Search

Abandoned rookeries belonging to any of the Pygoscelis species are very particular taphocoenosis, usually preserved due to the accumulations of bones, pebbles, and guano year after year in the same nesting area, that condense together with other biogenic material and form ornithogenic sediments. The results of the excavation, sieved and analyses of sediment and materials found in two rookeries formed during the last 8000 years, named Pingfo I and Pingfo II and found in the 25 de Mayo/King George Island (South Shetland Islands, West Antarctica) are presented here. The analyses of the bones and eggshells, taxonomic and ontogenetic composition, elements representation, transport degree, predation, and scavenging marks, together with the micropalaeontological content provided informative tools for the reconstruction of the nesting areas, suggesting that bones were transported and accumulated in Pingfo I that would represent high energy beach, whereas a breeding colony was settled in Pingfo II. The preservation of hexactinellid spicules and several arthropod remains are particularly informative for the levels at Pingfo I. The preservation of a Culicidae (Diptera) wing could be the first middle Holocene record of the group in Antarctica, the only continent without extant mosquitoes. [ABSTRACT FROM AUTHOR]

A new extinct sclerorhynchoid sawfish, Ptychotrygon ameghinorum sp. nov., is presented here based on abundant isolated teeth and some dermal denticles, which were recovered from the Mata Amarilla Formation, belonging to the lower Upper Cretaceous of the Santa Cruz Province in the Austral Basin of Patagonia, Argentina. This new species is the first Ptychotrygon occurrence in the southern hemisphere, which so far only has been reported from northern hemisphere deposits (Europe, North Africa, and North America). The presence of P. ameghinorum sp. nov. in these southern high-latitude deposits of Patagonia, Argentina, extends the geographic range of Ptychotrygon considerably southwards. This distribution pattern in the "middle" Cretaceous seems to correlate with the South Atlantic opening at the end of the Albian. The presence of lateral cephalic dermal denticles and the simultaneous absence of rostral denticles in the abundant fossil material support the view that Ptychotrygon did not develop such rostral structures. A reinvestigation of all known species assigned to Ptychotrygon reveals that P. ellae is a junior synonym of P. boothi, P. benningensis belongs to Texatrygon, P. rugosum belongs to Asflapristis, and P. clementsi represents an unidentifiable species (Ptychotrygon? sp.). The stratigraphic distribution demonstrates that Ptychotrygon might have originated in the Albian in south-western Europe and subsequently dispersed to obtain its widest distribution during the Cenomanian. In the Coniacian, a steep diversity decline is recognizable with a subsequent distribution shift from Europe to North America. [ABSTRACT FROM AUTHOR]

Protolipterna ellipsodontoides is a small bunodont South American native ungulate, generally considered an early litoptern, exclusively found in the Palaeogene Itaboraí Basin. Its dentition is well known; however, its mandibular morphology was only known by fragmentary materials. Here, we describe the first complete mandible of this species. A micro-CT scan reveals the first case of alveolus resorption in this putative early litoptern. Two accessory canals on the retromolar region are also described. Canals on the retromolar region are documented for other mammalian orders; however, this represents the first description of this feature for the Protolipternidae. Unlike more advanced litopterns, this species lacks specialisations related to strict herbivory, and its dental and mandibular morphology suggests an omnivore habit. A comparison with the mandible of another Itaboraian protolipternid, Miguelsoria parayirunhor, indicates the presence of different dietary specialisations. Body mass estimations for both species are also provided. [ABSTRACT FROM AUTHOR]

Notoungulates were the most diverse group of South American native ungulates during the Cenozoic. They ranged from small rodent-like to heavy rhino-like forms and, despite this morphological diversity, their monophyly is widely accepted. Within Notoungulata, Typotheria and Toxodontia (the two major clades) are well supported, whereas phylogenetic relationships between early diverging lineages (formerly grouped as 'Notioprogonia') are still a matter of debate. Within Toxodontia, 'Notohippidae' sensu Simpson (1967) is a paraphyletic group lacking systematic consensus and represented by small to medium-sized taxa from the late Eocene to early/middle Miocene, but that were especially diverse during the late Oligocene. In this context, we describe a new toxodont (Teushentherium camaronensis gen. et sp. nov.), found at Barrancas Blancas, an Oligocene locality in the south-east of Chubut (Patagonia, Argentina). It is represented by the anterior portion of the skull (palate and anterior snout) and the associated horizontal rami of the mandible. A phylogenetic analysis places the new taxon as closely related to taxa traditionally regarded as 'Notohippidae'. In addition, extensive taxonomic sampling allowed us to assess phylogenetic relationships among other representatives. As expected, only Homalodotheriidae, Leontiniidae and Toxodontidae were recovered as monophyletic groups, whereas neither 'Notohippidae' nor 'Isotemnidae' were supported. We also identified a clade (sister to Homalodotheriidae) for which we propose the name Eutoxodontia. It includes 'Notohippidae' sensu Simpson, Leontiniidae and Toxodontidae, and provides a more accurate definition for middle and later diverging toxodonts, avoiding terminology such as 'advanced' or 'derived'. We hope to contribute to the stabilization of toxodontian taxonomy, to highlight the main gaps in this respect, and to promote future contributions dealing with this intricate issue. [ABSTRACT FROM AUTHOR]

Xenungulates are a peculiar group of bilophodont ungulates, widespread over South America during the Paleocene and early Eocene. Here we describe, illustrate and analyse a new Xenungulata, Rodcania kakan gen. et sp. nov., the first from the lower latitudes of Argentina. It was recovered from the Río Loro Formation (Tucumán Province), for which a Paleocene age was estimated. The material comprises a fragment of the left dentary with an incomplete m2, eroded over the enamel surface, and an almost complete m3. Both teeth share with Xenungulata strong enamel, vertically oriented Hunter–Schreger bands (HSB), and wear facets sloping distally. Rodcania kakan differs from other xenungulates in the m3 trigonid, simplified and mesiodistally short; absence of a paraconid; more oblique protolophid in relation to the mesiodistal axis and a straight cristid obliqua, pointing to the protoconid position; and has a wider and longer talonid. A phylogenetic analysis of 13 species and 36 craniodental characters recovered R. kakan as a basal member of the Carodniidae, supported by 10 synapomorphies in the four most parsimonious trees. The body mass estimation of the Río Loro Fauna and of the rest of the xenungulate taxa revealed that R. kakan is the largest mammal of the Río Loro assemblage, weighing around 165 kg and with a size comparable to Carodnia feruglioi. The increase in body mass showed no clear relation with evolutionary trends in xenungulates. [ABSTRACT FROM AUTHOR]

The fossil record of the Charadriiformes in South America is scarce and limited to the Neogene of Argentina and Peru. In the present contribution, we present and describe a nearly complete tarsometatarsus of Thinocorus rumicivorus (Least Seedsnipe) from the Ensenadan Age/Stage (early-middle Pleistocene) of Punta Hermengo, Buenos Aires province, Argentina, which constitutes the youngest record for the species to date. We also compare the material with extant and fossil Thinocoridae. The stratigraphic range of the fossil predates the Matuyama/Brunhes boundary and is coincident with the biozone of Mesotherium cristatum, which indicates a more humid and warmer climate than the present for the species. [ABSTRACT FROM AUTHOR]

New remains from the La Meseta (Thanetian – Lutetian) and Submeseta (Lutetian – Rupelian) formations (Seymour Island, Antarctica) are tentatively assigned to Diomedeidae and Procellariidae (Procellariiformes). Based on the fossil record and several analyses that attempt to explain the evolutionary patterns of Diomedeidae,Notoleptos gigliigen. et sp. nov., based on a small tarsometatarsus, was an ancestral form that lived in Antarctica before the rise of large-sized albatrosses. Subsequent environmental cooling since the late Oligocene could have selected against small body size, to the detriment of small-sized albatrosses likeNotoleptos, thus favoring large body size and setting the stage for the development of the specialized albatross flight. ZooBank ID (LSID): urn:lsid:zoobank.org:pub:C8D9C862-1536-4EA3-8A76-70903AA75639 [ABSTRACT FROM AUTHOR]

A new litoptern Cramaucheniinae species,Pternoconius bondi, sp. nov., from Colhuehuapian levels of the Sarmiento Formation in Bajada del Diablo (Chubut, Argentina) is described herein. The specimen belongs to an adult animal and preserves the anterior portion of the skull with the maxillary region, some fragments of nasal bones, a small portion of the left zygomatic process, and most of the upper dentition (i.e., left P2–M3, right C, and right P1–M3). It is compared with the Deseadan species ?Coniopternium primitivumCifelli and Soria 1983 andPternoconius polymorphoidesCifelli and Soria 1983, and also with the Colhuehuapian speciesCramauchenia normalisAmeghino andTheosodon lydekkeriAmeghino. Although the hypocone and precingulum development, the paracone and metacone heights, and the connection between paraconule and protocone are singular features, the main characters that diagnose this new species are lack of a mesostyle pillar, soft labial bending of the ectoloph, absence of the metaconule in molars, and the smaller size with respect to other species of the genus. Comparative study leads us to recognize this specimen as a new species that increases the diversity of the Macraucheniidae in the early Miocene of Patagonia. http://zoobank.org/urn:lsid:zoobank.org:pub:F68802D8-305-45CA-8076-5AEC81B56483. Citation for this article: Cheme-Arriaga, L., M. T. Dozo, and J. N. Gelfo. 2016. A new Cramaucheniinae (Litopterna, Macraucheniidae) from the early Miocene of Patagonia, Argentina. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1229672. [ABSTRACT FROM PUBLISHER]