Jorge G. Martínez

Collagen Sequence Analysis of the Extinct Giant Ground Sloths Lestodon and Megatherium

For over 200 years, fossils of bizarre extinct creatures have been described from the Americas that have ranged from giant ground sloths to the ‘native’ South American ungulates, groups of mammals that evolved in relative isolation on South America. Ground sloths belong to the South American xenarthrans, a group with modern although morphologically and ecologically very different representatives (anteaters, armadillos and sloths), which has been proposed to be one of the four main eutherian clades. Recently, proteomics analyses of bone collagen have recently been used to yield a molecular phylogeny for a range of mammals including the unusual ‘Malagasy aardvark’ shown to be most closely related to the afrotherian tenrecs, and the south American ungulates supporting their morphological association with condylarths. However, proteomics results generate partial sequence information that could impact upon the phylogenetic placement that has not been appropriately tested. For comparison, this paper examines the phylogenetic potential of proteomics-based sequencing through the analysis of collagen extracted from two extinct giant ground sloths, Lestodon and Megatherium. The ground sloths were placed as sister taxa to extant sloths, but with a closer relationship between Lestodon and the extant sloths than the basal Megatherium. These results highlight that proteomics methods could yield plausible phylogenies that share similarities with other methods, but have the potential to be more useful in fossils beyond the limits of ancient DNA survival.

Breakage Patterns on Fishtail Projectile Points: Experimental and Archaeological Cases

Abstract Fishtail projectile points, also known as Fell 1, are dated between 11,000 and 9,500 14C yr B.P. in South and Central America and have been traditionally considered diagnostic of the early peopling of the continent. In this paper, experimental observations of impact breakage patterns on fishtail projectile point replicas are compared with archaeological points from the Cerro El Sombrero Cima site, in the Argentinian pampas, which exhibit a high breakage ratio and suggest that impact was a major cause of breakage in the assemblage. The position of these fractures is also briefly compared to patterns described by J. Bird (1969) for fishtail projectile points from Ecuador and Southern Chile.

Stable isotope analysis on human remains from the final Early Holocene in the southern Puna of Argentina: The case of Peñas de las Trampas 1.1

In this work are presented the results of isotopic analyses made on bone remains of human individuals (n = 6) from the southern Puna of Argentina dated to the final Early Holocene (ca. 8230–8000 BP). They were found in structures located in Peñas de las Trampas 1.1, a rockshelter at 3582 m.a.s.l. in Antofagasta de la Sierra, in the southern Argentinian Puna. They contain multiple secondary burials. Bone fragments were recovered from at least six individuals, three in each structure. Stable isotopes of Carbon (δ13C) and Nitrogen (δ15N) analysis were aimed at defining aspects related to the palaeodiet of the six individuals within the palaeo-economic subsistence spectrum typical of hunter–gatherers. It is worth noting that these human remains are among the earliest from North-Western Argentina, where funeral practices are related with the transportation of certain anatomical parts. The palaeodietary inference considers, on the one hand, the extreme aridity of this geographical area and its impact on the isotopic ecology. And, on the other, it takes into account the fact that four of the six individuals under study were breastfed infants. The results are in agreement with the expected values of the period, which has been characterized as the beginning of the arid Altithermal.

Ticks (Acari: Argasidae, Ixodidae) from Middle and pre-Hispanic Late Holocene associated with human activities in northwestern Argentina.

One male of Amblyomma parvitarsum and one male and a female of Ornithodoros sp. were recovered from archaeological layers of the Middle Holocene in a rock shelter in the province of Catamarca, used by hunter-gatherer groups. Another two ticks identified as a female and a nymph of Argas cf. neghmei were recovered from a layer of the Late Holocene in other rock shelter in the province of Tucumán used by humans of agro-pastoral complex societies previous to the Hispanic invasion. The presence of Amblyomma parvitarsum is probably related to hunting activity, while Ornithodoros sp. was probably an opportunistic parasite established in the shelter. Argas cf. neghmei was probably a parasite of birds as is A. neghmei, a tick that has been found in the nests of birds, chicken houses, but also in human dwellings. The presence of A. cf. neghmei may originate from birds naturally breeding in the shelter or from the nests of birds introduced into the shelter by humans.

“LA TRANSICIÓN” VISTA DESDE LOS VALLES INTERMONTANOS DEL NOROESTE ARGENTINO: NUEVOS DATOS DE LA QUEBRADA DE LOS CORRALES (EL INFIERNILLO, TUCUMÁN, ARGENTINA)

La quebrada de Los Corrales (El Infiernillo, Tucuman, Argentina) se ubica por encima de los 3.000 msm en el sector norte del Sistema de las Sierras del Aconquija. Los trabajos de investigacion desarrollados hasta el momento permitieron identificar diversos tipos de evidencias arqueologicas correspondientes a distintos momentos de ocupaciones humanas que se inician en el Holoceno Medio inicial (ca. 7.800-600 a.p.). La larga secuencia ocupacional convierte a esta microrregion en un buen punto de partida para reflexionar acerca de diversos procesos prehispanicos ocurridos en el noroeste argentino desde las ocupaciones mas tempranas hasta el establecimiento de una importante aldea agropastoril durante el 1er milenio de la Era Cristiana. En este trabajo presentamos una serie de evidencias correspondientes al periodo de transicion entre un modo de vida cazador-recolector a otro agropastoril ocurrido -a escala macrorregional- entre ca. 4.000 y 2.000 a.p. y evaluamos las posibilidades de la ocurrencia de un proceso transicional de caracter local.