First osteohistological and histotaphonomic approach of Equus occidentalis Leidy, 1865 (Mammalia, Equidae) from the late Pleistocene of Rancho La Brea (California, USA)

Rancho La Brea (California, USA) is the most emblematic Quaternary fossiliferous locality in the world, since both the high number and diversity of the specimens recovered and their excellent preservational quality. In the last decades, paleobiological and paleoecological knowledge of the different groups of mammals from this site has increased notably; however, some aspects have not yet been inquired or there is little information. In this work we provide information on one of the most abundant mammals of this site, the equid Equus occidentalis, based on the study, from osteohistological and histotaphonomic perspectives, of thin sections of different limb bones. On the one hand, from an osteohistological viewpoint, we observe that the distribution and characterization of bone tissues in the different skeletal elements are, in general lines, similar to that mentioned for other extant and extinct equids. Cyclical growth marks allowed us to propose preliminary skeletochronological interpretations. On the other hand, from a taphonomic viewpoint, we note that all the samples reflect an excellent preservation of the bone microstructure, slightly altered by different pre- and post-burial processes. The variations recorded evidence different taphonomic history and preservation conditions among pits. This is the first study including fossil material from Rancho La Brea exclusively based on the analysis of the bone microstructure features.

Review of the current objectives and modern approaches to studying extant and extinct shrews (Soricomorpha: Soricidae) investigation: the origin of the modern subfamilies and diversity of Crocidosoricinae

The current review is devoted to topical issues of the origin of modern shrew’ subfamilies Soricinae Fischer, 1817 and Crocidurinae Milne-Edwards, 1868 (Soricomorpha: Soricidae), as well as to the consideration of the possibility of using morphological analysis to search for ancestral groups of modern soricine and crocidurine shrews within the extinct subfamily Crocidosoricinae Reumer, 1987. The data on the taxonomic composition of the Crocidosoricinae subfamily and the preliminary results of a comparative analysis of the Neogene shrews Miosorex Kretzoi, 1959 and Shargainosorex Zazhigin et Voyta, 2018 (Crocidosoricinae) shrews with the representatives of Soricinae and Crocidurinae according to the shape of the first upper molar M1 are presented as an example to substantiate urgent problems in this area. The problem of relations of molecular and morphological data are discussed using individual groups as examples. Modern approaches of geometric morphometry are described, which together with phylogenetic data allow assessing the expression of the phylogenetic signal when analysing the shape of morphological structures. Possible prospects for the practical application of these approaches for the study of fossil material and the search for ancestral lineages of modern shrews among Crocidosoricinae are described.

Ethics, law, and politics in palaeontological research: The case of Myanmar amber

Fossil material in Myanmar amber can provide important insights into mid-Cretaceous forest ecosystems, but has been receiving increased international attention due to reported links between amber mining and the ongoing humanitarian crisis in northern Myanmar, as well as the legal issues associated with its exportation. Here, we conduct a bibliometric analysis of Myanmar amber publications (1990–2021) and demonstrate how research interest in Myanmar amber is explicitly linked to major political, legal, and economic changes. An analysis of the authorship networks for publications on amber inclusions reveals how current research practices have excluded Myanmar researchers from the field. In addition, the international trade of Myanmar amber with fossil inclusions falls into a legal ‘grey-zone’ which continues to be exploited. This case study vividly demonstrates that systemic changes, alongside an increased awareness of inequitable research practices amongst the broader scientific and allied communities, are urgently needed to curb illegal practices in palaeontology.

Revised Description of the Early Permian Recumbirostran “Microsaur” Nannaroter mckinziei Based on New Fossil Material and Computed Tomographic Data

The early Permian Richards Spur locality of Oklahoma has produced abundant material of numerous terrestrial fossil tetrapods, including various “microsaurs,” several of which are considered to belong to the clade Recumbirostra. We present a new partial skull of the recumbirostran “microsaur” Nannaroter mckinziei; through computed tomography (CT) analysis of both this new specimen and the holotype, we provide an updated description of the taxon. This new description provides novel information regarding several regions that could not be examined previously due to either being absent in the holotype or difficult to access. This includes missing and obscured aspects of the skull roof, braincase, lower jaw, and the palatal region. Furthermore, the new information obtained from this description was used to update phylogenetic character codings of Nannaroter, and a revised phylogenetic analysis was conducted. The results of this updated analysis are congruent with those of other recent phylogenetic analyses of recumbirostran “microsaurs.” This new information adds to the ever-growing body of early tetrapod CT data, which has been, and will continue to be, important in revealing details regarding early tetrapod anatomy, interrelationships, paleoecology, and evolution.

A new species of dog from the Early Pleistocene site of Venta Micena (Orce, Baza Basin, Spain)

The site of Venta Micena (Orce, Spain), c. 1.6 Ma, preserves one the best paleontological records of the early Pleistocene large mammals fauna in Europe. Here we describe the specimens of the genus Canis Linnaeus, 1758 in the context of the late Villafranchian and Epivillafranchian fossil dogs from Eurasia. Anatomical and metric data suggest that the Venta Micena Canis form differs from the classical records of Canis etruscus Forsyth Major, 1877 and Canis arnensis Del Campana, 1913, and that it forms part of the younger Canis mosbachensis Soergel (1925) lineage, also recorded in two slightly younger sites of the Orce site complex, Barranco León and Fuente Nueva-3, dated to c. 1.4 Ma. The anatomy of the Venta Micena fossil material shows features that resemble the Canis forms from the Caucasian site of Dmanisi, dated to 1.8 Ma, and Canis ex gr. C. mosbachensis. Nevertheless, dental peculiarities support the creation of a new chrono-species, Canis orcensis n. sp., from the town of Orce. Morphological and paleoecological data suggest that this species probably consumed more vertebrate flesh than other similar sized early Pleistocene canids (i.e., a trend to hypercarnivory), which had more omnivorous dietary habits.

Geology and taphonomy of a unique tyrannosaurid bonebed from the upper Campanian Kaiparowits Formation of southern Utah: implications for tyrannosaurid gregariousness

Tyrannosaurids are hypothesized to be gregarious, possibly parasocial carnivores engaging in cooperative hunting and extended parental care. A tyrannosaurid (cf. Teratophoneus curriei) bonebed in the late Campanian age Kaiparowits Formation of southern Utah, nicknamed the Rainbows and Unicorns Quarry (RUQ), provides the first opportunity to investigate possible tyrannosaurid gregariousness in a taxon unique to southern Laramidia. Analyses of the site’s sedimentology, fauna, flora, stable isotopes, rare earth elements (REE), charcoal content and taphonomy suggest a complex history starting with the deaths and transport of tyrannosaurids into a peri-fluvial, low-energy lacustrine setting. Isotopic and REE analyses of the fossil material yields a relatively homogeneous signature indicating the assemblage was derived from the same source and represents a fauna living in a single ecospace. Subsequent drying of the lake and fluctuating water tables simultaneously overprinted the bones with pedogenic carbonate and structurally weakened them through wet-dry cycling. Abundant charcoal recovered from the primary bone layer indicate a low temperature fire played a role in the site history, possibly triggering an avulsion that exhumed and reburied skeletal material on the margin of a new channel with minimal transport. Possible causes of mortality and concentration of the tyrannosaurids include cyanobacterial toxicosis, fire, and flooding, the latter being the preferred hypothesis. Comparisons of the RUQ site with other North American tyrannosaur bonebeds (Dry Island-Alberta; Daspletosaurus horneri-Montana) suggest all formed through similar processes. Combined with ichnological evidence, these tyrannosaur mass-burial sites could be part of an emerging pattern throughout Laramidia reflecting innate tyrannosaurid behavior such as habitual gregariousness.

Pseudostaurosira crateri sp. nov. (Fragilariaceae, Bacillariophyta), a new small araphid, fossil diatom species from the Pleistocene (Atlantic Forest, Brazil)

Pseudostaurosira crateri sp. nov. is described from fossil material analyzed from a Quaternary sediment core retrieved from the Colônia basin (located in the Brazilian Coastal Plain, Atlantic Forest, São Paulo Metropolitan Region). Light and scanning electron microscopy revealed its morphology and enabled its comparison with morphologically similar species from European and African rivers and lakes. The new species features wide and short vimines, a particular characteristic of the genus Pseudostaurosira, in addition to many other exclusive features that distinguish it from any other species in the genus reported to date. Some of these characteristics are: (i) apical pore fields composed of small poroids placed within cavernous troughs carved deep into the valve, (ii) absence of blisters or depositions along the valve mantle edge, (iii) small-sized valve, (iv) presence of incipient or rudimentary spines located on raised virgae at the valve face/mantle junction, and (v) internal accumulations of siliceous material on the volae appearing as concentric discs partially occluding the depression into which the areolae open internally. We further discuss the morphological features of similar species ascribed to the genera Pseudostaurosira, Pseudostaurosiropsis, Staurosirella, Frankophila, and Popovskayella based on literature information. Finally, this study contributes to the knowledge on diatom diversity and its biogeography, especially those from tropical regions, in addition to providing a taxonomical basis for its use as biological markers for paleoenvironmental reconstruction.