The humerus of Aegyptopithecus zeuxis: a primitive anthropoid

Two complete humeri of Aegyptopithecus zeuxis have been recovered from Oligocene deposits in the Fayum Province of Egypt. These new specimens support previous interpretations of the locomotor adaptations of this species and indicate that A. zeuxis was a robust, slowly moving arboreal quadruped. While the previously described distal articular region of the humerus is virtually identical with the same region in many extant ceboids and the Miocene hominoid Pliopithecus vindobonensis, the more proximal parts of the humerus show many primitive "prosimianlike" features not found the limbs of extant anthropoids. The primitive features include the absence of a distinct deltoid plane, a broad shallow bicipital groove, a large brachialis flange, and an entepicondylar foramen. In most features, the humerus of Aegyptopithecus zeuxis is more primitive than the hypothetical last common ancestor of extant cercopithecoids and hominoids based on neontological comparisons. This supports other lines of evidence indicating that the hominoids from the Egyptian Oligocene are morphologically ancestral to both Old World monkeys and apes.     

Patterns of dental emergence in early anthropoid primates from the Fayum Depression,Egypt

Abstract

Paleontological field work in the Fayum Depression of Egypt has produced a remarkable diversity of fossil anthropoids, and this, combined with advances in genetic analyses of living anthropoids, has led to establishment of a temporal and phylogenetic framework for anthropoids that is achieving some degree of consensus. Less well understood are the evolutionary mechanisms and selective factors behind the origin and early diversification of anthropoids. One area that has remained under explored is investigation into the life history patterns of early anthropoids, a major omission given that understanding patterns of growth and development is essential for interpreting the paleobiology of fossil species. Here we detail dental emergence sequences for five species in four families of early anthropoid primates from the Fayum, and use these data to test Schultz’s Rule concerning the timing of emergence of molars versus premolars in mammals. Two important results are generated: (1) only one species had a dental eruption sequence identical to that observed among crown catarrhine primates; and (2) in all cases, the permanent canine was the last post-incisor dental element to fully erupt, a finding that may be significant for interpreting early anthropoid behavioral strategies.     

New faces of Aegyptopithecus from the Oligocene of Egypt

Three recently discovered faces of Aegyptopithecus zeuxis from the Oligocene Jebel Qatrani Formation of Egypt provide new information about the shape and variation of the facial cranium, the earliest preserved for a presumed forerunner of apes and humans. Although varying considerably in details of shape and proportion, the new finds and a skull found in 1966 all appear to be of males, a conclusion based in part on the development of temporal and sagittal crests and on the large size of upper canines or their sockets (female canines are much smaller). The snouts of the three new faces all are shorter and broader than that of the earlier found skull as reconstructed. As in most later species of Anthropoidea, variation between these specimens is high.Aegyptopithecus helps define the nature of the oldest Anthropoidea and generally most resembles later-occurring apes. Many features, both derived and shared primitive, link Aegyptopithecus, the large Miocene great apes of the Proconsul group, and modern great apes. That these shared features and proportions are not direct allometric consequences of body size is indicated by Aegyptopithecus' resemblance to the large apes and its many distinctions from similar-sized Hylobates.In Aegyptopithecus brain volume scales smaller than in later catarrhines relative to facial size, the ectotympanic tube is less developed and the premaxilla is more primitive than in later higher primates. In closure of orbits and conformation of forehead, face and dentition, Aegyptopithecus closely resembles higher primates and not prosimians. Taken together, its overall cranial and dental anatomy constitutes one of the most important connecting links in primate evolutionary history.     

Late Eocene and early Oligocene teleost and associated ichthyofauna of the Jebel Qatrani Formation, Fayum, Egypt

Fishes from the late Eocene and Oligocene Jebel Qatrani Formation of the Fayum, Egypt, have been collected for many years, but have not been extensively studied. Collections from various sites in the formation, predominantly representing riverine and shallow lake deposits, include remains of several fishes not known previously. The teleost fishes from these collections [representing Characiformes, Siluriformes, Cichlidae, Latidae (= Centropomidae), and Channidae] include species that are similar to those found in the older, underlying, Qasr el Sagha Formation (catfishes), as well as species of fishes previously unrecorded from the Fayum (cichlids and latids), or even from the Tertiary of Africa (channids). It has been suggested that the Jebel Qatrani Formation represents an area of swampy rivers with overgrown banks and floating vegetation and at least one small lake. The fish remains support this reconstruction of the palaeoenvironment, and further indicate that open riverine habitat was also probably available.     

Scapula of Apidium phiomense: a small anthropoid from the Oligocene of Egypt

A scapular fragment from the Upper Fossil Wood Zone, Quarry I, Fayum Depression, Egypt, is assigned to the taxon Apidium phiomense. This animal may have approximated the size of Galago crassicaudatus or Nycticebus coucang, as predicted by regressing body weight on glenoid surface area and fossa length for an assortment of living primates. Morphometric values for spinoglenoid, axilloglenoid, and axillospinal angles indicate locomotor affinities of A. phiomense with colobine monkeys. Other nonmetric traits align the fossil with Saimiri sciureus, probably its closest behavioral analogue. A. phiomense is thus characterized as an arboreal quadruped with a locomotor repertoire that includes a considerable amount of leaping and the use of forelimbs for clinging and/or suspending during landing.     

Oligocene larger foraminifera from United Arab Emirates,Oman and Western Desert of Egypt

An early Oligocene (Rupelian) diagnostic larger foraminiferal assemblage is described and illustrated from marls and limestones of the Asmari Formation, at Jabals Hafit and Malaqet in the UAE. An equivalent assemblage is identified in the mudstones of the Tahwah Formation, Wadi Suq, Oman. Although Nummulites intermedius (D'Archiac 1846) and N. fichteli are fully synonymous (e.g. Roveda 1970; Schaub 1981; Sirel 2003), in this study both species are biometrically differentiated, distinct and both names are valid. N. fichteli Michelotti 1841, N. intermedius (D'Archiac 1846) and N. emiratus n. sp., which are index for the early Oligocene (Rupelian), and they are replacing each others competitively and environmentally.

The presence of Blondeauina bouillei n.gen., N. emiratus n.sp., N. intermedius, N. fichteli, Planoperculina complanata (Defrance 1822) and Austrotrillina asmariensis Adams 1968 ascribed the section of the Asmari Formation to the early Oligocene (Rupelian). The studied marls and limestones were deposited in outer and inner shelf environments, respectively. The Asmari Formation in the area studied consists mainly of marl in its lower portion and reefal limestone in its upper part, indicating a major marine regression. The Tahwah Formation in Oman is composed of bioturbated silty and muddy marls and is a facies equivalent to the Asmari Formation marls. The Asmari Formation facies change probably relates to a mid-Oligocene fall in global sea level.

In this study, the Dabaa Formation, a subsurface unit of late Eocene–Oligocene marine shales in the north Western Desert of Egypt, was chosen to correlate with the Oligocene of Emirates and Oman. The Dabaa Formation comprises Spiroclypeus ornatus (Henson 1937) and Eulepidina dilatata (Michelotti 1861). The environment of deposition was inner shelf to littoral, which become estuarine towards the top in many areas. This Oligocene Dabaa sequence is correlatable with Wadi El Arish sequence recently discovered by Kuss and Boukhary (2008) from Risan Aneiza, Northern Sinai, Egypt.     

Forelimb anatomy of New World monkeys: myology and the interpretation of primitive anthropoid models

The forelimbs of 12 genera of New World monkeys, two genera of Old World monkeys, and a gibbon were dissected. Of the 54 muscles examined, 19 exhibited significant intergeneric variation. We present arguments for which morphologies are primitive and which are derived within platyrrhines and within anthropoids. We conclude that the forelimbs of Cebus apella and Callicebus moloch represent good models of the ancestral anthropoid morphology. Thus among living anthropoids they are most appropriate for comparisons with early fossil anthropoids. They are also useful for determining whether myological anomalies of human aneuploids are atavistic. Wagner tree analyses were conducted to assess the value of these myological characters in phylogenetic studies of platyrrhines. In most respects the Wagner trees were consonant with phylogenies previously proposed, although some hypothesized trees are less parsimonious than others in explaining our data. There is an unexpected number of derived features shared by Aotus and the Atelines. There are marked dissimilarities in forelimb musculature between Aotus and Callicebus.     

New specimens of Oligopithecus savagei, early Oligocene primate from the Fayum, Egypt

New specimens of the early Oligocene anthropoidean, Oligopithecus savagei, from the Fayum, Egypt, include unworn specimens of lower teeth plus the first known upper molar, premolar, and incisor. These finds confirm the anthropoidean status of Oligopithecus. Comparisons with other Fayum taxa suggest that Oligopithecus is more closely related to Propliopithecidae than to Parapithecidae. Dental similarities between Oligopithecus and early platyrrhines are probably primitive retentions that do not support the hypothesis of an Oligocene trans-Atlantic crossing by primates. Among prosimians, the upper teeth of Oligopithecus very closely resemble those of Protoadapis and allied forms (Europolemur, Mahgarita, Periconodon, Hoanghonius), but differ substantially from other prosimian taxa. Most of the dental and osteological resemblances between Oligopithecus and the Protoadapis group are derived features, thus favoring the hypothesis that Oligopithecus and other Anthropoidea are descended from Adapidae.     

Non-metric features in the ulna of Aegyptopithecus, Alouatta, Ateles, and Lagothrix.

A comparison of the non-metric features of the ulnar fragment (YPM 23940) referred to Aegyptopithecus zeuxis with those in the same bone of Alouatta, Ateles, and Lagothrix -- the three living taxa whose ulnae most closely resemble that of the fossil -- reveals that the closest similarities of the fragment are with the ulna of Alouatta.     

Anatomy of the nasal cavity and paranasal sinuses in Aegyptopithecus and early Miocene African catarrhines

Neontological comparisons suggest that paranasal sinus anatomy is diagnostic of several catarrhine clades such as Cercopithecoidea, Hominoidea, Homininae, and Ponginae. However, while the loss of sinuses in cercopithecoids is generally recognized as a derived condition, determining the polarity of character-state changes within noncercopithecoid catarrhines requires knowledge of the primitive catarrhine condition. To address this problem, the paranasal sinus anatomy of Aegyptopithecus and several early Miocene catarrhines was investigated. Two partial facial skeletons of Aegyptopithecus were subjected to computed tomography in order to reveal their internal anatomy. These data were compared with facial and palatal specimens of Proconsul, Limnopithecus, Dendropithecus, Rangwapithecus, and Kalepithecus in the National Museums of Kenya in Nairobi, and to wet and dry specimens of living taxa. Results confirm that cercopithecoid paranasal anatomy is derived, and reveal that the sinus anatomy of stem catarrhines included a hominoid-like maxillary sinus as well as an ethmofrontal system like that of hominines. Accordingly, these two features do not constitute evidence for the hominoid, hominid, or hominine status of any fossil species. Conversely, the absence of the ethmofrontal sinus system in Sivapithecus and Pongo is synapomorphic. In addition, features of the nasal cavity of Limnopithecus and Kalepithecus support previous suggestions that these taxa are stem catarrhines rather than hominoids.     

Selective regimes and functional anatomy in the mustelid forelimb: Diversification toward specializations for climbing,digging, and swimming

Anatomical traits associated with locomotion often exhibit specializations for ecological niche, suggesting that locomotor specializations may constitute selective regimes acting on limb skeletal traits. To test this, I sampled 42 species of Mustelidae, encompassing climbing, digging, and swimming specialists, and determined whether trait variation reflects locomotor specialization by performing a principal components analysis on 14 forelimb traits. In addition to Brownian motion models, three Ornstein–Uhlenbeck models of selective regimes were applied to PC scores describing trait variation among mustelids: one without a priori defined phenotypic optima, one with optima based upon locomotor habit, and one with a single phenotypic optimum. PC1, which explained 43.8% of trait variance, represented a trade‐off in long bone gracility and deltoid ridge length vs. long robustness and olecranon process length and distinguished between climbing specialists and remaining mustelids. PC2, which explained 17.4% of trait variance, primarily distinguished the sea otter from other mustelids. Best fitting trait diversification models are selective regimes differentiating between scansorial and nonscansorial mustelids (PC1) and selective regimes distinguishing the sea otter and steppe polecat from remaining mustelids (PC2). Phylogenetic half‐life values relative to branch lengths suggest that, in spite of a strong rate of adaptation, there is still the influence of past trait values. However, simulations of likelihood ratios suggest that the best fitting models are not fully adequate to explain morphological diversification within extant mustelids.     

Functional anatomy and biomechanics of the postcranial skeleton of Simocyon batalleri (Viret, 1929) (Carnivora, Ailuridae) from the Late Miocene of Spain

We describe the postcranial anatomy of the Miocene puma-sized ailurid Simocyon batalleri , discussing some aspects of its biomechanics and inferring a probable life style. The postcranial anatomy of S. batalleri was previously unknown due the fragmentary nature of its fossil record, and most of the available fossils corresponded to cranial and dental material. With the discovery of a rich sample from the Late Miocene natural trap of Batallones-1, to the south of Madrid (Spain), including the remains of at least two individuals of S. batalleri , it is possible to study for the first time the anatomy of the cervical and lumbar vertebrae, complete forelimb and partial hind limb. The morphology of the forelimb, the lumbar region and the unexpected presence of a false-thumb are strongly suggestive of arboreal capabilities. Such locomotor abilities are consistent with a palaeobiological model of a generalized carnivore that foraged mainly on the ground but could readily climb to trees for safety if faced with the threat of larger competing carnivores.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 593–621.     

Relating neuromuscular control to functional anatomy of limb muscles in extant archosaurs

Electromyography (EMG) is used to understand muscle activity patterns in animals. Understanding how much variation exists in muscle activity patterns in homologous muscles across animal clades during similar behaviours is important for evaluating the evolution of muscle functions and neuromuscular control. We compared muscle activity across a range of archosaurian species and appendicular muscles, including how these EMG patterns varied across ontogeny and phylogeny, to reconstruct the evolutionary history of archosaurian muscle activation during locomotion. EMG electrodes were implanted into the muscles of turkeys, pheasants, quail, guineafowl, emus (three age classes), tinamous and juvenile Nile crocodiles across 13 different appendicular muscles. Subjects walked and ran at a range of speeds both overground and on treadmills during EMG recordings. Anatomically similar muscles such as the lateral gastrocnemius exhibited similar EMG patterns at similar relative speeds across all birds. In the crocodiles, the EMG signals closely matched previously published data for alligators. The timing of lateral gastrocnemius activation was relatively later within a stride cycle for crocodiles compared to birds. This difference may relate to the coordinated knee extension and ankle plantarflexion timing across the swing-stance transition in Crocodylia, unlike in birds where there is knee flexion and ankle dorsiflexion across swing-stance. No significant effects were found across the species for ontogeny, or between treadmill and overground locomotion. Our findings strengthen the inference that some muscle EMG patterns remained conservative throughout Archosauria: for example, digital flexors retained similar stance phase activity and M. pectoralis remained an ‘anti-gravity’ muscle. However, some avian hindlimb muscles evolved divergent activations in tandem with functional changes such as bipedalism and more crouched postures, especially M. iliotrochantericus caudalis switching from swing to stance phase activity and M. iliofibularis adding a novel stance phase burst of activity.     

Dioscoreaceae fossils from the late Oligocene and early Miocene of Ethiopia

Dioscorea section Lasiophyton leaflets from the late Oligocene (27.23 Ma) and Tacca leaves from the early Miocene (21.73 Ma) of north‐western Ethiopia greatly expand the known fossil record of Dioscoreaceae and represent the earliest and only known records of the Afro‐Asian trifoliate, palmately veined yams (Dioscorea) and bat flowers (Tacca). Both fossils occur in volcaniclastic and clastic sediments associated with a high water table, and the palaeofloral assemblages are indicative of tropical moist forest formations. These fossils provide insight into the evolutionary history of the family in Africa during the mid‐Cenozoic and provide well‐dated taxa that can assist in phylogenetic analyses and evolutionary divergence studies for Dioscoreales and Dioscoreaceae. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 17–28.     

Morphology and locomotor adaptations of the foot in early Oligocene anthropoids

Newly discovered foot bones of Aegyptopithecus are described and compared to those of Apidium and Dolichocebus. Locomotor adaptations are inferred for African early Oligocene propliopithecids, parapithecids, and for Argentine early Oligocene Dolichocebus. All show an anthropoid grade of development in their foot anatomy. Tarsals of Aegyptopithecus compare best with those of Miocene hominoids. Apidium shares derived calcaneal features that link it with Old World monkeys. Dolichocebus exhibits a very generalized platyrrhine talar morphology akin to that seen in Saimiri, Callicebus, Cebus, and Aotus. The morphology of early Oligocene primate foot bones suggests that at least three quite distinct groups, corresponding to three recognized superfamilies, were present in the early Oligocene of South America and Africa.