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The false killer whale (Pseudorca crassidens (Owen, 1846)) is a globally distributed delphinid that shows geographical differentiation in its skull morphology. We explored cranial morphological variation in a sample of 85 skulls belonging to a mixed sex population stranded in the Moray Firth, Scotland, in 1927. A three-dimensional digitizer (Microscribe 2GX) was used to record 37 anatomical landmarks on the cranium and 25 on the mandible to investigate size and shape variation and to explore sexual dimorphism using geometric morphometric. Males showed greater overall skull size than females, whereas no sexual dimorphism could be identified in cranial and mandibular shape. Allometric skull changes occurred in parallel for both males and females, supporting the lack of sexual shape dimorphism for this particular sample. Also, fluctuating asymmetry did not differ between crania of males and females. This study confirms the absence of sexual shape dimorphism and the presence of a sexual size dimorphism in this false killer whale population. Key words: toothed whale, morphology, asymmetry, partial least squares, Pseudorca crassidens, false killer whale. Le faux-orque (Pseudorca crassidens (Owen, 1846)) est un delphinidé de répartition planétaire dont la morphologie crânienne présente une différentiation géographique. Nous avons examiné les variations morphologiques du crâne au sein d'un échantillon de 85 crânes provenant d'une population mixte sur le plan du sexe échouée dans le Moray Firth (Ecosse) en 1927. Un numériseur tridimensionnel (Microscribe 2GX) a été utilisé pour enregistrer 37 repères anatomiques sur les crânes et 25 sur les mâchoires afin d'examiner les variations de taille et de forme et d'explorer le dimorphisme sexuel à l'aide de la morphométrie géométrique. Si la taille des crânes de mâles est généralement plus grande que celle des crânes de femelles, aucun dimorphisme sexuel n'est relevé en ce qui concerne la forme du crâne ou de la mâchoire. Des changements allométriques parallèles sont observés pour les crânes mâles et femelles, ce qui appuie l'interprétation de l'absence de dimorphisme sexuel sur le plan morphologique pour cet échantillon. En outre, il n'y a pas de différence en ce qui concerne l'asymétrie fluctuante entre les crânes de mâles et de femelles. L'étude confirme l'absence d'un dimorphisme sexuel de la forme et la présence d'un dimorphisme sexuel de la taille au sein de cette population de faux-orques. [Traduit par la Rédaction] Mots-clés: cétacé à dents, morphologie, asymétrie, moindres carrés partiels, Pseudorca crassidens, faux-orque., Introduction The false killer whale (Pseudorca crassidens (Owen, 1846)) is a large cetacean with a cosmopolitan distribution that ranges mainly between 50[degrees]N and 50[degrees]S in latitude (Baird 2009a). Adults can [...]

The Messinian Salinity Crisis and its precursor events have been the greatest environmental perturbation of the Mediterranean Sea to date, offering an opportunity to study the response of marine ecosystems to extreme hydrological change and a large-scale biological invasion. The restriction of the marine connection between the Mediterranean and the Atlantic Ocean already since the Tortonian-Messinian boundary resulted in stratification of the water column and increase water temperature and salinity variations. Here, we present a unified and revised marine fossil record of the Mediterranean that covers the Tortonian stage, the pre-evaporitic Messinian and the Zanclean stage and encompasses 22988 occurrences of calcareous nannoplankton, dinoflagellates, foraminifera, corals, ostracods, bryozoans, echinoids, mollusks, fishes, and marine mammals. This record adheres to the FAIR principles, it is updated in terms of taxonomy, and it follows the currently accepted stratigraphic framework. Based on this record, knowledge gaps are identified, which are due to spatiotemporal inconsistencies in sampling effort and the distribution of sedimentary facies, and the inherent differences in the preservation potential between the groups. Additionally, sampling bias in old records may have distorted the record in favor of larger, more impressive taxa within groups. This record is now ready to be used to answer both geological and biological questions, and is amendable when new fossil data are brought to light. [ABSTRACT FROM AUTHOR]

Simple Summary: Nowadays, the infraorder Delphinida consists of oceanic dolphins and porpoises plus a handful of riverine and (sub-)Arctic forms. Overall, the delphinidans account for more than half of the living cetacean species, thus comprising the core of present-day marine mammal diversity. The fossil record indicates that a critical phase of the evolutionary history of Delphinida occurred during the Early Miocene (c. 23.0–16.0 million years ago) when the extinct genus Kentriodon first appeared and became widespread worldwide. Our paper deals with a new delphinidan fossil from northeastern Italy, namely, an incomplete skull with ear bones dating back to 20.4–19.0 million years ago. This new specimen is recognized herein as a representative of Kentriodon and specifically as the first unambiguous member of this genus from the Euro-Mediterranean region. Our new find represents the best candidate for being the most ancient member of Kentriodon. The evolutionary success of Kentriodon (which lasted until the Late Miocene, less than 11.3 million years ago) may have been favored by the evolution of a peculiar biosonar system exploiting narrow-band high-frequency sounds, which in turn would have been hardly detectable by large-bodied, predatory toothed whales. Furthermore, Kentriodon was seemingly characterized by a proportionally larger brain compared to many coeval toothed whales, which in turn may evoke enhanced behavioral capabilities. Nowadays, the infraorder Delphinida (oceanic dolphins and kin) represents the most diverse extant clade of Cetacea, with delphinids alone accounting for more than 40% of the total number of living cetacean species. As for other cetacean groups, the Early Miocene represents a key interval for the evolutionary history of Delphinida, as it was during this time span that the delphinidans became broadly distributed worldwide, first and foremost with the widespread genus Kentriodon and closely related forms. Here, we report on a new odontocete find from Burdigalian (20.4–19.0 Ma) deposits of the Friulian-Venetian Basin of northeastern Italy, consisting of the partial cranium of a small delphinidan with associated ear bones (right periotic, stapes, malleus and tympanic bulla). Osteoanatomical considerations and comparisons allow us to assign the studied specimen to the genus Kentriodon. This is the first confirmed record of Kentriodon from Europe as well as from the whole proto-Mediterranean region. Stratigraphic and phylogenetic considerations suggest that our new specimen may represent the geologically oldest member of Kentriodon. The evolutionary success of Kentriodon may correlate with the emergence of narrow-band high-frequency echolocation as a possible strategy to escape acoustic detection by large marine predators such as the squalodontids. In addition, the relatively high encephalization quotient of Kentriodon spp. may have provided these early dolphins with some kind of competitive advantage over the coeval non-delphinidan odontocetes. [ABSTRACT FROM AUTHOR]

A fossil mysticete was discovered along the southwestern coast of Spain, occurring in a block detached from the Neogene deposits exposed along a coastal cliff at the locality of Conil de la Frontera (Cádiz, Spain). These deposits range from Pliocene to Pleistocene in age and include shallow-marine, mixed carbonate–siliciclastic sediments, with the whale being found in occurrence of a stratigraphic unconformity marked by Thalassinoides burrows. 87Sr/86Sr analyses on oyster shells associated with the skeleton suggest an Early Pliocene age, in agreement with the age of the lowermost unit cropping out at the study site. The studied cetacean specimen consists of an articulated, almost complete balaenopteroid skeleton exposed in the field dorsal side up; being contained in an upside-down block, however, it is preserved in ventral disposition. Bones exhibit a low degree of preservation of the cortical bone tissue, which locally features shark bite marks and Osedax traces as well as abundant encrustations of barnacles and ostreids. Two shark teeth were also found near the skeleton. Bones have preserved their main histological features, even though they locally exhibit microcracks, dissolution, substitution by Fe oxides, and microborings. Sediment particles and late diagenetic cements fill the medullary cavities. We propose that the whale carcass experienced refloating before sinking to the seafloor and that the skeleton was probably exposed on the seafloor for some time before being eventually buried. [ABSTRACT FROM AUTHOR]