scholarly journals Reappraisal of the extinct seal “Phoca”vitulinoidesfrom the Neogene of the North Sea Basin, with bearing on its geological age, phylogenetic affinities, and locomotion

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3316 ◽  
Author(s):  
Leonard Dewaele ◽  
Eli Amson ◽  
Olivier Lambert ◽  
Stephen Louwye
Keyword(s):  
Phylogenetic Analysis ◽  
North Sea ◽  
Comparative Anatomy ◽  
Phylogenetic Position ◽  
The North ◽  
Early Diversification ◽  
Geological Age ◽  
The North Sea ◽  
Phylogenetic Affinities ◽  
Stratigraphic Range

BackgroundDiscovered on the southern margin of the North Sea Basin, “Phoca”vitulinoidesrepresents one of the best-known extinct species of Phocidae. However, little attention has been given to the species ever since its original 19th century description. Newly discovered material, including the most complete specimen of fossil Phocidae from the North Sea Basin, prompted the redescription of the species. Also, the type material of “Phoca”vitulinoidesis lost.Methods“Phoca”vitulinoidesis redescribed. Its phylogenetic position among Phocinae is assessed through phylogenetic analysis. Dinoflagellate cyst biostratigraphy is used to determine and reassess the geological age of the species. Myological descriptions of extant taxa are used to infer muscle attachments, and basic comparative anatomy of the gross morphology and biomechanics are applied to reconstruct locomotion.ResultsDetailed redescription of “Phoca”vitulinoidesindicates relatively little affinities with the genusPhoca, but rather asks for the establishment of a new genus:Nanophocagen. nov. Hence, “Phoca”vitulinoidesis recombined intoNanophoca vitulinoides. This reassignment is confirmed by the phylogenetic analysis, grouping the genusNanophocaand other extinct phocine taxa as stem phocines. Biostratigraphy and lithostratigraphy expand the known stratigraphic range ofN. vitulinoidesfrom the late Langhian to the late Serravallian. The osteological anatomy ofN. vitulinoidesindicates a relatively strong development of muscles used for fore flipper propulsion and increased flexibility for the hind flipper.DiscussionThe extended stratigraphic range ofN. vitulinoidesinto the middle Miocene confirms relatively early diversification of Phocinae in the North Atlantic. Morphological features on the fore- and hindlimb of the species point toward an increased use of the fore flipper and greater flexibility of the hind flipper as compared to extant Phocinae, clearly indicating less derived locomotor strategies in this Miocene phocine species. Estimations of the overall body size indicate thatN. vitulinoidesis much smaller thanPusa, the smallest extant genus of Phocinae (and Phocidae), and than most extinct phocines.

scholarly journals OnProphocaandLeptophoca(Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3024 ◽  
Author(s):  
Leonard Dewaele ◽  
Olivier Lambert ◽  
Stephen Louwye
Keyword(s):  
North America ◽  
Middle Miocene ◽  
New Combination ◽  
Phylogenetic Position ◽  
Appendicular Skeleton ◽  
Original Diagnosis ◽  
Sediment Samples ◽  
The North ◽  
The North Sea ◽  
Phylogenetic Affinities

BackgroundProphocaandLeptophocarepresent the oldest known genera of phocine seals, dating from the latest early to middle Miocene. Originally,Prophoca rousseauiandProphoca proximawere described based on fragmentary remains from the Miocene of Belgium. However, several researchers contested the union ofProphoca rousseauiandProphoca proximainto one genus, without providing evidence. The stratigraphic context ofProphocaremained poorly constrained due to the lack of precise data associated with the original specimens collected in the area of Antwerp (north of Belgium).MethodsProphocaandLeptophocaare redescribed and their phylogenetic position among Phocidae is reassessed using PAUP. Dinoflagellate biostratigraphy has been carried out on sediment samples associated with specimens fromProphocaandLeptophocato elucidate their approximate ages.ResultsWhereas the speciesProphoca rousseauiis redescribed,Prophoca proximais considered synonymous toLeptophoca lenis, with the proposal of a new combinationLeptophoca proxima(Van Beneden, 1877). Sediment samples from specimens of both taxa have been dated to the late Langhian–early Serravallian (middle Miocene). Following a reinvestigation ofLeptophoca amphiatlantica, characters from the original diagnosis are questioned and the specimens ofLeptophoca amphiatlanticaare consideredLeptophocacf.L. proxima. In a phylogenetic analysis,Prophoca rousseauiandLeptophoca proximaconstitute early branching stem-phocines.DiscussionLeptophoca proximafrom the North Sea Basin is younger than the oldest known find ofLeptophoca proximafrom North America, which does not contradict the hypothesis that Phocinae originated along the east coast of North America during the late early Miocene, followed by dispersal to Europe shortly after. Morphological features of the appendicular skeleton indicate thatProphoca rousseauiandLeptophoca proximahave archaic locomotory modes, retaining a more prominent use of the fore flipper for aquatic propulsion than extant Phocidae.

scholarly journals A new balaenopterid species from the Southern North Sea Basin informs about phylogeny and taxonomy of Burtinopsis and Protororqualus (Cetacea, Mysticeti, Balaenopteridae)

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9570 ◽  
Author(s):  
Michelangelo Bisconti ◽  
Mark E.J. Bosselaers
Keyword(s):  
Phylogenetic Analysis ◽  
New Species ◽  
Atlantic Ocean ◽  
North Sea ◽  
North Atlantic Ocean ◽  
The Past ◽  
The North ◽  
The North Sea ◽  
Morphological Transformations ◽  
The 19Th Century

Background An extensive radiation can be inferred among balaenopterid mysticetes in the last 10 million years based on a rich fossil record. Many extinct genera and species have been established in the past by the study of fossil rorquals from northern and southern hemispheres. In many cases, the new fossils are used to create new genera. However, in very recent times, new species of known genera have been described that help our understanding of the speciation processes and the biogeography of these whales. Here, a new species of balaenopterid whales is described in order to better understand the past diversity of Balaenopteridae and to analyze its paleobiogeographical implications. As the new species closely resembles a taxon established in the 19th century (i.e., Burtinopsis), a detailed analysis of this taxon was necessary to support the new taxonomic statements of this article. Methods A new partial skeleton including skull and earbones is described and compared to an extended sample of living and fossil mysticete species. A phylogenetic analysis including 355 character states scored in 88 taxa was performed to understand its relationships within the genus Protororqualus, to allow paleobiogeographic inferences and to better understand the relationships of Protororqualus within Balaenopteridae. Maximum parsimony analyses of character evolution were performed to understand morphological transformations within Balaenopteridae. The revision of Burtinopsis was carried out based on detailed descriptions and comparisons of the type materials that were figured and measured. Results Protororqualus wilfriedneesi sp. nov. was established based on a comparative analysis of the skull and earbone morphology. The specimen is dated back to the Zanclean (Lower Pliocene, between c. 5.3 and 3.6 Ma). A taphonomical study of the holotype skeleton revealed evidence of interactions with sharks and fishes before the definitive burial of the carcass. Based on the phylogenetic analysis, the monophyly of the genus Protororqualus was confirmed. Protororqualus wilfriedneesi sp. nov. was more derived than Protororqualus cuvieri suggesting that it resulted from an invasion of the North Sea Basin (and the North Atlantic ocean) from the Mediterranean basin. Several specimens from western and eastern sides of the Atlantic Ocean are described that suggest that Protororqualus wilfriedneesi had a trans-Atlantic distribution in the Pliocene.

scholarly journals II.—Studies in Edrioasteroidea. VI. Pyrgocystis n.g.

1915 ◽  
Vol 2 (1) ◽  
pp. 5-12 ◽  
Author(s):  
F. A. Bather
Keyword(s):  
New Species ◽  
North Sea ◽  
Type Species ◽  
Upper Ordovician ◽  
The North ◽  
Geological Age ◽  
Lower Ordovician ◽  
The North Sea ◽  
Firm Basis

Materials for the study of this very distinctive genus have been accumulating for many years, and at last afford a firm basis for certain definite conclusions. Some important matters remain obscure, and the comparison of the Swedish material has been hindered by the dangerous state of the North Sea, but further delay in publication does not seem advisable. Various reasons make it convenient to deal with the species in the order of their geological age, beginning with the oldest, which is the most complete and is taken as the type-species of the genus. The new species are— Pyrgocystis sardesoni, Lower Ordovician, Minnesota (genotype).Pyrgocystis grayae, Upper Ordovician, Girvan.Pyrgocystis ansticei, Middle Silurian, Shropshire.

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