Additional postcranial remains of omomyid primates from the Uinta Formation, Utah and implications for the locomotor behavior of large-bodied omomyids

Most omomyids are relatively small bodied (e.g. <500 g), but beginning in the middle Eocene, some omomyids began to grow larger. The largest omomyids occur in the late middle Eocene during the Uintan NALMA, reaching an estimated body mass over 1 kg. The hind limb skeleton of small omomyids is relatively well known, and is generally thought to show active arboreal quadrupedal and leaping adaptations. New postcranial specimens of previously unknown elements from the larger Uintan omomyids, Ourayia (two species), Chipetaia lamporea, and Mytonius hopsoni have recently been recovered from the Uinta Formation, Utah, and from the Mission Valley Formation, California, and they provide additional information concerning their locomotor behavior.The new specimens include several distal tibiae, partial calcanei, a complete talus and a proximal first metatarsal of Chipetaia; distal femora, distal tibiae, cuboids, and partial calcanei of Ourayia uintensis; a complete calcaneus of Ourayia sp.; and a partial calcaneus and talus of Mytonius. Metric analysis of these elements, together with qualitative observations of non-metric traits, indicate that Ourayia and Chipetaia show equal or greater development of traits associated with leaping behavior (including elongation of the calcaneus, navicular and cuboid) than do smaller omomyids from North America. The elements of Mytonius, although fragmentary, lack some leaping features that are well-developed in Ourayia and Chipetaia, suggesting that Mytonius may have relied more on arboreal quadrupedal locomotion than on leaping.     

Body size and premolar evolution in the early‐middle eocene euprimates of Wyoming

The earliest euprimates to arrive in North America were larger‐bodied notharctids and smaller‐bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small‐ and increasingly mid‐sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P₄ displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P₄ can also provide important paleoecological insights. We analyzed the P₄ from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two‐dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P₄ than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P₄ disparity and convergent evolution of the semimolariform condition in the largest omomyines. P₄ morphology relates to diet in early euprimates, although patterns vary between families. Am J Phys Anthropol 153:15–28, 2014. © 2013 Wiley Periodicals, Inc.     

Proximal femoral anatomy of a sivaladapid primate from the late middle Eocene Pondaung formation (central Myanmar)

The postcranial anatomy of the Asian sivaladapid adapiforms is still virtually undocumented, whereas dental remains of these primates have been known for several decades. Little is known about their positional behavior as a result. In this article, we describe a partial left femur of a medium-sized primate preserving its entire proximal portion and a significant length of its shaft. This fossil was recently recovered from the fossiliferous locality of Thamingyauk in the late middle Eocene Pondaung Formation (central Myanmar). This femur is considered to pertain to the same individual as two tarsal elements (fragmentary talus and calcaneus) from the same locality (same location), and attributed to a medium-sized sivaladapid adapiform primate (Kyitchaungia takaii). This new postcranial element provides the first documentation of femoral anatomy among Sivaladapidae from Asia. The mechanical implications deriving from the musculoskeletal interpretation of this bone indicate an animal that probably engaged in a kind of active arboreal quadrupedalism with some degree of proficiency in leaping. Even though many musculoskeletal aspects suggest that branch walking and running were important parts of its locomotor repertoire, in other details it appears that relatively complex movements at the hip joint were actually possible and probably associated with climbing or some hindlimb suspensory activities.     

An omomyid primate from the Pontide microcontinent of north-central Anatolia: Implications for sweepstakes dispersal of terrestrial mammals during the Eocene

A new genus and species of omomyid primate is described from the middle Eocene (Lutetian) Lülük Member of the Uzunçarşidere Formation, Orhaniye Basin, north-central Anatolia, Turkey. This is the first Eocene primate to be reported from the vast area between Switzerland and Pakistan. The new taxon is currently represented by a single dentary fragment, limiting the scope of morphological comparisons that can be made with related taxa. Nevertheless, its dentition differs fundamentally from that of contemporary European microchoerids. The new taxon most closely resembles North American middle Eocene omomyines such as Mytonius hopsoni, and it is therefore interpreted as a member of the Asian/North American omomyine radiation. Its occurrence on the Pontide microcontinent must have resulted from sweepstakes dispersal across the intervening Tethyan barrier that separated the Pontides from adjacent parts of Eurasia during the Lutetian. Sweepstakes dispersal by various terrestrial mammal clades, especially rodents and primates, was facilitated by Eocene greenhouse climatic conditions, which promoted extreme precipitation events and frequent flooding of major river drainages.     

Anatomical features associated with preaxial duplication (pd): a recessive mutation in the rat

Preaxial polydactyly of the fore- and hindlimbs was found in Wistar-derived rats in 1978. Genetic analysis indicated that the polydactyly was due to the effects of an autosomal recessive gene (gene symbol; pd). Polydactylous homozygous rats had two or three pollices (six or seven digits) in the forelimbs and one to three preaxial extra digits (six to eight digits) in the hindlimbs. Skeletal examination revealed the presence of the extra carpal, metacarpal, and phalangeal bones that seemed to be complete or incomplete duplication of the navicular, greater multangular, first metacarpal, and phalanges of digit I in the forelimbs. In the hindlimbs, extra tarsal, metatarsal, and phalangeal bones were also observed preaxially. These extra elements seemed to be mirror-image duplications of the talus, navicular, second cuneiform, third cuneiform, cuboid, and metatarsals and phalanges of digits II-V with the absence of the first cuneiform, tibiale, first metatarsal, and phalanges of digit I. In addition, morphological changes were observed in the humerus, radius, and ulna in the forelimbs and femur, tibia, and fibula in the hindlimbs. Especially in the radius and tibia, thickening and bifurcation were found, indicating incomplete duplication of these bones. Based on these findings, the limb anomaly was classified as preaxial carpometacarpal/tarsometatarsal-type polydactyly with incomplete duplication of the radius and tibia. The mutant rats had other associated anomalies such as accessory spleens and cryptorchism. The males are sterile, whereas the females breed normally.     

New primate hind limb elements from the middle Eocene of China

The continued washing, sorting, and identification of middle Eocene (45 Mya) primates from the Shanghuang fissure-fillings (Jiangsu Province, China) have produced additional hind limb elements. All are isolated elements. The strepsirhine hind limb elements include a first metatarsal and a talus, which are appropriate in size and morphology to pertain to Adapoides troglodytes. Adapoides is interpreted as a quadrupedal-climbing (nonleaping) primate with similarities to living lorises and the fossil primate Adapis. The haplorhine hind limb elements are estimated to span a range of adult body sizes from tiny (17 g) to small (200 g). Included among the new sample of haplorhine hind limb specimens is the smallest primate talus reported thus far. These new postcranial specimens expand our understanding of early haplorhine hind limb anatomy and demonstrate additional similarities between Shanghuang eosimiids and other anthropoids.     

Postcranial Morphology of the Extinct Rodent Neoepiblema (Rodentia: Chinchilloidea): Insights Into the Paleobiology of Neoepiblemids

In this paper, we study the postcranial morphology (humerus, ulna, innominate, femur, tibia, astragalus, navicular, and metatarsal III) of Neoepiblema, a giant Late Miocene South American rodent, searching for evidence about its paleobiology based on unpublished specimens from Solimões Formation (Upper Miocene, Brazil). The study includes a morphofunctional analysis of the postcranial bones and a comparison with extant and extinct rodents, especially Phoberomys. The morphofunctional analysis of the postcranial bones suggests that Neoepiblema (as well as Phoberomys) would have a crouched forelimb that was not fully extended, with powerful pectoral and triceps musculature, and able to produce movements of pronation/supination and possibly with a hand able to grasp. The combination of characters of the innominate bone, femur, and tibia indicates a predominance of parasagittal movements and a thigh with powerful musculature used during propulsion. In sum, the analyzed postcranial features are consistent with the limb morphology of ambulatory rodents, but with faculty to dig or swim. The sedimentary evidence of the localities in which fossils of neoepiblemids have been found suggests that these rodents lived in wet and water-related environments (near swamps, lakes, and/or rivers).

Graphical abstract

     

Mandibular form and function in North American and European Adapidae and Omomyidae

Previous experimental and comparative studies among a wide variety of primate and nonprimate mammals provide a unique source of information for investigating the functional and phylogenetic significance of variation in the masticatory apparatus of Eocene primates. To provide a quantitative study of mandibular form and function in Eocene primates, the scaling of jaw dimensions and the development of symphyseal fusion was considered in a broad sample of North American and European Adapidae and Omomyidae. Statistical analyses indicate a significant size-related pattern of symphyseal fusion across Eocene primates, with larger taxa often having a greater degree of fusion than smaller species; this trend is also evident at the family level. As adapids are mostly larger than omomyids and these taxa show allometry of symphyseal fusion, this may explain why no omomyids evince complete fusion. Controlling for jaw size, species with greater symphyseal fusion tend to have more robust jaws than those with a lesser amount of fusion. Upon further examination, a primary reason why adapids have more robust mandibles than omomyids is associated with the presence of taxa with fused symphyses, and thus more robust jaws, in the adapid sample, whereas no omomyids have fused symphyses. In addition, there is little indication of a dietary effect, as measured by molar shear-crest development, on symphyseal fusion. Moreover, as there is no correlation between molar shear-crest development and skull size, this also points to the absence of a size-related pattern of dietary preference underlying the allometry of symphyseal fusion. Based on the interspecific and ontogenetic allometry of symphyseal ossification in Eocene primates, jaw-scaling patterns are used to further examine the functional determinants of fusion in this group. This study indicates that greater dorsoventral shear during mastication is a more likely factor than lateral transverse bending (“wishboning”) in the evolution of symphyseal fusion among “late-fusing” mammals like adapids and omomyids. Given that wishboning is an important functional determinant of symphyseal form in recent anthropoids, apparently the evolutionary development of marked wishboning occurs only in taxa that shift the timing of fusion to a growth stage preceding the onset of weaning (before adult masticatory patterns are fully developed) and perhaps first ossified the symphysis to counter elevated dorsoventral shear stress. As early anthropoids probably consisted of members varying interspecifically and ontogenetically in the degree of ossification, it is especially informative to analyze the adaptive setting in which anthropoid symphyseal fusion evolved from a similar primitive “prosimian” perspective. © 1996 Wiley-Liss, Inc.     

Patient-specific modelling of the foot: automated hexahedral meshing of the bones

Subject-specific finite element modelling is a powerful tool for carrying out controlled investigations of the effects of geometric and material property differences on performance and injury risk. Unfortunately, the creation of suitable meshes for these models is a challenging and time-intensive task. This paper presents an automated method of generating fully hexahedral meshes of the bones of the feet which requires only surface representations as inputs. The method is outlined and example meshes, using two human feet and the foot of a Japanese macaque, are given to demonstrate its flexibility. Mesh quality is also evaluated for the calcaneus, first metatarsal, navicular and talus. Streamlining the generation of finite element meshes of the foot will ease investigations into the patient-specific biomechanics of injury.     

A NEW MICROCHOERINE OMOMYID (PRIMATES, MAMMALIA) FROM THE ENGLISH EARLY EOCENE AND ITS PALAEOBIOGEOGRAPHICAL IMPLICATIONS

Abstract:  A new genus and species of omomyid primate, Melaneremia bryanti , is described from the Early Eocene Blackheath Beds of Abbey Wood, London, UK. It shares unique derived characters with the European subfamily Microchoerinae and is its most primitive member. It is nevertheless more derived than the primitive omomyid Teilhardina belgica from the beginning of the European Eocene. Cladistic analysis shows that the Microchoerinae are sister group to a clade comprising subfamilies Omomyinae and Anaptomorphinae, but excluding Teilhardina belgica and T. asiatica , which are stem omomyids. The Mammalian Dispersal Event (MDE), which marks the beginning of the Eocene (55·8 Ma), saw the dispersal of primates, perissodactyls and artiodactyls into the Northern Hemisphere. At this time similar species of Teilhardina lived in Europe, Asia and North America. The Abbey Wood microchoerine lived about 1 million years later. It co-occurs with non-primate species identical or very similar to those that lived in North America. The latter were ground-dwellers, whereas the microchoerine and others that show distinct differences from North American relatives were tree-dwellers. Land-bridges connected North America and Europe via Greenland at the beginning of the Eocene, but 2 million years later these had been severed by submarine rifting. North American species at Abbey Wood indicate that a land connection still remained at c . 55 Ma. However, the forest belt that must have been continuous during the MDE to allow tree-dwellers to disperse between the continents is likely by this time to have been disrupted, perhaps by volcanic eruption.     

A description of the Omo I postcranial skeleton, including newly discovered fossils

Recent fieldwork in the Kibish Formation has expanded our knowledge of the geological, archaeological, and faunal context of the Omo I skeleton, the earliest known anatomically modern human. In the course of this fieldwork, several additional fragments of the skeleton were recovered: a middle manual phalanx, a distal manual phalanx, a right talus, a large and a small fragment of the left os coxae, a portion of the distal diaphysis of the right femur that conjoins with the distal epiphysis recovered in 1967, and a costal fragment. Some researchers have described the original postcranial fragments of Omo I as anatomically modern but have noted that a variety of aspects of the specimen's morphology depart from the usual anatomy of many recent populations. Reanalysis confirms this conclusion. Some of the unusual features in Omo I--a medially facing radial tuberosity, a laterally flaring facet on the talus for the lateral malleolus, and reduced dorsovolar curvature of the base of metacarpal I--are shared with Neandertals, some early modern humans from Skhul and Qafzeh, and some individuals from the European Gravettian, raising the possibility that Eurasian early modern humans inherited these features from an African predecessor rather than Neandertals. The fragment of the os coxae does not unambiguously diagnose Omo I's sex: the greater sciatic notch is intermediate in form, the acetabulum is large (male?), and a preauricular sulcus is present (female?). The preserved portion of the left humerus suggests that Omo I was quite tall, perhaps 178-182 cm, but the first metatarsal suggests a shorter stature of 162-173 cm. The morphology of the auricular surface of the os coxae suggests a young adult age.     

Comparison of radiologic and gross examination for detection of cancer in defleshed skeletons

The reliability of visual examination of defleshed bones was assessed for detection of postcranial metastatic disease in individuals known to have had cancer. This was compared with standard clinical radiologic techniques. The skeletons of 128 diagnosed cancer patients from an early 20th century autopsied skeletal collection (Hamann-Todd Collection) were examined. Radiologic examination detected evidence of metastatic disease in 33 individuals, compared to 11 by visual examination of the postcranial skeletons. Four of these cases were detected by both techniques. Blastic lesions were most commonly overlooked on visual examination, because they were localized to trabecular (internal bone) structures. The ilium was the most commonly affected bone, with lytic or blastic lesions detected in 30 of 33 individuals. While the proximal femur was affected in only nine individuals, x-ray of the proximal femur and ilium detected all individuals with postcranial evidence of metastatic disease. Skeletal distribution of metastases provides no clue to the location of origin or histologic subtype of the cancer. Survey of archeological human remains for metastatic cancer requires radiologic examination. Such skeletal surveys should x-ray at least the ilia and femora. © 1995 Wiley-Liss, Inc.     

New foot remains from the Gran Dolina-TD6 Early Pleistocene site (Sierra de Atapuerca, Burgos, Spain)

This paper presents and describes new foot fossils from the species Homo antecessor, found in level TD6 of the site of Gran Dolina (Sierra de Atapuerca, Burgos, Spain). These new fossils consist of an almost complete left talus (ATD6-95) and the proximal three-quarters of a right fourth metatarsal (ATD6-124). The talus ATD6-95 is tentatively assigned to Hominin 10 of the TD6 sample, an adult male specimen with which the second metatarsal ATD6-70+107 (already published) is also tentatively associated. Analysis of these fossils and other postcranial remains has made possible to estimate a stature similar to those of the specimens from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain). The morphology of the TD6 metatarsals does not differ significantly from that of modern humans, Neanderthals and the specimens from Sima de los Huesos. Talus ATD6-95, however, differs from the rest of the comparative samples in being long and high, having a long and wide trochlea, and displaying a proportionally short neck.     

Dietary ecospace and the diversity of euprimates during the Early and Middle Eocene

This study examined adapoid and omomyoid euprimate dietary and body size diversity from the Eocene of North America and Europe. Estimates of body weights and shearing quotients calculated from lower molars were plotted on a coordinate graph as a representation of dietary niche space (dietary ecospace) occupied by extinct species. By computing the areas, average intertaxon distances, and average distances from the centroid of the resulting polygons, comparisons of Eocene euprimate dietary and body size diversity were made. Results indicate that euprimate dietary niche space expanded significantly in North America from the Early to Middle Eocene, and at all times during the Early and Middle Eocene, the niche space occupied by North American euprimates exceeded that of corresponding European euprimates. These results confirm that fossil euprimate diversity, as measured by diet and body size, significantly differed across biogeographic areas. There are many possible explanations as to why North American euprimates were significantly more diverse in terms of diet and body size than their European counterparts. The explanation advocated here as most responsible for the increased diversity during the Early and Middle Eocene relates to the existence and increased sampling of more ecologically diverse environments, such as basin margins in the western interior of North America. These diverse environments could have promoted biological processes that led to the generation of increased diversity in North America compared to the isolated island refugia of Western Europe during this time.     

Middle Eocene primate tarsals from China: implications for haplorhine evolution

We describe tarsal remains of primates recovered from the Middle Eocene (approximately 45 mya) Shanghuang fissures in southern Jiangsu Province, China. These tarsals document the existence of four higher-level taxa of haplorhine primates and at least two adapid species. The meager and poorly preserved adapid material exhibits some similarities to European adapines like Adapis. The haplorhine primates are divided into two major groups: a "prosimian group" consisting of Tarsiidae and an unnamed group that is anatomically similar to Omomyidae; and an "anthropoid group" consisting of Eosimiidae and an unnamed group of protoanthropoids. The anthropoid tarsals are morphologically transitional between omomyids (or primitive haplorhines) and extant telanthropoids, providing the first postcranial evidence for primates which bridge the prosimian-anthropoid gap. All of the haplorhines are extremely small (most are between 50-100 g), and the deposits contain the smallest euprimates ever documented. The uniqueness of this fauna is further highlighted by the fact that no modern primate community contains as many tiny primates as does the fauna from Shanghuang.     

Notharctine primates (Adapiformes) from the early to middle Eocene (Wasatchian-Bridgerian) of Wyoming: transitional species and the origins of Notharctus and Smilodectes

Notharctine adapiform primates are an abundant element of early (Wasatchian) and middle (Bridgerian) Eocene faunal assemblages from the western interior of North America. Early Eocene notharctine samples are dominated by Cantius with Pelycodus and Copelemur being much rarer and more restricted in their geographic distribution. Cantius is replaced in the middle Eocene by Notharctus and Smilodectes, both of which are common but less widespread, being best known from southwestern Wyoming. The origin of these two middle Eocene taxa has not been well understood, due to a lack of transitional Wasatchian-Bridgerian notharctine faunal samples or because known samples had not been adequately studied. Field work at South Pass in the Greater Green River Basin has produced a relatively large sample of earliest Bridgerian notharctines. Combining this sample with a large, but previously under-studied, sample of notharctines from the latest Wasatchian and earliest Bridgerian in the Wind River Basin has clarified the relationships among Notharctus,Smilodectes, and earlier occurring notharctines. Notharctus first appears in the latest Wasatchian (Wa7), represented by N. venticolus. Phylogenetic analysis supports a Notharctus clade that shares sister taxon status with Cantius nunienus and indicates that Notharctus arose through bifurcation of the lineage containing the last common ancestor of C. nunienus and Notharctus. The origins of Smilodectes are less clear. Phylogenetic analysis supports a clade consisting of Smilodectes and Copelemur, but the origins of both taxa are not established as yet. North American notharctines are typified by relatively low taxonomic diversity, but relatively high abundance and high dental morphological variation (disparity). These attributes are opposite to those of North American omomyids, reflecting differences in ecomorphospace between these two primate radiations.     

In vitro study of foot kinematics using a dynamic walking cadaver model

There is a dearth of information on navicular, cuboid, cuneiform and metatarsal kinematics during walking and our objective was to study the kinematic contributions these bones might make to foot function. A dynamic cadaver model of walking was used to apply forces to cadaver feet and mobilise them in a manner similar to in vivo. Kinematic data were recorded from 13 cadaver feet. Given limitations to the simulation, the data describe what the cadaver feet were capable of in response to the forces applied, rather than exactly how they performed in vivo. The talonavicular joint was more mobile than the calcaneocuboid joint. The range of motion between cuneiforms and navicular was similar to that between talus and navicular. Metatarsals four and five were more mobile relative to the cuboid than metatarsals one, two and three relative to the cuneiforms. This work has confirmed the complexity of rear, mid and forefoot kinematics. The data demonstrate the potential for often-ignored foot joints to contribute significantly to the overall kinematic function of the foot. Previous emphasis on the ankle and sub talar joints as the principal articulating components of the foot has neglected more distal articulations. The results also demonstrate the extent to which the rigid segment assumptions of previous foot kinematics research have over simplified the foot.     

Latest Cretaceous hadrosauroid (Dinosauria: Ornithopoda) remains from Bulgaria

Disarticulated dinosaur bones have been discovered in a fossiliferous lens in the Labirinta Cave, southwest of the town of Cherven Bryag, in NW Bulgaria. This cave is formed within marine limestones belonging to the Kajlâka Formation of Latest Cretaceous age. Associated fossils and Sr isotopy suggest that the fossiliferous sediments belong to the uppermost part of the Upper Maastrichtian. The dinosaur bones discovered in this lens include the distal portion of a left femur, a right tibia, the proximal part of a right fibula, a left metatarsal II, the second or third phalanx of a left pedal digit IV, the proximal end of a second metacarpal, and a caudal centrum. All the bones undoubtedly belong to ornithopod dinosaurs and more accurately to representatives of the hadrosauroid clade. All belong to small-sized individuals, although it cannot be assessed whether they belong to juveniles or small-sized adults, pending histological analyses. Hadrosauroid remains have already been discovered in Late Maastrichtian marine sediments from western, central and eastern Europe, reflecting the abundance of these dinosaurs in correlative continental deposits. Indeed, hadrosauroids were apparently the dominating herbivorous dinosaurs in Eurasia by Late Maastrichtian time.