Early anthropoid femora reveal divergent adaptive trajectories in catarrhine hind-limb evolution

The divergence of crown catarrhines—i.e., the split of cercopithecoids (Old World monkeys) from hominoids (apes and humans)—is a poorly understood phase in our shared evolutionary history with other primates. The two groups differ in the anatomy of the hip joint, a pattern that has been linked to their locomotor strategies: relatively restricted motion in cercopithecoids vs. more eclectic movements in hominoids. Here we take advantage of the first well-preserved proximal femur of the early Oligocene stem catarrhine Aegyptopithecus to investigate the evolution of this anatomical region using 3D morphometric and phylogenetically-informed evolutionary analyses. Our analyses reveal that cercopithecoids and hominoids have undergone divergent evolutionary transformations of the proximal femur from a similar ancestral morphology that is not seen in any living anthropoid, but is preserved in Aegyptopithecus, stem platyrrhines, and stem cercopithecoids. These results highlight the relevance of fossil evidence for illuminating key adaptive shifts in primate evolution

The southernmost record of a Neuryurini Hoffstetter, 1958 (Mammalia, Xenarthra, Glyptodontidae)

Fil: González Ruiz, Laureano Raúl. Universidad Nacional de La Patagonia; ArgentinaFil: Zurita, Alfredo Eduardo. Centro de Ecologia Aplicada del Litoral (CECOAL). Universidad Nacional del Nordeste; CorrientesFil: Fleagle, John G.. Stony Brook University State University of New York. Department of Anatomical Sciences. Stony Brook United States; ArgentinaFil: Scillato-Yané, Gustavo Juan. División Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Dozo, María Teresa. Laboratorio de Paleontología, Centro Nacional Patagónico CONICET, Blvd. Alte. Guillermo Browns/n, 9120 Puerto Madryn, Chubut, ArgentinaFil: Zamorano, Martín. División Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

The evolution of mammalian brain size

Relative brain size has long been considered a reflection of cognitive capacities and has played a fundamental role in developing core theories in the life sciences. Yet, the notion that relative brain size validly represents selection on brain size relies on the untested assumptions that brain-body allometry is restrained to a stable scaling relationship across species and that any deviation from this slope is due to selection on brain size. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often primarily characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved large relative brain sizes by highly divergent paths. These findings prompt a reevaluation of the traditional paradigm of relative brain size and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size

Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology

The best European locality for complete Eocene mammal skeletons is Grube Messel, near Darmstadt, Germany. Although the site was surrounded by a para-tropical rain forest in the Eocene, primates are remarkably rare there, and only eight fragmentary specimens were known until now. Messel has now yielded a full primate skeleton. The specimen has an unusual history: it was privately collected and sold in two parts, with only the lesser part previously known. The second part, which has just come to light, shows the skeleton to be the most complete primate known in the fossil record.We describe the morphology and investigate the paleobiology of the skeleton. The specimen is described as Darwinius masillae n.gen. n.sp. belonging to the Cercamoniinae. Because the skeleton is lightly crushed and bones cannot be handled individually, imaging studies are of particular importance. Skull radiography shows a host of teeth developing within the juvenile face. Investigation of growth and proportion suggest that the individual was a weaned and independent-feeding female that died in her first year of life, and might have attained a body weight of 650-900 g had she lived to adulthood. She was an agile, nail-bearing, generalized arboreal quadruped living above the floor of the Messel rain forest.Darwinius masillae represents the most complete fossil primate ever found, including both skeleton, soft body outline and contents of the digestive tract. Study of all these features allows a fairly complete reconstruction of life history, locomotion, and diet. Any future study of Eocene-Oligocene primates should benefit from information preserved in the Darwinius holotype. Of particular importance to phylogenetic studies, the absence of a toilet claw and a toothcomb demonstrates that Darwinius masillae is not simply a fossil lemur, but part of a larger group of primates, Adapoidea, representative of the early haplorhine diversification

New infant cranium from the African Miocene sheds light on ape evolution

The evolutionary history of extant hominoids (humans and apes) remains poorly understood. The African fossil record during the crucial time period, the Miocene epoch, largely comprises isolated jaws and teeth, and little is known about ape cranial evolution. Here we report on the, to our knowledge, most complete fossil ape cranium yet described, recovered from the 13 million-year-old Middle Miocene site of Napudet, Kenya. The infant specimen, KNM-NP 59050, is assigned to a new species of Nyanzapithecus on the basis of its unerupted permanent teeth, visualized by synchrotron imaging. Its ear canal has a fully ossified tubular ectotympanic, a derived feature linking the species with crown catarrhines. Although it resembles some hylobatids in aspects of its morphology and dental development, it possesses no definitive hylobatid synapomorphies. The combined evidence suggests that nyanzapithecines were stem hominoids close to the origin of extant apes, and that hylobatid-like facial features evolved multiple times during catarrhine evolution

Systematics, Biostratigraphy, and Dental Evolution of the Palaeothentidae, Later Oligocene to Early-Middle Miocene (Deseadan-Santacrucian) Caenolestoid Marsupials of South America

The family Palaeothentidae contains some of the dentally more specialized of the small-bodied marsupials of South America and was a clade almost equivalent with the Abderitidae in having been the most abundant caenolestoids. They were unquestionably the most diverse, containing two subfamilies, nine genera, and 19 species, with a distribution ranging from Colombia to Tierra del Fuego. The best and most continuous record of the Palaeothentidae is from Patagonian Argentina where eight genera and 17 species are recognized. There, the Palaeothentidae ranged in age from the Deseadan (later Oligocene) through the late Santacrucian (middle Miocene-the Santacrucian record lasting from about 19.4 m.y. to considerably less than 16.05 m.y. before the present) e i. The family appears to have survived longer in Colombia. The palaeothentine Palaeothentes boliviensis (Bolivia) and the incertae sedis genus and species Hondathentes cazador (Colombia) are the only taxa restricted to an extra-Argentine distribution

New Palaeothentid Marsupials (Caenolestoidea) from the Early Miocene of Patagonian Argentina

Recent fieldwork in Argentina has resulted in the recovery of numerous new specimens of palaeothentid marsupials, an important component of the Deseadan-Santacrucian (Oligocene-middle Miocene) mammalian fauna of Patagonia. The 1994 collections include a new genus and species from the early Miocene Pinturas Formation at Estancia La Cafnada and the first complete lower dentition of Acdestis oweni from a locality in the Santa Cruz Formation along the Rio Chalia

Age of the Earliest African Anthropoids

The earliest fossil record of African anthropoid prunates (monkeys and apes) comes from the Jebel Qatrani Formation in the Fayum depression of Egypt. Reevaluation of both geologic and faunal evidence indicates that this formation was deposited in the early part of the Oligocene Epoch, more than 31 million years ago, earlier than previous estimates. The great antiquity of the fossil higher prunates from Egypt accords well with their primitive morphology compared with later Old World higher prunates. Thus, the anthropoid primates and hystricomorph rodents from Fayum are also considerably older than the earliest higher primates and rodents from South America