Abstract

For two hundred years the status of rodent suborders has been unstable. What are the natural groupings of extant rodent families? The formal recognition of rodent suborders has remained challenging and consensus has been elusive. Classically conceived rodent suborders are widely viewed as artificial, but no universally accepted classification has emerged to reflect the major features of rodent evolution. Over the last two decades molecular studies have established that extant rodents comprise three monophyletic clades. We review the molecular basis for these groups and recognize them as taxonomic units: Suborder Ctenohystrica HUCHON et al., 2000, Suborder Supramyomorpha D’ELÍA et al., 2019, and a group of families clustered with Sciuridae. The latter differs from Sciuromorpha as traditionally conceived because the suborder includes Aplodontiidae but excludes Castoridae. We review morphological character complexes that are distributed broadly within these three clades, name the third group Eusciurida, new suborder, and find this three-fold division of extant Rodentia to reflect well the major features of rodent phylogeny. That some morphological features do not characterize all families within suborders, or are not unique to individual suborders, indicates major parallel innovations and reversals in rodent evolution. These incongruent morphologies invite future study.

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The enamel microstructure of molars in Mexican soricines Megasorex and Cryptotis is described and compared to the six types of schmelzmuster found in fossil and recent Soricidae. These types of schmelzmuster show a high correlation to the current systematics of Soricidae. In Megasorex, the relatively simple schmelzmuster is dominated by radial enamel. However, a very thin innermost layer of differentiated enamel indicates the beginning of a two-layered schmelzmuster. This corresponds to the Notiosorex-schmelzmuster. The teeth of Megasorex lack pigmentation, which is not reflected in its schmelzmuster. Similarities to the white-toothed Crocidura-schmelzmuster are superficial. Cryptotis has the typical two-layered enamel of derived Soricinae. The specific enamel type of the inner layer and the strong lateral inclination of its prisms represent a new modification of the highly derived Blarina-schmelzmuster.

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A thorough consideration is given to the geological, palaeotheriological and malacological materials obtained from the Pleistocene Sanmanych locality, which is the only locality with mammal fauna in the Manych depression (46°24′53′′ N, 42°36′25′′ E). The brackish-water mollusk composition indicated that the bone-bearing series should be correlated to the Early Khvalynian transgression. The fossil record gives an insight into the palaeoenvironment at the time that the Caspian Sea water broke through the Manych depression into the Black Sea basin. The faunal evidence points to arid conditions and a cool climate. The rodent species composition is rather poor; it exclusively includes species indicative for an open environment, which suggests a wide spread occurrence of steppe and semi-deserts in the Manych valley during the Late Glacial (~16–12 ka BP).

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A new species, Myotis gerhardstorchi sp. n., supposedly close to M. sicarius and M. frater group, is described from MN 15 site Beremend 26 (Hungary). M. frater group, now restricted to vicariant ranges in E Asia, Siberia and Central Asia, is further reported from three Pliocene and two Early Pleistocene mass bat assemblages from the Czech Republic, Poland and Slovakia. The odontological diagnosis of the group is presented, together with comparisons of the fossil material with extant species of the group, and W Palearctic taxa of the genus, both fossil and Recent. Molecular phylogenetics reveals that the above-mentioned Asiatic taxa, together with the European species M. daubentonii and M. bechsteinii, the index fossil of the W Palearctic Late Cenozoic bat communities, compose a distinct phylogenetic entity called Myotis Clade III. Here we argue that the history of Clade III in the W Palearctics was contributed also by clades close to its stem line, and those related to the Asiatic forms that later disappeared from that region. Finally, a list of taxa, both fossil and Recent, composing the Myotis Clade III is provided.

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Small fossil vertebrates from several Pliocene and Pleistocene localities in Central Anatolia (Turkey) are reviewed. Data on small mammals represent assemblages from the early Pliocene (MN 14: Nasrettinhoca 1, 2 and Hamamkarahisar A, B), and late Pliocene (MN 16: Hoyhoytepe 1, 2, 3 and Mercan 1); Early Pleistocene (MN 17: Mercan 2), and Middle Pleistocene (MQ 1/MQ 2: Yenişarbademli). The biochronology related characters of arvicolines Promimomys, Mimomys, Microtus, Lagurus and Clethrionomys are briefly discussed. Data on the systematics of fossil amphibians and reptiles is also described from these localities. The early Pliocene (MN 14) assemblages significantly add to knowledge on the herpetofaunal composition of this stratigraphic level, which until now was poorly characterized in Turkey. Remains of Pelobatidae, Bufonidae, Ranidae, Amphisbaenia and Natricinae are reported for the first time from the MN 14 biozone of Turkey. Palaeobatrachus from Mercan 1 extends the temporal range of this group in the Eastern Mediterranean into the late Pliocene. The described remains of amphibians and reptiles from Turkey span a considerable stratigraphic range from the early Pliocene to the Middle Pleistocene (time interval of about 5 Ma) and partly fill a gap in the palaeoherpetofaunal record of the Eastern Mediterranean.

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An assemblage of the early Miocene Sayimys giganteus (Ctenodactylinae, Rodentia) from its type locality Keseköy, and smaller assemblages of Yapıntı and Horlak (Anatolia, Turkey) are described. Almost all Sayimys species are known from small collections of isolated cheek teeth. The very large assemblage from Keseköy is of special interest, because it allows the study of the intra-specific variation of dental morphology: size, the morphological changes through wear and the criteria for recognition of the tooth position of molars. The results have been used to review the formally named Sayimys species and to evaluate the dental features used to define the species. The review of the early and middle Miocene succession of Sayimys in the Siwaliks (Pakistan) resulted in the resurrection of S. minor; S. baskini is considered to be a junior synonym of S. minor. S. sivalensis and S. obliquidens are nomina dubia, and restricted to their holotypes, S. hintoni n. sp. is established for medium-sized Sayimys from the Kamlial, lower Chinji and Manchar Formations and S. chinjiensis is resurrected for Sayimys from the upper Chinji and Nagri Formations. It is suggested that the middle Miocene species Sayimys intermedius and S. assarrarensis from Saudi Arabia are synonymous.

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Remains of platacanthomyids from Leilao, a late Miocene hominoid locality in Yuanmou, Yunnan, China are described. Five species in three genera are recognized: Neocometes sp., Platacanthomys dianensis QIU, 1989, Typhlomys aff. T. primitivus QIU, 1989, T. hipparionum QIU, 1989 and T. storchi n. sp. Leilao is the only locality that produces fossils of all three known genera of the family Platacanthomyidae. The new species T. storchi is characterized by its huge dimensions and continuous endoloph(id)s and ectoloph(id)s incorporated with the anteroloph(id)s and posteroloph(id)s to encircle the occlusal surface. That the genus Neocometes from southeastern Asia shows a tendency of forming an ectoloph on the upper molars and an endolophid on the lower molars indicates that the South China species probably represents an evolutionary lineage independent from that of European Neocometes. Both P. dianensis and T. aff. T. primitivus exhibit more derived dental morphology than the related species from Shihuiba of Lufeng, suggesting a younger age of the Leilao Fauna, which is incompatible with the conclusion drawn from the studies of other groups of small mammals.

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New Amphicyonidae fossil remains from the early Miocene site of Tuchořice (the Czech Republic) confirm the presence of a new Thaumastocyoninae taxon: Peignecyon felinoides n. gen. et n. sp. It is characterized by a peculiar combination of plesiomorphic and derived morphological traits. The new genus can be defined by a long and sharp mandible diastema, loss of mesial premolars (p2–p3), p4 with an inclined distally high main cuspid, moderate sectorial carnassial teeth, m1 with relict metaconid, and talonid and trigonid of similar width, and reduced M2 and m2. In the phylogenetic analysis the Thaumastocyoninae form a monophyletic group characterized by the start of the m2/M2 reduction, still moderate in Crassidia intermedia (VON MEYER, 1849), but remarkable in the other species of the clade. Peignecyon felinoides already shows the advanced features defining the Thaumastocyoninae, and constitutes the sister group of the most specialized genera Tomocyon VIRET, 1929b and Thaumastocyon STEHLIN et HELBING, 1925. Consequently, it can be considered an excellent link between this group and the more primitive members of the tribe Ysengrini (Ysengrinia GINSBURG, 1966 and Crassidia HEIZMANN et KORDIKOVA, 2000). Peignecyon felinoides shows that the trend towards hypercarnivory had already emerged in the European early Miocene fauna, thus helping to understand the complex evolution of the Amphicyonidae during the Miocene.

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Fossil bats are described from the karstic deposits of the Erkertshofen 1, Erkertshofen 2 and Petersbuch 2 sites in eastern Bavaria, southern Germany (MN 4). Fossils are discussed with regard to taxonomic, stratigraphic and palaeoecologic significance. The rich fossil material represents at least 12 different bat species belonging to Megadermatidae, Rhinolophidae and Vespertilionidae. The syntopic appearance of four different rhinolophids is demonstrated for the first time for the Neogene bat assemblages of Europe. The remains of Rhinolophidae and Vespertilionidae are the most numerous, of which the proportion of typically early Miocene species Rhinolophus aff. lemanensis, R. dehmi, Hanakia agadjaniani and Miostrellus cf. petersbuchensis are significant. However, there are also remains of R. cf. delphinensis, M. cf. noctuloides, Plecotus cf. atavus and H. aff. antiquus, which are characteristic of the younger middle Miocene faunas of Central Europe. Analysis of the composition of the bat fauna has allowed biostratigraphic correlation of the studied faunas to be estimated at a number of other early Miocene localities in Europe.

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A large-sized species of Parasorex is common in the MN 13 mammal assemblages from the uppermost Messinian sandy-marly fissure fillings within the Gessoso Solfifera Formation at Brisighella (Northern Apennine). This erinaceid has been classified as Galerix sp. in the first papers on the Brisighella fauna. Later, it was described in detail in an unpublished Ph.D. dissertation by Fanfani (1999), who referred it to Galerix depereti. Van den Hoek Ostende (2001) included G. depereti in the genus Parasorex, Parasorex depereti has been described by Crochet (1986) on scarce material from a few Early Pliocene (MN 14–15) localities of southern France and Spain. Parasorex cf. depereti has been reported from the Early Pliocene fauna of Capo Mannu (Mandriola, Sardinia; Furió and Angelone 2010). The species seems actually distributed in south-western Europe, where it represents the youngest occurrence of the genus Parasorex. The very abundant sample of P. depereti from fissure filling BRS 25 enables a more accurate and comprehensive description of the species. It also permits inspection of the mesial elements of the dentition, which were lacking in the material examined by Crochet (1986). The systematic position of the species has been revisited and compared with those of other Galericini of the Parasorex group.

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This paper clarifies the identification of the three species referred by Tobien (1954) to the genus Masillamys from Messel, and more specifically provides a revision of their diagnosis and differential dental features, using an updated terminology. Based on specimens better preserved than the holotype (M. beegeri), it appears that this genus had an infraorbital area more hystricomorphous than sciuromorphous. As the genus shares dental features – like a long oblique postprotocristid or the occurrence of a metalophid I on the lower molars, the relatively well-developed hypocone on the upper molars, as well as hystricomorphy –, notably with Hartenbergeromys and Pantrogna, Masillamys is here included among the basal Theridomorpha.

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Cranial skeletal material of the Eocene palaeanodont Metacheiromys marshi was examined using high-resolution CT scans. The present study represents the first time that CT scans have been conducted on skulls of this extinct fossorial mammal. The bony osteology of the auditory region is described in detail, including the ectotympanic and entotympanic, the petrosal in both tympanic and endocranial views, and the middle ear ossicles. The results of this investigation confirm a number of derived resemblances between palaeanodonts and xenarthrans, including a large entotympanic element in the medial wall of the auditory bulla, the presence of an anteroventral process of the tegmen tympani, and a posttemporal canal. However, the present study also provides novel derived auditory features linking palaeanodonts and pangolins, consistent with current understanding of palaeanodont phylogenetic relationships, including the absence of an ectotympanic styliform process, a posterolaterally oriented aperture to the cochlear fossula, and a convex mallear head / concave incudal head. Several autapomorphic features characterizing the auditory osteology of Metacheiromys are also noted. The presence of a large, spherical mallear head, and of a capacious tympanic cavity extended into sinuses in surrounding bones, likely represent adaptations for fossoriality, consistent with palaeobiological inferences drawn from the postcranial anatomy of Metacheiromys.

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An upper “triconodont” molar from the Late Jurassic (late Kimmeridgian) of the Langenberg Quarry in northern Germany is attributed to Storchodon cingulatus gen. et sp. nov. of Morganucodonta. The molar is characterized by continuous lingual and buccal cingula, and a relatively large, buccally-shifted cusp D which is not integrated in the buccal cingulum. With a length of 3.07 mm, the tooth is less than 10 % smaller than the lower holotype molar of Paceyodon davidi, the largest known morganucodontan. The Langenberg morganucodontan possibly represents an example of insular gigantism on an adjacent paleoisland.

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To the article: Friis, E. M., Crane, P. R., Pedersen, K. R. (2019): The Early Cretaceous mesofossil flora of Torres Vedras (NE of Forte da Forca), Portugal: a palaeofloristic analysis of an early angiosperm community. – Fossil Imprint, 75(2): 153–257.