The early Miocene balaenid Morenocetus parvus from Patagonia (Argentina) and the evolution of right whales

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ~20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length ofMorenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene-early Pliocene as represented by Eubalaena shinshuensis.Facultad de Ciencias Naturales y Muse

A new species of tapir from the Amazon

All known species of extant tapirs are allopatric: 1 in southeastern Asia and 3 in Central and South America. The fossil record for tapirs, however, is much wider in geographical range, including Europe, Asia, and North and South America, going back to the late Oligocene, making the present distribution a relict of the original one. We here describe a new species of living Tapirus from the Amazon rain forest, the 1st since T. bairdii Gill, 1865, and the 1st new Perissodactyla in more than 100 years, from both morphological and molecular characters. It is shorter in stature than T. terrestris (Linnaeus, 1758) and has distinctive skull morphology, and it is basal to the clade formed by T. terrestris and T. pinchaque (Roulin, 1829). This highlights the unrecognized biodiversity in western Amazonia, where the biota faces increasing threats. Local peoples have long recognized our new species, suggesting a key role for traditional knowledge in understanding the biodiversity of the region

On the Supposed Presence of Miocene Tayassuidae and Dromomerycinae (Mammalia, Cetartiodactyla) in South America

The earliest record of North American mammals in South America is significant for constraining the timing of intercontinental faunal interchange. At present, the oldest securely dated remains of a North American terrestrial mammal in South America pertain to a late Miocene procyonid; a few other North American mammal groups are present in late Miocene and early Pliocene outcrops in South America, but most are not recorded until the late Pliocene or Pleistocene, after the complete emergence of the Panamanian Isthmus. This long-established pattern has recently been called into question by reports of a proboscidean, two tayassuids, and a dromomerycine cervoid in supposed late Miocene deposits of Peruvian Amazon. In this contribution, we analyze the taxonomic identities and stratigraphic provenances of the tayassuid and dromomerycine fossils in detail. We conclude that these specimens are not distinguishable from modern tayassuids (Tayassu pecari and Dicotyles tajacu) and cervids, and that previous taxonomic identifications are based on misinterpretation of characters or inadequate specimens. In addition, there is insufficient evidence to support a late Miocene age for these terrestrial cetartiodactyl fossils; the stratigraphic provenance of the specimens is highly dubious, and the fossils are likely Quaternary in age.Fil: Gasparini, Germán Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; ArgentinaFil: Parisi Dutrá, Rodrigo. Universidade Federal de Minas Gerais; BrasilFil: Perini, Fernando A.. Universidade Federal de Minas Gerais; BrasilFil: Croft, Darin. Case Western Reserve University; Estados UnidosFil: Cozzuol, Mario Alberto. Universidade Federal de Minas Gerais; BrasilFil: Missagia, Rafaela V.. Universidade Federal de Minas Gerais; BrasilFil: Lucas, Spencer G.. New Mexico Museum Of Natural History And Science; Estados Unido

The early Miocene balaenid Morenocetus parvus from Patagonia (Argentina) and the evolution of right whales

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ~20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length ofMorenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene-early Pliocene as represented by Eubalaena shinshuensis.Facultad de Ciencias Naturales y Muse

Aquatic mammal fossils in Latin America – a review of records, advances and challenges in research in the last 30 years

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 Hemispher

Formation of the Isthmus of Panama

The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed manymillions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways,withformationof theIsthmus of Panama sensustricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.Facultad de Ciencias Naturales y Muse

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Descifrando la historia evolutiva de los Neoceti: los odontocetos del Mioceno de Patagonia (Argentina) como caso de estudio

La historia evolutiva de los cetáceos estuvo marcada por al menos tres radiaciones adaptativas. La segunda radiación (Oligoceno-Mioceno Temprano) marcó la aparición de los Neoceti (Odontoceti y Mysticeti), y estuvo principalmente influenciada por la apertura del Océano Austral y cambios en el ecosistema oceánico y su productividad. Durante la tercera radiación (Mioceno Medio-Tardío), surgen los linajes modernos de cetáceos y hay una fuerte disminución de las formas antiguas. En este escenario evolutivo, el objetivo del presente trabajo es analizar el registro fósil de odontocetos del Mioceno de Patagonia y sus implicancias paleobiogeográficas. Para el Mioceno Temprano (Fm. Gaiman y Monte León) se registran representantes de Platanistoidea, Physeteroidea, Kentriodontidae y Eurhinodelphinidae. En contraste, sólo dos grupos se registran para el Mioceno Tardío (Fm. Puerto Madryn, Barranca Final y Bajo Gualicho): Physeteroidea y Ziphiidae. Durante el Mioceno Temprano, encontramos una gran diversidad de grupos relacionado a la segunda radiación adaptativa de los cetáceos. Dichos grupos tuvieron una gran dispersión y diversidad, la cual estaría ligada a la formación de la Corriente Circumpolar Antártica y otros cambios relacionados. Hacia el Mioceno Tardío, se observa la extinción de varios linajes (Kentriodontidae, Platanistoidea y Eurhinodelphinidae) y se mantienen linajes con representantes actuales en la región (Ziphiidae y Physeteroidea), en concordancia con la tercera radiación. Durante este período, el enfriamiento de las aguas y cambios en la circulación oceánica, entre otros, propiciaron la formación de nichos ecológicos que rápidamente ocuparon formas actuales, (por ej. delfínidos). Finalmente, el registro mioceno de odontocetos de Patagonia contribuye a completar hiatos en el registro estratigráfico (Physeteroidea), y a delinear el panorama paleobiogeográfico de algunos grupos (por ej. Platanistoidea, Physeteroidea y Ziphiidae). Por ejemplo, los registros de fiseteroideos y zífidos indicarían que estos grupos tuvieron una temprana y rápida dispersión, alcanzando una amplia distribución geográfica hacia finales del Mioceno.Fil: Viglino, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Cozzuol, Mario A.. Universidade Federal de Minas Gerais; Brasil6ta Jornada de Presentación de BecariosPuerto MadrynArgentinaCentro Nacional Patagónic

Los Mysticeti del Mioceno de Patagonia: una ventana hacia la historia evolutiva temprana de las ballenas

El origen de los misticetos, uno de los eventos macroevolutivos más importantes en la historia de los cetáceos, ha sido vinculado con profundos cambios en la dinámica de los océanos. Dicho evento estuvo asociado a una primera radiación (Eoceno tardío-Oligoceno) marcada por el origen de los misticetos dentados y de los primeros misticetos con barbas (=Chaeomysticeti) y así, por la co-existencia de diferentes morfo-tipos (p. ej. disparidad de tamaños corporales y de la estructura cráneo-mandibular). La disparidad cráneo-mandibular sugiere, asimismo, la co-existencia de diferentes métodos de alimentación (macrofagia, succión y filtración). Hacia finales del Oligoceno-principios del Mioceno, se produjo dentro de este linaje un notable incremento en la especialización hacia cierto tipo de alimentación (filtración), según lo sugiere la extinción de las formas dentadas y la aparición de linajes de Chaeomysticeti con representantes actuales. Es en este contexto en el cual los registros miocenos de Patagonia adquieren relevancia, ya que documentan la aparición linajes modernos (Balaenidae, Balaenopteroidea y Neobalaeninae). De este modo, para el Mioceno temprano (Burdigaliano; Fm. Gaiman) se registra el balénido más antiguo Morenocetus parvus, así como también uno de los registros más tempranos de balenopteroideos (Aglaocetus moreni). Hacia el Mioceno tardío (Tortoniense, Fm. Puerto Madryn), se registran representantes de los Balaenidae (con un nuevo taxón que junto con Morenocetus forma un clado basal dentro de este grupo); Neobalaeninae (correspondiente al primer registro para el Atlántico Sudoccidental y el más antiguo del Hemisferio Sur); y un posible Balaenopteroidea (que correspondería al primer registro para este período en el Atlántico Sudoccidental). La presencia de los registros más antiguos de balénidos, neobalenines y balenopteroideos en el Atlántico Sudoccidental sugiere un origen austral y temprano de estos linajes de misticetos, en consonancia con eventos climáticos globales (p. ej. establecimiento de la Corriente Circumpolar Antártica) con incidencia en la dinámica oceánica regional.Fil: Buono, Mónica Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Viglino, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Fernández, Marta Susana. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cozzuol, Mario A.. Universidade Federal de Minas Gerais; Brasil6ta Jornada de Presentación de BecariosPuerto MadrynArgentinaCentro Nacional Patagónic