Abstract
BackgroundThe rich fossil record of rorqual and humpback whales (Cetacea, Mysticeti, Balaenopteridae) is mainly characterized by monotypic genera since genera including more than one species are extremely rare. The discovery of new species belonging to known genera would be of great importance in order to better understand ancestor-descendant relationships and paleobiogeographic patterns in this diverse group. Recent discoveries in the southern North Sea Basin yielded a number of reasonably well preserved fossil balaenopterids from the Late Miocene; this sample includes a balaenopterid skull from Liessel, The Netherlands, which shares key characters with Archaebalaenoptera castriarquati from the Pliocene of Mediterranean. This skull is permanently held by Oertijdmuseum, Boxtel, The Netherlands, with the number MAB002286 and is investigated here.MethodsA detailed comparative anatomical analysis of the skull MAB002286 is performed in order to understand its relationships. The age of the skull is determined by dinocyst analysis of the associated sediment. A paleobiogeographic analysis is performed to understand paleobiogeographic patterns within the balaenopterid clade the new skull belongs to.ResultsOur work resulted in the description of Archaebalaenoptera liesselensis new species. The geological age of the holotype skull is between 8.1 and 7.5 Ma. The phylogenetic relationships of this species reveals that it is monophyletic with Archaebalaenoptera castriarquati from the Italian Pliocene. Moreover, in combination with a more basal species of Archaebalaenoptera from the late Miocene of Peru, our paleobiogeographic analysis suggests that the North Atlantic ocean played a major role as a center of origin of a number of balaenopterid clades including Protororqualus, Archaebalaenoptera and more advanced balaenopterid taxa. From a North Atlantic center of origin, two dispersal events are inferred that led to the origins of Archaebalaenoptera species in the South Pacific and Mediterranean. The distribution of Archaebalaenoptera was antitropical in the late Miocene. The role played by the Mediterranean salinity crisis is also investigated and discussed.
Highlights
The fossil record of baleen bearing whales (Mammalia, Cetacea, Mysticeti) is mainly characterized by genera known only by one specimen (Bisconti, 2010)
The analysis revealed the existence of an additional Archaebalaenoptera species from the late Miocene of Peru that will be described elsewhere (Bisconti et al, 2020, unpublished data)
We considered that taxa described from the Miocene and Pliocene outcrops of the southern North Sea basin to be widespread in the North Atlantic ocean as it is hard-to-impossible to demonstrate that living or fossil balaenopterid species may have had a range reduced only to the southern North Sea basin because of their ability to swim across ocean basins of today
Summary
The fossil record of baleen bearing whales (Mammalia, Cetacea, Mysticeti) is mainly characterized by genera known only by one specimen (Bisconti, 2010). A few examples exist of chaeomysticete genera with multiple species found at different localities (e.g., Parietobalaena, Diorocetus, Balaena, Eubalaena, Balaenula) This fact represents a problem for morphologists as it makes it hard or impossible to assess the degree of morphological variation in extinct mysticete species and does not provide safe information about the past distributions of these cetaceans. The discovery of additional species in known genera may assist in reconstructing the different paths of morphological transformations occurring in separate rorqual lineages Discoveries of such kind would help in assessing paleobiogeographic patterns of single balaenopterid clades. Recent discoveries in the southern North Sea Basin yielded a number of reasonably well preserved fossil balaenopterids from the Late Miocene; this sample includes a balaenopterid skull from Liessel, The Netherlands, which shares key characters with Archaebalaenoptera castriarquati from the Pliocene of Mediterranean.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
