An Early Jurassic fossil bivalve specimen belonging to the pectinid genus
Ce travail analyse la découverte d’un bivalve fossile du Jurassique inférieur correspondant à un pectinidé du genre
This article is part of a project which studies the interrelation between human occupation sites in Quebrada de La Cueva and neighbouring productive regions, as well as interaction/interchange networks within the valley and with both nearby and distant regions. We believe La Cueva could have been a circulation passageway between different areas, and this makes it a privileged space for the study of those interactions and for regional social dynamics comprehension. Evidence based on possibly allochthonous pottery, as well as the alternative communication routes will be briefly treated, but the main purpose of this paper is to discuss the discovery of a fossil bivalve specimen belonging to the Early Jurassic pectinid genus
Allochthonous fossil specimens are not frequently recorded in American archaeological sites, and thus the present discovery has a great interest. We will discuss it in relation to interchange networks, and also consider its potential symbolic meaning.
The Quebrada de La Cueva is a gorge located in Humahuaca department, eastern Jujuy province (
According to its geological features, the region belongs to the Cordillera Oriental. The La Cueva valley is mostly developed on fine grained rocks of Ordovician age, belonging to the Santa Victoria Group (
The studied sites are, from north to south: El Antigüito, Pueblo Viejo de La Cueva, Chayamayoc, Pukara Morado, Pueblo Viejo del Morado, Pukara de La Cueva and Angosto de La Cueva, plus several areas of archaeological agriculture (see map in
The age of the sites within the valley can be referred to the Regional Development Period, and they could reach the Inka Period (
The La Cueva valley was first mentioned at the beginning of the 20th century by
Basílico resumed research in the area with a regional approach around the 1980s, doing a planimetric survey at Pukara de La Cueva (
The pre-Hispanic exchange of goods in the Andean area was (and still is) extensively investigated, some of the research being referred to various general models, such as those by
The valley can easily communicate with the Puna through roads starting at Pueblo Viejo de La Cueva. One of those paths goes west, passing Abra de Cortaderas (4300 m) and reaches Cangrejillos (Dto. Yavi) and then La Quiaca; another goes north, through Abra de Casillas (4700 m) and then west to join the previous path about 10 km before Cangrejillos; two paths to the east reach Nazareno and Iruya (
Diverse issues related to the “contacts” between separate regions are now studied with different theoretical-methodological approaches, variously referred to as interaction, circulation and interchange, this last one meaning an economical aspect of other social activities (information and relationship networks, symbolic spheres, etc., see
Following the interactions between regions on the basis of ceramic material, Basílico excavated at Pueblo Viejo de La Cueva and analyzed the surface and buried pottery from both the techno-typologic and techno-morphologic points of view, and she dated the site as Middle Period. She compared the ceramic record with material from the Isla collection at the Museo Etnográfico in Buenos Aires, emphasizing the presence of Isla type ceramics as a result of inter-site contacts (
After many years of research, in her last paper
In relation with the record here reported,
Finally, we should mention another important clue of the circulation and exchange in quebrada de La Cueva.
In synthesis, based on the information obtained by previous authors on the circulation and exchange in Quebrada de La Cueva (communication roads with diverse areas; Isla, Yavi and Alfarcito styled pottery; allochthonous shell material; and rock art related to the caravan traffic), we will further discuss the subject in relation to a fossil bivalve found in Pukara de La Cueva originally from regions which are far away, but which were always integrated to its interaction area, such as the Main Cordillera of northern Chile or southern Perú.
The fossil mollusc was recovered in 2007 during the excavation of structure No 50 (according to Basílico's internal code on her 1998 published map;
The associated material is pottery, especially fragments of bodies, bases and handles of large pieces. They were possibly painted in purple, but due to the abundant soot cover and superficial cementation (saltpetre and/or calcareous concretions) this cannot be assured. There are a few pots with geometric decoration in Black on Red (similar to late Quebrada de Humahuaca styles) and Black on Purple. There are also abundant fragments painted in purple (purple painted ceramics are very common at La Cueva, and are currently under study, suggesting a local manufacture) over red slip, some showing purple paint strokes on edges or inner parts, but most externally painted; and only one fragment with inner polished black. Also associated are some faunistic remains, especially camelids, malachite beads, and a possible zoomorphic rock carving (presently being studied by S. Pérez).
Unfortunately, and although one of us (P.R.) was present when the piece was found, since Dr Basílico's death we had no access to her original records about other context details of the fossil mollusc. Nevertheless, we feel that the potential interest of this finding, related to issues such as exchange relations and symbolism, fully validates this analysis.
The specimen (
The specimen from Pukara de La Cueva is an incomplete shell, with parts of both valves slightly displaced, the convex right valve more complete than the flat left one (
Trying to locate the original source of the Pukara de La Cueva specimen, we need first to analyse in detail the paleogeographic distribution of the taxon. The known geographic distribution of
Regarding the specimen preservation, the calcareous original shell material was partially silicified, as evidenced by the concentric structures known as beekite (a variety of chalcedony) rings or discs present on the shell external surface (
Specimens most similar in size, morphology and preservation type were illustrated from Quebrada Asientos, Atacama region, northern Chile, aprox. 26°27'S (
By the combined analysis of the special preservation type and of the matrix rock, we can possibly limit the source region of the La Cueva specimen to the Chilean Andes north of 27° S, or, less probably, to central Perú north of Cuzco.
The archaeological records of fossil elements, particularly molluscs, appear to be extremely rare in north-western Argentina, at least those that were published, or still unpublished results personally communicated.
Regarding fossil findings (not only molluscs), we mention as an example (they are not the only ones), a trilobite in the Márquez Miranda Collection at La Plata Museum, from Rodeo Colorado (Iruya department, Salta province) (Ventura, 2010, personal communication). Trilobites are most probably local elements, and it is interesting to note that some North American indigenous tribes used trilobites, also locally abundant, as luck tokens (
On the other hand, at an international scale, several authors recorded the presence of fossil molluscs in archaeological contexts. About the “symbolic” use of those molluscs in Europe,
A “symbolic character” is generally attributed in Europe to mollusc beads (either fossil or not) (
In the central Andean area, several mollusc species [ cyclic rains and draughts in coasts between Manta port (Manabí) and Guayaquil gulf (Guayas); the fluctuations in the hot water currents which create most favourable conditions for both rains and the proliferation of the El Niño phenomenon (ENSO: El Niño Southern Oscillation) which produces hot rains south of Tumbes and Piura (Perú) in coasts where it never rains (
For
Applying the ideas of this author (
Also trying to find the ritual sense or meaning of the molluscs, when
This symbolic factor was highlighted by
Along this article we dealt with two aspects: first, we presented new evidence about the widely known subject of interaction, circulation and/or goods interchange in Quebrada de La Cueva; and second, we stressed the possible symbolic character of the mentioned evidence.
Other authors already considered the interaction in the area through: the study of the communication channels between Quebrada de La Cueva and the Puna, Quebrada de Humahuaca and the Argentine West Forests zone; the presence of ceramics of a similar style to those of Humahuaca and Puna; the existence in Quebrada de La Cueva of indicators of the caravan traffic, such as the rock art in Chayamayoc and Angosto de La Cueva.
Moreover, we discuss here a different element, found in the low levels of occupation of a building and/or dwelling structure in Pukara de La Cueva, which implies three important aspects: the source of this fossil mollusc shell was far away from the studied area, but within the region always regarded as interactive with Quebrada de La Cueva. The possible source area is restricted to the Andes of Chile north of 27° S, or, less probably, to central Perú north of Cuzco. This species, its matrix type and mode of preservation are common in the Atacama region, and then we confirm through this new evidence the interaction between the two regions (Atacama – Quebrada de La Cueva) already suggested by other authors; the fossil nature of the specimen makes it more interesting; together with the fact that it was not modified but preserved in its original state (other molluscs were generally transformed in beads or suffered other modifications). It had no clear function apart from the symbolic one we attribute based on bibliography and similar findings. Furthermore, it is interesting to note that both the shape and size of this fossil bivalve are particularly similar to the living in relation to the previous point, the possible symbolic character of this specimen, probably linked to multiple (and not necessarily excluding) factors (according to research in Europe, Mesoamerica, central Andes, Puna region and northern Argentina). Molluscs were related to symbolic entities of ideological, political or religious power; to religious and funeral rituals; to ornamentation, distinction or prestige factors for elite sectors; to water (much needed in certain Andean regions) propitiatory rituals; or to their possible function as authority “corporative emblems” (
These considerations suggest that the Pukara de La Cueva specimen could eventually have supported the roles of certain society groups, related to their social status and the needs of a space surrounded by agricultural land. In this sense, if we consider that the Pukara de La Cueva is placed in an agricultural environment (
The Quebrada de La Cueva still encloses many mysteries regarding its occupation and use. Current research is framed in the need to sort out these queries within a larger regional context, and this paper in particular aims at dealing with these aspects and contributing to shed some light on its complex reality.
P.S.R. thanks Dr J. López Gappa and H. Camacho (Museo de Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires) for the early orientation about the fossil specimen, who referred her to Dr S. Damborenea. We are grateful to Dr E. Pérez d’Angelo and A. Rubilar Rodríguez (Sernageomin, Santiago de Chile), for photographing and allowing the reproduction of the material illustrated in
Regional location map (A) and detail of Quebrada de La Cueva area (B). The general map shows the maximum extension of Late Sinemurian-Late Pliensbachian marine deposits according to
Carte régionale de localisation (A) et détail de la zone de Quebrada de la Cueva area (B). La carte générale montre l’extension maximum des dépôts marins Sinémurien supérieur-Pliensbachien supérieur, selon
Plan of structure No 50 of Pukara de la Cueva archaeological site, with location of the finding place of the fossil bivalve discussed here.
Plan de la structure No 50 du site archéologique de Pukara de la Cueva, avec localisation de l’endroit où le bivalve fossile, dont il est question ici, a été trouvé.
Field photograph of structure No 50 of Pukara de la Cueva archaeological site, general view from the north.
Photographie de terrain de la structure No 50 du site archéologique de Pukara de la Cueva, vue générale prise depuis le nord.
Specimen of
Spécimen de