Organically-preserved multicellular eukaryote from the early Ediacaran Nyborg Formation, Arctic Norway.

Eukaryotic multicellularity originated in the Mesoproterozoic Era and evolved multiple times since, yet early multicellular fossils are scarce until the terminal Neoproterozoic and often restricted to cases of exceptional preservation. Here we describe unusual organically-preserved fossils from mudrocks, that provide support for the presence of organisms with differentiated cells (potentially an epithelial layer) in the late Neoproterozoic. Cyathinema digermulense gen. et sp. nov. from the Nyborg Formation, Vestertana Group, Digermulen Peninsula in Arctic Norway, is a new carbonaceous organ-taxon which consists of stacked tubes with cup-shaped ends. It represents parts of a larger organism (multicellular eukaryote or a colony), likely with greater preservation potential than its other elements. Arrangement of open-ended tubes invites comparison with cells of an epithelial layer present in a variety of eukaryotic clades. This tissue may have benefitted the organism in: avoiding overgrowth, limiting fouling, reproduction, or water filtration. C. digermulense shares characteristics with extant and fossil groups including red algae and their fossils, demosponge larvae and putative sponge fossils, colonial protists, and nematophytes. Regardless of its precise affinity, C. digermulense was a complex and likely benthic marine eukaryote exhibiting cellular differentiation, and a rare occurrence of early multicellularity outside of Konservat-Lagerstätten.

Computed tomography examination of the face of Macaca anderssoni (Early Pleistocene, Henan, northern China): Implications for the biogeographic history of Asian macaques.

Macaca anderssoni, a fossil macaque from the Early Pleistocene of northern China, has attracted much attention from researchers in terms of reconstructing the biogeographic history of Asian macaques, while its phylogenetic position remains debatable. In the present study, we evaluated patterns of variation in external and internal craniofacial morphologies among four phylogenetic groups of extant macaques (the fascicularis, sinica, silenus, and sylvanus groups), using computed tomography and multivariate analyses. We also reassessed the holotype of M. anderssoni, a partial cranium preserving the face and palate, to evaluate the phylogenetic group to which M. anderssoni is most closely related. Facial elongation was found to be significantly influenced by size. The particular combination of some allometric and non-allometric shape components was found to reflect phylogenetic relationships; however, these features of M. anderssoni fall intermediate among the four phylogenetic groups, with no typical similarities to any one group. The variations in nasal cavity shape were found to reflect phylogenetic relationships but those of the maxillary sinus did not. Macaca anderssoni has a nasal cavity that is laterally expanded anteriorly and constricted posteriorly, a unique morphology among macaques and shared only with larger members of the sinica group. This unique feature is considered to be a derived condition among macaques, suggesting that M. anderssoni is phylogenetically related to the sinica group (especially M. assamensis, M. thibetana, and M. arctoides) and that the populations of the sinica group were distributed in northern China during the Early Pleistocene. Currently, the populations of the sinica group are not distributed in northern East Asia, while those of the fascicularis group are. Thus, probably due to climatic deterioration in the Late Pleistocene, the former lineage has retreated southward or has become extinct in this region, being replaced by the latter lineage.