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1
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Aspects of diversity in early Antarctic penguins

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Jadwiszczak P., Mors T.
Acta Palaeontologica Polonica
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2011
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tom 56
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nr 2
Penguin bones from the Eocene La Meseta Formation (Seymour Island, Antarctic Peninsula) constitute the only extensive fossil record of Antarctic Sphenisciformes. Here, we synonymize some of the recognized genera (Anthropornis with Orthopteryx, Delphinornis with Ichtyopteryx) and species (Anthropornis nordenskjoeldi with Orthopteryx gigas, Delphinornis gracilis with Ichtyopteryx gracilis). Moreover, we suggest that Antarctic species of Anthropornis and Palaeeudyptes, so−called giant penguins, may in fact comprise only one species each instead of two, based on evidence of well−marked sexual dimorphism. We also present new estimates of body mass based on femora testifying to the impressive scope of interspecific body−size variation in Eocene Antarctic penguins.
2
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The castorid Steneofiber from NW Germany and its implications for the taxonomy of Miocene beavers

100%
Mors T., Stefen C.
Acta Palaeontologica Polonica
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2010
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tom 55
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nr 2
189-198
Craniodental remains of a medium−sized beaver from the early middle Miocene of Hambach (MN 5) in the Lower Rhine Basin of northwestern Germany are described and assigned to Steneofiber depereti. The relatively rich material (6 mandibles and 56 isolated teeth) was collected from a single locality, Hambach 6C, and comprises specimens representing juvenile to very old individuals. This makes it possible to assess the morphologic and metric variability of a single population of Steneofiber depereti. Metrically, the mandibular tooth rows compare favorably in size to those of three subspecies described from the Loire Basin in France: Steneofiber depereti janvieri, Steneofiber d. caliodorensis, and Steneofiber d. depereti. Therefore in our opinion, division into subspecies cannot be applied to S. depereti in general. The difference in size between the smaller beaver from Hambach and the contemporaneous larger S. d. carnutense from the Loire Basin is remarkable. The taxonomy of early middle Miocene medium−sized castorids, referred to Steneofiber depereti, Steneofiber subpyrenaicus, and Chalicomys jaegeri is discussed. The presence of the derived beaver C. jaegeri in MN 4 to MN 6 is questioned and assignment to Steneofiber suggested. The occasional appearance of single C. jaegeri features in S. depereti supports the existence of a European lineage from the Orleanian S. depereti to the Vallesian C. jaegeri. The taxonomic status of S. subpyrenaicus remains unresolved.
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A new endemic genus of eomyid rodents from the early Miocene of Japan

71%
Kimura Y., Tomida Y., Kalthoff D. C., Casanovas-Vilar I., Mors T.
Acta Palaeontologica Polonica
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2019
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tom 64
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nr 2
Fossil rodents are generally scarce in the Miocene of Japan. However, as much as three taxa of eomyid rodents had been reported from the early Miocene Nakamura Formation (ca. 18.5 Ma) in Gifu Prefecture, central Japan. In this study, we revisit one of them—the small-sized taxon—and assign this material to a new genus, Japaneomys, which is so far known only from the type locality. The new genus is closely related to but distinguished from Asianeomys, which is more widely distributed in Central and East Asia, by having: (i) more bunodont cheek teeth with lower lophids, yet complete transverse lophids; (ii) two-rooted p4; (iii) anterior lobe narrower than posterior lobe on m1, correspondingly synclinid I shorter and shallower than synclinid IV; (iv) hypolophid anteriorly concave on m1. Japaneomys shows a derived but peculiar four-layered enamel microstructure with longitudinally oriented Hunter-Schreger bands, compared to three-layered microstructure in typical eomyid rodents. A phylogenetic analysis indicates that Japaneomys is more basal than Asianeomys and likely diverged in the late Oligocene when Japan was still part of the eastern margin of continental Asia, suggesting that certain small mammal populations could have undergone allopatric speciation isolated from inner-continental regions of Asia.
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A late Paleocene fauna from shallow-water chemosynthesis-based ecosystems, Spitsbergen, Svalbard

51%
Hryniewicz K., Amano K., Bitner M. A., Hagstrom J., Kiel S., Klompmaker A. A., Mors T., Robins C. M., Kaim A.
Acta Palaeontologica Polonica
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2019
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tom 64
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nr 1
We present a systematic study of late Paleocene macrofauna from methane seep carbonates and associated driftwood in the shallow marine Basilika Formation, Spitsbergen, Svalbard. The fauna is composed of 22 taxa, comprising one brachiopod, 14 bivalves, three gastropods, three crustaceans, and one bony fish. The reported fish remains are among the first vertebrate body fossils from the Paleogene of Spitsbergen. One genus is new: the munidid decapod Valamunida Klompmaker and Robins gen. nov. Four new species are described: the terebratulide brachiopod Neoliothyrina nakremi Bitner sp. nov., the protobranch bivalve Yoldiella spitsbergensis Amano sp. nov., the xylophagain bivalve Xylophagella littlei Hryniewicz sp. nov., and the munidid decapod Valamunida haeggi Klompmaker and Robins gen. et sp. nov. New combinations are provided for the mytilid bivalve Inoperna plenicostata, the thyasirid bivalve Rhacothyas spitzbergensis, the ampullinid gastropod Globularia isfjordensis, and the munidid decapod Protomunida spitzbergica. Thirteen taxa are left in open nomenclature. The fauna contains a few last occurrences of Cretaceous survivors into the Paleocene, as well as first occurrences of Cenozoic taxa. It is composed of chemosymbiotic thyasirid bivalves and background species common in the northern Atlantic and Arctic during the Paleocene. Our results provide no evidence for a Paleocene origin of vesicomyid and bathymodiolin bivalves typical for Eocene and younger seep environments; instead, the Paleo cene seeps of the Basilika Formation are more similar to their Late Cretaceous equi valents rich in thyasirids.
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