Bone histology has proved to be a valuable tool to obtain information about the palaeobiology and early taphonomic history of fossil vertebrates. However, there are still many extinct taxa for which bone histology studies could be applied to deduce information about their life history and early diagenetic changes. Here, we partially fill this gap by studying bone microstructure and bone micropreservation in the third metapodia of Hipparion and Equus recovered from several Miocene, Pliocene, and Pleistocene localities in Turkey. Our histological analysis reveals that most of the bone cortices under study are composed of a well-vascularized fibrolamellar bone. Furthermore, we record the presence of compact coarse cancellous bone in a Hipparion metatarsal. In terms of histological preservation, our findings provide supporting evidence that differences in moisture, oxygen, and/or temperature during fossilisation at the different localities impacted the quality of bone preservation. Bacterial bioerosion was extensive in the samples, and we also identified a specific tunnelling morphology that we tentatively consider to be damage caused by freshwater algae. The present study provides novel insight into the palaeobiology and early diagenetic history of extinct horses from Turkey and sets the stage for further research in this area.

Cremated and unburnt human remains have been recovered from a variety of British Bronze and earliest Iron Age archaeological contexts (c. 2500–600 BC). Chronological modelling of 189 new and extant radiocarbon dates from a selection of these deposits provides evidence for the curation of human remains for an average of two generations following death, while histological analysis of bone samples indicates mortuary treatment involving both excarnation and the exhumation of primary burials. Curated bones came from people who had been alive within living or cultural memory, and their power probably derived from relationships between the living and the dead.

Intentional mummification is a practice usually associated with early Egyptian or Peruvian societies, but new evidence suggests that it may also have been widespread in prehistoric Britain, and possibly in Europe more generally. Following the discovery of mummified Bronze Age skeletons at the site of Cladh Hallan in the Western Isles of Scotland, a method of analysis has been developed that can consistently identify previously mummified skeletons. The results demonstrate that Bronze Age populations throughout Britain practised mummification on a proportion of their dead, although the criteria for selection are not yet certain.

Ichthyosaurs, a lineage of extinct Mesozoic marine reptiles, have garnered attention in both the palaeontological and developmental literature for the unique limb morphology seen in derived genera. These morphologies include an increase in the number of phalanges per digit (hyperphalangy) and in the number of digits (hyperdactyly), but most interestingly also a shift in element identity. Elements distal to the stylopodium acquire characteristics of mesopodial elements, such as a rounded, nodular shape and a loss of perichondral bone on the anterior and posterior surfaces. Here, we examine numerous aspects of the loss of proximodistal identity in ichthyosaur limbs including phylogenetic progression of the loss of perichondral bone, histology and microstructure of the elements retaining perichondral bone in derived taxa, and correlates of intraspecific variation in degree of perichondral bone reduction in a derived ichthyosaur, Stenopterygius quadriscissus. Results show that loss of limb element identity occurred progressively over ichthyosaurian evolution, and the notches seen on the anterior surface of limb elements in derived ichthyosaurs are homologous to the long bone shafts in terrestrial tetrapods. Variation in the number of notches in S. quadriscissus can best be explained through delayed ossification of the anterior perichondrium, indicating a heterochronic component to the loss of identity. We propose a developmental mechanism – gradual expansion of the polyalanine region of HoxD13 over ichthyosaurian evolution – to explain the progressive loss of limb regionalization as well as the heterochronic delay in perichondral ossification.

Psephophorus polygonus Meyer, 1847, the first fossil leatherback turtle to be named, was described on the basis of shell ossicles from the middle Miocene (MN6–7/8?) of Slovakia. The whereabouts of this material is uncertain but a slab on display at the Naturhistorisches Museum Wien is considered the neotype. We rediscovered further type locality ossicles in four European institutions, re-evaluated their gross morphology and described for the first time their microstructure by comparing them with Dermochelys coriacea, the only living dermochelyid turtle. The gross morphology is congruent with that already described for P. polygonus, but with two significant exceptions: the ridged ossicles of P. polygonus may have a distinctly concave ventral surface as well as a tectiform shape in cross-section. They do not develop the external keel typical of many ossicles of D. coriacea. Both ridged and non-ridged ossicles of P. polygonus are characterized by compact diploe structures with an internal cortex consisting of a coarse fibrous meshwork, whereas the proportionately thinner ossicles of D. coriacea tend to lose the internal cortex, and thus their diploe, during ontogeny. The ossicles of both P. polygonus and D. coriacea differ from those of other lineages of amniotes whose carapace is composed of polygonal ossicles or platelets, in having growth centres situated at the plate centres just interior to the external bone surface and not within the cancellous core or closer to the internal compact layer. The new diagnosis of P. polygonus allows us to preliminarily re-evaluate the taxonomy of some of the Psephophorus-like species. Despite some macro- and micromorphological differences, it seems likely that Psephophorus was as cosmopolitan as extant Dermochelys and had a broadly similar ecology, with a possible difference concerning the dive depth.