Bárbara Vera

Deseadan Archaeohyracidae (Notoungulata) from Quebrada Fiera (Mendoza, Argentina) in the Paleobiogeographic Context of the South American Late Oligocene

Abstract Recent field work at the Deseadan (late Oligocene) locality of Quebrada Fiera (Mendoza Province, Argentina) has provided new fossil remains that greatly increased the faunal assemblage of this site. A good number of specimens correspond to the Family Archaeohyracidae (Notoungulata) and are presented in this paper. Most of them are recognized as a unique taxon, corresponding to the genus Archaeohyrax, characterized by the presence of a strong, shallow, wide sulcus on the labial side of the talonid of m3. At specific level, it is identified with the species A. suniensis previously recognized at Salla (Bolivia). Specimens with different tooth wear degree show an intraspecific variation in occlusal morphology comparable to that observed among the Bolivian material. In addition to A. suniensis, an isolated p2 is tentatively related to Archaeotypotherium, due to their hypsodont but rooted condition and larger size. Two other isolated lower molars from this site had been previously related to this genus but they are comparable to the new specimens ascribed to Archaeohyrax. The identification of Archaeotypotherium is not well supported at present, but if later confirmed, it would increase the temporal distribution of the genus, so far recorded in Tinguirirican (early Oligocene) localities of Chile and Argentina. The recognition of A. suniensis in Quebrada Fiera establishes a greater affinity with the lower latitude Deseadan fauna of Salla than with that from Patagonia, where the genus is represented by A. patagonicus. Other faunal elements from Quebrada Fiera, however, do not support this affinity with Bolivia. Xenarthrans or some marsupials are equivalent to those from Patagonia, while other taxa such as the recently described notohippid or a rare, tiny metatheria are at present exclusive for Mendoza. The increasing knowledge of the Quebrada Fiera assemblage contributes to a better understanding of the paleogeographic scenario of Southern South America during late Oligocene.

An almost complete skeleton of a new Mesotheriidae (Notoungulata) from the Late Miocene of Casira, Bolivia

A partial mesotheriine skeleton (Notoungulata, Mesotheriidae) from the Late Miocene Casira locality, southern Bolivia, is fully described and reinterpreted taxonomically. This specimen (MNHN-Bol-V-003724) was partially described previously without a taxonomic discussion, as it was considered to be Plesiotypotherium sp. After comparison with other Bolivian, Argentinean and Chilean mesotheres, we recognize a new species of the genus Plesiotypotherium Villarroel, P. casirense sp. nov., characterized by: nasals slightly enlarged posteriorly; zygomatic arch with strong antero-distal angle; zygomatic plate starting at the level of P4 and reaching the level of the anterior part of M3; lacrimal bony process; large infraorbital foramen; posterior border of the mandible very convex; P4 without lingual groove and with narrow and projected parastyle; M3 with simple third lobe; larger and more robust skeleton than other Plesiotypotherium species. Most postcranial elements are described in detail for the first time for Plesiotypotherium. The incomplete skull GB-KKL 740 from the same locality is also referred to the new taxon. P. casirense is the sister group of P. achirense Villarroel in the phylogenetic analysis, but the genus Plesiotypotherium appears as paraphyletic. The revised partial skull GB-ACH 100 from Achiri, Bolivia, which was labelled as Plesiotypotherium sp., does not belong to this genus, and it appears phylogenetically closer to Pseudotypotherium and Mesotherium. Plesiotypotherium casirense sp. nov. increases the known diversity of the Mesotheriidae in both the Miocene of Bolivia and the South American faunal context.

Mendozahippus fierensis, gen. et sp. nov., new Notohippidae (Notoungulata) from the late Oligocene of Mendoza (Argentina)

ABSTRACT Since 2006, new field studies at the late Oligocene site of Quebrada Fiera (Mendoza, Argentina) have increased the previous faunal record from these levels that are presently considered as the base of the Agua de la Piedra Formation. Former faunal lists included Pyrotherium and Proborhyaena gigantea, representatives of the Deseadan Age. Among new materials, a complete skull and two associated metatarsals, two maxillary fragments with left I1-M2 and right I1-P3, and five isolated upper teeth represent the Family Notohippidae. Even though some characters are not comparable between the skull and maxillaries, shared features lead us to consider them as a unique and new taxon, Mendozahippus fierensis, gen. et sp. nov., and the isolated molars as cf. M. fierensis. As in previous phylogenies, our analysis indicates the Family Notohippidae is a paraphyletic group. The inclusion of Plexotemnus, Pampahippus, and Puelia within Notohippidae is not supported, but without them, the group is still paraphyletic. Leontiniids appear as basal taxa to the remaining notohippids and toxodontids. Mendozahippus presents one autapomorphy (lingually projected protocone of M3) and four homoplastic characters. It occupies a basal position with respect to other notohippids plus toxodontids. Mendozahippus increases the diversity and geographic distribution of Notohippidae during the late Oligocene. This and other taxa add some distinctiveness to this Deseadan fauna compared to other better-known assemblages from Patagonia or Salla (Bolivia), whereas other groups maintain clear affinities. The intermediate latitudinal position of Mendoza might explain these faunal characteristics.

Phylogenetic revision of the South American notopithecines (Mammalia: Notoungulata)

A phylogenetic analysis of all Eocene taxa assigned to Notopithecinae has been conducted, evaluating relationships amongst notopithecines, basal interatheriids and Interatheriinae. Other groups of native ungulates were also included. New dental and postcranial characters are considered with respect to previously published data; some characters are evaluated in notoungulates for the first time. Two different searches were performed under parsimony and equal weights. The inclusion of postcranial characters strongly influenced tree topology. The most significant result of the phylogenetic analysis was the identification of a novel monophyletic group, including species traditionally grouped as Patagonian Notopithecinae. The ‘notopithecid’ name is linked to the new clade defined as the clade stemming from the most recent common ancestor of the species Notopithecus adapinus, Antepithecus brachystephanus, Transpithecus obtentus and Guilielmoscottia plicifera. This phylogeny supports the main morphological differences of the new clade with respect to Interatheriinae Interatheriidae. In consequence, a diagnosis is proposed based on phylogenetic results, to which some other morphological characters are added. The Chilean basal interatheriids Johnbell and Ignigena as well as Punapithecus (Argentinean Puna) are excluded from the notopithecid clade, implying biostratigraphical and biogeographical changes. Notopithecid distribution now becomes restricted to the middle–late Eocene part of the Sarmiento Formation outcropping in central Chubut and north-east Santa Cruz provinces, Argentina. Other extra-Patagonian records of notopithecids are not confirmed. The resulting phylogeny resolves some relationships within basal interatheriids differently from previous analyses. Interatheriinae is not recovered as a monophyletic group, and Oldfieldthomasiidae and Henricosborniid are paraphyletic. The position of the Archaeopithecidae Acropithecus rigidus is controversial; it appears at the base of the Typotheria lineage or in the notopithecid clade, but systematic taxonomy and phylogenetic relationships amongst members of Archaeopithecidae remain to be established.

First Skull and Associated Postcranial Bones of Macraucheniidae (Mammalia, Litopterna) from the Deseadan Salma (Late Oligocene) of Cabeza Blanca (Chubut, Argentina)

ABSTRACT The first skull associated with postcranial elements of Macraucheniidae (Litopterna) from the Sarmiento Formation in Cabeza Blanca (Chubut, Argentina) are described herein. The material consists of a nearly complete skull, nearly complete right humerus, left metacarpal IV, and three phalanges (proximal, intermediate, and distal of the same digit) of the same individual. It is compared with the Santacrucian genus Theosodon Ameghino, the Colhuehuapian Cramauchenia Ameghino, and the Deseadan species Coniopternium andinum and C. primitivum Soria and Hoffstetter. The comparative study leads us to recognize this specimen as Cramauchenia normalis. The presence of this species in Cabeza Blanca increases its biochronological distribution to Deseadan South American Land Mammal Age (SALMA) (late Oligocene).

New Data on Diversity of Notohippidae from the Oligocene of Mendoza, Argentina

ABSTRACT Notohippidae (Notoungulata) specimens from the late Oligocene Quebrada Fiera locality (Mendoza, Argentina) were previously identified as a new taxon, Mendozahippus fierensis Cerdeño and Vera. New cranial, mandibular, and postcranial remains allow enhanced description of this species and its ontogenetic variation. The ectocuneiform corresponding to the holotype (MCNAM-PV 4004) of M. fierensis was discovered when reexamining a block belonging to the sediment surrounding the holotype. It corresponds with the metatarsal III that was associated with the holotype skull. On the other hand, MCNAM-PV 3851, a poorly preserved maxillary fragment, is recognized as a second notohippid taxon, which differs from M. fierensis in the different position and relative size of I3—C. The canine is placed labially to P1 and its section shows a similar size to that of the latter; ahead of the canine, the preserved root of I3 is also labially placed, and its section is clearly larger than that of the canine. This condition differs from other Deseadan notohippids. Enlargement of the muzzle at the level of I3—C and a developed paracone on premolars are present in Eurygenium and Pascualihippus; the convergence of the premaxillae anterior to I3 in MCNAM-PV 3851 is closer to the condition in Eurygenium. The incompleteness of this specimen, however, prevents its proper definition and it is considered as Notohippidae indet.

Postcranial Morphology of Notopithecus Ameghino, 1897 (Notoungulata, Interatheriidae) from the Middle Eocene of Patagonia, Argentina

ABSTRACT The genus Notopithecus is the best known and most abundant among the genera traditionally grouped as “Notopithecinae” (Notoungulata, Interatheriidae). Previous studies have described in detail the morphology of the skull of Notopithecus; however, its scarce appendicular bones were poorly characterized. Until now neither skulls nor associated skeletons were known for the other genera of this group. In this paper, the most complete individual of Notopithecus is described. The specimen MPEF-PV 1113 is in the vertebrate paleontology collection at the Museo Paleontológico Egidio Feruglio, Trelew, and comes from Valle Hermoso, Chubut Province, Argentina. It includes the articulated cranium and mandible and most of the postcranial skeleton, with almost all the elements in anatomical position: many articulated vertebrae, scapula, humerus, radius, femur, tibia, fibula, calcaneum, astragalus, metapodials, and phalanges. The present contribution constitutes the first comparative study of the postcranial skeleton associated with the skull of an individual of Notopithecus, clarifying some systematic contradiction relative to the holotype of this taxon; at the same time, most of these elements are known for the first time for notopithecines. The appendicular skeleton of Notopithecus is significantly distinct from other known interatheriine interatheriids such as Federicoanaya sallaensis and Eopachyrucos ranchoverdensis from the Deseadan SALMA or Interatherium and Protypotherium from the Santacrucian SALMA. On the other hand, it presents some similarities with the Mesotheriidae Trachytherus and the generalized notoungulate Colbertia magellanica. The new specimen of Notopithecus offers the potential for morphofunctional studies and improving our understanding of the phylogeny of this group.

A new Leontiniidae (Notoungulata) from the Late Oligocene beds of Mendoza Province, Argentina

The present paper deals with the leontiniid remains recovered from the Late Oligocene (Deseadan) levels of Quebrada Fiera, Mendoza Province, central-western Argentina. The material consists of an almost complete skull associated with 11 vertebrae, as well as some maxillary and mandibular fragments and postcranial elements of different individuals, enabling a life reconstruction. The comparative study allows morphological differences with respect to other Deseadan taxa to be established, such as Scarrittia, Leontinia, Ancylocoelus, Anayatherium and Elmerriggsia, leading to the proposal of the new taxon Gualta cuyana gen. et sp. nov. The new genus and species is close to Scarrittia canquelensis in having upper I1 more developed than I2–3, mainly by its greater crown-height, and the canine overlapping the P1; it differs from this species by the longer, narrower nasals, longer rostrum, I2 not reduced, P3–4 with shallow lingual sulcus, shorter cervical vertebrae, and shorter calcaneum, lacking navicular facet. The complete dentition and/or the larger I1 differentiate Gualta cuyana from Leontinia, Ancylocoelus and Anayatherium ekecoa, as well as from the Miocene Colpodon. The lingual sulcus on P3–4 is much shallower than in Scarrittia barranquensis, Leontinia, Anayatherium and Elmerriggsia. The phylogenetic analysis shows poorly resolved relationships among leontiniids; when using equal weights, the analysis shows that Gualta cuyana is more related to the species of Anayatherium and Scarrittia canquelensis, whereas under implied weights, the new taxon is basal to other Palaeogene taxa. Gualta cuyana adds to other endemic taxa of the peculiar Deseadan assemblage from Quebrada Fiera. The new leontiniid constitutes a low percentage of fossil mammals within the Quebrada Fiera fauna, as is also true for this family in Salla (Bolivia), but in contrast with some Patagonian localities or the Brazilian Tremembé Formation where leontiniids are the best-represented mammal group. http://zoobank.org/urn:lsid:zoobank.org:pub:17749C84-4028-4FC8-A140-E1A6FE02466D

Acoelodus Connectus Ameghino, 1901, Sinónimo de Transpithecus Obtentus Ameghino, 1901, “Notopithecinae" del Eoceno de Patagonia

La revision sistematica de los “Notopithecinae” de la Edad Casamayorense (Eoceno medio), incluidos en la Familia Interatheriidae (Notoungulata), permitio esclarecer el estatus taxonomico y nomenclatural de este grupo y de otros notoungulados paleogenos de Patagonia. En esta nota, se propone una nueva interpretacion taxonomica de Acoelodus connectus, especie descrita en la Familia Acoelodidae por Ameghino y cuyo nombre fue sinonimizado posteriormente por Simpson con el ?Henricosbornidae Paginula parca. Tanto el holotipo de Acoelodus connectus como otros atribuidos a la misma especie y a Paginula parca se reconocen aqui como Transpithecus obtentus, un notopitecino casamayorense (Subedad Barranquense) de Patagonia

Dusky Dolphin Trophic Ecology: Their Role in the Food Web

Publisher Summary Like most top predators, dusky dolphins (Lagenorhynchus obscurus) may play different roles in marine ecosystems, although they are still poorly known. Dusky dolphins are an integral part of several marine ecosystems of the southern hemisphere. Among other cetaceans, pinnipeds, seabirds, and sharks, dusky dolphins represent the near-terminal links in the food webs in which they are embedded. This set of species is also referred to as the “top predators” or “upper trophic level predators” and the study of the trophic role dusky dolphins play in marine ecosystems is driven mostly by the same interests that one has in top predators. The goal of this chapter is to briefly summarize what is known about their trophic ecology and to attempt to develop, within the limitations of the available data, an initial description of the trophic role of dusky dolphins in their ecosystems. To achieve this goal, several topics are presented, including diet and feeding habits, relationships with other top predators, competition and kleptoparasitism, the role in the transmission of parasites, and finally their trophic relationships with fisheries.