Laura Edith Cruz

The intertropical Brazilian species of Panochthus (Xenarthra, Cingulata, Glyptodontoidea): a reappraisal of their taxonomy and phylogenetic affinities

ABSTRACT Four species of Panochthus (P. greslebini, P. jaguaribensis, P. oliveira-roxoi, and P. rochai) have been described from the late Pleistocene of northeastern Brazil. P. oliveira-roxoi, and P. rochai have been considered loosely as synonyms of P. greslebini. This paper reevaluates the referred material, diagnostic characters, and validity of these species and includes a cladistic analysis of 25 caudal tube and carapace characters to determine their positioning relative to other species of Panochthus. P. greslebini and P. jaguaribensis are valid species and differ from the other species of Panochthus by unique combinations of caudal tube characters. Carapace fragments previously attributed to P. jaguaribensis are in fact fragments of cephalic shields. These fragments and the isolated ostoderms previously described for P. jaguaribensis cannot be confidently assigned to this species. We support the interpretation of P. rochai as a junior synonym of P. greslebini, but P. oliveira-roxoi is actually a nomen dubium instead of a synonym of P. greslebini. Our analysis yielded a fully resolved tree in which Panochthini, as traditionally defined, is paraphyletic and the species formerly attributed to Panochthus form a monophyletic group, echoing recent findings based on a different dataset. Within Panochthus, the Brazilian species form a clade with the Bonaerian species P. subintermedius, which is the sister species to P. greslebini. Instead of a more basal position suggested in early and recent works, P. jaguaribensis is deeply nested within the clade encompassing the species of Panochthus.

ASOCIACIONES FAUNÍSTICAS DEL CUATERNARIO DE SAN FRANCISCO, PROVINCIA DE CÓRDOBA, ARGENTINA. IMPLICANCIAS BIOESTRATIGRÁFICAS Y TAXONÓMICAS

Abstract. FAUNAL ASSEMBLAGES FROM THE QUATERNARY OF SAN FRANCISCO, CÓRDOBA PROVINCE, ARGENTINA. BIOSTRATIGRAPHIC AND TAXONOMIC IMPLICATIONS. The chronological scale and continental biostratigraphy of South America was established on the base of fossil mammals from the Pampean Region. This scheme consists of Stages/Ages based on Biozones, with the late Miocene—early Holocene type localities in the Buenos Aires province. In the Córdoba province, several geological and stratigraphical studies have been undertaken since the 1990s and have provided a regionally useful scheme for biostratigraphic studies of the Quaternary. The aim of this work is to perform a biostratigraphic study of the San Francisco locality, in the east central region of the Cordoba province through the analysis of its mammal assemblages and to analyze the correlation with the scale proposed for the Pampean Region. We describe two faunal assemblages from two stratigraphical levels: (1) the faunal assemblage from the stratigraphic level 2 consisting of Lomaphorus sp., Neosclerocalyptus ornatus Owen, Catonyx tarijensis (Gervais and Ameghino), Scelidotheriinae indet., Macrauchenia patachonica Owen, Hemiauchenia paradoxa Gervais and Ameghino, Smilodon populator Lund and Panthera onca (Linnaeus) and assigned to the Ensenadan (early—middle Pleistocene) of the Pampean region; and (2) the faunal assemblage from the stratigraphic level 3 consisting of Neosclerocalyptus paskoensis (Zurita), Equus (Amerhippus) sp., Toxodon sp., Arctotherium sp., and cf. Lagostomus Brokes and assigned to the Lujanian (late Pleistocene—early Holocene) of the Pampean region. New records for Córdoba Province include Neosclerocalyptus ornatus, Panthera onca, and Arctotherium sp.; in addition, the latter represents the first record of the Ursidae family.

A new genus of Sigmodontinae (Mammalia, Rodentia, Cricetidae) from the Pliocene of central Argentina

ABSTRACT Chukimys favaloroi, new genus and species, is added to the past diversity of sigmodontine rodents, the largest subfamily of Neotropical mammals. It is based on a maxillary with the entire tooth row and both first and second lower molars collected in sediments of the Brochero Formation (Late Pliocene) that crop out in Córdoba Province, Argentina. The new genus represents a small rodent (about 40 g) and has a unique combination of traits, including a zygomatic plate with deeply excavated anterior border and conspicuous zygomatic spine, incisive foramen reaching the level of the protocone of the first upper molar, palate narrow and flat, molars moderately hypsodont, and the first lower molar four-rooted. The new sigmodontine shows similarities with several extant members of the tribes Phyllotini and Reithrodontini, as well as with the extinct Dankomys vorohuensis from the Pliocene of Buenos Aires, Argentina. The comparisons performed suggest that Chukimys has anatomical features related to omnivory and the incorporation of hard material in its diet. Chukimys is the first fossil genus of sigmodontine described from central Argentina and probably represents a new member of the currently monotypic tribe Reithrodontini.

LOS MAMÍFEROS FÓSILES DEL PLEISTOCENO TARDÍO-HOLOCENO TEMPRANO DEL SUDESTE DE LA PROVINCIA DE CÓRDOBA Y SUS IMPLICANCIAS PALEOAMBIENTALES PARA EL CENTRO DE ARGENTINA

MAMMALS OF LATE PLEISTOCENE-EARLY HOLOCENE OF SOUTHEAST OF THE PROVINCE OF CORDOBA, AND THEIR PALEOENVIRONMENTAL IMPLICATIONS FOR THE CENTER OF ARGENTINA. Paleontological exploration on the eastern plain of Cordoba Province is scarce, only referring to mammal assemblages from Mar Chiquita lake or San Francisco localities in the northeast of the Cordoba province, or specifi c discoveries in the centre and southeast of this province. In the present study is described a new faunistic assemblage from Isla Verde, in the southeast plain of Cordoba province. This assemblage is composed by Eutatus seguini Gervais, Zaedyus pichiy (Desmarest) Osgood, Tolypeutes sp., Neosclerocalyptus sp., N. paskoensis (Zurita) (Cingulata), Scelidotheriinae indet. (Tardigrada), Ctenomys sp., Lagostomus sp., Galea sp. (Rodentia), Macrauchenia sp. (Litopterna) and Equus (Amerhippus) sp. (Perissodactyla). This fauna is refered to Lujanian Stage (late Pleistocene-early Holocene) of the Pampean Region. The fossiliferous level is consistent with a semiarid and herbaceous steppe and refers to La Invernada Formation. From a paleoclimatic point of view, the record of these species suggests arid to semiarid conditions, between cold and warm. These conditions also agree with the interpretations realized studying morphological adaptations of some fossils.

On the Type Specimen of Panochthus frenzelianus Ameghino, 1889 (Xenarthra, Glyptodontia, Panochthidae)

Abstract. Panochthus frenzelianus was described by Ameghino in 1889 based on a skull, mandible, cephalic shield, osteoderms from the posteriormost rows of carapace, and caudal rings. Unfortunately, the type specimen was not specified and the provenance and repository of the described specimens were not informed. In 1903, Osborn stated that the holotype of this species was part of a collection of fossil mammals that Cope bought in France in 1878 and later deposited in the AMHN of New York. In 1942, Castellanos published a photograph of the purported holotype of P. frenzelianus (a mounted skeleton) and confirmed that it was deposited at the AMNH, as previously stated by Osborn. However, the specimen presents some differences with the material described in 1889 by Ameghino. Here we attempt to determine the true type specimen of P. frenzelianus and its repository based on information available on the literature, the AMNH collection, archives (e.g., notes, catalogs), and on a morphological analysis of some elements assigned to Panochthus housed in that institution. We found that: (1) the specimen figured by Castellanos and exhibited at the AMNH is a composite specimen formed by remains of at least three individuals; (2) these remains do not bear the diagnostic features mentioned by Ameghino and, therefore, they cannot be assigned to the holotype of P. frenzelianus; (3) a cephalic shield and a mandible belonging to another specimen at the AMNH bear the diagnostic characters mentioned by Ameghino, and are the only parts that we could confidently assign to the holotype of P. frenzelianus.

New Vertebrates of the Brochero Formation (Córdoba, Argentina): A Review of the Pliocene of Central Argentina

The “Horizonte Brocherense” sensu Castellanos was created on the basis of a mammal assemblage recovered from the San Alberto Valley and Los Reartes Valley (Córdoba, Argentina). This mammal association was placed in the “Uquian Stage” (early Pliocene) according to the stratigraphic scheme proposed by Castellanos in 1944. Later, different authors considered this association to belong either to the Montehermosan Stage/Age (early Pliocene) or Huayquerian Stage/Age (late Miocene), based on more updated stratigraphic schemes. Here, we present new vertebrates recovered from the type locality (San Alberto or Traslasierra Valley) of the Brochero Formation; we provide the first paleoenvironmental interpretation for this unit, and discuss the age of the fauna and its bearing sediments. As the main result, this work contributes to the knowledge of the Pliocene faunas, providing the first records of some anurans, snakes, and mammals for the Brochero Formation, and the biostratigraphic and chronological implications of such findings when comparing the fossil assemblage with its counterparts from South America.