A multidisciplinary team has carried out, for the first time, the biomineral analysis of two complete fossilized shearwater eggs (Family Procellariidae) recovered from one of the Roman sites on Lobos Island (Canary Islands), dating from the mid-1st century BC to the mid-1st century AD. The results of this research have been published in the scientific journal Diversity, in a study led by Carmen Núñez-Lahuerta, Juan de la Cierva postdoctoral researcher at the Catalan Institute of Human Paleoecology and Social Evolution (IPHES-CERCA) and in which researchers from the University of La Laguna, the Archaeological Museum of Tenerife and the University of Zaragoza have also participated.
The article was authored by Carmina del Arco Aguilar, Penélope Cruzado-Caballero, and Carolina Castillo-Ruiz, all from La Laguna. Fossil remains of birds are common in Quaternary sites, especially bones. Eggs are less common, although small fragments can sometimes be preserved and recovered, or, very rarely, whole eggs.
In the Canary Islands, fossilized egg remains are relatively common and have been the subject of research since the 1970s. Despite this long-standing research tradition, studies focusing on their biomineral structure are very scarce, a fact that underscores the relevance of the recently published study. Regarding the question of why understanding their structure is important, Núñez-Lahuerta explains that “although all bird eggs appear very similar at first glance, they have a complex and highly variable structure.” The researcher points out that the eggshell is composed of three layers, but the relative thickness can vary, as can the presence and distribution of other structures such as cuticles and vesicles. Therefore, this set of variations “is typical of each species, and its study allows for the identification of the laying bird.”.
Eggshells under the scanning electron microscope and the petrographic microscope. Photo: Carmen Núñez-Lahuerta/IPHES-CERCA/Carmina del Arco Aguilar.
The team that produced this publication has described the methodology used for the first time in this type of Canary Island fossils: the handling of various microscopy techniques has been used, requiring the preparation of samples in thin sections to be observed in a petrographic microscope and samples in test tubes, for observation in an electron microscope.
These analyses have allowed us to observe the three-layered structure typical of bird eggs. The proportions between the thickness of these layers, as well as the distribution of structures called vesicles along the layers, have made it possible to attribute the eggs to shearwaters, long-winged seabirds typical of temperate and cold waters. Thanks to the fact that the eggs were recovered almost complete, their size and sphericity could also be measured. These analyses have allowed us to assign the eggs to the taxa cf. Calonectris/Puffinus and cf. Puffinus.
The study of fossils from the Canary Islands has allowed the description of two species of shearwater endemic to the islands, which are currently extinct: Puffinus holeae y Puffinus olsoni. Therefore, the next line of work for this multidisciplinary team is the characterization of the biomineral structure of the eggs of extinct Canary shearwaters, with the aim of increasing knowledge about their fossil record, and learning more about their behavior and extinction.
Lobos, the only Roman site in the Canary Islands
The Lobos-3 archaeological site is located on a small, volcanic island of approximately 500 hectares in the La Bocaina Strait, between the islands of Fuerteventura and Lanzarote. It is the only Roman site in the Canary Islands, dating back more than 2,000 years.
According to Carmina del Arco, Professor of Archaeology at the University of La Laguna, who has led the excavations since their inception, “Lobos is a privilege” and, at the same time, an “exotic” site for the cultures of the Canary Islands. “It is solely Roman, with no material related to indigenous Canarian cultures,” and “it underscores the economic interests that
Situation of the two complete eggs analyzed and recovered at the Lobos-3 site. Photo: Carmen Núñez-Lahuerta / IPHES-CERCA / Carmina del Arco Aguilar.
There was a desire to exploit the resources of the Canary Islands territories from very ancient times.”.
Archaeological excavation work has identified the settlement as a purple dye workshop that operated from the mid-1st century BC to the mid-1st century AD. The evidence found in Lobos (shell middens of Haemastoma purpura, (amphorae for salted fish, wine and olive oil, common pottery, fishing tools, etc.) reflects the frequenting of the Canary Islands by Roman populations, probably originating in Gades, with the aim of exploiting its natural resources, in this case the purple dye.
Purple-dyed fabrics enjoyed great popularity throughout the ancient world, from the Greeks and Phoenicians to the Romans, and fostered the development of profitable purple dye industries in antiquity. They were considered luxury items and a sign of social distinction, to the point that the state itself controlled their monopoly and organized commercial and military expeditions in search of the necessary materials for their production.
According to IPHES-CERCA researcher Carmen Núñez, “the identification and distribution of egg remains in the different levels that make up the Lobos-3 site have allowed us to corroborate that the use of the workshop occurred seasonally, since the shearwaters lay their eggs in the summer months, and the exploitation of the mollusks used to obtain the purple dye occurs in autumn and winter.”.
(Text and images provided by IPHES-CERCA).
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