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Several dolphin lineages have independently invaded freshwater systems. Among these, the evolution of the South Asian river dolphin Platanista and its relatives (Platanistidae) remains virtually unknown as fossils are scarce. Here, we describe Pebanista yacuruna gen. et sp. nov., a dolphin from the Miocene proto-Amazonia of Peru, recovered in phylogenies as the closest relative of Platanista. Morphological characters such as an elongated rostrum and large supraorbital crests, along with ecological interpretations, indicate that this odontocete was fully adapted to fresh waters. Pebanista constitutes the largest freshwater odontocete known, with an estimated body length of 3 meters, highlighting the ample resource availability and biotic diversity in the region, during the Early to Middle Miocene. The finding of Pebanista in proto-Amazonian layers attests that platanistids ventured into freshwater ecosystems not only in South Asia but also in South America, before the modern Amazon River dolphin, during a crucial moment for the Amazonian evolution.

The Pampean Region in the eastern central part of Argentina is today an agricultural zone, the main national food producer, and the base for a population that holds in big cities more than half of the 46 million inhabitants of the country. A century ago, Pampean landscapes were dominated by native grasslands, gallery forests confined to riverbanks, sparse dry forests towards the west of the area, and on the horizon of the flat Pampas, occasional isolated ombú trees (Phytolacca dioica) and eucalyptuses planted by the increasing population to provide shade in hot days and protection during storms for domesticated animals and people. Native birds, reptiles, and mammals, now replaced by humans and human activities, were certainly more frequent than today. However, these same riverbanks and lowlands were places where fossil hunters such as Santiago Roth could find bizarre extinct creatures that lived hundreds of thousands of years ago. The main attractions were the bones and teeth of megamammals, such as huge ground sloths (Megatherium americanum) which weighed more than four tonnes; big armadillos, such as Panochthus tuberculatus, with the size of a small car; strange ungulates having nasal apertures on the top of the skull that likely sported a trunk, as in the case of Macrauchenia patachonica; predators with hyper-enlarged sabertooth canines like the felid Smilodon populator, all contemporaneous with local gigantic spectacled bear relatives; proboscideans; native horses; deer with elaborate antlers; and other creatures living in South America in the near past of the Pleistocene. The Pampean Region was and still is a region where the remaining of these lost species can be found. Radiocarbon dating has demonstrated that several of these megammamals coexisted with the first humans in the area around 12,000– 11,000 years ago. Did they interact? Did humans hunt them, and perhaps cause their extinction? Santiago Roth contributed to all of these topics by making new discover

Records of aquatic mammal fossils (e.g. cetaceans, pinnipeds, sirenians, mustelids, and desmostylians) from Latin America (Mexico to Tierra del Fuego, including Antartica) span since the mid-1800s. Aquatic mammal fossils received little attention from the scientific community, with most of the first studies conducted by Northern Hemisphere researchers. Over the last 30 years, paleontological research in Latin America has increased considerably, with descriptions of several new species and revisions of published original records. The Latin American fossil record of marine mammals spans from the Eocene to the Pleistocene, with formations and specimens of global significance. All three main groups of cetaceans are represented in the continent (Archaeoceti, Mysticeti, and Odontoceti). Pinnipedia are represented by the families Otariidae and Phocidae, with records starting in the Middle Miocene. Both living families of Sirenia (Trichechidae and Dugongidae) are recorded. While less common, but still relevant, records of desmostylians and mustelids are known from Oligocene and Miocene deposits. This review provides a summary of the aquatic mammals known to date, with a special focus on the advances and developments of the last 30 years, since Cozzuol’s (1996) review of the South American fossil record. An up-to-date complete list of species based on the literature and unpublished data is also provided. The study also provides future directions for paleontological research in Latin America, and discusses the challenges and opportunities in the field, including the emergence of a strong new generation of Latin American researchers, many of whom are women. Keywords: Cetacea, Pinnipedia, Sirenia, Southern Hemisphere

We studied the mass growth trajectories of middle ear ossicles and tympanic membrane and oval window area in 19 specimens of postnatal ages 30–180 days of the gray short-tailed opossum Monodelphis domestica. We weighed the skull mass and the mass of the three middle ear ossicles with appropriate balances. Using a binocular microscope provided with a grid, we measured the length of malleus and incus, as well as the longest axis and the one perpendicular to it on both the tympanic membrane and the stapes footplate. The size variation was studied with least squares regression analyses between various measurements. The incus and stapes change little in mass after 40 days of postnatal life, while the malleus does, reaching maximum mass at around 100 PND (postnatal days). This modularity in growth trajectory is in contrast with the shared evolutionary origin of malleus and incus from branchial arch 1. The maturation of the middle – and as indicated by previous work, that of the inner ear – is coupled with the improvement of hearing sensitivity at low and high frequencies after the initial onset of hearing at 29 PND.

The Swiss Upper Marine Molasse (OMM) documents a transgression event dated to around 21 to 17 million years in which dolphin and other vertebrate remains have been reported. We revised the whole cetacean (whales and dolphins) OMM assemblage available in main collections, focusing on the identification and interpretation of periotics (bone that contains the inner ear). Periotics are rare, but they provide the richest taxonomic information in the sample and hint to environmental associations. Micro-computerized tomography allowed the reconstruction of bony labyrinths for comparisons and environmental interpretations. Three families are represented by periotics: Kentriodontidae, Squalodelphinidae and Physeteridae. The cetacean taxonomic composition of the Swiss OMM reinforces biogeographical patterns reported for the Mediterranean and Paratethys during the Burdigalian at a regional scale and the Calvert cetacean fauna of the northwest Atlantic at oceanic scale.

Musical instruments provide material evidence to study the diversity and technical innovation of music in space and time. We employed a cultural evolutionary perspective to analyse organological data and their relation to language groups and population history in South America, a unique and complex geographic area for human evolution. The ethnological and archaeological native musical instrument record, documented in three newly assembled continental databases, reveals exceptionally high diversity of wind instruments. We explored similarities in the collection of instruments for each population, considering geographic patterns and focusing on groupings associated with language families. A network analysis of panpipe organological features illustrates four regional/cultural clusters: two in the Tropical Forest and two in the Andes. Twenty-five percent of the instruments in the standard organological classification are present in the archaeological, but not in the ethnographic record, suggesting extinction events. Most recent extinctions can be traced back to European contact, causing a reduction in indigenous cultural diversity.

The dense Miocene record of cetaceans is known from localities along the coasts of all continents, mostly in the northern Atlantic or the eastern Pacific regions, but Antarctica. Fossils from the Caribbean region are few and include of a couple of findings from Panama and Venezuela. Here, we report a partly complete skull from the Caujarao Formation (middle Miocene), Falcon State, Caribbean region of Venezuela. Our phylogenetic analyses indicate that the Caujarao specimen is a ‘stem delphinidan’, a group that includes several taxa of early diverging odontocetes whose phylogenetic affinities remain a matter of debate. The fossil record has shown that this group of stem delphinidans was taxonomically diverse, but displayed a somewhat homogeneous cranial patterning, with most of the variations being found within the mandible or tympanoperiotic characters. As other stem delphinidans the Caujarao odontocete displays an enlarged temporal fossa and a fairly symmetrical cranium. Because the skull is missing several key diagnostic characters due to the preservation state of the specimen, a more precise taxonomic identification is not possible. Despite this, the finding of this specimen highlights the importance of the fossil record from the Neogene of Venezuela, and the importance of the area to understand cetacean evolution in the proto-Caribbean.

The panpipe is a musical instrument composed of end-blown tubes of different lengths tied together. They can be traced back to the Neolithic, and they have been found at prehistoric sites in China, Europe and South America. Panpipes display substantial variation in space and time across functional and aesthetic dimensions. Finding similarities in panpipes that belong to distant human groups poses a challenge to cultural evolution: while some have claimed that their relative simplicity speaks for independent inventions, others argue that strong similarities of specific features in panpipes from Asia, Oceania and South America suggest long-distance diffusion events. We examined 20 features of a worldwide sample of 401 panpipes and analysed statistically whether instrument features can successfully be used to determine provenance. The model predictions suggest that panpipes are reliable provenance markers, but we found an unusual classification error in which Melanesian panpipes are predicted as originating in South America. Although this pattern may be signalling a diffusion event, other factors such as convergence and preservation biases may play a role. Our analyses show the potential of cultural evolution research on music that incorporates material evidence, which in this study includes both archaeological and ethnographic samples preserved in museum collections.

The domestication of the fowl resulted in a large diversity of integumental structures in chicken breeds. Several integumental traits have been investigated from a developmental genetics perspective. However, their distribution among breeds and their developmental morphology remain unexplored. We constructed a discrete trait-breed matrix and conducted a disparity analysis to investigate the variation of these structures in chicken breeds; 20 integumental traits of 72 chicken breeds and the red junglefowl were assessed. The analyses resulted in slight groupings of breed types comparable to standard breed classification based on artificial selection and chicken type use. The red junglefowl groups together with bantams and European breeds. We provide new data on the red junglefowl and four chicken breeds, demonstrating where and when variation arises during embryonic development. We document variation in developmental timing of the egg tooth and feather formation, as well as other kinds of developmental patterning as in the anlagen of different type of combs. Changes in epithelial-mesenchymal signaling interactions may drive the highly diverse integument in chickens. Experimental and comparative work has revealed that the cranial neural crest mesenchyme mediates its interactions with the overlying epithelium and is the likely source of patterning that generates diversity in integumental structures.

We provide a description of the remains of a fossil whale from western Panama. The record consists of appendicular remains of a mysticete, which has been assigned to Balaenopteridae. These remains, found in the sediments of the late Pliocene Burica Formation, represent the first record of a marine mammal in the Neogene sedimentary succession of the Burica Peninsula. Two different types of shark bite marks, serrated and deep-unserrated, found on the radius and phalanges suggest scavenging by at least two white shark (Carcharodon) individuals. The deep, unserrated marks were possibly caused by continual biting by sharks. Both the morphology of the shark bite marks and their relative location on the whale limb bones constitute evidence of shark-cetacean trophic interaction. Although the specimen lacks diagnostic features that would allow a species-level identification, it does provide new information on the vertebrate fauna of a very poorly prospected Central Eastern Pacific exposure, thus opening an opportunity for exploring the marine fauna during a critical episode in Earth history, the Plio-Pleistocene transition. Dirley Cortés. Redpath Museum, McGill University, 859 Sherbrooke St. W., Montreal QC H3A 0C4, Canada. Smithsonian Tropical Research Institute, Balboa-Ancón 0843-03092, Panamá, Panamá. dirley.cortes@mail.mcgill.ca Carlos De Gracia. Smithsonian Tropical Research Institute, Balboa-Ancón 0843-03092, Panamá, Panamá. degraciac@gmail.com Jorge D. Carrillo-Briceño. Paläontologisches Institut und Museum, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland. Smithsonian Tropical Research Institute, Balboa-Ancón 0843-03092, Panamá, Panamá. jorge.carrillo@pim.uzh.ch Gabriel Aguirre-Fernández. Paläontologisches Institut und Museum, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland. gabriel.aguirre@pim.uzh.ch Carlos Jaramillo. Smithsonian Tropical Research Institute, Balboa-Ancón 0843–03092, Panamá, Panamá. ISEM, U. Montpellier, CNRS, EPHE, IRD, Montpellier, France. Jaramillo

Fossil information is essential for estimating species divergence times, and can be integrated into Bayesian phylogenetic inference using the fossilized birth–death (FBD) process. An important aspect of palaeontological data is the uncertainty surrounding specimen ages, which can be handled in different ways during inference. The most common approach is to fix fossil ages to a point estimate within the known age interval. Alternatively, age uncertainty can be incorporated by using priors, and fossil ages are then directly sampled as part of the inference. This study presents a comparison of alternative approaches for handling fossil age uncertainty in analysis using the FBD process. Based on simulations, we find that fixing fossil ages to the midpoint or a random point drawn from within the stratigraphic age range leads to biases in divergence time estimates, while sampling fossil ages leads to estimates that are similar to inferences that employ the correct ages of fossils. Second, we show a comparison using an empirical dataset of extant and fossil cetaceans, which confirms that different methods of handling fossil age uncertainty lead to large differences in estimated node ages. Stratigraphic age uncertainty should thus not be ignored in divergence time estimation and instead should be incorporated explicitly.

The systematic value of the middle-ear ossicles, in particular the malleus, has been long recognized for diverse groups. We present systematic work on the characters of the middle-ear ossicles of pinnipeds, focusing on until now poorly studied Southern Hemisphere species. Mallei were extracted from 16 specimens of pinnipeds belonging to five austral and one boreal species of Phocidae and two austral species of Otariidae. Several characters used in this study have been described previously, and some were here modified. Three new characters are here defined and analysed. All characters were mapped onto the phylogeny. Our character analysis shows the transformations that have occurred in the evolution of middle ear ossicles in pinnipeds and identifies diagnostic features of many of its clades. Beyond the identification of specific changes within eachclade, our study of pinniped ossicle evolution documents the occurrence of anatomical convergences with other groups of mammals that live in an aquatic environment, as has occurred in other organsystems as well.

The inner ear of toothed whales (odontocetes) is known to have evolved particular shapes related to their abilities to echolocate and move under water. While the origin of these capacities is now more and more examined, thanks to new imaging techniques, little is still known about how informative inner ear shape could be to tackle phylogenetic issues or questions pertaining to the habitat preferences of extinct species. Here we show that the shape of the bony labyrinth of toothed whales provides key information both about phylogeny and habitat preferences (freshwater versus coastal and fully marine habitats). Our investigation of more than 20 species of extinct and modern odontocetes shows that the semi-circular canals are not very informative, in contrast to baleen whales, while the cochlea alone bears a strong signal. Inner ear shape thus provides a novel source of information to distinguish between morphologically convergent lineages (e.g. river dolphins

A new small probable Oligocene dolphin from Ecuador represents a new genus and species, Urkudelphis chawpipacha. The new taxon is known from a single juvenile skull and earbones; it differs from other archaic dolphins in features including widely exposed frontals at the vertex, a dorsally wide open vomer at the mesorostral groove, and a strongly projected and pointed lateral tuberosity of the periotic. Phylogenetic analysis places it toward the base of the largely-extinct clade Platanistoidea. The fossil is one of a few records of tropical fossil dolphins.