Daniel Perea

Tacuarembemys kusterae, gen. et sp. nov., a new Late Jurassic–?earliest Cretaceous continental turtle from western Gondwana

ABSTRACT A new continental turtle, Tacuarembemys kusterae, gen. et sp. nov., is described on the basis of a partial external mold of the carapace and associated shell bone fragments recovered from the Batovi Member (Late Jurassic—? earliest Cretaceous) of the Tacuarembó Formation, Paraná Basin, Uruguay. The estimated length of the carapace is 18 cm. This new genus and species shows a unique combination of characters: a large nuchal notch, a pair of anterior supernumerary scales, the absence of a cervical scale, and an external surface ornamentation that is macroscopically smooth with some thin linear ridges perpendicular to the margins of the plates and microscopically composed of small, randomly distributed pits. The first two characters resemble those seen in the solemydid Naomichelys speciosa from the Cretaceous of North America, although the ornamentation is markedly different. Although this combination of characters—some shared with other taxa (including cryptodires and pleurodires) and some others that are autapomorphic—allows the recognition of a new genus and species, additional remains are yet needed in order to clarify its phylogenetic relationships. Tacuarembemys kusterae is part of the Priohybodus arambourgi Assemblage Zone, which is of Late Jurassic—?earliest Cretaceous age. This is the first turtle to be discovered in South American continental deposits of that age and thus increases the knowledge on the regional evolution of Mesozoic turtles. The paleoenvironment for this species includes lakes and permanent and ephemeral rivers in arid-to-semiarid climatic conditions.

Archaeological evidences are still missing: a comment on Fariña et al. Arroyo del Vizcaíno site, Uruguay

Farina et al. [[1][1]] suggest the possibility of human presence ca 30 ka in the Arroyo del Vizcaino site (AVS) (southern Uruguay). This is based mainly on the record of cutmarks made by human artefacts on Pleistocene animal bones. They also inform of the finding of a single tiny stone tool and

First Record of Theropod and Ornithopod Tracks and Detailed Description of Sauropod Trackways from the Tacuarembó Formation (Late Jurassic-?Early Cretaceous) of Uruguay

The record of dinosaur tracks and trackways from the Tacuarembó Formation (Late Jurassic-?Early Cretaceous) is described in detail: two trackways and four isolated tracks. Ichnites are preserved in sandstones of interdune facies of the Batoví (lower) Member. The interpretation herein presented indicates a sauropod affinity of the trackways, while the isolated prints are considered to have been made by an ornithopod and small theropods. The fossil record for this formation was primarily integrated by fresh-water organisms. The presence of new groups (sauropods and ornithopods) has specially contributed to the reconstruction of the terrestrial fauna, represented up until this time only by theropods.

Marine Isotope Stage 3 (MIS 3) and Continental Beds from Northern Uruguay (Sopas Formation): Paleontology, Chronology, and Climate

The Sopas Formation is a late Pleistocene continental unit that includes trace fossils, woods, fresh-water mollusks, and vertebrates with mammals being the predominant taxa. Likely, relationships with the Last Interglacial Stage or with the Last Interstadial were proposed. The paleontological content of the Sopas Formation is updated, and the climatic and environmental signals provided by the fossil content are evaluated. Radiocarbon AMS dates ranging from 33,560 ± 700 year B.P. (cal 36,089 − 39,426 year) to 39,900 ± 1,100 (cal 42,025 − 45,389 year) and TL/OSL ages from 27,400 ± 3,300 to 71,400 ± 11,000 year (being the 45–28 ka time interval better represented), support a relationship with Marine Isotopic Stage 3 (MIS 3) in most outcrops. In the fossil assemblage are taxa that indicate open habitats, savannahs, and woodlands including gallery forests and perennial rivers; living representatives of taxa related to benign climatic conditions (mostly tropical to temperate climates), some taxa that suggest arid to semiarid environments, migrants, and seasonality indicators. A replacement versus mixed faunal models is discussed in the light of available evidence.

La presencia del xenartro palaeopeltis inornatus Ameghino, 1894, en la formación Fray Bentos (Oligoceno tardío), Uruguay

Se describe material de Palaeopeltis inornatus para la Formacion Fray Bentos (Oligoceno tardio), Uruguay. Este registro es el primero de la especie fuera de la Patagonia Argentina y confirma la afinidad deseadense de la fauna de dicha unidad. El hallazgo tambien apunta en favor de la hipotesis de uniformidad cronoestratigrafica en toda la extension de la Formacion Fray Bentos en Uruguay.

New Canid Remains from Dolores Formation, late Pleistocene-early Holocene, Uruguay

The fossil record of carnivorous mammals in Uruguay is scarce and fragmentary, but informative. In the present contribution, two new records of canids allocated in sediments of the Dolores Formation (late Pleistocene-early Holocene) are described. These records, based on their anatomical-comparative study and multivariate analysis, correspond to two foxes: one of medium size, Cerdocyon thous, conforms to the first record of this taxon in the country, meanwhile the other one, of larger size, is referred to Dusicyon avus and is the first fossil record of this animal in the south of the territory and the second record in the whole country. Until now, the only carnivorous mammals registered in this formation were the hunters of large herbivores (Arctotherium sp. and Smilodon populator). In this way, these discoveries complement and expand the set of placental mammals with a carnivorous diet for this unit, particularly with the capacity to predate over small- and medium-size mammals.

The Humerus of Proterotheriidae (Mammalia, Litopterna) and Its Systematic Usefulness: The Case of “Proterotherium berroi” Kraglievich, 1930

Abstract. Proterotheriidae constitute a group of small-medium native South American ungulates with high diversity during the early Miocene and the late Miocene (Santacrucian and Huayquerian SALMAs). Recent studies demonstrated the wide dental variability, useful in the discrimination of the species. The aim of this work is to analyze the humerus as a postcranial element that is usually not found in association with cranial remains, and to evaluate (qualitatively and quantitatively) its systematic usefulness. We used the only known specimen of “Proterotherium berroi”, re-describing and re-illustrating it. The Principal Components Analysis resulted in 2 components explaining 86% of the variance. The PCA showed a differentiation between the largest species—Diadiaphorus majusculus and Anisolophus floweri—and the remaining ones (an intermediate group consisting of “Proterotherium”, Tetramerorhinus, Eoauchenia, Proterotheriidae indet., and the smallest, Thoatherium minusculum). We establish that, although there are slight morphological differences in the distal epiphysis of the humeri of Proterotheriidae, they mostly correspond to gradual changes in characters with continuous variations not linked to any particular taxonomic entity. These are not enough to assure a generic or specific determination, except for Eoauchenia. The differences in humeri size are considerable and they could be used as a criterion for discriminating Diadiaphorus and Anisolophus, to which the largest specimens would belong. We consider “P. berroi” a probable synonym of Neolicaphrium recens, but we ratify that a reliable systematic determination is only possible if it is based on cranial or dental remains.