The Tasmanian tiger or thylacine (Thylacinus cynocephalus) was an iconic Australian marsupial predator that was hunted to extinction in the early 1900s. Despite sharing striking similarities with canids, they failed to evolve many of the specialized anatomical features that characterize carnivorous placental mammals. These evolutionary limitations are thought to arise from functional constraints associated with the marsupial mode of reproduction, in which otherwise highly altricial young use their well-developed forelimbs to climb to the pouch and mouth to suckle. Here we present the first three-dimensional digital developmental series of the thylacine throughout its pouch life using X-ray computed tomography on all known ethanol-preserved specimens. Based on detailed skeletal measurements, we refine the species growth curve to improve age estimates for the individuals. Comparison of allometric growth trends in the appendicular skeleton (fore- and hindlimbs) with that of other placental and marsupial mammals revealed that despite their unique adult morphologies, thylacines retained a generalized early marsupial ontogeny. Our approach also revealed mislabelled specimens that possessed large epipubic bones (vestigial in thylacine) and differing vertebral numbers. All of our generated CT models are publicly available, preserving their developmental morphology and providing a novel digital resource for future studies of this unique marsupial.

Wood mice of the genus Apodemus are an essential component of small mammal communities throughout Europe. Molecular data suggest the postglacial colonization of current ranges from south European glacial refugia, different in particular species. Yet, details on the course of colonization and Holocene history of particular species are not available, partly because of a lack of reliable criteria for species identification in the fossil record. Using a sample of extant species, we analyzed variation patterns and between-species overlaps for a large set of metric and non-metric dental variables and established the criteria enabling the reliable species identification of fragmentary fossil material. The corresponding biometrical analyses were undertaken with fossil material of the genus (2528 items, 747 MNI) from 22 continuous sedimentary series in the Czech Republic and Slovakia, from LGM to Recent. In Central Europe, the genus is invariantly absent in LGM assemblages but regularly appears during the Late Vistulian. All the earliest records belong to A. flavicollis, the species clearly predominating in the fossil record until the Late Holocene. A. uralensis accompanied it in all regions until the late Boreal when disappeared from the fossil record (except for Pannonia). A few items identified as A. sylvaticus had already appeared in the early Holocene assemblages, first in the western part of the region, yet the regular appearance of the species is mostly in the post-Neolithic age. A. agrarius appeared sparsely from the Boreal with a maximum frequency during the post-Neolithic period. The results conform well to the picture suggested by molecular phylogeography but demonstrate considerable differences among particular species in dynamic of the range colonization. Further details concerning Holocene paleobiogeography of individual species in the medium latitude Europe are discussed.

Molecular phylogeography suggests that Micromys minutus, the sole extant species of the genus, colonized its extensive range quite recently, during the Late Pleistocene-Holocene period. Rich Pliocene and Pleistocene fossil records both from Europe and China suggest rather continuous and gradual in situ phenotype rearrangements from the Pliocene to the Recent periods. To elucidate the discrepancy we reexamined a considerable part of the European fossil record of the genus (14 sites from MN15 to Q3, 0.4–4.2 Ma, including the type series of M. preaminutus from MN15 Csarnóta 2), analyzed them with the aid of detailed morphometric comparisons, and concluded that: (a) The European Pliocene form, M. praeminutus, differs significantly from the extant species; (b) it exhibits a broad phenotypic variation covering the presumptive diagnostic characters of MN16 M. caesaris; (c) despite having smaller dimensions, the Early and Middle Pleistocene forms (MN17-Q3, 2.6–0.4 Ma) seem to be closer to M. praeminutus than to the extant species; (d) the extinction of M. praeminutus during Q3 and the re-occupation of its niche by the recent expansion of M. minutus from E-European – C Asiatic sources (suggested by phylogeographic hypotheses) cannot be excluded. Discussing interpretations of the phylogenetic past of the genus we emphasize the distinct history of the West Palearctic clade (Late Miocene-Early Pleistocene) terminating with M. praeminutus and the East Asiatic clade (chalceus, tedfordi, minutus), and the possible identity of the Western clade with the Late Miocene genus Parapodemus.

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Abstract The extant species of the genus Apodemus represent the most common small mammals of Central Europe. Unfortunately, their phylogenetic past is only poorly known. With the aid of detailed biometric analyses we tried to identify the first appearance of the phenotypic patterns characterizing the extant populations. We examined dental material of Apodemus from 53 community samples from the territory of the Czech Republic and Slovakia dated from the early Villanyian (MN 16/17) to the late Middle Pleistocene (Q 3) with particular respect to their correspondence with the morphometric characteristics of the extant species. While the Toringian (Q 3) interglacial samples invariably include forms identical with the extant taxa A. flavicollis, A. sylvaticus and supposedly A. uralensis (including the items corresponding to A. maastrichtiensis), the samples of Early Pleistocene age (MN 17 – Q 2) exhibited clear differences in the variation pattern which results in questioning the possibility of their co-identification with the respective extant species. In most instances they varied within the limits in resembling A. sylvaticus but exceeded its variation ranges in some non-metric characters. Regarding serious doubts on real taxonomic status of other named fossil species we propose to denote these Plio-Pleistocene sylvaticus-like phenotypes provisionally with the prior name A. atavus Heller, 1936.