meffordorum into the early Oligocene, its geographic range into South Carolina, and expand our paleobiological understanding of the Xenorophidae.

xenorophidae
oligocene
cranial cavity
brain
extant cetacean


A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot

Abstract: Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.

argentina
sauropod
hind foot
notocolossus
humerus


Origin and Diversification of Major Clades in Parmelioid Lichens (Parmeliaceae, Ascomycota) during the Paleogene Inferred by Bayesian Analysis

Abstract: There is a long-standing debate on the extent of vicariance and long-distance dispersal events to explain the current distribution of organisms, especially in those with small diaspores potentially prone to long-distance dispersal. Age estimates of clades play a crucial role in evaluating the impact of these processes. The aim of this study is to understand the evolutionary history of the largest clade of macrolichens, the parmelioid lichens (Parmeliaceae, Lecanoromycetes, Ascomycota) by dating the origin of the group and its major lineages. They have a worldwide distribution with centers of distribution in the Neo- and Paleotropics, and semi-arid subtropical regions of the Southern Hemisphere. Phylogenetic analyses were performed using DNA sequences of nuLSU and mtSSU rDNA, and the protein-coding RPB1 gene. The three DNA regions had different evolutionary rates: RPB1 gave a rate two to four times higher than nuLSU and mtSSU. Divergence times of the major clades were estimated with partitioned BEAST analyses allowing different rates for each DNA region and using a relaxed clock model. Three calibrations points were used to date the tree: an inferred age at the stem of Lecanoromycetes, and two dated fossils: Parmelia in the parmelioid group, and Alectoria. Palaeoclimatic conditions and the palaeogeological area cladogram were compared to the dated phylogeny of parmelioid. The parmelioid group diversified around the K/T boundary, and the major clades diverged during the Eocene and Oligocene. The radiation of the genera occurred through globally changing climatic condition of the early Oligocene, Miocene and early Pliocene. The estimated divergence times are consistent with long-distance dispersal events being the major factor to explain the biogeographical distribution patterns of Southern Hemisphere parmelioids, especially for Africa-Australia disjunctions, because the sequential break-up of Gondwana started much earlier than the origin of these clades. However, our data cannot reject vicariance to explain South America-Australia disjunctions.

parmeliaceae
ascomycota
evolutionary history
lecanoromycetes


How a Paleogenomic Approach Can Provide Details on Bioarchaeological Reconstruction: A Case Study from the Globular Amphorae Culture

Abstract: Ancient human remains have the potential to explain a great deal about the prehistory of humankind. Due to recent technological and bioinformatics advances, their study, at the palaeogenomic level, can provide important information about population dynamics, culture changes, and the lifestyles of our ancestors. In this study, mitochondrial and nuclear genome data obtained from human bone remains associated with the Neolithic Globular Amphorae culture, which were recovered in the Megalithic barrow of Kierzkowo (Poland), were reanalysed to gain insight into the social organisation and use of the archaeological site and to provide information at the individual level. We were able to successfully estimate the minimum number of individuals, sex, kin relationships, and phenotypic traits of the buried individuals, despite the low level of preservation of the bone samples and the intricate taphonomic conditions. In addition, the evaluation of damage patterns allowed us to highlight the presence of “intruders”—that is, of more recent skeletal remains that did not belong to the original burial. Due to its characteristics, the study of the Kierzkowo barrow represented a challenge for the reconstruction of the biological profile of the human community who exploited it and an excellent example of the contribution that ancient genomic analysis can provide to archaeological reconstruction.

case study
human remain
archaeological reconstruction


Mesozoic and Tertiary Anura of Laurasia

Abstract: Anurans of Laurasia have a long history that begins with the earliest known anuran, Prosalirus, from the Early Jurassic of Arizona, USA. At that time, western Laurasia (North America) was still connected with Gondwana, so faunal interchange was still possible between those parts of the former Pangean supercontinent. The anuran fossil record from the Jurassic and Cretaceous of Laurasia is mainly represented by disarticulated skeletal elements similar to those of Prosalirus (e.g. amphicoelous vertebrae indicating the presence of continuous notochord; ilia without dorsal crest and dorsal tubercle; small body size). Because the morphology of the ilium, the most commonly preserved element of Mesozoic anurans, superficially recalls that of Recent Alytes, Bombina or Pelobates , Mesozoic anurans often were assigned to discoglossids and pelobatids. The Cretaceous portion of the Laurasian anuran record is marked by the appearance of procoelous and opisthocoelous vertebrae, ilia bearing a dorsal crest and dorsal tubercle (although such ilia may rarely be found as early as in the Jurassic) and larger body sizes. Cretaceous anuran assemblages include a mix of generalised taxa that are comparable to Recent basal anurans and more specialised taxa lacking clear affinities with any extant anurans. Some of these forms survived into the Paleocene, but in general anuran faunas on all Laurasian continents were markedly depleted in the Paleocene. Major groups of anurans appeared in the Eocene. The early Miocene is the interval when Eurasian and American herpetofaunas reached their peak taxonomic diversities. In the Pliocene, some extant anuran species appeared, but at the same time taxa that had been dominant throughout the Oligocene and Miocene (e.g. Eopelobates , palaeobatrachids) became extinct during this interval or during the subsequent Pleistocene glaciation. The brief biochronological synopsis presented here is followed by a systematic review of taxa with their diagnoses and published data on their stratigraphic and geographic distributions.

laurasia
north america
miocene
europe
ontogenetic series


Decoupled Plant and Insect Diversity After the End-Cretaceous Extinction

Abstract: Food web recovery from mass extinction is poorly understood. We analyzed insect-feeding damage on 14,999 angiosperm leaves from 14 latest Cretaceous, Paleocene, and early Eocene sites in the western interior United States. Most Paleocene floras have low richness of plants and of insect damage. However, a low-diversity 64.4-million-year-old flora from southeastern Montana shows extremely high insect damage richness, especially of leaf mining, whereas an anomalously diverse 63.8-million-year-old flora from the Denver Basin shows little damage and virtually no specialized feeding. These findings reveal severely unbalanced food webs 1 to 2 million years after the end-Cretaceous extinction 65.5 million years ago.


The Eocene–Oligocene transition: a review of marine and terrestrial proxy data, models and model–data comparisons

Abstract: Abstract. The Eocene-Oligocene transition (EOT) from a largely ice-free greenhouse world to an icehouse climate with the first major glaciation of Antarctica was a phase of major climate and environmental change occurring ~34 million years ago (Ma) and lasting ~500 kyr. The change is marked by a global shift in deep sea δ18O representing a combination of deep-ocean cooling and global ice sheet growth. At the same time, multiple independent proxies for sea surface temperature indicate a surface ocean cooling, and major changes in global fauna and flora record a shift toward more cold-climate adapted species. The major explanations of this transition that have been suggested are a decline in atmospheric CO2, and changes to ocean gateways, while orbital forcing likely influenced the precise timing of the glaciation. This work reviews and synthesises proxy evidence of paleogeography, temperature, ice sheets, ocean circulation, and CO2 change from the marine and terrestrial realms. Furthermore, we quantitatively compare proxy records of change to an ensemble of model simulations of temperature change across the EOT. The model simulations compare three forcing mechanisms across the EOT: CO2 decrease, paleogeographic changes, and ice sheet growth. We find that CO2 forcing provides by far the best explanation of the combined proxy evidence, and based on our model ensemble, we estimate that a CO2 decrease of about 1.6× across the EOT (e.g. from 910 to 560  ppmv) achieves the best fit to the temperature change recorded in the proxies. This model-derived CO2 decrease is consistent with proxy estimates of CO2 decline at the EOT.

proxy data
eot
antarctica
cooling
major change


The complete lithostratigraphic section of the geothermal wells in Rittershoffen (Upper Rhine Graben, eastern France): a key for future geothermal wells

Abstract: Between 2012 and 2014, in Rittershoffen, in the Upper Rhine Graben, two geothermal boreholes (GRT-1 and GRT-2) reached the granitic basement at a depth of around 2150 m. The wells crossed about 1160 m of Cenozoic and 1050 m of Mesozoic. In the Cenozoic, these wells crossed the greatest part of the Eocene, the lower part of the Oligocene and a thinner Pliocene. The Quaternary is poorly represented (less than 10 m). In the Mesozoic, the wells crossed the Lower Dogger, the entire Lias and the entire Triassic. A reduced thickness of about 50 m of Upper Permian terminates the sedimentary column before entering into the granitic basement. A major erosional unconformity separates the Middle Jurassic from the Tertiary units (the Upper Jurassic, entire Cretaceous and Paleocene are absent). The Rittershoffen drilled doublets were the subject of particular attention concerning the acquisition of a very precise stratigraphic profile. In this paper, we give the recognition criteria for the fifty-seven formations crossed by the GRT-1 well and their upper and lower boundaries as well as their specific gamma ray signatures. The data are presented in four figures: a general complete log displaying the main sets and three detailed, precise logs showing the sedimentary formations overhanging the granitic basement: the Tertiary, the Jurassic, the Triassic, the Permian and the basement.

geothermal borehole
granite
mesozoic sedimentary succession
paleozoic
landau


A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology

Abstract: Azhdarchid pterosaurs were among the most widespread and successful of pterosaur clades, but their paleoecology remains controversial. Morphological features common to all azhdarchids include a long, shallow rostrum; elongate, cylindrical cervical vertebrae that formed a long and unusually inflexible neck; and proportionally short wings with an abbreviated fourth phalanx. While azhdarchids have been imagined as vulture-like scavengers, sediment probers, swimmers, waders, aerial predators, or stork-like generalists, most recent authors have regarded them as skim-feeders, trawling their lower jaws through water during flight and seizing aquatic prey from the water's surface. Although apparently widely accepted, the skim-feeding model lacks critical support from anatomy and functional morphology. Azhdarchids lack the many cranial specialisations exhibited by extant skim-feeding birds, most notably the laterally compressed lower jaw and shock absorbing apparatus required for this feeding style. Well-preserved azhdarchid skulls are rare, but their rostra and lower jaws appear to have been sub-triangular in cross-section, and thus dissimilar to those of skim-feeders and sediment probers. Taphonomic data indicates that azhdarchids predominately inhabited inland settings, and azhdarchid morphology indicates that they were poorly suited for all proposed lifestyles bar wading and terrestrial foraging. However, azhdarchid footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading. We argue that azhdarchids were stork- or ground hornbill-like generalists, foraging in diverse environments for small animals and carrion. Proficient terrestrial abilities and a relatively inflexible neck are in agreement with this interpretation.

azhdarchid
morphology
paleoecology
vertebrae
low jaw


THE ENIGMATIC EARLY CAMBRIAN SALANYGOLINA– A STEM GROUP OF RHYNCHONELLIFORM CHILEATE BRACHIOPODS?

Abstract: Abstract:  New material of the enigmatic brachiopod Salanygolina obliqua Ushatinskaya from the Early Cambrian of Mongolia shows that it has a colleplax– a triangular plate – in the umbonal perforation, which is enlarged by resorption. This structure is otherwise only known from the equally enigmatic Palaeozoic orders Chileida and Dictyonellida (Rhynchonelliformea, Chileata). The colleplax in Salanygolina is here considered to be homologous with that of the chileates. Salanygolina is also provided with a ridge‐like pseudodeltidium, which is another chileate feature. Other characters of Salanygolina, like the radial arrangement of adductor muscle scars and postero‐medially placed internal oblique muscles are characteristic of chileates, but also found in the paterinates. In contrast, mixoperipheral dorsal valves with low rudimentary interareas are well known in paterinates, but not yet recorded from chileates. Thus, Salanygolina shows a mosaic combination of morphologic characters, known both from the paterinates and chileates, indicating that it may represent a stem group of the rhynchonelliform chileate brachiopods. The laminar phosphatic secondary shell of Salanygolina is composed of closely packed and nearly identical hexagonal prisms, oriented with their long axis normal to the laminae in a honeycomb pattern. The prism walls appear to have originally been composed of organic membranes and might represent precursors of the organic sheaths of calcite fibers that are typical of calcitic shells with a fibrous microstructure.

salanygolina
stem group
hexagonal prism
laminae


New method to estimate paleoprecipitation using fossil amphibians and reptiles and the middle and late Miocene precipitation gradients in Europe

Abstract: Existing methods for determining paleoprecipitation are subject to large errors (6350- 400 mm or more using mammalian proxies), or are restricted to wet climate systems due to their strong facies dependence (paleobotanical proxies). Here we describe a new paleo- precipitation tool based on an indexing of ecophysiological groups within herpetological communities. In recent communities these indices show a highly significant correlation to annual precipitation (r 2 5 0.88), and yield paleoprecipitation estimates with average errors of 6250-280 mm. The approach was validated by comparison with published paleopre- cipitation estimates from other methods. The method expands the application of paleo- precipitation tools to dry climate systems and in this way contributes to the establishment of a more comprehensive paleoprecipitation database. This method is applied to two high- resolution time intervals from the European Neogene: the early middle Miocene (early Langhian) and the early late Miocene (early Tortonian). The results indicate that both periods show significant meridional precipitation gradients in Europe, these being stronger in the early Langhian (threefold decrease toward the south) than in the early Tortonian (twofold decrease toward the south). This pattern indicates a strengthening of climatic belts during the middle Miocene climatic optimum due to Southern Hemisphere cooling and an increased contribution of Arctic low-pressure cells to the precipitation from the late Miocene onward due to Northern Hemisphere cooling.

paleoprecipitation
europe
annual precipitation


Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

Abstract: Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ∼40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ∼8× PAL to ∼5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction.

glacial maximum
latitudinal temperature gradient
polar front


Cope's Rule in a modular organism: Directional evolution without an overarching macroevolutionary trend

Abstract: Cope's Rule describes increasing body size in evolutionary lineages through geological time. This pattern has been documented in unitary organisms but does it also apply to module size in colonial organisms? We address this question using 1169 cheilostome bryozoans ranging through the entire 150 million years of their evolutionary history. The temporal pattern evident in cheilostomes as a whole shows no overall change in zooid (module) size. However, individual subclades show size increases: within a genus, younger species often have larger zooids than older species. Analyses of (paleo)latitudinal shifts show that this pattern cannot be explained by latitudinal effects (Bergmann's Rule) coupled with younger species occupying higher latitudes than older species (an “out of the tropics” hypothesis). While it is plausible that size increase was linked to the advantages of large zooids in feeding, competition for trophic resources and living space, other proposed mechanisms for Cope's Rule in unitary organisms are either inapplicable to cheilostome zooid size or cannot be evaluated. Patterns and mechanisms in colonial organisms cannot and should not be extrapolated from the better‐studied unitary organisms. And even if macroevolution simply comprises repeated rounds of microevolution, evolutionary processes occurring within lineages are not always detectable from macroevolutionary patterns.

cheilostome bryozoan
evolutionary history
zooid
cope


The laterosphenoid bone of early archosauriforms

Abstract: ABSTRACT The laterosphenoid is an ossification of the pila antotica neurocranial cartilage in the anterior sidewall of the braincase of crocodylians and birds. Contrary to published reports, the bone is present in the basal archosauriforms Proterosuchus fergusi, Euparkeria capensis, and Erythrosuchidae, taxa that diverged prior to the origin of the archosaurian crown group. Its presence is thus a synapomorphy of Archosauriformes rather than of Archosauria. The bone appears to have been induced by shifting jaw muscle origins from the skull roof to the anterolateral wall of the braincase. Additional innovations in the archosauriform feeding apparatus, such as a mandibular fenestra, appear to reflect changes in jaw muscles that may, in turn, facilitate predaceous habits. We review the historical development of the names of bones in the anterior sidewall of the amniote braincase and argue for the use of the term laterosphenoid, rather than either pleurosphenoid or orbitosphenoid, for this bone in all Archosau...

laterosphenoid
archosauriformes
ossification
pila antotica


The Euro-American genus Eopelobates, and a re-definition of the family Pelobatidae (Amphibia, Anura)

Abstract: The extinct Eopelobates (Eocene of western North America; Eocene-Pliocene of Europe) and Pelobates (Oligocene-Recent of Europe; Recent of northern Africa and the Middle East) are superficially toad-like anurans that are united within the family Pelobatidae mainly on the basis of a unique, tripartite frontoparietal complex. Both genera have a relatively good fossil record consisting of isolated bones, skeletons, and developmental series of tadpoles through adults, all of which are potentially informative for tracing the evolutionary history of the family. Eopelobates is of interest for several reasons. Of the two pelobatid genera, Eopelobates appears earlier in the fossil record (early Eocene vs. late Oligocene) and it is more primitive in lacking many of the features associated with fossoriality in extant Pelobates. The taxonomic composition of Eopelobates has been contentious and at least one putative new species has long been recognised, but never formally named. Here, we provide updated taxonomic accounts for Pelobatoidea, Pelobatidae, Pelobates, and Eopelobates and document development within a series of tadpoles and juveniles of E. bayeri from Bechlejovice (late Oligocene in age), Czech Republic. We also provide updated accounts for the five previously named and currently accepted species of Eopelobates. For the European congeners, E. anthracinus (late Oligocene) and E. bayeri (early Oligocene-middle Miocene) can confidently be regarded as separate species; although the distinction between E. hinschei and E. wagneri (both middle Eocene) is less certain, we provisionally maintain them as separate species. Micro-CT scans for the holotype skeleton of E. grandis (latest Eocene, USA) help resolve some problematic features, most notably showing that the cranial sculpture is of the pit-and-ridge style that is typical for Eopelobates. A sixth congener is named and described based on two skeletons from the middle Eocene portion of the Green River Formation, in Wyoming, USA. We caution that reports of Eopelobates-like anurans from the pre-Eocene of western North America and the early Eocene of India are based on isolated bones that cannot be assigned with confidence to that genus. The presence of Eopelobates in both North America and Europe may be explained by dispersal via the high latitude land bridge that connected those two continents during the late Paleocene through Eocene. The pelobatid fossil record is informative for documenting the nature and timing of changes in cranial features (e.g. ornament patterns, shape of nasals, pattern of frontoparietal-squamosal contact) from the inferred primitive condition seen in most Eopelobates to the more derived condition seen in extant Pelobates, but it is less informative for tracing the evolution of fossoriality, which is a key attribute of extant Pelobates.

family pelobatidae
north america
pelobates
oligocene


New Information on the Pterosaur Tupandactylus imperator, with Comments on the Relationships of Tapejaridae

Abstract: A new specimen of Tupandactylus imperator, comprising an incomplete skull with associated lower jaw, is described. The material is the best preserved specimen of this species known so far and provides new information on the anatomy of this pterodactyloid pterosaur, especially with respect to the morphology of the lower jaw, the first one formally described for the species. Also, the new specimen shows an extensive preservation of soft tissues such as the soft-tissue component of the headcrest, ramphoteca associated with the premaxillae and lower jaw, as well as probable pycnofibres. A phylogenetic analysis was performed in order to test the relationships of the taxon within Tapejaridae. The results of the analysis support Tapejaridae, as well as monophyly of Tapejarinae and Thalassodrominae.

tapejaridae
skull
respect
new information


Diverse new Middle Jurassic Osmylopsychopidae (Neuroptera) from China shed light on the classification of psychopsoids

Abstract: A well-preserved diverse fauna of fossil neuropterans of the family Osmylopsychopidae has been discovered at the Middle Jurassic locality of Daohugou, China. Daopsychops dissectus gen. et sp. nov., D. clausus gen. et sp. nov., D. inanis gen. et sp. nov., D. bifasciatus gen. et sp. nov., D. cubitalis gen. et sp. nov., Eupypsychops ferox gen. et sp. nov., E. confinis gen. et sp. nov., Nematopsychops unicus gen. et sp. nov., Ochropsychops multus gen. et sp. nov. and Stenopteropsychops trifasciatus gen. et sp. nov. are described. These new taxa allow a better understanding of the relationships between the psychopsoid families Osmylopsychopidae, Psychopsidae and Brongniartiellidae. The type of the latter (Brongniartiella gigas from the Late Jurassic of Germany) is redescribed. The venation of the new genera of Osmylopsychopidae shows that Brongniartiellidae is a synonym of this family. Of the genera ascribed to Brongniartiellidae, only Pseudopsychopsis belongs to Osmylopsychopidae with certainty. Gigantopsychops reticulatus gen. et sp. nov. from Daohugou (Psychopsidae) is an important taxon providing a new insight into the definition of the family. Wings of Psychopsidae may be distinguished from those of Osmylopsychopidae by a combination of the following character states: in both wings, the costal space is very broad distally; Rs1 is not deeply forked; the distal nygma is lost; the distal R1 is straight, not curved posteriad; in the hind wing, 1r-m is short and straight. It is clear now that the family Osmylopsychopidae was a dominant psychopsoid group during the Mesozoic, and Psychopsidae was relatively rare. http://zoobank.org/urn:lsid:zoobank.org:pub:E3E3F401-747F-427B-A46C-51B4148A5D0D


THE FOSSIL RECORD AND EVOLUTION OF MOUSEBIRDS (AVES: COLIIFORMES)

Abstract: Abstract:  Recent mousebirds are the smallest of the living neognathous bird orders – just two genera comprising six species. Understanding the evolutionary dynamics of this avian lineage is important because these birds occupy a critical position within Neoaves and can be used as a model for patterns of morphological diversification in other taxa. We present a review of all known fossil mousebirds (Aves: Coliiformes), which formed a diverse assemblage in the Paleogene (65–23.8 ma). We also present a new phylogenetic analysis including the living and fossil representatives of the order, on the basis of a larger character/taxon matrix. This analysis suggests that the Lower Eocene Eocolius is the most basal member of clade Coliiformes, while the Lower–Middle Eocene Sandcoleidae form a basal clade with respect to all other known coliiforms. We show that the Eocene taxon Chascacocolius is the sister group of the crown Coliidae, and that the Middle Eocene taxon Selmes is basal to a clade comprising Chascacocolius and Coliidae. On the basis of this phylogenetic analysis, we propose a new classification for the order Coliiformes including two new families, Chascacocoliidae and Selmeidae. For all families (clades) of mousebirds we provide descriptive osteological diagnoses and discuss a number of functional considerations related to the evolution of their hindlimbs; these considerations can be extended across all extant and fossil perching birds because we show that the hindlimb morphology of Coliiformes is strongly related to their lifestyle, as reflected in their evolutionary history.


Comparative cranial morphology of the Late Cretaceous protostegid sea turtle Desmatochelys lowii

Abstract: Background The phylogenetic placement of Cretaceous marine turtles, especially Protostegidae, is still under debate among paleontologists. Whereas protostegids were traditionally thought to be situated within the clade of recent marine turtles (Chelonioidea), some recent morphological and molecular studies suggest placement along the stem of Cryptodira. The main reason why the evolution of marine turtles is still poorly understood, is in part due to a lack of insights into the cranial anatomy of protostegids. However, a general availability of high-quality fossil material, combined with modern analysis techniques, such as X-ray microtomography, provide ample opportunity to improve this situation. The scope of this study is to help resolve its phylogenetic relationships by providing a detailed description of the external and internal cranial morphology of the extinct protostegid sea turtle Desmatochelys lowii Williston, 1894. Material and Methods This study is based on the well-preserved holotype of Desmatochelys lowii from the Late Cretaceous (middle Cenomanian to early Turonian) Greenhorn Limestone of Jefferson County, Nebraska. The skulls of two recent marine turtles, Eretmochelys imbricata (Linnaeus, 1766) (Cheloniidae) and Dermochelys coriacea Lydekker, 1889 (Dermochelyidae), as well as the snapping turtle Chelydra serpentina (Linnaeus, 1758) (Chelydridae) provide a comparative basis. All skulls were scanned using regular or micro CT scanners and the scans were then processed with the software program Amira to create 3D isosurface models. In total, 81 bones are virtually isolated, figured, and described, including the nature of their contacts. The novel bone contact data is compiled and utilized in a preliminary phenetic study. In addition, an update phylogenetic analysis is conduced that utilizes newly obtained anatomical insights. Results The detailed examination of the morphology of the herein used specimens allowed to explore some features of the skull, to refine the scoring of Desmatochelys lowii in the recent global matrix of turtles, and develop five new characters. The alleged pineal foramen in the type skull of Desmatochelys lowii is shown to be the result of damage. Instead, it appears that the pineal gland only approached the skull surface, as it is in Dermochelys coriacea. Whereas the parasphenoid in confirmed to be absent in hard-shelled sea turtles, ist possible presence in Desmatochelys lowii is unclear. The results of the phenetic study show that Desmatochelys lowii is least similar to the other examined taxa in regards to the nature of its bone contacts, and therefore suggests a placement outside Americhelydia for this protostegid sea turtle. The phylogenetic study results in a placement of Protostegidae along the stem of Chelonioidea, which is a novel position for the group.

cranial morphology
turtle
protostegidae
cheloniidae


Comparison of spatial downscaling methods of general circulation model results to study climate variability during the Last Glacial Maximum

Abstract:
Abstract. The extent to which climate conditions influenced the spatial
distribution of hominin populations in the past is highly debated.
General circulation models (GCMs) and archaeological data have been
used to address this issue. Most GCMs are not currently capable of
simulating past surface climate conditions with sufficiently
detailed spatial resolution to distinguish areas of potential
hominin habitat, however. In this paper, we propose a statistical
downscaling method (SDM) for increasing the resolution of climate
model outputs in a computationally efficient way. Our method uses a
generalised additive model (GAM), calibrated over present-day
climatology data, to statistically downscale temperature and
precipitation time series from the outputs of a GCM simulating the
climate of the Last Glacial Maximum (19 000–23 000 BP) over western
Europe. Once the SDM is calibrated, we first interpolate the
coarse-scale GCM outputs to the final resolution and then use the
GAM to compute surface air temperature and precipitation levels
using these interpolated GCM outputs and fine-resolution
geographical variables such as topography and distance from an
ocean. The GAM acts as a transfer function, capturing non-linear
relationships between variables at different spatial scales and
correcting for the GCM biases. We tested three different techniques
for the first interpolation of GCM output: bilinear, bicubic and
kriging. The resulting SDMs were evaluated by comparing downscaled
temperature and precipitation at local sites with paleoclimate
reconstructions based on paleoclimate archives (archaeozoological
and palynological data) and the impact of the interpolation
technique on patterns of variability was explored. The SDM based on
kriging interpolation, providing the best accuracy, was then
validated on present-day data outside of the calibration period. Our
results show that the downscaled temperature and precipitation
values are in good agreement with paleoclimate reconstructions at
local sites, and that our method for producing fine-grained
paleoclimate simulations is therefore suitable for conducting
paleo-anthropological research. It is nonetheless important to
calibrate the GAM on a range of data encompassing the data to be
downscaled. Otherwise, the SDM is likely to overcorrect the
coarse-grain data. In addition, the bilinear and bicubic
interpolation techniques were shown to distort either the temporal
variability or the values of the response variables, while the
kriging method offered the best compromise. Since climate
variability is an aspect of the environment to which human
populations may have responded in the past, the choice of
interpolation technique is therefore an important consideration.

glacial maximum
climate condition
topography
spatial scale


Advances in insect phylogeny at the dawn of the postgenomic era.

Abstract: Most species on Earth are insects and thus, understanding their evolutionary relationships is key to understanding the evolution of life. Insect relationships are increasingly well supported, due largely to technological advances in molecular sequencing and phylogenetic computational analysis. In this postgenomic era, insect systematics will be furthered best by integrative methods aimed at hypothesis corroboration from molecular, morphological, and paleontological evidence. This review of the current consensus of insect relationships provides a foundation for comparative study and offers a framework to evaluate incoming genomic evidence. Notable recent phylogenetic successes include the resolution of Holometabola, including the identification of the enigmatic Strepsiptera as a beetle relative and the early divergence of Hymenoptera; the recognition of hexapods as a crustacean lineage within Pancrustacea; and the elucidation of Dictyoptera orders, with termites placed as social cockroaches. Regions of the tree that require further investigation include the earliest winged insects (Palaeoptera) and Polyneoptera (orthopteroid lineages).


Mitochondrial haplotypes and phylogeography of Phlebotomus vectors of Leishmania major

Abstract: Haplotypes of eight phlebotomine species were characterized by cycle sequencing a mitochondrial (mt) DNA fragment (cytochrome b to NADH1) amplified from single sandflies by PCR. Phlebotomus (Phlebotomus) papatasi displayed little variation throughout its large geographical range. We conclude that this vector of Leishmania major suffered a population bottleneck late in the Pleistocene and then radiated out from the eastern Mediterranean subregion. There was no support for a recent domestic lineage of P. papatasi. The mtDNA molecular clock in phlebotomines (subgenera Phlebotomus and Larroussius) was calibrated by reference to palaeogeographical events in Africa and the Mediterranean subregion. It fitted a pairwise nucleotide sequence divergence rate of 1.0–2.5% per million years. Co‐evolution of L. major, its Phlebotomus vectors and mammalian reservoirs is discussed.

phlebotomus vector
leishmania major
mediterranean sandfly fauna
miocene diversification
speciation


A Complete Reconstruction of the Hyolithid Skeleton

Abstract: Abstract Hyolithids are a group of Paleozoic lophotrochozoans with a four-pieced skeleton consisting of a conch, an operculum, and a pair of lateral ‘spines' named helens. Both the conch and operculum are relatively well known and, to a certain extent, have modern analogues in other lophotrochozoan groups. The helens, on the other hand, are less well known and do not have clear modern analogues. This has hindered the knowledge of the complete morphology of the hyolithid skeleton, as well as other aspects of hyolithid biology, such as the organization of soft parts, and their ability to move. The material studied herein, consisting of disarticulated skeletal elements from the Silurian of Gotland, Sweden, illustrates a complete developmental sequence of a hyolithid species and includes the first complete, three-dimensionally preserved helens. Our material confirms that helens were massive skeletal elements, whose growth started proximally with the deposition of a central, coherent lamella. Further shell accretion took place around this lamella, but followed a particular accretion pattern probably constrained by the presence of marginal muscle attachment sites on the proximal-most portion of the helens. These muscle attachment sites were ideally located to allow a wide range of movements for the helens, suggesting that hyolithids may have been relatively mobile organisms.

hyolithid skeleton
conch
operculum
pair
spine


Infaunal molting in Trilobita and escalatory responses against predation

Abstract: The outstanding fossil record of trilobites contrasts with our limited knowledge of their lifestyles and strategies. Aspects such as infaunalism and behavioral defensive skills in this group have yet to be demonstrated conclusively. We report new insights based on a striking sclerite configuration exhibited by three phacopid trilobite species, part of a late Silurian–Early Devonian Paciphacops ( Paciphacops ) Maksimova, 1972, lineage. An unusual molt pattern provides compelling evidence of infaunal behavior, which accounts for a hiding, antipredatory adaptation. In addition, strengthening of the exoskeleton and acquisition of spines indicate an evolutionary trend toward morphological defensive strategies. Both trends in active and passive traits are considered escalatory in nature, thus providing unequivocal support for understanding the ecological role of trilobites as a main prey group in the context of the global diversification of predators recorded during middle Paleozoic time.

predation
trilobite moulting
environment


Phylogeny of the great cats (Felidae: Pantherinae), and the influence of fossil taxa and missing characters

Abstract: Molecular phylogenetic studies of the extant Pantherinae have resulted in a variety of different hypotheses of relationships. This study presents the results of a cladistic study encompassing 45 osteological and dental characters in the skull and mandible, as well as 13 soft‐tissue and behavioural characters. Analyzing extant pantherines with osteological data only resulted in two equally parsimonious trees, which differed only with respects to the jaguar, a taxon which shows morphological affinity to the tiger as well as the lion + leopard. Addition of soft‐tissue characters resolved this ambiguity, and led to markedly improved bootstrap values. The inclusion of fossil taxa did not have an impact on topology, but was important for a correct understanding of character evolution, due to the fossils having a combination of characters unlike those of any extant taxon. The clouded leopard is the most basal pantherine, followed by the snow leopard. The large pantherines are a well supported group, to which the snow leopard does not belong, contrary to some molecular studies. Panthera palaeosinensis is no tiger, but may be close to the stem group from which the tiger evolved. P. atrox and P. spelaea are not on the lion lineage, as traditionally assumed, but are successive outgroups to the lion + leopard, although the position of P. spelaea is tentative, but is supported by other lines of evidence such as brain anatomy.

pantherinae
fossil taxa
lion
leopard
outgroup


Pluridisciplinary evidence for burial for the La Ferrassie 8 Neandertal child

Abstract: The origin of funerary practices has important implications for the emergence of so-called modern cognitive capacities and behaviour. We provide new multidisciplinary information on the archaeological context of the La Ferrassie 8 Neandertal skeleton (grand abri of La Ferrassie, Dordogne, France), including geochronological data -14C and OSL-, ZooMS and ancient DNA data, geological and stratigraphic information from the surrounding context, complete taphonomic study of the skeleton and associated remains, spatial information from the 1968–1973 excavations, and new (2014) fieldwork data. Our results show that a pit was dug in a sterile sediment layer and the corpse of a two-year-old child was laid there. A hominin bone from this context, identified through Zooarchaeology by Mass Spectrometry (ZooMS) and associated with Neandertal based on its mitochondrial DNA, yielded a direct 14C age of 41.7–40.8 ka cal BP (95%), younger than the 14C dates of the overlying archaeopaleontological layers and the OSL age of the surrounding sediment. This age makes the bone one of the most recent directly dated Neandertals. It is consistent with the age range for the Châtelperronian in the site and in this region and represents the third association of Neandertal taxa to Initial Upper Palaeolithic lithic technocomplex in Western Europe. A detailed multidisciplinary approach, as presented here, is essential to advance understanding of Neandertal behavior, including funerary practices.

burial
child
archaeological context
dna data
western europe


Autochthonous to parautochthonous bivalve concentrations within transgressive marginal marine strata of the Upper Jurassic of Portugal

Abstract: Bivalve concentrations are a conspicuous feature of the Upper Jurassic rock succession of the central Lusitanian Basin. In order to illustrate the mode of their formation and their palaeoecological and sequence stratigraphic significance, we describe and interpret in detail 27 assemblages of bivalves based on their taphonomic and ecological features. Bivalve concentrations are particularly widespread in marginally marine, salinity-controlled environments and less common in open shelf settings. Only the Eomiodon and Myophorella concentrations are dominated by a shallow infaunal bivalve; all other concentrations are composed mainly of epi-or endobyssate [Isognomon (Rostroperna), I. (Isognomon), Pteria, Alaperna, Juranomia] and cementing taxa (Praeexogyra, Actinostreon). Most of the concentrations are mono-to paucispecific, except for the highly diverse Alaperna polita-Pteria credneriana concentrations, which occur in nearshore shelf environments. Lack of sorting, a high percentage of articulated shells, and shells preserved in growth position are evidence that, with few exceptions, the concentrations are autochthonous. Main factors leading to their formation are, apart from a gregarious life habit, a high productivity and a reduced rate of sedimentation. Autogenic and allogenic successional stages can be recognized on the basis of their spatial separation. The time involved in the formation of the concentrations is generally in the order of 10 2 -10 3 years. Due to the lack of compositional changes within concentrations, time-averaging played no or only a minor role, except in the Alaperna polita-Pteria credneriana concentrations. In sequence stratigraphic terms, most of the concentrations are the product of the maximum flooding zone, but in some cases they constitute the transgressive systems tract. Invariably, they are useful tools for defining depositional sequences. Several of the concentrations described here are not restricted to the Lusitanian Basin but also occur elsewhere in the epicontinental seas bordering the northern margin of the Neotethys.

bivalve concentration
benthic faunal association
palaeoenvironment
late jurassic unit


The Big Deal about Blades: Laminar Technologies and Human Evolution

Abstract: Despite the rapid expansion of archaeological knowledge of the Paleolithic over the past several decades, some generalized interpretive frameworks inherited from previous generations of researchers are remarkably tenacious. One of the most persistent of these is the assumed correlation between blade technologies, Upper Paleolithic industries, and anatomically (and behaviorally) modern humans. In this paper, we review some of the evidence for the production of early blade technologies in Eurasia and Africa dating to the late Lower and the Middle Paleolithic. The basic techniques for blade production appeared thousands of years before the Upper Paleolithic, and there is no justification for linking blades per se to any particular aspect of hominid anatomy or to any major change in the behavioral capacities of hominids. It is true that blades came to dominate the archaeological records of western Eurasia and Africa after 40,000 years ago, perhaps as a consequence of increasing reliance on complex composite tools during the Upper Paleolithic. At the same time, evidence from other regions of the world demonstrates that evolutionary trends in Pleistocene Eurasia were historically contingent and not universal. [Middle Paleolithic, Upper Paleolithic, blade technology, human evolution, hominid behavior and capacities]


A standard protocol for documenting modern and fossil ichnological data

Abstract: The collection and dissemination of vertebrate ichnological data is struggling to keep up with techniques that are becoming commonplace in the wider palaeontological field. A standard protocol is required to ensure that data is recorded, presented and archived in a manner that will be useful both to contemporary researchers, and to future generations. Primarily, our aim is to make the 3D capture of ichnological data standard practice, and to provide guidance on how such 3D data can be communicated effectively (both via the literature and other means) and archived openly and in perpetuity. We recommend capture of 3D data, and the presentation of said data in the form of photographs, false‐colour images, and interpretive drawings. Raw data (3D models of traces) should always be provided in a form usable by other researchers (i.e. in an open format). If adopted by the field as a whole, the result will be a more robust and uniform literature, supplemented by unparalleled availability of datasets for future workers.

standard protocol
ichnological data
researcher
recommendation
photogrammetric mesh


Early Miocene CO2 estimates from a Neotropical fossil leaf assemblage exceed 400 ppm.

Abstract:
PREMISE OF THE STUDY
The global climate during the early Miocene was warmer than the present and preceded the even warmer middle Miocene climatic optimum. The paleo-CO2 records for this interval suggest paradoxically low concentrations (<450 ppm) that are difficult to reconcile with a warmer-than-present global climate.

METHODS
In this study, we use a leaf gas-exchange model to estimate CO2 concentrations using stomatal characteristics of fossil leaves from a late early Miocene Neotropical assemblage from Panama that we date to 18.01 ± 0.17 Ma via 238 U/206 Pb zircon geochronology. We first validated the model for Neotropical environments by estimating CO2 from canopy leaves of 21 extant species in a natural Panamanian forest and from leaves of seven Neotropical species in greenhouse experiments at 400 and 700 ppm.

KEY RESULTS
The results showed that the most probable combined CO2 estimate from the natural forests and 400 ppm experiments is 475 ppm, and for the 700 ppm experiments is 665 ppm. CO2 estimates from the five fossil species exhibit bimodality, with two species most consistent with a low mode (528 ppm) and three with a high mode (912 ppm).

CONCLUSIONS
Despite uncertainties, it is very likely (at >95% confidence) that CO2 during the late early Miocene exceeded 400 ppm. These results revise upwards the likely CO2 concentration at this time, more in keeping with a CO2 -forced greenhouse climate.


Hind Limbs of Eocene Basilosaurus: Evidence of Feet in Whales

Abstract: New specimens of middle Eocene Basilosaurus isis from Egypt include the first functional pelvic limb and foot bones known in Cetacea. These are important in corroborating the intermediate evolutionary position of archaeocetes between generalized Paleocene land mammals that used hind limbs in locomotion and Oligocene-to- Recent whales that lack functional pelvic limbs. The foot is paraxonic, consistent with derivation from mesonychid Condylarthra. Hind limbs of Basilosaurus are interpreted as copulatory guides.


Clay Mineralogy, Alteration History, and Economic Geology of the Whitemud Formation, Southern Saskatchewan, Canada

Abstract: The Upper Cretaceous (Maastrichtian) Whitemud Formation is a potentially commercial kaolin deposit located in southern Saskatchewan and southeastern Alberta. The Whitemud Formation contains a lower kaolinitic sandstone, a middle lignite and carbonaceous shale, and an upper interbedded siltstone and claystone. The sediments that comprise the rocks of the Whitemud Formation were deposited on alluvial or upper deltaic plains located along the northwest flank of the Williston Basin.Mineralogy and textures were determined by X-ray powder diffraction, scanning electron microscopy, and optical microscopy. Kaolinite abundance increases upward from the underlying rocks of the Eastend Formation through the Whitemud Formation, and the abundance of smectite, micas, and feldspars decreases from the Eastend Formation into the Whitemud Formation. Vermiform kaolinite crystals are in close spatial association with feldspar and mica grains. Near the top of the Whitemud Formation, etched quartz and feldspar grains, and gibbsite suggest the presence of a strong chemical leaching environment.Mineral distributions, presence of root remains, pédologie mottles, grain coatings composed of clay, and soil horizons indicate the Whitemud Formation sediments were modified by intense weathering in a paleosol environment.Kaolin concentrated from selected kaolinitic sandstone deposits, and beneficiated by oxidation, leaching, and high-intensity wet-magnetic separation has a product brightness up to filler quality. Recovery of lowabrasion kaolin is low and viscosity of a fine-particle kaolin fraction is high. Economics of producing a wet-processed filler-grade kaolin is marginal.

southern saskatchewan
williston basin
clay


Ruminant mandibular tooth mesowear: a new scheme for increasing paleoecological sample sizes

Abstract: Extension of the mesowear method to include the lower cheek teeth of ruminants will dramatically increase sample sizes and thus the statistical power of paleodietary inferences. However, the mesowear method of Fortelius and Solounias, which was designed for application to the upper molars, does not effectively separate ruminant species by diet when applied to the lower teeth. Upper and lower mesowear scores have sometimes been compared among non-analogous cusps (i.e. the buccal cusps of the maxillary teeth, which experience incursion and the buccal cusps of the mandibular teeth, which experience excursion during the chewing stroke). We therefore compare mesowear scores between the buccal cusps of maxillary cheek teeth and the lingual cusps of mandibular cheek for a large sample of ruminants because both cusps experience incursion during the chewing stroke. Using the original mesowear scoring method, we find dietary signal in both the maxillary and mandibular cheek teeth and a high correlation between them using both non-phylogenetic and phylogenetic comparative methods. Noting unique patterns of mesowear among the mandibular teeth, we also propose a new scoring method with additional wear categories that improves dietary inference when applied to the lower teeth and is highly repeatable. We also find that mandibular mesowear scores are consistently lower than for their maxillary counterparts. Although differential wear among the upper and lower teeth is much less apparent when applying our new scoring method, wear differences might relate to anisodonty (i.e. mandibular cheek teeth are narrower). Overall, we recommend our new scoring method for application to the lingual cusps of the lower second molars of fossil ruminants.


A new cardiid bivalve from the Pliocene Baklan Basin (Turkey) and the origin of modern Ponto‐Caspian taxa

Abstract: Abstract:  We present the first record of the cardiid genus Monodacna from the Pliocene of Anatolia, Turkey. Monodacna imrei sp. nov. was found in the Pliocene Killik Formation from the western margin of the Baklan Basin, in very marginal brackish to freshwater lacustrine deposits. The new record extends the stratigraphic range of the modern Ponto‐Caspian genus back into the Pliocene and adds to earlier evidence that modern Ponto‐Caspian taxa originated in the Pliocene of south‐western Turkey.

turkey
modern ponto‐caspian taxa
mollusc assemblage
micromammal fossil
basin-fill


Birth of a biome: insights into the assembly and maintenance of the Australian arid zone biota

Abstract: The integration of phylogenetics, phylogeography and palaeoenvironmental studies is providing major insights into the historical forces that have shaped the Earth's biomes. Yet our present view is biased towards arctic and temperate/tropical forest regions, with very little focus on the extensive arid regions of the planet. The Australian arid zone is one of the largest desert landform systems in the world, with a unique, diverse and relatively well-studied biota. With foci on palaeoenvironmental and molecular data, we here review what is known about the assembly and maintenance of this biome in the context of its physical history, and in comparison with other mesic biomes. Aridification of Australia began in the Mid-Miocene, around 15 million years, but fully arid landforms in central Australia appeared much later, around 1-4 million years. Dated molecular phylogenies of diverse taxa show the deepest divergences of arid-adapted taxa from the Mid-Miocene, consistent with the onset of desiccation. There is evidence of arid-adapted taxa evolving from mesic-adapted ancestors, and also of speciation within the arid zone. There is no evidence for an increase in speciation rate during the Pleistocene, and most arid-zone species lineages date to the Pliocene or earlier. The last 0.8 million years have seen major fluctuations of the arid zone, with large areas covered by mobile sand dunes during glacial maxima. Some large, vagile taxa show patterns of recent expansion and migration throughout the arid zone, in parallel with the ice sheet-imposed range shifts in Northern Hemisphere taxa. Yet other taxa show high lineage diversity and strong phylogeographical structure, indicating persistence in multiple localised refugia over several glacial maxima. Similar to the Northern Hemisphere, Pleistocene range shifts have produced suture zones, creating the opportunity for diversification and speciation through hybridisation, polyploidy and parthenogenesis. This review highlights the opportunities that development of arid conditions provides for rapid and diverse evolutionary radiations, and re-enforces the emerging view that Pleistocene environmental change can have diverse impacts on genetic structure and diversity in different biomes. There is a clear need for more detailed and targeted phylogeographical studies of Australia's arid biota and we suggest a framework and a set of a priori hypotheses by which to proceed.

biome maintenance aridification australia


A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny

Abstract: Recently it was suggested that the phylogenetic clustering of Mesozoic marine reptile lineages, such as thalattosaurs, the very successful fish-shaped ichthyosaurs and sauropterygians (including plesiosaurs), among others, in a so-called ‘superclade’ is an artefact linked to convergent evolution of morphological characters associated with a shared marine lifestyle. Accordingly, partial ‘un-scoring’ of the problematic phylogenetic characters was proposed. Here we report a new, exceptionally preserved and mostly articulated juvenile skeleton of the diapsid reptile, Eusaurosphargis dalsassoi, a species previously recovered within the marine reptile ‘superclade’, for which we now provide a revised diagnosis. Using micro-computed tomography, we show that besides having a deep skull with a short and broad rostrum, the most outstanding feature of the new specimen is extensive, complex body armour, mostly preserved in situ, along its vertebrae, ribs, and forelimbs, as well as a row of flat, keeled ventrolateral osteoderms associated with the gastralia. As a whole, the anatomical features support an essentially terrestrial lifestyle of the animal. A review of the proposed partial character ‘un-scoring’ using three published data matrices indicate that this approach is flawed and should be avoided, and that within the marine reptile ‘superclade’ E. dalsassoi potentially is the sister taxon of Sauropterygia.

eusaurosphargis dalsassoi
diapsida
sauropterygia


Late Cenozoic mammals from northwestern Mexico

Abstract: ABSTRACT Ten geographically restricted vertebrate faunas are recognized in late Cenozoic deposits of northwestern Mexico. The late Hemphillian Yepomera fauna of Chihuahua with 27 mammal genera and the Irvingtonian El Golfo of Sonora with 23 mammal genera are the most diverse and most securely placed in a temporal framework among the ten late Cenozoic faunas of northwestern Mexico. The presently known Hemphillian (early Pliocene) vertebrate record of northwestern Mexico indicates an abundance and diversity of both horses and cricetid rodents, and suggests a center of diversificacion for these mammal groups in Mexico prior to the Great American Interchange.

northwestern mexico
chihuahua
early pliocene


CLASSIFICATION AND CONTROLS OF INTERNAL BANDING IN PALAEOZOIC STROMATOPOROIDS AND COLONIAL CORALS

Abstract: Abstract:  Palaeozoic corals and stromatoporoids exhibit a variety of internal banding phenomena, many of which have been commonly interpreted as annual growth bands. We evaluate bands through analysis of colonial corals and stromatoporoids from three stratigraphic intervals: Upper Ordovician of Manitoba Canada, and Llandovery–Wenlock and Ludlow of Gotland, Sweden. Banding features are divided into four categories: (1) absence of banding; (2) density banding formed by variation in density or form of elements; (3) growth‐interruption banding indicating growth cessation and regeneration; and (4) post‐mortem banding caused by compaction or diagenesis. For discrimination of band types, it is essential to examine internal structures and skeletal margins in thin sections or acetate peels. Species vary considerably in degree and type of banding; each has a distinct pattern of variation. We propose criteria to determine if banding is consistent with seasonally induced growth variation: (1) consistency in band character and thickness; (2) continuity of skeletal growth; (3) marginal features; and (4) evidence of diagenetic alteration. Density bands in tabulate and rugose corals probably represent annual growth variations, but results for stromatoporoids are more ambiguous; although stromatoporoids commonly show banding, unequivocal density banding is poorly developed and growth interruption generated most stromatoporoid banding. Cerioid rugose and tabulate corals possess the thickest density bands; the thinnest bands are in stromatoporoids and heliolitid tabulates.


A new dwarf seal from the late Neogene of South America and the evolution of pinnipeds in the southern hemisphere

Abstract: Along the south‐western coast of South America, three genera of fossil phocids (true seals) have been formally described from the late Neogene: Acrophoca and Piscophoca from Chile and Peru, and, more recently, Hadrokirus from Peru, which all represent medium‐ to large‐sized phocids. Here, we report the discovery of Australophoca changorum gen. et sp. nov., a diminutive phocid from the late Miocene of the Bahía Inglesa Formation (northern Chile) and Pisco Formation (southern Peru), comparable in size with the smallest species of modern phocids. This taxon is based on diagnostic postcranial material, including a humerus that has an elongated deltopectoral crest but lacks an entepicondylar foramen; a femur with a subtrochanteric fossa, among other characters; in combination with a relatively small body size. All these features together distinguish A. changorum from all other reported pinnipeds. This new taxon not only increases the taxonomic and morphological diversity of phocids of the late Neogene of the eastern South Pacific Ocean, but it also provides new insights about the evolutionary history of fossil pinniped assemblages in South America and, broadly, in the southern hemisphere.


Environmental determinants of marine benthic biodiversity dynamics through Triassic–Jurassic time

Abstract: Abstract Ecology is thought to be of crucial importance in determining taxonomic turnover at geological time scales, yet general links between ecology and biodiversity dynamics are still poorly explored in deep time. Here we analyze the relationships between the environmental affinities of Triassic–Jurassic marine benthic genera and their biodiversity dynamics, using a large, taxonomically vetted data set of Triassic–Jurassic taxonomic occurrences. On the basis of binomial probabilities of proportional occurrence counts, we identify environmental affinities of genera for (1) carbonate versus siliciclastic substrates, (2) onshore versus offshore depositional environments, (3) reefs versus level-bottom communities, and (4) tropical versus non-tropical latitudinal zones. Genera with affinities for carbonates, onshore environments, and reefs have higher turnover rates than genera with affinities for siliciclastic, offshore, and level-bottom settings. Differences in faunal turnover are largely due to differences in origination rates. Whereas previous studies have highlighted the direct influence of physical and biological factors in exploring environmental controls on evolutionary rates, our analyses show that the patterns can largely be explained by the partitioning of higher taxa with different evolutionary tempos among environments. The relatively slowly evolving bivalves are concentrated in siliciclastic rocks and in level-bottom communities. Furthermore, separate analyses on bivalves did not produce significant differences in turnover rates between environmental settings. The relationship between biodiversity dynamics and environments in our data set is thus governed by the partitioning of higher taxa within environmental categories and not directly due to greater chances of origination in particular settings. As this partitioning probably has ecological reasons rather than being a simple sampling artifact, we propose an indirect environmental control on evolutionary rates. Affinities for latitudinal zones are not linked to systematically different turnover rates, possibly because of paleoclimatic fluctuations and latitudinal migrations of taxa. However, the strong extinction spike of tropical genera in the Rhaetian calls for an important paleoclimatic component in the end-Triassic mass extinction.

biodiversity dynamic
environmental affinity
fluctuation


Mississippian crinoid biodiversity, biogeography and macroevolution

Abstract: Abstract:  The biodiversity and biogeography of 217 genera of Mississippian crinoids from North America and the British Isles shed light on the macroevolutionary turnover between the Middle Palaeozoic and Late Palaeozoic Crinoid Evolutionary Faunas. This turnover resulted from steady differential extinction among clades during the middle Mississippian after crinoids reached their Phanerozoic peak of generic richness during the early Mississippian. This peak richness was primarily a function of Mississippian originations rather than Devonian–holdover taxa. North America had 100 per cent higher generic richness than the British Isles, but rarefaction analysis adjusts the difference to only 37 per cent higher. Rarefaction demonstrated that North America had increased biodiversity, compared to the British Isles, almost entirely among monobathrid camerates, disparids and primitive cladids. In contrast, diplobathrid camerates, advanced cladids and flexibles had the same generic biodiversity between regions, when compared using rarefaction. The early Mississippian radiation resulted from two primary causes: (1) the expansion of Tournaisian carbonate ramps following the Frasnian mass extinction of reef faunas and (2) the predatory release in the Tournaisian following the end‐Famennian Hangenberg extinction of durophagous fishes. A majority of crinoid genera from the British Isles are cosmopolitan. When combined with rarefaction analysis and evidence for more first occurrences in North America, this suggests higher origination rates in North America, especially when carbonate ramps were widespread. With the gradual reduction in the area of carbonate ramps from the early to late Mississippian, in conjunction with the radiation of new durophagous fishes, camerate crinoids in particular experienced continuous background extinction, without replacement, beginning during the earliest Viséan (late Osagean). By middle Viséan time (late Meramecian) advanced cladids were dominant in all settings. This resulted in the transition from the Middle Palaeozoic to the Late Palaeozoic Crinoid Macroevolutionary Fauna.

biogeography
phanerozoic peak
early mississippian
cladid
crinoid genera


Cranial biomechanics underpins high sauropod diversity in resource-poor environments

Abstract: High megaherbivore species richness is documented in both fossil and contemporary ecosystems despite their high individual energy requirements. An extreme example of this is the Late Jurassic Morrison Formation, which was dominated by sauropod dinosaurs, the largest known terrestrial vertebrates. High sauropod diversity within the resource-limited Morrison is paradoxical, but might be explicable through sophisticated resource partitioning. This hypothesis was tested through finite-element analysis of the crania of the Morrison taxa Camarasaurus and Diplodocus. Results demonstrate divergent specialization, with Camarasaurus capable of exerting and accommodating greater bite forces than Diplodocus, permitting consumption of harder food items. Analysis of craniodental biomechanical characters taken from 35 sauropod taxa demonstrates a functional dichotomy in terms of bite force, cranial robustness and occlusal relationships yielding two polyphyletic functional ‘grades’. Morrison taxa are widely distributed within and between these two morphotypes, reflecting distinctive foraging specializations that formed a biomechanical basis for niche partitioning between them. This partitioning, coupled with benefits associated with large body size, would have enabled the high sauropod diversities present in the Morrison Formation. Further, this provides insight into the mechanisms responsible for supporting the high diversities of large megaherbivores observed in other Mesozoic and Cenozoic communities, particularly those occurring in resource-limited environments.

sauropod diversity
environment
robustness
skull
innovation


150 million years old isopods on fishes: a possible case of palaeo-parasitism

Abstract: Parasites are found in all habitats and within all groups of animals, and their influence on food webs, ecosystems and evolutionary development is significant. However, the fossil record of direct parasitism is very scarce. We present here probable examples of parasitic isopods on fishes from the Upper Jurassic Solnhofen Lithographic Limestones (150 million years old, southern Germany). Individual fishes appear to be infested with one to three isopods each. All specimens were documented with up-to-date imaging methods (macrophotography, stereo-photography, composite imaging). Position, orientation and other aspects clearly indicate that the isopods were already attached to the fishes before they died and hence do not represent scavengers but (more or less permanently) attached parasites. While the morphology of the specimens is somewhat uninformative about the systematic position of the isopods, their specific type of parasitism is an indicator for a position in the early lineage towards Cymothoidae. This would represent the first fossil record of this group of obligate fish parasites.


Redescription of Hexaconularia He and Yang, 1986 (Lower Cambrian, South China): implications for the affinities of conulariid‐like small shelly fossils

Abstract: Abstract:  Hexaconularia, a Lower Cambrian small shelly fossil (SSF) that has been allied with conulariids and scyphozoan cnidarians, is redescribed and refigured. A salient feature of this monospecific genus is the presence of distinct apical and abapical regions. The apical region probably represents an embryonic shell that apparently lacked a basal attachment structure. Comparisons of this feature with the apical end of the smallest known conulariids and with conulariids terminating in an apical wall (schott) reveal substantial differences in structure and ornamentation. Differences in apical anatomy between conulariids and Arthrochites, possibly the nearest SSF relative of Hexaconularia, are also apparent. Comparisons of Hexaconularia with Punctatus, an SSF taxon showing distinct apical and abapical regions in both posthatching specimens and prehatching embryos, suggest that the early development of Hexaconularia was direct. These results have important implications for hypotheses of a conulariid/scyphozoan affinity for Hexaconularia and its possible SSF relatives, and they suggest that Hexaconularia‐bearing strata may yield prehatching embryos of this genus.

small shelly fossil
conulariid
embryonic shell


The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals

Abstract: Let There Be Mammals The timing of the evolution and radiation of placental mammals and their most recent common ancestor has long been debated, with many questions surrounding the relationships of groups that pre- and postdate the Cretaceous-Paleogene boundary (66 million years ago). While the fossil record suggests that placental mammals radiated after the Cretaceous, molecular clocks have consistently placed the ancestors of mammalian lineages earlier. O'Leary et al. (p. 662; see the Perspective by Yoder) examined the morphology of fossil and extant taxa and conclude that living placentals originated and radiated after the Cretaceous and reconstruct the phenotype of the ancestral placental mammal. Fossil and DNA phylogenies suggest that placental mammals diversified in the Cenozoic and reconstruct the ancestral form. [Also see Perspective by Yoder] To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated with fossils, shows that crown clade Placentalia and placental orders originated after the K-Pg boundary. Many nodes discovered using molecular data are upheld, but phenomic signals overturn molecular signals to show Sundatheria (Dermoptera + Scandentia) as the sister taxon of Primates, a close link between Proboscidea (elephants) and Sirenia (sea cows), and the monophyly of echolocating Chiroptera (bats). Our tree suggests that Placentalia first split into Xenarthra and Epitheria; extinct New World species are the oldest members of Afrotheria.

placental
common ancestor
cenozoic
k-pg
molecular data


Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania

Abstract: Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1–3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3–5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of footprints at site A are readily distinguished from those at site G, indicating that a minimum of two hominin taxa with different feet and gaits coexisted at Laetoli.


The first hyaenodont from the late Oligocene Nsungwe Formation of Tanzania: Paleoecological insights into the Paleogene-Neogene carnivore transition

Abstract: Throughout the Paleogene, most terrestrial carnivore niches in Afro-Arabia were occupied by Hyaenodonta, an extinct lineage of placental mammals. By the end of the Miocene, terrestrial carnivore niches had shifted to members of Carnivora, a clade with Eurasian origins. The transition from a hyaenodont-carnivore fauna to a carnivoran-carnivore fauna coincides with other ecological changes in Afro-Arabia as tectonic conditions in the African Rift System altered climatic conditions and facilitated faunal exchange with Eurasia. Fossil bearing deposits in the Nsungwe Formation in southwestern Tanzania are precisely dated to ~25.2 Ma (late Oligocene), preserving a late Paleogene Afro-Arabian fauna on the brink of environmental transition, including the earliest fossil evidence of the split between Old World monkeys and apes. Here we describe a new hyaenodont from the Nsungwe Formation, Pakakali rukwaensis gen. et sp. nov., a bobcat-sized taxon known from a portion of the maxilla that preserves a deciduous third premolar and alveoli of dP4 and M1. The crown of dP3 bears an elongate parastyle and metastyle and a small, blade-like metacone. Based on alveolar morphology, the two more distal teeth successively increased in size and had relatively large protocones. Using a hyaenodont character-taxon matrix that includes deciduous dental characters, Bayesian phylogenetic methods resolve Pakakali within the clade Hyainailouroidea. A Bayesian biogeographic analysis of phylogenetic results resolve the Pakakali clade as Afro-Arabian in origin, demonstrating that this small carnivorous mammal was part of an endemic Afro-Arabian lineage that persisted into the Miocene. Notably, Pakakali is in the size range of carnivoran forms that arrived and began to diversify in the region by the early Miocene. The description of Pakakali is important for exploring hyaenodont ontogeny and potential influences of Afro-Arabian tectonic events upon mammalian evolution, providing a deep time perspective on the stability of terrestrial carnivore niches through time.


Palaeoneurological clues to the evolution of defining mammalian soft tissue traits

Abstract: A rich fossil record chronicles the distant origins of mammals, but the evolution of defining soft tissue characters of extant mammals, such as mammary glands and hairs is difficult to interpret because soft tissue does not readily fossilize. As many soft tissue features are derived from dermic structures, their evolution is linked to that of the nervous syutem, and palaeoneurology offers opportunities to find bony correlates of these soft tissue features. Here, a CT scan study of 29 fossil skulls shows that non-mammaliaform Prozostrodontia display a retracted, fully ossified, and non-ramified infraorbital canal for the infraorbital nerve, unlike more basal therapsids. The presence of a true infraorbital canal in Prozostrodontia suggests that a motile rhinarium and maxillary vibrissae were present. Also the complete ossification of the parietal fontanelle (resulting in the loss of the parietal foramen) and the development of the cerebellum in Probainognathia may be pleiotropically linked to the appearance of mammary glands and having body hair coverage since these traits are all controlled by the same homeogene, Msx2, in mice. These suggest that defining soft tissue characters of mammals were already present in their forerunners some 240 to 246 mya.

non-mammaliaform prozostrodontia
non-ramified infraorbital canal
canal


Learning by Heart: Cultural Patterns in the Faunal Processing Sequence during the Middle Pleistocene

Abstract: Social learning, as an information acquisition process, enables intergenerational transmission and the stabilisation of cultural forms, generating and sustaining behavioural traditions within human groups. Archaeologically, such social processes might become observable by identifying repetitions in the record that result from the execution of standardised actions. From a zooarchaeological perspective, the processing and consumption of carcasses may be used to identify these types of phenomena at the sites. To investigate this idea, several faunal assemblages from Bolomor Cave (Valencia, Spain, MIS 9-5e) and Gran Dolina TD10-1 (Burgos, Spain, MIS 9) were analysed. The data show that some butchery activities exhibit variability as a result of multiple conditioning factors and, therefore, the identification of cultural patterns through the resulting cut-marks presents additional difficulties. However, other activities, such as marrow removal by means of intentional breakage, seem to reflect standardised actions unrelated to the physical characteristics of the bones. The statistical tests we applied show no correlation between the less dense areas of the bones and the location of impacts. Comparison of our experimental series with the archaeological samples indicates a counter-intuitive selection of the preferred locus of impact, especially marked in the case of Bolomor IV. This fact supports the view that bone breakage was executed counter-intuitively and repetitively on specific sections because it may have been part of an acquired behavioural repertoire. These reiterations differ between levels and sites, suggesting the possible existence of cultural identities or behavioural predispositions dependant on groups. On this basis, the study of patterns could significantly contribute to the identification of occupational strategies and organisation of the hominids in a territory. In this study, we use faunal data in identifying the mechanics of intergenerational information transmission within Middle Pleistocene human communities and provide new ideas for the investigation of occupational dynamics from a zooarchaeological approach.

middle pleistocene
action
bone breakage
butchery tradition
anatomical constraint


The Femoral Ontogeny and Long Bone Histology of the Middle Triassic (?Late Anisian) Dinosauriform Asilisaurus kongwe and Implications for the Growth of Early Dinosaurs

Abstract: ABSTRACT The ontogeny of early-diverging dinosauromorphs is poorly understood because few ontogenetic series from the same species-level taxon are known and what is available has not been extensively documented. The large numbers of skeletal elements of the silesaurid Asilisaurus kongwe recently recovered from Tanzania provide an opportunity to examine the ontogenetic trajectory of the earliest known member of Ornithodira and one of the closest relatives to Dinosauria. We examined the ontogeny of the femur and the histology of a series of long bone elements. We observed bone scar variation in a series of femora (n = 27) of different lengths (73.8–177.2 mm). We hypothesize that most femora follow a similar developmental trajectory; however, we observed sequence polymorphism in the order of appearance and shape of bone scars, and we quantified this polymorphism using ontogenetic sequence analysis (OSA). Additionally, five femora, three tibiae, a fibula, and a humerus were thin-sectioned to examine osteological tissues. No lines of arrested growth (LAGs) are present in any specimen, and there is little histological information about the ontogenetic stage of femora, although none have slowed or ceased growth. The woven-fibered bone present in the cortex of elements sectioned is similar to that of the earliest dinosaurs. This sequence polymorphism provides an alternate hypothesis for the robust/gracile dichotomy found in early dinosaurs often interpreted as sexual dimorphism. The shared femoral features found in Asilisaurus and early dinosaurs suggest that this ontogenetic pattern is plesiomorphic for Dinosauria, and that size is a poor predictor of maturity in early dinosauriforms.

early dinosaur
ontogenetic sequence analysis
osa


Eustatic variations during the Paleocene‐Eocene greenhouse world

Abstract: We reconstruct eustatic variations during the latest Paleocene and earliest Eocene (∼58-52 Ma). Dinoflagellate cysts, grain size fractions, and organic biomarkers in marine sections at four sites from three continents indicate an increased distance to the coast during the Paleocene-Eocene thermal maximum (PETM). The same trend is recognized in published records from other sites around the world. Together, the data indicate a eustatic rise during the PETM, beginning 20 to 200 ka before the globally recorded negative carbon isotope excursion (CIE) at ∼55.5 Ma. Although correlations are tentative, we recognize other global transgressions during Chrons C25n and C24n. The latter may be associated with Eocene Thermal Maximum 2 (∼53.5 Ma) or the "X"-event (∼52 Ma). These results suggest a link between global sea level and "hyperthermal" intervals, potentially because of the melting of small alpine ice sheets on Antarctica, thermal expansion of seawater, or both. However, the early onset of sea level rise relative to the CIE of the PETM suggests contributions from other mechanisms, perhaps decreasing ocean basin volume, on sea level rise. Copyright 2008 by the American Geophysical Union.

petm
sea level
thermal expansion
onset
eustatic variation


In search of the Burdigalian GSSP: new evidence from the Contessa Section (Italy)

Abstract: The Contessa Section is a reference section for the early Miocene in the Mediterranean. Along this 36 m thick section 115 samples were collected and analysed for an integrated bio-magnetostratigraphic study through the Scaglia Cinerea and Bisciaro formations. Planktonic foraminifera were analysed semi-quantitatively, while calcareous nannofossils were examined using the standard quantitative method. A reliable biozonation for both fossil groups was then accomplished. The paleomagnetic analyses identified a sequence of magnetozones, then correlated with the ATNTS using the calcareous plankton bioevents. The investigated interval extends from foraminiferal Zone P22 (Chattian) to MMi2c (Burdigalian) and from calcareous nannofossils Zone MNP25a to MNN3a, thus from Chron C7An to C5En. Therefore, the section chronologically spans from 24.80 Ma to18.10 Ma. Three hiatuses were recognised along the section: H1 at 0.63 m from the base (comprising a minimum time interval from 24.36 Ma to 23.38 Ma), H2 at 12.33 m (between 21.80 Ma and 21.35 Ma) and H3 at 34.03 (between 19.21 Ma and 18.40 Ma). All three hiatuses were correlated with regional megahiatuses identified in the North Atlantic Ocean and in the Paratethys area. Furthermore, the First Occurrenceof the calcareous nannofossil Helicosphera ampliaperta is recognised within Chron C6An.2n at 19.77 m from the base (6 m above the volcaniclastic Raffaello Level). This event provisionally defines the Aquitanian/Burdigalian boundary according to the literature. Thus, the Contessa Section is a possible candidate for the definition of theBurdigalian Global Stratigraphic Section and Point. Finally, the age of the Raffaello Level (a regional marker horizon for the early Miocene) is discussed in this new integrated stratigraphic framework, falling in Chron C6AAn and dated between 21.09 Ma and 21.08 Ma.


Fossil lemurs from Egypt and Kenya suggest an African origin for Madagascar’s aye-aye

Abstract: In 1967 G.G. Simpson described three partial mandibles from early Miocene deposits in Kenya that he interpreted as belonging to a new strepsirrhine primate, Propotto. This interpretation was quickly challenged, with the assertion that Propotto was not a primate, but rather a pteropodid fruit bat. The latter interpretation has not been questioned for almost half a century. Here we re-evaluate the affinities of Propotto, drawing upon diverse lines of evidence to establish that this strange mammal is a strepsirrhine primate as originally suggested by Simpson. Moreover, our phylogenetic analyses support the recognition of Propotto, together with late Eocene Plesiopithecus from Egypt, as African stem chiromyiform lemurs that are exclusively related to the extant aye-aye (Daubentonia) from Madagascar. Our results challenge the long-held view that all lemurs are descended from a single ancient colonization of Madagascar, and present an intriguing alternative scenario in which two lemur lineages dispersed from Africa to Madagascar independently, possibly during the later Cenozoic.


Early high rates and disparity in the evolution of ichthyosaurs

Abstract: How clades diversify early in their history is integral to understanding the origins of biodiversity and ecosystem recovery following mass extinctions. Moreover, diversification can represent evolutionary opportunities and pressures following ecosystem changes. Ichthyosaurs, Mesozoic marine reptiles, appeared after the end-Permian mass extinction and provide opportunities to assess clade diversification in a changed world. Using recent cladistic data, skull length data, and the most complete phylogenetic trees to date for the group, we present a combined disparity, morphospace, and evolutionary rates analysis that reveals the tempo and mode of ichthyosaur morphological evolution through 160 million years. Ichthyosaur evolution shows an archetypal early burst trend, driven by ecological opportunity in Triassic seas, and an evolutionary bottleneck leading to a long-term reduction in evolutionary rates and disparity. This is represented consistently across all analytical methods by a Triassic peak in ichthyosaur disparity and evolutionary rates, and morphospace separation between Triassic and post-Triassic taxa.

ichthyosaur
diversification
mesozoic marine reptile
ecological opportunity
ptme


Ester-Mediated Amide Bond Formation Driven by Wet–Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth**

Abstract: Although it is generally accepted that amino acids were present on the prebiotic Earth, the mechanism by which α-amino acids were condensed into polypeptides before the emergence of enzymes remains unsolved. Here, we demonstrate a prebiotically plausible mechanism for peptide (amide) bond formation that is enabled by α-hydroxy acids, which were likely present along with amino acids on the early Earth. Together, α-hydroxy acids and α-amino acids form depsipeptides—oligomers with a combination of ester and amide linkages—in model prebiotic reactions that are driven by wet–cool/dry–hot cycles. Through a combination of ester–amide bond exchange and ester bond hydrolysis, depsipeptides are enriched with amino acids over time. These results support a long-standing hypothesis that peptides might have arisen from ester-based precursors.

bond formation
prebiotic earth
amino acid
reaction
ester-amide exchange