Despite chronicles from the 16th century describing fertile alluvial plains and densely populated wetlands, archaeology in western Mexico has been little studied. The Directorate of Archaeological Salvage (DSA) of National Institute of Anthropology and History (INAH) has initiated a study of two sites in Costa Canuva, at the southern part of Nayarit state: Becerros and Naranjos. Thirty charcoal and shell samples were radiocarbon (14C) dated to determine occupation history. A Bayesian approach was used to build a chronological modeling from charcoal samples. Charcoal and shell samples found in the same context allowed us to calculate the ΔR values of marine offset for this period. In general, the archaeological sites of this area are divided into three major periods: Formative, Classic, and Postclassic. The 14C dating of Becerros recovered materials provided a chronological framework for the site’s occupation, from cal AD 169–1025, corroborating the ceramic studies in the sense that human settlement activities date from the Formative (300 BC–AD 600) to the Early Postclassic (AD 900–1200). Naranjos started in the Classic period and reached its occupancy peak in the Late Classic. The site’s occupation may have persisted for at least two centuries after the conquest of the Altiplano in 1521. The comparison of charcoal dates and associated shell samples from the Naranjos Unit gave a probability distribution for ΔR, that ranged from 118.5 to 199.5 with a mean value of 159 ± 4, slightly higher than other values obtained at nearby sites.

Rock art of the Middle and Upper Orinoco River in South America is characterised by some of the largest and most enigmatic engravings in the world, including snakes exceeding 40m in length. Here, the authors map the geographic distribution of giant snake motifs and assess the visibility of this serpentine imagery within the Orinoco landscape and Indigenous myths. Occupying prominent outcrops that were visible from great distances, the authors argue that the rock art provided physical reference points for cosmogonic myths, acting as border agents that structured the environment and were central to Indigenous placemaking along the rivers of lowland South America.

The complex geographical scenario of Mexico allowed the cultural diversification and development of multiple cultures such as Tolteca, Teotihuacan, Mexica, and Maya, among others. Despite this rich cultural heritage, radiometric dating of Mexican cultural samples with radiocarbon (14C) began only in the 1980s and with accelerator mass spectrometry (AMS) in 2013. Analysis of 14C with AMS is the most widely used technique to date archaeological objects and cultural heritage. Since 2013, the Accelerator Mass Spectrometry Laboratory (LEMA) facility of the Institute of Physics at UNAM (IF-UNAM) has supported archaeological research in Mexico, but also investigation in other areas such as geology, physics, chemistry, and environmental sciences through the analysis of 14C, 10Be, 26Al, 129I, and Pu. The absolute dating with 14C continues to be the core of LEMA’s work, where different geographical scenarios of the country and climatic conditions present very diverse analytical challenges. This work presents a basic description of the AMS system of the LEMA laboratory and describes some applications that are currently being developed.

Detailed documentation of thousands of petroglyphs and recent excavations conducted at the site of Toro Muerto in Peru reveal new information about the symbolic spatial organisation and ritual functions of the largest pre-Columbian rock art complex.

Despite the high degree of technological sophistication visible in other aspects of urban engineering, the archaeology of pre-Columbian Mesoamerica has revealed curiously few examples of bridges or formal, permanent water-crossing structures. The ancient city of Cotzumalhuapa, where at least five such structures have been identified, is a notable exception. The author reviews the archaeological and historical evidence for these bridges, and reflects upon the diversity of engineering technologies that they reveal. Although it remains unclear why bridges are absent at many other contemporaneous sites, these examples offer a fascinating glimpse into the urban planning of structured mobility in Mesoamerica.

The technique of depletion gilding is well evidenced in pre-Columbian Andean gold work. Artefacts from the Nahuange period in Colombia (c. AD 100–1000) were subject to metallographic, chemical and microscopic analyses to provide regional comparative data on metalworking traditions. Results suggest that depletion gilding may have been an accidental discovery and, contrary to widespread assumptions, not always a desirable feature. This research illustrates how technological innovation may not always be immediately adopted, and considers how the life-history of gold artefacts may affect their appearance and microstructure. It also offers directions for future studies of depletion gilding elsewhere.

We present a multiproxy study of land use by a pre-Columbian earth mounds culture in the Bolivian Amazon. The Monumental Mounds Region (MMR) is an archaeological sub-region characterized by hundreds of pre-Columbian habitation mounds associated with a complex network of canals and causeways, and situated in the forest–savanna mosaic of the Llanos de Moxos. Pollen, phytolith, and charcoal analyses were performed on a sediment core from a large lake (14 km2), Laguna San José (14°56.97′S, 64°29.70′W). We found evidence of high levels of anthropogenic burning from AD 400 to AD 1280, corroborating dated occupation layers in two nearby excavated habitation mounds. The charcoal decline pre-dates the arrival of Europeans by at least 100 yr, and challenges the notion that the mounds culture declined because of European colonization. We show that the surrounding savanna soils were sufficiently fertile to support crops, and the presence of maize throughout the record shows that the area was continuously cultivated despite land-use change at the end of the earth mounds culture. We suggest that burning was largely confined to the savannas, rather than forests, and that pre-Columbian deforestation was localized to the vicinity of individual habitation mounds, whereas the inter-mound areas remained largely forested.

Chemical analysis of the stunning Muisca metalwork shows that the alloys of copper and gold were especially composed for each offering. Traditionally, the Muisca objects have been collected and studied as works of art. Our authors show that when it comes to drawing understanding of people from the objects they have left us, context is all. The results have much to reveal to metallurgists and students of symbolic metalwork everywhere.

It's an ill wind that blows nobody any good. The combination of land cleared of its rainforest for grazing and satellite survey have revealed a sophisticated pre-Columbian monument-building society in the upper Amazon Basin on the east side of the Andes. This hitherto unknown people constructed earthworks of precise geometric plan connected by straight orthogonal roads. Introducing us to this new civilisation, the authors show that the ‘geoglyph culture’ stretches over a region more than 250km across, and exploits both the floodplains and the uplands. They also suggest that we have so far seen no more than a tenth of it.