Juan Carlos Fernicola

A new cingulate (Mammalia: Xenarthra), Pachyarmatherium brasiliense sp. nov., from the Late Pleistocene of Northeastern Brazil

ABSTRACT Pachyarmatherium is an enigmatic cingulate genus formerly recognized as Dasypodoidea, but tentatively assigned to the poorly known subfamily Glyptatelinae (Glyptodontidae) by later authors. A new species is described from the late Pleistocene of northeastern Brazil. The material comprises several isolated osteoderms, carapace fragments, and miscellaneous postcranial material. The new species, Pachyarmatherium brasiliense, differs from the North American Pachyarmatherium leiseyi in being larger and in having osteoderms with heptagonal shape, main figures with oblong, subrounded and polygonal outline (instead of only polygonal), and a larger number of peripheral figures. To clarify the affinities of Pachyarmatherium, a cladistic analysis was conducted of 48 morphological postcranial characters and scored for 11 cingulates (the new species, four dasypodids, one pampathere and five glyptodontids) and two pilosans used as outgroup taxa. In the most parsimonious topology obtained, Pachyarmatherium is the sister-group to a clade including Pampatheriidae and Glyptodontidae. This result contradicts the previous tentative allocation of Pachyarmatherium to the Glyptodontidae, and indicates that the glyptodont-like characters of the carapace and osteoderms of Pachyarmatherium are homoplasies shared with glyptodonts. The taxonomic validity of the genera Pachyarmatherium and Neoglyptatelus is recognized, but the morphological evidence from the external ornamentation of osteoderms does not offer support for the placement of Pachyarmatherium within Glyptatelinae.

Revisiting the intertropical Brazilian species Hoplophorus euphractus (Cingulata, Glyptodontoidea) and the phylogenetic affinities of Hoplophorus

ABSTRACT The genus Hoplophorus is one of the most distinctive glyptodonts from the Quaternary deposits of the intertropical area of Brazil. In this paper, we redescribe cranial and postcranial elements and describe some new tarsal elements belonging to the species Hoplophorus euphractus from caves from Minas Gerais state, southern Brazil, in order to provide a better diagnosis for the genus. The material examined shows several striking, distinctive characters relative to Neosclerocalyptus, besides those previously reported, reinforcing the validity of Hoplophorus. On the other hand, we find that the postcrania of Hoplophorus presents striking, unreported resemblances with Panochthus (e.g., more lateromedially elongated cuboid facet of navicular and caudal tube with large lateral figures separated from the terminal ones by a wide space). In order to infer the relationships of Hoplophorus and to reevaluate the monophyly of the tribe Hoplophorini and the subfamily Hoplophorinae (in which Hoplophorus was previously allocated), we carried out a cladistic analysis of 18 taxa, including 13 glyptodont genera and five cingulate outgroups, scored for 151 cranial, dental, and postcranial characters. The most parsimonious tree shows that Hoplophorinae and Hoplophorini are both paraphyletic and has Hoplophorus as the sister group to Panochthus based mostly on synapomorphies of the caudal tube. We propose: (1) restricting the definition of the tribe Hoplophorini to the lineage represented by Hoplophorus, making it the sister group to Panochthini within Panochthinae (= Hoplophorus + Panochthus); and (2) a new subfamily, Neosclerocalyptinae, represented by Neosclerocalyptus, the sister group to Panochthinae.

The phylogenetic affinities of the extinct glyptodonts

Among the fossils of hitherto unknown mammals that Darwin collected in South America between 1832 and 1833 during the Beagle expedition were examples of the large, heavily armored herbivores later known as glyptodonts. Ever since, glyptodonts have fascinated evolutionary biologists because of their remarkable skeletal adaptations and seemingly isolated phylogenetic position even within their natural group, the cingulate xenarthrans (armadillos and their allies). In possessing a carapace comprised of fused osteoderms, the glyptodonts were clearly related to other cingulates, but their precise phylogenetic position as suggested by morphology remains unresolved. To provide a molecular perspective on this issue, we designed sequence-capture baits using in silico reconstructed ancestral sequences and successfully assembled the complete mitochondrial genome of Doedicurus sp., one of the largest glyptodonts. Our phylogenetic reconstructions establish that glyptodonts are in fact deeply nested within the armadillo crown-group, representing a distinct subfamily (Glyptodontinae) within family Chlamyphoridae. Molecular dating suggests that glyptodonts diverged no earlier than around 35 million years ago, in good agreement with their fossil record. Our results highlight the derived nature of the glyptodont morphotype, one aspect of which is a spectacular increase in body size until their extinction at the end of the last ice age.

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.

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.

ON THE TYPE OF SCHISMOTHERIUM FRACTUM AMEGHINO, 1887 (XENARTHRA, FOLIVORA, MEGATHERIOIDEA) FROM THE EARLY MIOCENE SANTA CRUZ FORMATION (SANTA CRUZ PROVINCE, ARGENTINA)

Schismotherium fractum, the type species for the genus, is a basal Megatherioidea (Xenarthra, Folivora) from the Santa Cruz Formation (Early Miocene) of Patagonia. The type specimen, currently lost, was described as a fragmented left mandible. Several years later, Ameghino refined his description based on additional material that included the skull and mandible, and several postcranial elements, all deposited in the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (Buenos Aires, Argentina; MACN-A 6445-70). A neotype for this species is required to permit further systematic and taxonomic work on several sloth taxa, and we designate MACN-A 6445-70 as neotype for Schismotherium fractum.

Systematic Revision and Evolutionary History of Acarechimys Patterson in Kraglievich, 1965 (Rodentia, Caviomorpha, Octodontoidea)

Abstract. The octodontoid rodent Acarechimys was abundant during the early Miocene and had the widest temporal and geographic distribution of any extinct caviomorph. Despite this extensive fossil record Acarechimys has not been well characterized. In this work, we systematically revise Acarechimys, describe new early—middle Miocene fossils from Argentina and Bolivia, corroborate its monophyly, and study its evolutionary history. Acarechimys has brachydont molars, retained deciduous premolars, four crests on upper molars, lowers with variably developed mesolophid and metalophulid II, and absence of mental foramen in the mandible. Acarechimys includes: Acarechimys leucotheae (late Oligocene, Chubut, Argentina), A. gracilis and A. constans (early Miocene, Chubut and Santa Cruz, Argentina), and A. minutus and A. minutissimus (early—middle Miocene of Patagonia Argentina, Bolivia, and Colombia). The temporal and geographic distributions suggest that Acarechimys could have evolved in Patagonia, by the early late Oligocene. Its acme was during the late early Miocene in Southern Patagonia. By the middle Miocene, Acarechimys decreased in diversity and was last recorded in high latitudes of South America (Patagonia). In lower latitudes, the oldest record is from the late early Miocene of Chucal, northern Chile, and during the late middle Miocene, the genus is recorded in localities of Colombia, Bolivia, and Peru. The available evidence suggests that Acarechimys was probably not present in lower latitudes (N of ~ 30° S) before the early Miocene. The reasons Acarechimys dispersed northward at this time remain to be elucidated, but the timing coincides with a massive disappearance of other octodontoids from Patagonia.

On the Publication and Pagination of Ameghino's (1894) Taxonomy of Santacrucian Mammals

1Department of Ecology and Evolutionary Biology, University of Toronto, 25 Harbord St., Toronto, Ontario, Canada, M5S 3G5, and Section of Palaeobiology, Department of Natural History, Royal Ontario Museum,100 Queen’s Park Crescent, Toronto, M5S 2C6, Ontario, Canada. 2Consejo Nacional de Investigaciones Científicas y Técnicas. División Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Av. Ángel Gallardo 470, C1405DJR Ciudad Autónoma de Buenos Aires, Argentina. 3Universidad Nacional de Luján, Departamento de Ciencias Básicas, Ruta Nacional 5 y Av. Constitución, 6700, Luján, Buenos Aires, Argentina. GERARDO DE IULIIS1 JUAN C. FERNICOLA2,3 AUGUSTO RACCO2