New Paratethyan dwarf baleen whales mark the origin of cetotheres

Background Family Cetotheriidae sensu stricto and several closely related taxa comprise the Cetotherioidea and represent a lineage of Neogene baleen whales that includes the smallest edentulous baleen whales in Earth history. Most of known cetotheriids came from the Late Miocene to Quaternary, and the earliest records from the latest Middle Miocene. The Paratethys region shows a great diversity of Middle to Late Miocene cetotheriids. That includes nominative taxon of the family, Cetotherium rathkii, and this suggests that the earliest cetotheriids may have lived in that region. Materials and methods Here, Ciuciulea davidi, a new genus and species from the Middle Miocene of southeastern Europe, is described as the chronologically earliest and earliest diverging member of Cetotheriidae. Also, a new specimen of Otradnocetus, a basal Cetotherioidea sensu Gol’din & Steeman, 2015 is identified from the Late Miocene deposits of Caucasus and compared with Otradnocetus virodovi from the Middle Miocene of the same region. Results and discussion Ciuciulea davidi is a dwarf whale displaying primitive traits: posterior ends of facial bones forming a single transverse line, a narrow occipital shield, and a relatively long interparietal region. Meanwhile, it shares some cetotheriid apomorphies: posteriorly telescoped wedge-shaped facial bones and an ovoid tympanic bulla with shallow lateral and medial furrows, a short anterior lobe and a short sigmoid process. Phylogenetic analysis suggests that Parietobalaena and Otradnocetus are branches diverging before the clade Cetotheriidae + Neobalaenidae. This is confirmed by the stepwise evolution of the anatomy of the squamosal, mandible, and ear bones across these groups. The re-described juvenile specimen of Otradnocetus differs from O. virodovi in the more primitive anatomy of the mandible and the autapomorphic anatomy of the humerus. Records of the earliest cetotheriids and related taxa in the Paratethys support the idea that this could be the region where Cetotheriidae evolved before their worldwide dispersal and radiation

Genetic homogeneity in the face of morphological heterogeneity in the harbor porpoise from the Black Sea and adjacent waters (<i>Phocoena phocoena relicta</i>)

Absence of genetic differentiation is usually taken as an evidence of panmixia, but can also reflect other situations, including even nearly complete demographic independence among large-sized populations. Deciphering which situation applies has major practical implications (e.g., in conservation biology). The endangered harbor porpoises in the Black Sea illustrates this point well. While morphological heterogeneity suggested that population differentiation may exist between individuals from the Black and Azov seas, no genetic study provided conclusive evidence or covered the entire subspecies range. Here, we assessed the genetic structure at ten microsatellite loci and a 3904 base-pairs mitochondrial fragment in 144 porpoises across the subspecies range (i.e., Aegean, Marmara, Black, and Azov seas). Analyses of the genetic structure, including F ST, Bayesian clustering, and multivariate analyses revealed a nearly complete genetic homogeneity. Power analyses rejected the possibility of underpowered analyses (power to detect F ST ≥ 0.008 at microsatellite loci). Simulations under various demographic models, evaluating the evolution of F ST, showed that a time-lag effect between demographic and genetic subdivision is also unlikely. With a realistic effective population size of 1000 individuals, the expected “gray zone” would be at most 20 generations under moderate levels of gene flow (≤10 migrants per generation). After excluding alternative hypotheses, panmixia remains the most likely hypothesis explaining the genetic homogeneity in the Black Sea porpoises. Morphological heterogeneity may thus reflect other processes than population subdivision (e.g., plasticity, selection). This study illustrates how combining empirical and theoretical approaches can contribute to understanding patterns of weak population structure in highly mobile marine species. </p

Prehistoric and historic exploitation of marine mammals in the Black Sea

The recent exploitation of marine species is relatively well documented and understood in terms of impacts on species abundance, distribution, and resource use. In contrast, ancient exploitation of marine mammals remains poorly documented; in part, because a detailed meta-analysis of their presence in the zooarchaeological record is lacking. This is true in the Black Sea, where cetaceans are reported in the zooarchaeological record but have not yet been studied comprehensively. Here, we synthesize all available published and unpublished zooarchaeological data from 27 sites around the Black Sea, dating from the Mesolithic and Neolithic periods (6500-6000 BCE) to the Medieval period (641–1475 CE), to document the extent and nature of the exploitation of the Black Sea cetacean species. The results suggest that cetacean exploitation was practised continuously in the Black Sea over a period of 8500 years from the Neolithic through to the Medieval period. This suggests a much longer history of marine mammal exploitation in the Black Sea than previously understood, pushing back the timeline of human impacts on the Black Sea marine fauna.</p

Palaeogenomic analysis of black rat (Rattus rattus) reveals multiple European introductions associated with human economic history

The distribution of the black rat (Rattus rattus) has been heavily influenced by its association with humans. The dispersal history of this non-native commensal rodent across Europe, however, remains poorly understood, and different introductions may have occurred during the Roman and medieval periods. Here, in order to reconstruct the population history of European black rats, we first generate a de novo genome assembly of the black rat. We then sequence 67 ancient and three modern black rat mitogenomes, and 36 ancient and three modern nuclear genomes from archaeological sites spanning the 1st-17th centuries CE in Europe and North Africa. Analyses of our newly reported sequences, together with published mitochondrial DNA sequences, confirm that black rats were introduced into the Mediterranean and Europe from Southwest Asia. Genomic analyses of the ancient rats reveal a population turnover in temperate Europe between the 6th and 10th centuries CE, coincident with an archaeologically attested decline in the black rat population. The near disappearance and re-emergence of black rats in Europe may have been the result of the breakdown of the Roman Empire, the First Plague Pandemic, and/or post-Roman climatic cooling.Peer reviewe

Data from: A systematic review of cetothere baleen whales (Cetacea, Cetotheriidae) from the Late Miocene of Crimea and Caucasus, with a new genus

Nine taxa of Miocene baleen whales were described from the Black Sea region under the name Cetotherium before 1951, and a further four closely related species representing three genera have been added in recent years. This rich diversity requires taxonomic revision and ordering. Here, a new genus, Mithridatocetus, is described from the Tortonian of Crimea and Caucasus, with two species, M. eichwaldi and M. adygeicus (originally Kurdalagonus adygeicus); ‘Cetotherium’ mayeri (a nomen dubium) is also a member of this genus. In comparison with other Cetotheriinae, Mithridatocetus is distinguished by the autapomorphic shape of the tympanic bulla with the swollen main ridge, the lowered anterior portion of the involucrum and the oblique anterolateral margin; such synapomorphies, as a transversely narrow squamosal with the ventromedially oriented postglenoid process (shared with Eucetotherium), a squamosal cleft (shared with Kurdalagonus) and an oval surface of the compound posterior process of the tympanoperiotic on the posterolateral skull wall (shared with Brandtocetus); and a unique combination of a high neurocranium and a long and robust paroccipital process. The genus Kurdalagonus is redefined here as containing only one described species, K. mchedlidzei. Therefore, the group Cetotheriinae is now restricted to the latest Serravallian and Tortonian of the Eastern Paratethys and includes at least five genera: Cetotherium, Brandtocetus, Kurdalagonus, Mithridatocetus and Zygiocetus. In addition, ?Cetotherium priscum and C. incertum are considered to be nomina dubia; ‘Cetotherium’ klinderi and ‘Cetotherium’ pusillum require more complete specimens for reassessment; ‘Cetotherium’ maicopicum and Eucetotherium helmersenii require further research to identify their taxonomical affinities

Data from: Basilotritus uheni, a new cetacean (Cetacea, Basilosauridae) from the late Middle Eocene of Eastern Europe

A new basal basilosaurid cetacean, Basilotritus uheni n. gen. n. sp., comes from the late middle Eocene (Bartonian) of Ukraine. It is the earliest dated record of a cetacean from Eastern Europe. The tympanic bulla of Basilotritus uheni shares basilosaurid synapomorphies but possesses unusual traits inherited from protocetids. Cetaceans related to Basilotritus uheni and referred to as Eocetus or “Eocetus” have been recorded from Africa, Europe, North America and South America. “Eocetus” wardii from North America is recombined as Basilotritus wardii. Platyosphys paulsonii and Platyosphys einori from Ukraine are considered as nomina dubia; specimens prior referred to as Platyosphys sp. are similar or related to Basilotritus. Other records of the Eocene cetaceans from Ukraine and south Russia are identified as Basilotritus or related genera. Early basilosaurids are demonstrated to be a paraphyletic, morphologically and geographically diverse group of the genera that colonized the world ocean as late as in Bartonian age and were probably the ancestors of Neoceti, as well as of more derived basilosaurids

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A small whale reveals diversity of the Eocene cetacean fauna of Antarctica

Cetacean fossils have been recorded from middle and late Eocene deposits on Seymour Island since the beginning of the twentieth century and include fully aquatic Basilosauridae and stem Neoceti. Here, we report a small cetacean vertebra tentatively referred to as Neoceti from the late Eocene of Seymour Island. It shows a mosaic of traits, some of which are characteristic of early Neoceti (anteroposteriorly long transverse processes; a ventral keel on the ventral side of the centrum; thin pedicles of the neural arch), whereas others are shared with Basilosauridae (low-placed bases of the transverse processes). However, some traits are unique and may be autapomorphic: presence of separate prezygapophyses on the vertebra at the thoracic/lumbar boundary and a proportionally short centrum. Both traits imply a fast swimming style, which is characteristic of modern dolphins rather than Eocene cetaceans. Thus, this specimen can be identified as Neoceti indet., with some hypothetical odontocete affinities. Along with a few other Eocene whale taxa, it seems to be among the earliest known members of Neoceti on Earth. The finding of small and fast-swimming Neoceti in Antarctica also demonstrates early diversification of cetaceans and ecological niche partitioning by them dating back as early as the late Eocene