1.1. Castelo Velho de Safara

The site of Castelo Velho de Safara (Moura, southern Portugal; 38°08’25”, 7°13’08”; Fig 1) is located on a rocky outcrop at the confluence of the Safareja stream with the Ardila river. The settlement presents a Chalcolithic occupation phase, followed by an extended hiatus of occupation since only by the middle of 1^st millennium BCE a new settlement was built. The latter corresponds to an occupation of the Late Iron Age, which extended over to the Roman Republican period and to the early days of the Empire (1^st century BCE). Castelo Velho de Safara has been systematically excavated since 2018, when Trench 1 was opened perpendicular to the thick defensive wall that was visible on the east part of the settlement, in the escarpment that faces the Safareja stream. The continuation of the archaeological works exposed the presence of a street running parallel to the defensive wall, showing a residential area on its north-western side, and two compartments on its south-eastern side, Compartment 1 and Compartment 2 [21–23]. The former is the one we will be focusing on as part of this study, and it may correspond to a storage facility attached to the inner part of the defensive wall. The material culture recovered in Castelo Velho de Safara has been confirming the four different occupation phases of the site, even though the best represented chronologies are those of Roman Republican age, as well as the beginnings of the Roman Empire, with a particular focus on materials dating from the mid- and late 1^st century BCE. This is mostly due to the presence of Italian red-gloss ware known as terra sigillata, Italian black-gloss ware and their local imitations on grey common ware, thin-walled vessels, Kuass ware, stamped and roulette decorations, as well as several rims and handles of Roman Republican ovoid and Haltern 70 amphora [21–23].

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Fig 1. Archaeological discoveries at Castelo Velho de Safara.

A) The site’s location map. B) Examples of some of the very fragmented cetacean remains recovered from Compartment 1. C) Aerial view of Trench 1 and its northern expansion in July 2023, featuring the rectangular test pit in the middle of the Roman Republican street area (photo by João Vidigal). D) Aerial view of Trenches 1 and 2 in July 2019 (photo by João Vidigal). E) Trenches 1 and 2 layouts with a red line marking the stratigraphic profile represented underneath. F) Examples of diagnostic pottery fragments recovered from stratigraphic level 19 in Compartment 1, including a large storage container (1), stamped pottery (2), a base of local/regional amphora (3), grey ware decorated with roulette (4), painted pottery (5), bowl of common ware (6), handmade pottery pans (7, 8), handmade pottery decorated with excised triangles (9), handmade pottery with impressed cord design (10).

https://doi.org/10.1371/journal.pone.0310215.g001

Focusing on Compartment 1 and its stratigraphy (Fig 1), the oldest deposition is the stratigraphic level 19, where the cetacean remains were recovered, followed by levels 17, 14 and the most recent deposition that is level 3. The diagnostic pottery materials recovered are presented in Table 1 and they reflect two different phases. The most recent phase, and easier to characterise, is found in levels 3 and 14 since it is defined by a package of imported materials, such as amphora from the Guadalquivir (in Spain), Italian black-gloss ware and its Iberian imitations, thin-walled vessels, clay lamps and Italian terra sigillata. These are materials typical of the 1^st century BCE, of late Republican age, indicating the presence of a Roman army on site, which is also supported by the recovery of several slingshot bullets from surface levels during a systematic survey of the site carried out in 2019. The Italian terra sigillata from level 3 dates from the early days of the Roman Empire, when the site was abandoned. Level 17 can maybe correspond to an intermediate phase, between the most recent (levels 3 and 14) and the later one (level 19). This is because it presents a scarce presence of painted pottery similar to levels 3 and 14, but a high quantity of handmade ware similar to level 19. The oldest phase of Compartment 1 is reflected in the materials recovered from level 19, which is associated with the foundation levels of the Roman Republican building and the street that runs parallel to the settlement’s defensive wall. All imported pottery is absent from this level showing, instead, a large presence of painted pottery, handmade vessels and two fragments with roulette decorations, which points towards an early 1^st century BCE chronology.

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Table 1. Diagnostic pottery materials recovered from Compartment 1 of Castelo Velho de Safara.

The finds are categorised by stratigraphic levels, providing a preliminary inventory with the Minimum Number of Individuals (MNI) indicated at the bottom of the table. Frag = fragments.

https://doi.org/10.1371/journal.pone.0310215.t001

The discovery of whale remains within the Roman Republican level 19 of Compartment 1 at Castelo Velho de Safara is significant both archaeologically and for the study of historical ecology. This find, situated many kilometres away from the sea, underscores the remarkable mobility and trade networks of this ancient society. The presence of these cetacean remains in an inland location suggests a sophisticated level of organisation, and the capacity for long-distance transportation and preservation of marine resources. Such evidence indicates a trade, or exchange system, that valued such remains either for their material utility or symbolic significance.

3.1. Temporal and geographic distribution

Cetacean remains have been recorded in numerous archaeological sites all over the Portuguese mainland. The presence of such remains is sparse during the Palaeolithic; they have been found in only two sites: the Middle Palaeolithic cave of Figueira Brava [34], and the Upper Palaeolithic rockshelter of Lagar Velho [35]. So far, no cetacean remains have been reported for Mesolithic or Neolithic levels. However, there is a dramatic increase of cetacean evidence during the Chalcolithic and the Bell Beaker period in particular, followed by a lack of evidence during the Bronze Age (Fig 4). The Chalcolithic remains were mostly found in the Portuguese Estremadura. Cetacean evidence is scarcely reported for Iron Age levels but their frequency increases again with the Roman occupation of Iberia, with most evidence coming from littoral sites, except for Biblioteca de Mértola [36] and Castelo Velho de Safara (Figs 2 and 4).

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Fig 2. Distribution map of cetacean finds in Portugal.

Each point represents a specific site where remains were uncovered, ranging from the Middle Palaeolithic to the 18th century, with distinct symbols indicating the different time periods and cetacean species identified. Please refer to Table 2 for more information on each site.

https://doi.org/10.1371/journal.pone.0310215.g002

In later time periods, frequency data shows a clear increase in cetacean remains, mainly during Medieval times ranging between the 9^th and the 14^th centuries, but most markedly in the 12^th and 13^th centuries (Table 2). Such cetacean remains are generally associated with Moslem occupations in littoral areas particularly in the Algarve region, in the southern coast of Portugal. The evidence drops after the 14^th century, even though there are still remains recovered from sites dated until the 18^th century. Once more, the evidence is mainly recovered from coastal occupations, with the exception of the fragment found in Avenida Miguel Fernandes, located inland, in a 15^th century pit in Beja [37]. Lastly, it should be noted that all archaeological cetacean remains were recovered from the central and southern areas of Portugal, whereas evidence from the northern parts of the country is yet to be reported (Figs 2 and 4).

3.2. Species identification

A total of 196 cetacean remains were found in 37 Portuguese archaeological levels as referenced in published papers and other grey literature (Table 2, Fig 4), including the recent find from Castelo Velho de Safara. More than half of these levels (59.46%, corresponding to 22 archaeological levels) present remains that are not identifiable to species. Such bones are commonly recorded as “dolphin”, “whale” or “cetacean”, sometimes referring to a large or small cetacean, being the large specimens generally associated with whales and small specimens with dolphins. This calls for the need for biomolecular analyses (either ZooMS or aDNA analysis) to optimise species identification on these specimens.

A total of 15 archaeological levels show cetacean remains that were assigned to a taxonomic identification. On six occasions, cetaceans were identified through morphological analysis, mainly those recorded as common dolphin (Delphinus delphis, or cf. Delphinus delphis). Globicephala melas (a species from the Delphinidae family, but known as the long-finned pilot whale) was recovered from structure 8 of Arronchela [38], but there is no indication of the methods used in species identification. Other remains were recorded as “Cetacean, probably dolphin”, or simply as “Dolphin”, leaving it unclear what dolphin species these specimens represent.

A similar extrapolative line of reasoning is not as clear within whales, since two different species have been identified. Whale remains recovered from six sites of Bell Beaker chronology were identified as Physeter macrocephalus (sperm whale), using a combination of scientific methods, such as optical microscopy, measurement of specific gravity, measurement of hardness, Micro-Raman spectroscopy, elemental analysis, Isotopic Mass Spectrometry [39, 40]. A more detailed analysis, potentially using ZooMS, is needed to identify the cetacean remains found at the contemporary sites of Rotura, Alpena, Castro do Zambujal and Leceia [41–44].

The large assemblage of North Atlantic right whale (Eubalaena glacialis) recovered from Peniche was identified based on morphological skeletal traits. Uncharacteristically, many of the bone remains from Peniche were (relatively) complete, allowing to reach this identification based on the morphology of several cervical vertebral units and one ulna [45]. The same whale species was also determined for the remains found in Castelo Velho de Safara, despite not being able to be separated from the bowhead whale (Balaena mysticetus) using ZooMS (Fig 3), and thus being generally classified as Balaenidae. However, and chiefly based on the find location, the North Atlantic right whale is the most likely identification, as the bowhead whale primarily occurs in Arctic waters while the North Atlantic right whale is known to have historically occurred in Portuguese waters [10].

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Fig 3. Zooarchaeology by Mass-Spectrometry (ZooMS) analysis for Castelo Velho de Safara’s specimen, highlighting with arrows the diagnostic peaks for Balaenidae.

https://doi.org/10.1371/journal.pone.0310215.g003

3.3. Skeletal part representation and age at death

Most cetacean elements are often not anatomically identifiable. However, among those allowing identification, they are mainly vertebral fragments (NISP = 63, or 32.1% of the total number of cetacean remains listed in Table 2), although there are also mentions to other anatomical elements, such as skull bones (NISP = 14, or 7.1%), ribs (NISP = 9, or 4.6%), mandibles (NISP = 2, or 1.0%), some possible teeth (NISP = 6, or 3.1%), and one ulna. The remaining 74 (or 37.8%) cetacean fragments are recorded as anatomically indeterminate (Table 2).

The vertebrae found in the Medieval occupations of Alcáçova de Santarém, Castelo de Paderne, Rua Henrique Calado, and in the 17^th century pit of Carnide have been recorded as unfused. Additionally, there are also two unfused intervertebral discs from Roman Boca do Rio and the 16^th-17^th century assemblage from Peniche (Table 1). These can indicate the presence of young animals, but it should be cautioned that some larger whales can have unfused vertebra up to 30 years old [46]. Conversely, Peniche has also provided three sets of fused cervical vertebrae (the fusion of all seven cervical vertebrae is typical for Balaenidae, such as the North Atlantic right whale), therefore suggesting the presence of at least three individuals. All other sites were only represented by a single individual (Table 2).

3.4. Bone surface modifications

Some taphonomic alterations have been reported (Table 2). In the 13^th century Rua Henrique Calado, a total of eleven fragments of a probable whale show thermo-alterations related to high temperature exposure of more than 400°C, since the remains present blue and white burns [47].

Cut marks have also been reported for eleven archaeological levels (Table 2). Most of them–i.e. from seven archaeological levels–are interpreted as being related to the use of cetacean remains as chopping anvils. In two cases–in Castelo de Paderne and Rua Henrique Calado–cut marks were found on unfused dolphin vertebrae from Medieval sites in the Algarve, and show no interpretation associated to their possible use. In Castelo de Palmela and in Peniche, cuts seem to be associated with cetacean consumption. Cetacean consumption is also interpreted by researchers for another four levels, even though no marks have been reported (Table 2).

Finally, other marks are related to holes in the centre of vertebral elements, in which a metal bit was probably located, such as the case of Museu Nacional de Faro. One specimen from Monte Molião and most of the Chalcolithic remains are related to bone working activities, being the objects mainly interpreted as buttons. Other explanations of bone modification are related with their use as a board for spreading pigments (in Alpena), or their use as a fireplace bench (in Ponta do Castelo) (Table 2).

4.1. Spatiotemporal species distribution

The coast of central and southern Portugal has several important submarine valleys, such as the ones of Nazaré, Lisbon-Setúbal, São Vicente and Portimão [48, 49]. These deep waters close to the shore also benefit from predominant north-easterly trade winds, and from an upwelling system that occurs along the Portuguese mainland coast, resulting in a dynamic ecosystem that has very rich fishing grounds and is highly favourable to cetacean occurrences [50, 51]. These oceanographic characteristics can maybe explain why our review of cetacean remains from Portuguese sites show no archaeological evidence coming from the north of the country. However, this is contrasting with frequent current sightings of bottlenose and common dolphins in northern coastal areas of mainland Portugal, and sightings of some beaked whales that sometimes venture towards northern latitudes [52]. Historical references seem to support this idea of absence of cetacean remains in the north of the country. This is due to the accepted theory of Aguilar (1986 [9]) that active whaling started in the French Basque country in 1059 CE and then spread progressively westwards along the northern coast of Spain, until it got to Galicia in 1371. However, there is no timeline progression of whaling knowledge coming from the Basque country and Galicia to the north of Portugal [53], which led Teixeira et al (2014 [45]) to suggest that whaling in Portugal originated independently of direct Basque influence. Indeed, such whaling activity was most certainly performed on the Portuguese coast before the 14^th century since there are at least 38 historical accounts of scavenging of stranded animals and whaling between 1201 and 1728 CE [45]. So, if that is the case, then whaling in Portugal started in the central and southern parts of the country.

Scavenging of stranded cetaceans was carried out since the Palaeolithic, as shown by Gruta da Figueira Brava [34] and Abrigo do Lagar Velho [35]. This early human behaviour is generally thought to have been opportunistic, taking advantage of natural events where marine mammals became stranded on shore, easily accessible to human populations of that time. It is unexpected, however, to find no reports on cetaceans from the somewhat vast evidence of Mesolithic sites, when Portuguese human populations had a very close relationship with the shore and aquatic resources [54]. The absence of evidence continues into the Portuguese Neolithic. However, during this period, active exploitation of marine mammals was already occurring in the, so far only known example of contemporary sites, coastal Vlaardingen Culture, in current western Netherlands [10, 55]. The scenery is highly contrasting with the Chalcolithic evidence, which presents ten archaeological levels showing a total of 36 cetacean remains (Table 2, Fig 4). Most of them were carved into buttons made of sperm whale bones. This species is abundant in the Mediterranean, and in the strait of Gibraltar in particular [56]. They are very large animals and their pursuit was considered to be dangerous, which is reflected on their late active exploitation that may have not started until 1713 CE [57]. Therefore, sperm whale bones had an important significance to Chalcolithic people, and these carved sperm whale bones may be evidence for an integrated trading route system. They may have been originally obtained from Mediterranean shores, and then reaching central Portugal, sometimes arriving to inland positions, such as the case of Galeria da Cisterna [40]. These trades may have existed since the Upper Palaeolithic considering that whale bones from eleven sites dating to the era were found in the Spanish Pyrenees, implying transport of cetacean remains from the Mediterranean and/or the Atlantic coasts of Iberia [58, 59]. This is also the case of the cetacean remain found in Lagar Velho [35]. Such trading routes may have endured over time, since whale remains are found in inland Portugal during the Roman Republican occupations of Castelo Velho de Safara and of Biblioteca de Mértola [36], as well as in the 15^th century levels of Avenida Miguel Fernandes [37]. If cetacean bones were considered to be a valued product, they may have been traded to distant regions and preserved for many years [60].

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Fig 4. Comparison of cetacean remains across different Portuguese archaeological periods, showing the number of archaeological levels that display cetacean remains alongside the Number of Identified Specimens (NISP) for each period.

This figure highlights the distribution and quantitative analysis of cetacean remains illustrating temporal trends.

https://doi.org/10.1371/journal.pone.0310215.g004

Other than accommodating sperm whales, the central and southern Portuguese shores may have lodged North Atlantic right whales, with confirmed archaeological representation in Castelo Velho de Safara and Peniche [45]. Genetic evidence [61] and historical documentation [53, 62] and references therein] indicate that the whales hunted along the shores of Portugal were likely North Atlantic right whales. Calving and/or migrating right whales would have been reliably found close to the coast before they were overexploited leading to only few individuals surviving into the late 17^th century and the species becoming extirpated from eastern North Atlantic waters probably somewhere in the mid-20^th century [9, 10]. The Portuguese central and southern coasts are in similar latitudes to those where these whales calve nowadays in the western side of the North Atlantic, and right whales are one of the most frequently found species in the European archaeological record [10, 28, 63–65].

4.2. Whaling

Despite the relatively small proportion of cetacean bones generally found in archaeological sites, their type of procurement has been debated for some time [e.g. 57, 66]. Human exploitation of marine mammals in Portugal started in the Middle Palaeolithic, with evidences coming from Gruta da Figueira Brava [34]. They refer to remains of common dolphins, which have been resident in the river Sado estuary to this date. Even today, common dolphins get stranded due to marine currents or sudden tide movements. In such circumstances, these individuals become an easy target for human predation. This strategy was also the most probable for the Chalcolithic period. As described above, Chalcolithic cetacean remains are mainly represented by sperm whales, whose capture only started in the Modern era [57]. Additionally, there have not yet been identified any objects from the Chalcolithic, or the early Bronze Age, in Iberia that are interpreted as harpoons, or that could have been used as such [39]. This echoes Dutch evidence on whale remains, with very few findings coming from the Bronze Age period [67].

Given the rarity of cetacean remains in archaeological sites, it has been proposed that their use and exploitation were merely opportunistic [68]. However, the scarcity of bones is not incompatible with active cetacean exploitation, especially during periods of known use of boats, fishing gear, and marine resource consumption. In Iberia, it is suggested that active whaling started in the late Bronze and early Iron Ages [69, 70]. This becomes clearer in sites dating from the Roman period onwards. Although not discarding opportunistic exploitation of stranded animals, the technological sophistication in terms of fisheries and seafaring is undeniably compatible with active whaling [71]. This is supported by classic literature, such as Pliny’s description of an attack of an orca that entered the Port of Ostia, “Cæsar ordered a great number of nets to be extended at the mouth of the harbour, from shore to shore […] boats assailed the monster, while the soldiers on board showered lances upon it” (Naturalis Historia 9.14; [72]); or the Oppian’s description of the capture of a sea-monster, “(…) the fishers allow him all the length of the line; for there is not in men strength enough to pull him up and to overcome the heavy monster against his will” (Haliaeutica V; [64, 73]). Due to their location and functionality, it is possible that the Roman fish-salting industries found in Tróia and Creiro could perhaps have included cetaceans in their fishing activities, akin to what is suggested for Baelo Claudia in the south of Spain [56]. Cetaceans were historically hunted in the Sado estuary, encompassing Setúbal and Sesimbra, during Medieval and Modern times, with industrial whaling operations occurring in the Setúbal area in the early 20^th century [74, 75]. Between 1926 and 1927, the river Sado estuary was exploited by the “Portuguese Cetacean Society”. In those two years, a total of 372 fin whales, 55 sperm whales and one indeterminate whale were captured. These animals were processed in the large facilities built in Tróia, which included a 320-metre berth [76].

Literary sources become more helpful regarding Medieval periods. According to Brito and Sousa (2011 [77]), a total of sixteen cetacean laws were passed between the 12^th and 21^st century, in Portugal. Some Medieval examples show how laws regulated the capture and use of cetaceans, as well as the distribution of their spoils, therefore confirming that an active whaling exploitation was fruitful and already well established. Some examples are those of the charters (or “forais”, in Portuguese) conceded to cities in the south of Portugal by king D. Afonso III (in 1266) and king D. Manuel I (in 1504), both assuring the king’s property of all whales and other “royal fish” [78]. Other examples come from the description of taxes related with trading of whale products. In 1206, king D. Afonso II fixed high tax values for all cetacean goods from Atouguia’s seaport (in central Portugal, near Peniche). Again, in 1510, a new charter was conceded by king D. Manuel I to the same area, listing all economic activities that should be taxed, which included marine trade and fishing [45]. Whaling was highly profitable for the Portuguese kingdom, aligning with an increase in archaeological evidence from the Medieval period. This period accounts for 37.8% of the archaeological levels containing cetaceans, and 65.3% of all cetacean remains found, largely influenced by the significant finds from the Peniche shipwreck (Table 2, Fig 4).

The presence of possible juvenile cetaceans found in the Portuguese archaeological samples could maybe indicate a propensity to strand in younger and inexperienced animals due to their ease of handling. Moreover, a mother-calf pair could have been targeted, as the mother would not leave her calf behind, leading to the mother becoming an easy target as well. Cetaceans’ sightings from the coast in Medieval and Modern times were regular, since such marine populations were ten times greater than today and, hence, more cetaceans would inevitably be available for human hunting [77, 79]. As noted by Teixeira et al (2014 [45]), Portuguese references to whaling techniques are fairly inconclusive, but they surely used simple technology, which included lookout spots in high places on land, small open boats and hand-thrown harpoons [80]. Nonetheless, these basic techniques allowed overexploitation of these large marine mammals, likely contributing to one of the two whale historical extirpations in Portugal, the North Atlantic right whale [the other being the grey whale, Eschrichtius robustus, though findings of this species have not been reported in Portugal; evidence from all over Europe suggests the species was once present in Portuguese waters [10]]. This likely happened somewhere in the last couple of centuries [9, 45].

The final European catches of the North Atlantic right whale occurred in Portugal. In February 1967 a mother-calf pair was taken in Madeira, with a male individual which was accompanying them, being able to flee [81]. A pregnant female was also taken in Madeira in January 1959 [82]. The only sighting in mainland Portugal of this species since then was in 1995, even though it most probably referred to two wandering individuals from the western North Atlantic population, and not remnants of the eastern North Atlantic population [83]. Nonetheless, cetaceans continued to be hunted during the 20^th century, shifting the target towards the fin whale, which was mainly captured off the continental shelf of the southwestern coast [45]. It was only in 1981 that the first law of marine mammal protection and preservation was passed in Portugal [77].

4.3. Cetacean use

Assessing the function of archaeological cetacean remains is problematic, since they are often found in isolation and are normally damaged. Additionally, cetacean carcasses can have a number of uses, since they provide skin, meat, blubber/oil and bone, which can be used for consumption, illumination and in a myriad of artefacts, architecture and as fuel [45, 84].

Chopping boards, primarily made from cetacean vertebrae, appear to be one of the most common cetacean-related artefacts found in the archaeological record [85]. Similar examples have been discovered in The Netherlands, England, Scotland, and various other regions [10, 30, 65, 86–88]. Portuguese archaeological sites with cetacean remains follow a similar trend. Given the lack of chronological confirmation of the red pigment found on the Alpena vertebra [44], it is possible that this artefact could have been a blank for a chopping board. In the few instances when a taxonomic identification is attempted for chopping anvils recovered from Portuguese sites, whales are the animals typically mentioned. These chopping blocks were mainly made from large vertebra or large flat bones (e.g. Leceia or Alpena), likely associated with large cetaceans. Dolphins, providing smaller bones, are generally unsuitable as raw materials [84]. When consumption is proposed at Portuguese sites, it is often related to dolphins, except for the whales found in Peniche. Based on this evidence–chopping blocks are normally associated with whales, and dolphins are more frequently used for food–we propose that the dolphin remains identified on the 17^th century levels of Castelo de Palmela are most likely related to consumption, similar to the interpretation of the 13^th-14^th century levels of the same site.

The high presence of chopping anvils does not discard the possibility that these bones were initially the remains of meals. Although there is no evidence of skeletal part removal for joints of meat to be brought to site, Savelle and Friesen’s (1996 [89]) work on harbour porpoises showed that vertebrae ranked third on a meat utility index. Given this, and the presence of cetacean vertebrae at inland sites such as Biblioteca de Mértola and Avenida Miguel Fernandes, it is plausible that similar anatomical parts were found in the inland settlement of Castelo Velho de Safara. Vertebrae are relatively porous, fitting the characteristics of the cetacean remains found in Safara, although we cannot yet confirm this anatomical identification. If these vertebrae were transportatedinland as meat joints rather than just bones to be transformed into artefacts or tools, the meat would need to be preserved, possibly using salt. Bernal-Casasola (2010 [56]) proposed that some facilities of Roman fish-salting production centre of Baelo Claudia (Cádiz, southern Spain) could have been used to salt whale meat. It is further suggested that such a product could have been marketed in amphorae, supported by inscriptions on Italian amphora type Dressel 21/22 referring to ceti, known to be a large species of fish. Coincidentally, or not, these amphorae types had one of their production centres in Algeciras (not far from Baelo Claudia), during the late Roman Republican period and the early empire [56, 90], which match the chronology of the whale remains found in Castelo Velho de Safara.

Akin to the idea of Iberian Roman markets selling whale meat–which appears to have been accessible to people of different social strata–, some Medieval sources indicate a comparable trend in London markets [91]. Although cetacean meat was perceived as a high-status food during Medieval times, usually associated with clergymen and nobility, it was not restricted to these social groups. People of lower social status also had access to it, hoping to mimic the lifestyle and diet of nobility [91, 92]. With the expansion of Christianity and cetaceans being considered animals of the sea, they were classified as fish during the Medieval period [despite Aristotle recognising them as mammals as early as 350 BCE]. Consequently, cetacean meat was deemed acceptable fasting food and was frequently consumed during periods such as Lent [93]. From the early 17^th century, Portuguese references show that the prestige of whale meat decreased, and it began to be perceived as ordinary food, consumed primarily by poor people and slaves [94, 95] and historical references therein].

Oil can also be extracted from cetacean blubber and bone. Bernal-Casasola and Monclova (2011 [96]) suggest that the presence of spongy and light inner parts of cetacean bones–similar to those found in Castelo Velho de Safara–could indicate such a practice. Bones could have been boiled to extract fats and oils, but such proposal still lacks archaeometric confirmation [97]. However, it is known that cetacean oil was used for illumination in oil lamps during the Medieval period [98]. Furthermore, whale oil was the main driver for whaling in Portugal and Brazil since at least the 15^th century [99]. By the mid-18^th century, whale oil was the key fuel used to illuminate the most important urban centres in Portuguese America, and thousands of barrels of whale oil were exported from Brazil to Lisbon for this purpose [95]. Until the discovery of petroleum in 1859, whale oil was of utmost importance. As Eric Jay Dolin (2007 [100]) stated, it “lit the world”.

Cetacean bones could also have been used as fuel. Hambrecht and Gibbons [101] proposed this for a site in Iceland. This is likely the most probable interpretation for the burnt sample recovered from the Medieval levels of Rua Henrique Calado [102], due to their blue and white colouration, which indicates exposure to temperatures higher than those generally associated with cooking activities [47].

Cetacean bone is strong and resilient, making it suitable for artefact production [84]. It could have served as a substitute for the preferred elephant ivory used by Chalcolithic people, with the advantage of a higher bone hardness compared to elephant ivory [39]. Although sperm whale teeth are suggested as the material for carving Portuguese Chalcolithic buttons, other skeletal parts, such as mandibles, might also have been used, since they are composed entirely of solid cortical bone [103]. According to Mulville (2002 [84]), mandible bone is the preferred skeletal part used by the Maori carvers for bone working. Finally, pierced vertebrae or vertebral discs are often recovered from western European archaeological sites, similar to what was found in the Portuguese Roman sites of Boca do Rio [85] and Museu Municipal de Faro [104]. These have been interpreted as “pot lids”, possibly by comparison with those generally made of slab [105 cited by 84].