The last African metatherian

Funding Information: F.J.G. and V.D.C. thank Agencia (Foncyt, Mincyt; PICT 2019-03283) and CONICET (PIP KB2 - 11220200100150CO). Funding Information: We thank the Uganda Museum, Kampala (Rose Mwan-ja, Sarah Musalizi, Christopher Sebuyungo) for access to fossil material in its care, and the Uganda National Council for Science and Technology for authorization to carry out research in the country. Pierre Mein measured the specimen from Moroto and made preliminary identifications. Hugo Salais (Metazoa Studio) for the 3D reconstruction, Agustín Ruella for a previous version of the 3D reconstruction, Marcela Tomeo for the realisation of Figs 1 and 3, and Juana Yañez for the reconstruction of the palaeoenvironment. Francisco Javier Ruiz-Sánchez of University of València provided the use of the electron microscopy. Maria Dolores Marin-Monfort for the taphonomical comments. We should thank Frank Sénégas for making the casts (Sorbonne University). The fossils were collected by the Uganda Palaeontology Expedition led by B. Senut and funded by the Ministry of Foreign Affairs, Commission des Fouilles. We thank the villagers of Rupa for participating in the screening of the sediments which yielded the holotype of Morotodon aenigmaticus. The support of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) toward this research for V. D. Crespo is hereby acknowledged. V.D.C. is the beneficiary of a grant (ZA21-044) for the requalification Publisher Copyright: Copyright Vicente D.Morotodon aenigmaticus gen. et sp. nov. (Mammalia, Metatheria, ?Herpetotheriidae) from the early or early-middle Miocene of equatorial Africa (Moroto II locality, Moroto District, northeastern Uganda) is characterized by a short anterior cingulum, a buccal shelf, a well-developed hypoconulid in a central position, and a trigonid and talonid with similar mesio-distal lengths. Its small size and morphology suggest mostly insectivorous-faunivorous feeding habits. The faunal association of Moroto II, as well as previous palaeoenvironmental analyses, suggest that Morotodon lived in open woodland and bushland areas surrounded by grasses. Morotodon aenigmaticus shows several features reminiscent of early herpetotheriids, such as Golerdelphys stocki (late Paleocene of North America), and Amphiperatherium ambiguum (Eocene of Europe); this suggests an origin for its lineage previous to the Oligocene. In summary, its affinities lie with Northern Hemisphere herpetotheriids, and, most probably, with European ones.publishersversionpublishe

New cladotherian mammal from southern Chile and the evolution of mesungulatid meridiolestidans at the dusk of the Mesozoic era

In the last decades, several discoveries have uncovered the complexity of mammalian evolution during the Mesozoic Era, including important Gondwanan lineages: the australosphenidans, gondwanatherians, and meridiolestidans (Dryolestoidea). Most often, their presence and diversity is documented by isolated teeth and jaws. Here, we describe a new meridiolestidan mammal, Orretherium tzen gen. et sp. nov., from the Late Cretaceous of southern Chile, based on a partial jaw with five cheek teeth in locis and an isolated upper premolar. Phylogenetic analysis places Orretherium as the earliest divergence within Mesungulatidae, before other forms such as the Late Cretaceous Mesungulatum and Coloniatherium, and the early Paleocene Peligrotherium. The in loco tooth sequence (last two premolars and three molars) is the first recovered for a Cretaceous taxon in this family and suggests that reconstructed tooth sequences for other Mesozoic mesungulatids may include more than one species. Tooth eruption and replacement show that molar eruption in mesungulatids is heterochronically delayed with regard to basal dryolestoids, with therian-like simultaneous eruption of the last premolar and last molar. Meridiolestidans seem endemic to Patagonia, but given their diversity and abundance, and the similarity of vertebrate faunas in other regions of Gondwana, they may yet be discovered in other continents.Fil: Martinelli, Agustín Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad de Chile; ChileFil: Soto Acuña, Sergio. Universidad de Chile; ChileFil: Goin, Francisco Javier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Kaluza, Jonatan Ezequiel. Universidad Maimónides; Argentina. Universidad de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Bostelmann, J. Enrique. Universidad Austral de Chile; ChileFil: Fonseca, Pedro H. M.. Universidade Federal do Rio Grande do Sul; BrasilFil: Reguero, Marcelo Alfredo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Leppe, Marcelo. Instituto Antártico Chileno; ChileFil: Vargas, Alexander O.. Universidad de Chile; Chil

Deep time diversity of metatherian mammals: Implications for evolutionary history and fossil-record quality

Despite a global fossil record, Metatheria are now largely restricted to Australasia and South America. Most metatherian paleodiversity studies to date are limited to particular subclades, time intervals, and/or regions, and few consider uneven sampling. Here, we present a comprehensive new data set on metatherian fossil occurrences (Barremian to end Pliocene). These data are analyzed using standard rarefaction and shareholder quorum subsampling (including a new protocol for handling Lagerstätte-like localities). Global metatherian diversity was lowest during the Cretaceous, and increased sharply in the Paleocene, when the South American record begins. Global and South American diversity rose in the early Eocene then fell in the late Eocene, in contrast to the North American pattern. In the Oligocene, diversity declined in the Americas, but this was more than offset by Oligocene radiations in Australia. Diversity continued to decrease in Laurasia, with final representatives in North America (excluding the later entry of Didelphis virginiana) and Europe in the early Miocene, and Asia in the middle Miocene. Global metatherian diversity appears to have peaked in the early Miocene, especially in Australia. Following a trough in the late Miocene, the Pliocene saw another increase in global diversity. By this time, metatherian biogeographic distribution had essentially contracted to that of today. Comparison of the raw and sampling-corrected diversity estimates, coupled with evaluation of "coverage" and number of prolific sites, demonstrates that the metatherian fossil record is spatially and temporally extremely patchy. Therefore, assessments of macroevolutionary patterns based on the raw fossil record (as in most previous studies) are inadvisable.Fil: Bennett, C. Verity. University College London; Estados UnidosFil: Upchurch, Paul. University College London; Estados UnidosFil: Goin, Francisco Javier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Goswami, Anjadi. University College London; Estados Unido

New Early Eocene Mammalian Fauna from Western Patagonia, Argentina

Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia.Facultad de Ciencias Naturales y Muse

Un prédateur à dents de sabre des Néotropiques : morphologie crânienne d’<i>Anachlysictis gracilis</i> Goin, 1997 (Metatheria, Thylacosmilidae), d’après de nouveaux spécimens de La Venta (Miocène Moyen, Colombie)

L’assemblage des métathériens fossiles de La Venta (Miocène Moyen, Colombie), qui est l’un des plus diversifiés d’Amérique du Sud, est crucial pour la connaissance des radiations néogènes de ce groupe sur ce continent. Il présente le registre le plus septentrional de Thylacosmilidae Riggs, 1933 (Metatheria, Sparassodonta) : Anachlysictis gracilis Goin, 1997, la première espèce décrite pour cette famille sous les néotropiques. Ce taxon a été décrit principalement sur la base de restes mandibulaires. De nouvelles missions de terrain ainsi que la révision de matériel connu, ont permis la découverte de nouveaux restes pour cette espèce. Parmi ces spécimens nous pouvons mentionner l’existence d’un squelette, le plus complet découvert pour cette espèce de Sparassodonta Ameghino, 1894. Cette étude, qui consiste en une description détaillée de l’ostéologie crânienne et de la dentition d’A. gracilis, a permis de confirmer certaines hypothèses quant à l’anatomie, encore jamais démontrées. La phylogénie et les paramètres écomorphologiques de ce taxon (régime alimentaire et masse corporelle) ont été analysés afin d’établir le contexte évolutif de l’espèce, comprendre sa paléobiologie et évaluer les implications paléoécologiques. De plus, une reconsidération de la phylogénie des thylacosmilidés a permis d’obtenir une classification plus traditionnelle du groupe, où ils se différencient des proborhyaenidés et des borhyaenidés. Cette étude propose également une nouvelle reconstruction de la morphologie externe de la tête d’A. gracilis, sur la base de scans 3D des nouveaux spécimens étudiés.The fossil metatherian assemblage from La Venta (Middle Miocene, Colombia) is one of the most diverse in South America, and it is critical to understand the Neogene radiation of this group in this continent. La Venta contains the northernmost record of Thylacosmilidae Riggs, 1933 (Metatheria, Sparassodonta): Anachlysictis gracilis Goin, 1997, the first thylacosmilid species named for the Neotropics. This taxon was described mostly based on mandibular remains. Recent fieldwork and work in collections led to the discovery of new materials for this species, including the most complete skeleton ever found for this Sparassodonta Ameghino, 1894. Here, we present a detailed description of the cranial osteology and dentition of A. gracilis, which elucidates anatomical aspects previously inferred but hitherto unconfirmed. We investigate the phylogeny, and ecomorphological parameters of this taxon (diet and body mass) to set the evolutionary context of the species, understand its paleobiology, and evaluate palaeoecological implications. Additionally, we revise the phylogeny of the thylacosmilids, recovering the traditional classification of the group, differentiated from the proborhyaenids and borhyaenids. This work also proposes a new reconstruction of the external morphology of the head of A. gracilis based on 3D scans of the new referred materials.</p

A unique, Late Oligocene shrew-like marsupial from western Argentina and the evolution of dental morphology

<div><p>We describe a new metatherian mammal, <i>Fieratherium sorex</i> gen. et sp. nov., found in western Argentina (Quebrada Fiera locality, southern Mendoza Province), in Late Oligocene deposits (Agua de la Piedra Formation, Deseadan age). The only known specimen is a juvenile with fragments of both dentaries, the right maxilla and a fragment of the left premaxilla with dentition. The loci and the number teeth preserved suggest a dental formula of I?3/i3, C1/c1, P3/p3, M?3/m?3. <i>Fieratherium sorex</i> has a convergent shrew-like appearance and a unique combination of features among metatherians and other South American mammals of Palaeogene age, including the well-known faunas of Patagonia. An analysis of its phylogenetic affinities suggests that <i>Fieratherium</i> is the sister-group of the Paucituberculata. As already described by other authors for several mammalian taxa, the mainly Patagonian South American Palaeogene fossil record offers little information to understanding the evolution of northern lineages. <i>Fieratherium</i> may represent a taxon belonging to a lineage that had its origin in Neotropical regions, so far unrecorded in the southern region of South America.</p><p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:5F6D3A50-6345-4E66-BE3E-7FEF6CC66A9B" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:5F6D3A50-6345-4E66-BE3E-7FEF6CC66A9B</a></p></div

Data from: On the existence of non-microbiotherian Australidelphian marsupials (Diprotodontia) in the Eocene of Patagonia

A diverse assemblage of extinct mammals of early–middle Eocene age (Ypresian–Lutetian boundary) come from the Patagonian localities of La Barda and Laguna Fría around Paso del Sapo in northwestern Chubut Province (Argentina). Metatherians are well represented, mostly by dental remains of ‘Didelphimorphia’, Paucituberculata, Sparassodonta, Microbiotheria, and Polydolopimorphia. Here we analyse three calcanea and one astragalus referable to the same, indeterminate taxon, from La Barda, showing the fusion of their ectal and sustentacular facets. This facet arrangement characterizes the Australidelphia, a marsupial clade represented by Microbiotheria from South America and Antarctica, plus all Australasian lineages. Other australidelphian features shown by these tarsals include: in the calcanea, a reduced peroneal process and a tripartite cuboid facet; in the astragalus, a round, very small astragalar head in relation to the body; a convex trochlea with a half for the tibia and half, in slightly lower position, for the fibula. Their size and other anatomical features suggest that the new tarsals cannot be referred to the Microbiotheria. Phylogenetic analysis suggests that the La Barda taxon lies within the Australidelphia, and that it is either closely related or belongs to, the Diprotodontia. The existence of advanced australidelphians in Patagonia adds further evidence of the close relationship between Patagonia, Antarctica, and Australia during the Late Cretaceous – early Palaeogene

UNA NUEVA ESPECIE DE LUTREOLINA THOMAS, 1910 (MARSUPIALIA, DIDELPHIDAE) DEL PLEISTOCENO TEMPRANO DE LA PAMPA AUSTRAL (PROVINCIA DE BUENOS AIRES, ARGENTINA)

Se describe a Lutreolina tonnii sp. nov. (Mammalia, Metatheria, Marsupialia, Didelphimorphia, Didelphidae) procedente de niveles del Pleistoceno Temprano (o Temprano–Medio) de las barrancas costeras de los alrededores de Necochea, Provincia de Buenos Aires, Argentina. El holotipo, un maxilar derecho con los M1-3, se destaca por su gran tamaño comparado con el de las otras especies, fósiles y vivientes, del género. Difiere también de las restantes especies del género en que los protoconos de los molares superiores están más comprimidos anteroposteriormente. Difiere de las especies vivientes en que el contacto maxilo-yugal es menos horizontal en sus dos tercios posteriores, existe un ectoflexo más profundo en el M3, y en que los M1-3 tienen una cresta interna baja pero diferenciada que conecta las bases de las cúspides estilares B y D. La nueva especie es la cuarta forma extinta hasta ahora conocida para el registro sudamericano y la tercera para el Plio–Pleistoceno de la Región Pampeana, indicando una considerable diversidad para el género hacia fines de la Era Cenozoica en las latitudes medias del continente

Orientación de las crestas cortantes en el molar tribosfénico. Sus implicancias funcionales en didelfoideos (Marsupialia) fósiles y vivientes.

Se compararon parámetros angulares indicativos de la disposición espacial de las crestas cortantes de los molares superiores (metacristas) e inferiores (paracrístidas) de algunos didelfoideos sudamericanos, condatos conocidos sobre sus hábitos alimentarios. Se analizaron ejemplares de las especies vivientes Didelphisalbiventris Lund, Lutreolinacrassicaudata (Desmarest), y Monodelphisdimidiata (Wagner), así como tambiénespecímenes fósiles asignables a Thylatheridium cristatum Reig y Sparassocynus Mercerat. (1) Los valoresangulares de las crestas cortantes superiores (AS) e inferiores (AI) son relativamente constantes ycaracterísticos de cada una de las especies analizadas. (2) Dichos valores son más bajos en las formascarnívoras que en las insectívoras y omnívoras. (3) Por motivos no completamente esclarecidos, los registrosde AIml de los Didelphoidea estudiados muestran una llamativa variabilidad. (4) Todos los valores de AIy AS tienden a aumentar desde los primeros hasta los últimos molares, si bien la amplitud de dicho aumentodepende de los distintos tipos adaptativos: es mayor en los insectívoros y menor en los carnívoros yomnívoros. (5) Se comprobó una clara asimetría bilateral en los valores de AI y AS en todos los didelfoideos estudiados: por lo general, los AI y AS izquierdos son mayores que los derechos. (6) En los ejemplares analizados de Monodelphis dimidiata se comprobó que los AI y AS no muestran variaciones significativasentre machos y hembras, aunque sí lo hacen (sobre todo en los AIml) en función del peso de dichos especímenes. (7) Por último, las relaciones oclusales entre las crestas cortantes superiores e inferiores de losmolares de M. dimidiata muestran un más ajustado "efecto tijera" en los individuos adultos que en losjuveniles, lo cual parece corresponderse con cambios en los hábitos alimentarios de esta especie durante laontogenia -más insectívoros en los juveniles y más carnívoros en los adultos-