We reappraise the type and only known specimen of “Brachyodus” japonicus Matsumoto in Tokunaga, which is an anthracothere (Mammalia, Cetartiodactyla) discovered from the Oligocene Nakazato Formation of the Sasebo Group (Japan) in the early 20th Century. The specimen is a mandibular fragment with p4-m2 and is now housed in the National Museum of Japanese History (Sakura, Japan). The geologic age of the species is set at the middle part of the Oligocene on the basis of fission-track datings. Compared to Brachyodus, the present specimen is much smaller in size and has a more mesiodistally elongated p4, indicating that it is not referable to Brachyodus. Instead, it is comparable in dental morphology and size to Elomeryx in having moderately selenodont molars and a mesiodistally elongated p4 with a distinct paraconid and metaconid. Compared to other species of Elomeryx, it is unique in that p4 has a wider talonid and a better developed distobuccal cingulum, suggesting that “Brachyodus” japonicus is a distinct species of the genus Elomeryx. Therefore, we rename this species Elomeryx japonicus. Reconsidered as such, the specimen yields significant information concerning the paleobiogeography of the poorly understood East Asian Oligocene anthracotheres and the origination and early evolution of “advanced bothriodontines” on different landmasses.

The genus Ambolus was proposed by Ikeya et al. in 1998. Two Ambolus species, A. pumilus and A. coniunctus, from Australia have been described thus far. Here we describe four new Ambolus species, A. swansoni sp. nov., A. stewartus sp. nov., A. delicatulus sp. nov. and A. cavallius sp. nov. from New Zealand. To clarify the stability of their carapace characters, we focused our attention on the ontogenetic differentiation of the pore pattern and the shell ornamentation of the above six species. Based on these findings we demonstrated that A. delicatulus sp. nov. differed from the other five species at the A-2 moult stage. Ontogenetic differentiation of the shell ornamentation suggests that although the two Australian species are closely related and the four New Zealand species also resemble each other, these species differ in certain aspects.

Despite their small sizes (ca. 2–120 mm), chaetognaths, or arrow worms, are the most important planktonic carnivorous predators both in terms of biomass and abundance, and they represent the second most important component of modern marine ecosystems. The fossil record of chaetognaths is patchy and only consists of five Paleozoic species, which are still the object of a vigorous debate due to their unclear state of preservation.

The two main diagnostic characters for the assignment of a fossil to chaetognaths are the presence of caudal and lateral fins as well as the existence of grasping spines on both sides of the head. However, among the five putative chaetognaths from the Paleozoic, none shows simultaneously these two characters. Our new experiments on the decay process of benthic chaetognaths Paraspadella gotoi demonstrate the differential alteration of various diagnostic characters through time. Six individuals were dissected and their decay was checked regularly in separate dishes containing seawater during 72 hours. We could identify four successive stages of decay corresponding to a gradual attack of the bodies by both micro-zooplankton (ciliates) and bacteria, and we could successfully correlate them to morphologies observed in the fossil record. In conclusion, the two diagnostic characters previously used for assigning fossil chaetognaths (fins and spines) appeared insufficient, and the five fossil specimens that have been assigned to chaetognaths are systematically uncertain because they are strongly influenced by pre-diagenetic decay.

The fossil records of the Northern Caucasus (southwestern Russia) provide an exceptional opportunity to reveal the evolution of brachiopods during the Callovian-Albian time interval and to evaluate the regional evidence for a Jurassic/Cretaceous mass extinction. Stratigraphic ranges of 119 species, 52 genera, 25 families, 13 superfamilies, and 2 orders of brachiopods are considered to document the main patterns of their diversity dynamics. The total number of taxa was high in the Callovian-Oxfordian, then dropped in the Kimmeridgian, increased again in the Tithonian, decreased significantly in the Berriasian, and remained relatively low until the end of the Early Cretaceous except for a minor peak in the Barremian. Species, genera, families, and superfamilies of brachiopods declined remarkably in the Northern Caucasus in the Berriasian, which is regional evidence for a Jurassic/Cretaceous mass extinction. Both an acceleration in disappearance rate and a drop in appearance rate contributed to this collapse. Recovery began in the Valanginian-Hauterivian, but it was not completed at the level of species. Transgressions/regressions, growth of the carbonate platform, a salinity crisis, and oxygen depletion were important controls on the brachiopod diversity dynamics in the Northern Caucasus. A regressive episode around the Jurassic-Cretaceous transition seems to be a plausible cause of the relevant brachiopod decline. A comparison of changes in the total number of brachiopod taxa between the Neo-Tethys Ocean and the Alpine Tethys Ocean shows some difference, but both domains provide evidence for a Jurassic/Cretaceous mass extinction, which was less severe in the Swiss Alps and the Jura Mountains (Alpine Tethys) than in the Northern Caucasus (Neo-Tethys).

This study describes a brachiopod fauna, consisting of 12 species in 10 genera, from the Upper Permian (Wuchiapingian) Otori Formation of Okutadami, Joetsu Belt, Central Japan. The fauna includes a new species, Kochiproductus okutadamiensis. The Okutadami fauna, a Boreal fauna lacking Tethyan or Panthalassan elements, is the northernmost fauna of the Japanese Permian. Palaeobiogeographical data derived from the Okutadami fauna suggest that Okutadami was located at the northernmost area of Proto-Japan in the Late Permian. This conclusion supports a strike-slip tectonic model that describes large-scale sinistral strike-slip movement along the Tanakura Tectonic Line (TTL)-Median Tectonic Line (MTL) from the late Early Cretaceous to Palaeogene.