Terrestrial vertebrates from the karst filling in Cap d’Artrutx, situated in the extreme Southwest of Menorca (Balearic Islands, western Mediterranean) have yielded interesting information on the migration and extinction dynamics in the terrestrial island vertebrate faunas in Mallorca and Menorca between the late Pliocene and early Pleistocene. In this site, remains of the Menorcan giant tortoise (
L’étude d’ossements de vertébrés terrestres du gisement d’origine karstique du cap d’Artrutx, situé dans l’extrême Sud-Ouest de Minorque (îles Baléares, en Méditerranée occidentale), ont fourni des données très intéressantes relatives à la dynamique de migration et d’extinction des faunes de vertébrés terrestres insulaires de Majorque et Minorque pendant le Pliocène supérieur et le Pléistocène inférieur. Dans le gisement ont été découverts des restes de la tortue géante de Minorque (
Of the three islands that form the Balearic archipelago, Menorca is the second largest in size (702 km2) and the island which is located furthest from the European and African continents, as it is situated in the centre of the western Mediterranean. Its reduced size and isolation have had a notable influence during the periods of colonization of the different groups of terrestrial vertebrates between the middle Miocene and the Pleistocene (
In the case of the Balearic Islands, the reciprocal influences among the faunas of each island is evident from, principally, the palaeontological record preserved in the red limestones deposited in the interior part of caves. The influence between islands is not surprising, given their proximity (Mallorca, which is located in the centre of the archipelago is separated from Eivissa and Menorca by 81.5 and 36.5 km, respectively). Because of this, Mallorca presents some common faunistic elements with the so-called early faunas of Eivissa (
In contrast to what occurred in Mallorca and Eivissa, up to now, no sites have been found in Menorca preserving evidence of the arrival of the early faunas of the Messinian or early Pliocene, which should include, hypothetically, remains from the ancestor of the Menorcan giant rabbit (
In this way, the fauna described at Binigaus (Es Migjorn Gran, Menorca) (
This paper arises from the study of two known Menorcan sites (Cala en Bastó and Bol de Ses Sírvies;
The remains studied were recovered by chemical means, treating the matrix with acetic acid diluted to 10%. Once separated from the matrix, the remains were submerged in water to neutralize the residual acid and calcium acetate. Subsequently the fossils were dried and consolidated by applicating Paraloid B-72. The acid treatment affected, unexpectedly, the most fragile parts of one of the examples (the mandibular branch of
The measurements of the specimens were done based on photographs, using a digital camera incorporated in a stereoscopic microscope with a micrometric eyepiece. The measurements made on the photographs were taken with a digital calibrator with a ± 0.01 mm margin of error. The specimens are stored in the Museu Municipal des Bastio de sa Font (acronym: MMBF) (Ciutadella de Menorca, Balearic Islands, Spain).
The studied site is located on the eastern margin of Punta des Bregarol, to the east of Cap d’Artrutx (Ciutadella de Menorca) (
The Miocene calcarenites in which the cave is excavated are interpreted as belonging to a reef formation of Messinian age by
The giant tortoise from the Pliocene in Menorca is undergoing taxonomic revision. Therefore, in this paper the original name is preserved.
Despite their fragmentary state, the attribution of the remains to the giant turtle of Menorca is safe, because of their relatively large size and their characteristic bone structure.
The m1 has six transverse ridges: anterolophid, metalophid, centrolophid, mesolophid, posterotropid, and posterolophid. The anterolophid is medially interrupted. The metalophid is short, its lingual end connecting the lingual segment of the anterolophid. The centrolophid is long, its labial end connecting with the mesolophid and forming a “Y”-like pattern. The long mesolophid reaches the labial wall of the tooth. The isolated posterotropid is short in one case and long in the other. The hypoconid is anteriorly directed, although it does not connect to the mesoconid, even at a high level of wear.
As in the m1, the m2 has six transverse ridges: anterolophid, metalophid, centrolophid, mesolophid, posterotropid and posterolophid. Other than in the m1, there is in the two cases a continuous anterolophid along the anterior wall of the tooth. Long metalophid, that in one case reaches the metaconid.
The m3 has four transverse ridges: anterolophid, metalophid, mesolophid and posterolophid. A short posterotropid can be distinguished in one of the specimens. Anterolophid and metalophid are both fused labially and lingually, as it is also the case of the mesolophid and posterolophid. In one case, the mesoconid is anteriorly projected, not reaching the protoconid. Metaconid and entoconid are connected, forming a continuous endolophid along the lingual wall of the tooth.
The finding of three species belonging to two faunal episodes in the same site (Cap d’Artrutx) establishes the first evidence of faunal succession in the terrestrial vertebrates in the Plio-Pleistocene in Menorca. In this site, an endemic vertebrate from the island can be found, belonging to the so-called “second faunal episode of Menorca” (the giant tortoise
Cap d’Artrutx is comparable, to a certain extent, with the Holocene site located at Pas den Revull (Barranc d’Algendar, Ferreries, Menorca) where remains of
In the specific case of Cap d’Artrutx, it is unknown whether
In this sense,
The scarcity of remains of micromammals in Cap d’Artrutx also is not only interesting from a taphonomic point of view, but also because of its biogeographical implications. The rarity of these might reflect the existence of populations with few individuals at the moment of formation of the site or it may be due to the lack of vectors responsible for the concentration of these remains, despite the existence of high densities of individuals (e.g., absence, in the vicinity of the site of nocturnal birds of prey).
Notably, the site considered to have the oldest representatives of the genus
The fauna from the site at Cap d’Artrutx, located in the extreme Southeast of the island of Menorca, consists of two mammals (
The presence of
The development of this paper is a part of a project titled “Estudi de les faunes vertebrades de tres jaciments càrstics del Plio-Plistocè de Menorca” financed by research assistance provided by the
Geographical situation of the Punta des Bregarol cave (Menorca, Balearic Islands).
Situation géographique de la grotte de Punta des Bregarol (Minorque, îles Baléares).
(A) Panoramic view of the coastal area in which the cave is located with the remains of vertebrates, marked with a white arrow. In the background, towards the west, the lighthouse of Cap d’Artrutx. (B) Cross section of the cave (east–west direction), excavated in the Miocene calcarenites. The grey areas inside the cave represent the red silts in which the remains of vertebrates are conserved.
(A) Vue panoramique de la zone côtière où est située la grotte avec les restes de vertébrés, marquée par une flèche blanche. À l’arrière-plan, vers l’ouest, le phare du cap d’Artruts. (B) Coupe est–ouest de la grotte creusée dans les calcarénites miocènes. La zone grise dans la grotte représente les silts rouges dans lesquels les restes de vertébrés sont conservés.
Right mandible (MMBF/CA-1) of
Mandibule droite (MMBF/CA-1) de
Left (MMBF/CA-2, A) and a right mandible (MMBF/CA-3, B) of
Mandibules gauche (MMBF/CA-2, A) et droite (MMBF/CA-3, B) d’
Dental measurements of
Mesures dentaires de
Dental measurements of
Mesures dentaires d’