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Proboscideans are megamammals widely recorded in South America Quaternary deposits, especially in Brazil, where many specimens were found in tanks and caves. In tank deposits, the fossil remains are usually recognized as adult individuals, although highly and usually fragmented. The records of immature proboscideans are rare, consisting of isolated teeth and jaw fragments, especially from tank deposits. Here we describe a new and rare occurrence of an immature proboscidean — a second upper left deciduous premolar (DP2) of Notiomastodon cf. platensis — from Pernambuco state, Brazil. This record increases the number of immature individuals known for Notiomastodon in Brazil, contributes to the understanding of the frequency of immature individuals in tank deposits, and increases Notiomastodon geographic distribution in South America. Keywords: South America, Quaternary, Notiomastodon platensis, immature, tank deposit.

The Alianca Formation, within the Brazilian Reconcavo–Tucano–Jatoba Rift System, is a succession of Late Jurassic sedimentary rocks that record the maximum flooding surface of shallow Capianga Lake in the Afro-Brazilian Depression, Gondwana. Several aulacogens and drift-marginal Mesozoic basins of eastern Brazil and western Africa recorded the great extensional event that occurred during the early stage of Gondwana break-up. Lithologic, petrographic, micropaleontological and geochemical analyses of lacustrine carbonates collected near the city of Ibimirim, Pernambuco State, were carried out to establish the paleolimnological evolution of a marginal area of Capianga Lake, in the Jatoba Basin. The ostracode fauna, obtained from grainstone and calcareous quartzarenite, is constituted by Theriosynoecum pricei, Theriosynoecum uninodosa, Theriosynoecum quadrinodosum, Reconcavona? jatobaensis and Alicenula? spp. Carbon and oxygen stable isotopes in bulk rock, Theriosynoecum pricei and Alicenula? spp. were measured. Theriosynoecum pricei displays the most negative δ13C values, between − 2.1 and − 1.3‰. The δ13C values obtained from Alicenula? spp. and bulk rock were also negative. The δ18O values for Theriosynoecum pricei range from − 10.1 to + 4.1‰. Alicenula? spp. show δ18O values between − 4.6 and + 5.8‰. The bioclastic character of the carbonates and the presence of cross-bedding and ripple marks suggest deposition in a low-energy, low-gradient, ramp-type littoral zone of a shallow, balanced-fill lake. The ostracode association, characteristic of permanent, alkaline, freshwater bodies, corresponds to the Theriosynoecum pricei ostracode biozone, which is of Tithonian age. The lithofacies, along with covariation of δ13C and δ18O, and large δ18O fluctuations, suggest that this marginal area of Capianga Lake was characterized by stable hydrological conditions in a closed basin. The δ13C values display a slightly narrower range, suggesting oligotrophic to slightly mesotrophic conditions, and holomixis in this marginal area of Capianga Lake.

We performed a macroscopic and radiological inspection in a set of bones belonging to the fossil mammal assemblage of Zabele Paleontological Site (Late Pleistocene-Northgrippian), in northeastern B...

The Pediomyiodea has been largely regarded as a Late Cretaceous North American metatherian lineage; however, some studies have suggested that a few South American taxa could be related to this family. Herein, Austropediomys marshalli gen. et sp. nov. from the Itaborai Basin, Brazil (lower Eocene – Itaboraian SALMA), is described. Austropediomys gen. nov. represents the first report of a pediomyoid metatherian in the Paleogene of South America backed by a phylogenetic analysis. Several derived features in the upper molars support its belonging to the Pediomyoidea: presence of accessory ‘conular-like’ structures (here named conuloids) lingual to the conules; supernumerary stylar cusps; asymmetric stylar shelf, with parastylar shelf reduced to a narrow rim in M1; straight centrocrista; short and obliquely oriented prepacrista, which contacts StA in M2–3. The presence of ‘conular-like’ structures lingual to the paraconule and metaconule is identified in Austropediomys gen. nov. and in Late Cretaceous pediomyoids as well, and results in the phylogenetic analysis as a synapomorphy of the Pediomyoidea. Austropediomys gen. nov. is autapomorphyc in the presence of enlarged conuloids on protocristae. The record of a pediomyoid in the Paleogene of South America increases the temporal and biogeographical range of this lineage. Also, our results support the hypothesis that several non-related metatherian lineages dispersed from North to South America via the Caribbean Plate, most probably during the latest Cretaceous, in an island-hopping or sweepstakes model.

Xenarthran osteoderms are integumentary bones with high fossilization potential presenting a high degree of morphological and histological diversity. Here, new data on the osteoderms histology of two glyptodonts, Panochthus and Neuryurus are presented. The poor spatial organization of the mineralized fibers and a large trabecular area in the middle zone identified in Neuryurus indicate a different bone pattern than the one found in Panochthus, which is mainly characterized by a middle zone with less spongiosa. Through the Bone Profiler program, the degree of compactness of the specimens was obtained, with about 70% for Neuryurus sp. and approximately 90% for Panochthus sp., showing the difference in bone pattern. These values confirm the visible difference in the histological patterns of these taxa, especially in the middle zone. This work demonstrates the microstructural variation studied in osteoderms and shows the importance of paleohistology as a starting point for a better understanding of extinct taxa.

The Paleogene vertebrate-bearing sites of Brazil are restricted to few formations such as Maria Farinha (Late Cretaceous-early Paleocene), Itaborai (early Eocene), Entre-Corregos (Eocene-Oligocene), and Tremembe (late Oligocene-early Miocene). A new Paleogene fauna is reported from an outcrop of the Guabirotuba Formation located at Curitiba, Parana State, southern Brazil. The Guabirotuba Formation is a stratigraphic unit of the Curitiba Basin, which belongs to the Cenozoic continental rift system of southeastern Brazil, a predominantly half-graben and horst system. The sedimentary facies indicate a fluvial distributary depositional system associated with floodplain, generated under humid climate conditions alternating with drier periods. This new Paleogene fauna, here named the Guabirotuba Fauna, has invertebrate and vertebrate taxa, including mammals (Cingulata, Notoungulata, Astrapotheria, and Metatheria). The fossil remains of seven armored xenarthrans are identified, including the description of a new species and genus named Proeocoleophorus carlinii. The Guabirotuba ungulates are assigned to Interatheriidae, Oldfieldthomasiidae, and Astrapotheria. The metatherian mammals are represented by a sparassodont, a palaeothentoid, and an argyrolagoid. This new mammalian fauna preliminarily suggests a late middle Eocene age (Barrancan South American Land Mammal Age) for the Guabirotuba Formation.

The fossil mammals that lived in the Brazilian Intertropical Region during the Quaternary are found in different types of deposits (e.g. natural tanks, ponds, caves, rockshelter, and riverbeds) throughout the Brazilian territory. The state of Bahia, located on northeastern Brazil, stands out for the presence of large and important caves, which are characterized by the natural deposition of sediments and fossils. The study aims to identify the fauna found in the Borboletas Cave, and to provide the first paleoecological inferences for the environment during the Late Pleistocene-Holocene. Here we present the first record of Palaeolama major, Hippidion principale and Smilodon populator in Paripiranga, Bahia. Coendou sp., Mazama gouazoubira, and Toxodon platensis, already known to the region, were also collected and identified. Based on the chronological and geographical distribution of the taxa, it is suggested that the faunal content found lived during the Late Pleistocene – Holocene. The presence of the taxa found indicate an open paleoenvironment, similar to savanna, with areas covered with grasses associated with areas with forest cover. This study demonstrates that the Borboletas Cave is the richest paleontological site carrying the mammals in this region.

Occurrences of gomphotheres in northeastern Brazil there are in tank deposits, caves and lagoons and many of these records are from the Pleistocene tank deposits, formed by physical and chemical erosion in crystalline rock. These deposits are common in northwestern of State of Ceara and correspond to the most Pleistocene fossil findings. This paper presents the description of two specimens of gomphotheres identified as Gomphotheriidae constituting an unprecedented record for the City of Iraucuba, Ceara, located 150 km from Fortaleza. In the same place, Xenarthra, Liptoterna, Notoungulata and Perissodactyla were also found.

Pleistocene sites with mammals in Brazil are commonly recorded from limestone or dolomite caves, outcrops at rivers and creeks, coastal plain lagoon deposits, rock shelters, and natural tanks. This work presents a new late Pleistocene site containing bones and footprints of mammals. The footprints are assigned to llama (Lamaichnum), cervid (Pecoripeda), horse (Hippipeda), and at least one megamammal (?Toxodon), constituting the northernmost record for the late Pleistocene of South America and the first record from Brazil. Mammals are related to fluvial environments along with treeless vegetation during a sub-humid climate, in a region currently dominated by a semiarid biome.

Zeusdelphys complicatus is one of the most enigmatic metatherians from the Itaboraí Basin. The type and only known specimen was previously regarded as the upper dentition of Eobrasilia; an M4 of a new taxon; an M3 of a Kollpaniidae (now regarded as a group of “condylarths”); a probable M1 of an incertae sedis taxon; and as an M1 of a Protodidelphidae. Herein, we present a morphological review of the dental structures of Zeusdelphys complicatus, presenting new interpretations and comparing it with other North and South American taxa. We also perform a phylogenetic analysis in order to test the affinities of Zeusdelphys and the validity of most studied characters. The results recovered Zeusdelphys complicatus as more closely related to Hatcheritherium alpha than to any other metatherian. Glasbiidae were recovered as the sister lineage of Protodidelphidae within Didelphimorphia, as true marsupials. Ectocentrocristus was recovered as the sister taxon of Zeusdelphys + Hatcheritherium, as a Hatcheriformes. The analysis recovered this suborder as an independent lineage from Polydolopimorphia, being more closely related to “Alphadontidae”. The affinities with Protodidelphidae are a result of convergent evolution, as Zeusdelphys is more closely related to Hatcheritherium alpha from the Late Cretaceous of North America. The results support a North American origin for Hatcheriformes. The presence of strong sea-level lowstands and islands in the Caribbean Plate during the Late Cretaceous provide valid data to support a faunal interchange between Americas during the latest Late Cretaceous. Based on the results, Zeusdelphys represents a South American early Eocene surviving Hatcheriformes.

With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as a didelphid or a derorhynchid "ameridelphian," or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaborai Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians, Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Peru. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments.