Arboreal Lifestyle Research Articles

The ethnoprimatology of the Maijuna of the Peruvian Amazon and implications for primate conservation

BackgroundIn Amazonia, primates are not only an important food source but they also hold significant cultural and symbolic value for many indigenous groups. We document the relationship between primates and community members of the Maijuna indigenous community of Sucusari in the Peruvian Amazon and describe how ethnoprimatological studies provide a better understanding of the significance of primates in people’s lives. Additionally, we explore how ethnoprimatological studies can help inform and enhance primate conservation initiatives.MethodsSemi-structured interviews were conducted with 50 residents of the community of Sucusari to assess the classification, cultural significance and traditional uses, beliefs, ceremonies and stories of primates within the Sucusari River basin.ResultsPrimates play an important role in the lives of individuals in the Sucusari community. They are distinguished by their arboreal lifestyle, and among the 11 species reported in the area, seven (Lagothrix lagotricha, Alouatta seniculus, Pithecia monachus, Callicebus spp., Saimiri sciureus, Leontocebus nigricollis) are highly recognized and culturally salient. Primates are used as food, medicine, pets, domestic tools and in the production of handicrafts. They are primarily hunted for local consumption, with larger primates such as L. lagotricha being preferred. Lagothrixlagotricha was also the most commonly reported pet species and the only observed pet primate in the community during surveys. Maijuna traditional beliefs include ancestral dietary taboos for A. seniculus, which are referred to as sorcerer monkeys, but this taboo is no longer fully adhered to. Maijuna traditional stories associated with primates describe the origin of primates found in Sucusari.ConclusionPrimates are embedded in the intricate sociocultural system of the community of Sucusari. Better understanding the relationship between primates and people can help to focus conservation efforts on primate species of particularly high sociocultural importance as well as ecological value, such as L. lagotricha. We highly recommend the inclusion of ethnoprimatological studies into primate conservation initiatives to accomplish more effective conservation planning, ultimately integrating the goals of biodiversity conservation with the cultural and economic needs of indigenous and local communities.

Does the Morphology of the Forelimb Flexor Muscles Differ Between Lizards Using Different Habitats?

Lizards are an interesting group to study how habitat use impacts the morphology of the forelimb because they occupy a great diversity of ecological niches. In this study, we specifically investigated whether habitat use impacts the morphology of the forelimb flexor muscles in lizards. To do so, we performed dissections and quantified the physiological cross sectional area (PCSA), the fiber length, and the mass of four flexor muscles in 21 different species of lizards. Our results show that only the PCSA of the m. flexor carpi radialis is different among lizards with different ecologies (arboreal versus non-arboreal). This difference disappeared, however, when taking phylogeny into account. Arboreal species have a higher m. flexor carpi radialis cross sectional area likely allowing them to flex the wrist more forcefully which may allow them climb and hold on to branches better. In contrast, other muscles are not different between arboreal and non-arboreal species. Further studies focusing on additional anatomical features of the lizard forelimb as well as studies documenting how lizards use the arboreal niche are needed to fully understand how an arboreal life style may constrain limb morphology in lizards. Anat Rec, 301:424-433, 2018. © 2018 Wiley Periodicals, Inc.

A new Jurassic theropod from China documents a transitional step in the macrostructure of feathers

Genuine fossils with exquisitely preserved plumage from the Late Jurassic and Early Cretaceous of northeastern China have recently revealed that bird-like theropod dinosaurs had long pennaceous feathers along their hindlimbs and may have used their four wings to glide or fly. Thus, it has been postulated that early bird flight might initially have involved four wings (Xu et al. Nature 421:335-340, 2003; Hu et al. Nature 461:640-643, 2009; Han et al. Nat Commun 5:4382, 2014). Here, we describe Serikornis sungei gen. et sp. nov., a new feathered theropod from the Tiaojishan Fm (Late Jurassic) of Liaoning Province, China. Its skeletal morphology suggests a ground-dwelling ecology with no flying adaptations. Our phylogenetic analysis places Serikornis, together with other Late Jurassic paravians from China, as a basal paravians, outside the Eumaniraptora clade. The tail of Serikornis is covered proximally by filaments and distally by slender rectrices. Thin symmetrical remiges lacking barbules are attached along its forelimbs and elongate hindlimb feathers extend up to its toes, suggesting that hindlimb remiges evolved in ground-dwelling maniraptorans before being co-opted to an arboreal lifestyle or flight.

The Postcranial Musculoskeletal System of Xenarthrans: Insights from over Two Centuries of Research and Future Directions

Xenarthrans stand out among mammals for various reasons, one of them being their musculoskeletal postcranial specializations. Extant armadillos, anteaters, and sloths feature archetypical adaptations to digging and/or diverse arboreal lifestyles. Numerous extinct xenarthrans dramatically depart in size and morphology from their extant relatives, which has sparked functional interpretations since the end of the eighteenth century. Here, we review the diverse methodological approaches that have been used to investigate functional aspects of the postcranial musculoskeletal system in extant and extinct xenarthrans. Specifically, we address qualitative and quantitative bone morphology (including geometric morphometrics), body size and allometry, bone inner structure, myology, as well as in vivo, ex vivo, and in silico experimentation. Finally, a short account is given on those analyses that included xenarthrans to gain insight into primate anatomy. This review helped to identify potential future directions for the functional analysis of the xenarthran anatomy, a tradition over two centuries old.

Molecular phylogenetics and dating of the problematic New Guinea microhylid frogs (Amphibia: Anura) reveals elevated speciation rates and need for taxonomic reclassification

Asterophryinae is a large monophyletic subfamily of Anurans containing over 300 species distributed across one of the world's most geologically active areas – New Guinea and its satellite islands, Australia and the Philippines. The tremendous ecological and morphological diversity of this clade, with apparent specializations for burrowing, terrestrial, semi-aquatic, and arboreal lifestyle, suggests an evolutionary process of adaptive radiation. Despite this spectacular diversity, this and many other questions of evolutionary processes have received little formal study because until now the phylogeny of this spececies-rich clade has remained uncertain. Here we reconstruct a phylogeny for Asterophryinae with greatly increased taxon and genetic sampling relative to prior studies. We use Maximum Likelihood and Bayesian Inference methods to produce the most robust and comprehensive phylogeny to date containing 155 species using 3 nuclear and 2 mitochondrial loci. We also perform a time calibration analysis to estimate the age of the clade. We find support for the monophyly of Asterophryinae as well as need for taxonomic reclassification of several genera. Furthermore, we find increased rates of speciation across the clade supporting the hypothesis of rapid radiation. Lastly, we found that adding taxa to the analysis produced more robust phylogenetic results over adding loci.

NOCTURNAL ARBOREALITY IN SNAKES IN THE SWAMPLANDS OF THE ATCHAFALAYA BASIN OF SOUTH-CENTRAL LOUISIANA AND BIG THICKET NATIONAL PRESERVE OF SOUTHEAST TEXAS

The southeastern United States is home to a diverse assemblage of snakes, but only one species, the Rough Greensnake (Opheodrys aestivus), is considered specialized for a predominantly arboreal lifestyle. Other species, such as Ratsnakes (genus Pantherophis) and Ribbonsnakes/Gartersnakes (genus Thamnophis), are widely known to climb into vegetation and trees. Some explanations given for snake climbing behavior are foraging, thermoregulation, predator avoidance, and response to flood. Reports of arboreality in snake species typically not associated with life in the trees (such as terrestrial, aquatic, and even fossorial species) usually come from single observations, with no knowledge of prevalence of the behavior. Here, we report on arboreality of snake species detected during 8 years of night surveys in the Atchafalaya Basin of south-central Louisiana and 5+ years of night surveys in Big Thicket National Preserve in southeast Texas. We recorded a total of 1,088 detections of 19 snake species between the two study areas, with 348 detections above ground level (32%). The Rough Greensnake and Western Ribbonsnake (Thamnophis proximus) accounted for nearly 75% of total arboreal detections among the two study areas. However, with one exception, all snake species detected more than once between both study areas had at least one arboreal detection. These observations demonstrate that snakes with widely varying natural histories may be found in the trees at night, and for some species, this behavior may be more common than previously believed.

Vertical Locomotion in Micromys minutus (Rodentia: Muridae): Insights into the Evolution of Eutherian Climbing

Climbing is integral to scansorial and arboreal lifestyles as it enables access to and vertical ranging within the arboreal strata. As early eutherian mammals exhibit osteological correlates for arboreality, it is important to assess the behavioral mechanisms that are related to competent vertical climbing. In this context, we examined climbing gaits in one of the smallest extant rodents, the Eurasian harvest mouse. For these purposes, we filmed six adult Micromys minutus at 240 fps moving on four different substrate sizes (2 mm, 5 mm, 10 mm, 25 mm), during both vertical ascents and descents. All climbing cycles were lateral sequence slow gaits. Upward climbing was characterized by a higher contribution of the hind limbs, longer swing phases, and a significant involvement of stride frequency in velocity modulation. On the other hand, downward climbing was promoted by employing gaits of even lower diagonality, an increased contact with the substrate, enhanced role of the forelimbs, and a subtler modulation of velocity by stride frequency. Eurasian harvest mice effectively negotiate the finest substrates, but their effectiveness decreased significantly on the largest ones. The morphofunctional similarities of M. minutus to Juramaia sinensis and Eomaia scansoria imply analogous behaviors in early eutherians, which apparently contributed to the successful access and exploitation of the fine-branch arboreal milieu. In this way, extant small arboreal mammals can constitute good models for elucidating and comprehending the adaptive significance of behavioral mechanisms that are related to the evolution of arboreality in early mammals.

POSTURAL CLIMBING BEHAVIOUR OF DIDELPHID MARSUPIALS: PARALLELS WITH PRIMATES

Differences in body size and in the use of arboreal strata limit the climbing behaviour and performance of didelphids. Similarly to primates, the arboreal canopy dweller, Caluromys philander exhibits a diagonal-sequence gait. In contrast, terrestrial didelphids use a symmetrical lateral sequence in horizontal locomotion. Postural behaviour along thin supports may allow understanding the mechanisms behind the higher performance of arboreal didelphids climbing. Here in, we describe and compare gait sequence and postural behaviour of seven didelphids climbing a slender and flexible vertical support. Animals were stimulated to climb a vertical support of 1.25 cm diameter. Postural behaviour was qualitatively described for each species in the cycle of maximum velocity by a frame-by-frame analysis of gait cycles, evaluating (1) movements of the tail, (2) posture of hand and wrist when grasping, (3) distance of the body to the support, (4) lateral swinging of the body, (5) orientation of the head, (6) limb posture, and (7) stride cycle. Only arboreal species were capable of climbing with only two limbs grasping the support, keeping a straight body orientation at some distance from the support, and sustaining a more constant and regular climbing velocity. The tail played a role in didelphids with better climbing performance (i.e., higher relative velocity), counteracting the lateral swinging of the body, helping with the animal balance. However, the prehensile ability of the tail was not used in climbing. The most stunning result is that all didelphids grasped the rope between digits 2-3, a schizaxonic grasp, involving a neutral hand orientation regarding the ulna. The didelphids protracted the humerus at forelimb touchdown, and the angle between the arm and the horizontal body axis was greater than 90°. The same postures were already observed in horizontal locomotion of C. philander, Monodelphis domestica, and primates. Locomotory and postural adaptations for an arboreal lifestyle in didelphids seem to be limited to small to medium body sizes, up to the size of species of Caluromys. The arboreal locomotion of didelphids is an important key to understand adaptation and evolution of mammals to an arboreal niche, and the comparison with small primates may help to identify adaptive convergence to arboreal locomotion.

Bilateral Chondroepitrochlearis Muscle: Case Report, Phylogenetic Analysis, and Clinical Significance.

Anomalous muscular variants of pectoralis major have been reported on several occasions in the medical literature. Among them, chondroepitrochlearis is one of the rarest. Therefore, this study aims to provide a comprehensive description of its anatomy and subsequent clinical significance, along with its phylogenetic importance in pectoral muscle evolution with regard to primate posture. The authors suggest a more appropriate name to better reflect its proximal attachment to the costochondral junction and distal attachment to the epicondyle of humerus, as “chondroepicondylaris”; in addition, we suggest a new theory of phylogenetic significance to explain the twisting of pectoralis major tendon in primates that may have occurred with their adoption to bipedalism and arboreal lifestyle. Finally, the clinical significance of this aberrant muscle is elaborated as a cause of potential neurovascular entrapment and as a possible hurdle during axillary surgeries (i.e., mastectomy).

Landing on branches in the frog Trachycephalus resinifictrix (Anura: Hylidae).

Frogs (Lissamphibia: Anura) are famous for their saltatory or hopping locomotion, which is related to numerous anatomical specialisations that are characteristic for the group. However, while the biomechanics of take-off in frogs have been studied in detail, much less is known on how frogs land after a jump. Besides terrestrial and aquatic species, several lineages of frogs adopted an arboreal lifestyle and especially the biomechanics of landing on challenging, small, and unpredictable substrates, such as leaves or branches, are virtually unknown. Here we studied the landing kinematics of the arboreal frog Trachycephalus resinifictrix (Hylidae) on a wooden stick that was used to mimic a small tree branch. We observed two different landing behaviours: (1) landing on the abdomen and (2) attachment with the toes of either the forelimb or the hindlimb. In the latter case, the frogs performed a cartwheel around the stick, while they were only attached by their adhesive toe pads. We estimated the forces that act on the toes during this behaviour to be up to fourteen times the body weight of the animals. This behaviour demonstrates the remarkable adhesive capabilities of the toe pads and the body control of the frogs.Electronic supplementary materialThe online version of this article (doi:10.1007/s00359-016-1069-0) contains supplementary material, which is available to authorized users.

Molecular phylogeny of South‐East Asian arboreal murine rodents

Recent phylogenetic studies and taxonomic reviews have led to nearly complete resolution of the phylogenetic divisions within the old world rats and mice (Muridae, Murinae). The Micromys division and Pithecheir division are two notable exceptions where groupings of species into these divisions based on morphology and arboreal lifestyle have not been supported by phylogenetic evidence. Several enigmatic species from these divisions have been missing from molecular studies, preventing a rigorous revision of phylogenetic relationships. In this study, we sequenced for the first time one mitochondrial and three nuclear genes from South‐East Asian keystone species of these two arboreal divisions: Hapalomys delacouri (Micromys division), Lenothrix canus and Pithecheir parvus (Pithecheir division). We also complemented the molecular data already available for the two divisions with new data from Sundaic Chiropodomys, Indian Vandeleuria oleracea and the recently described Sulawesian Margaretamys christinae. Using this new phylogenetic framework and molecular dating methodologies, our study allows some more detailed classification of the former Micromys and Pithecheir divisions, while confirming their polyphyletic status. Specifically, the former Micromys division should now be split into four monotypic divisions: Chiropodomys, Hapalomys, Micromys and Vandeleuria divisions. The former Pithecheir division is likely to be refined and restricted to Pithecheir and probably Pithecheirops, whereas Lenothrix and Margaretamys should now be recognized as representatives of the Dacnomys division. Our findings have profound implications with regard to the systematics of Murinae, as well as to the early evolution of murine morphology and dental characters.

Diet specialization selects for an unusual and simplified gut microbiota in two- and three-toed sloths.

Symbiotic microbial communities are critical to the function and survival of animals. This relationship is obligatory for herbivores that engage gut microorganisms for the conversion of dietary plant materials into nutrients such as short-chain organic acids (SCOAs). The constraint on body size imposed by their arboreal lifestyle is thought to make this symbiosis especially important for sloths. Here, we use next-generation sequencing to identify the bacteria present in the fore and distal guts of wild two- and three-toed sloths, and correlate these communities with both diet and SCOAs. We show that, unlike other mammalian herbivores, sloth gut communities are dominated by the bacterial phyla Proteobacteria and Firmicutes. Specifically, three-toed sloths possess a highly conserved, low-diversity foregut community with a highly abundant Neisseria species associated with foregut lactate. In contrast, two-toed sloths have a more variable and diverse foregut microbiota correlated with a variety of SCOAs. These differences support the hypothesis that feeding behaviour selects for specific gut bacterial communities, as three-toed sloths subsist primarily on Cecropia tree leaves while two-toed sloths have a more generalist diet. The less diverse diet and gut microbiota of three-toed sloths may render them more susceptible to habitat loss and other diet-altering conditions.

Functional and phylogenetic approaches reveal the evolution of diversity in a hyper diverse biota

Ant communities in tropical forests may be governed by varying assembly mechanisms, depending on the particular habitat investigated. We compared phylogenetic diversity and structure across two forest biomes (dry and humid) and two vertical layers (arboreal and terricolous) in ant communities in Madagascar, and assessed the influence of invasive species on this community structure. We estimated phylogenetic signal and correlated evolution for habitat and several functional traits and tested for conservatism in relevant functional and habitat traits. Ancestral states were reconstructed to illuminate the evolution of habitat traits. All analyses utilized phylogenies estimated from newly generated data from three nuclear markers for 290 Malagasy ant taxa. Dry forests, although lower in species richness, were found to support equally high lineage diversity as humid forests. In contrast, phylogenetic diversity was much lower in arboreal than in terricolous communities. We observed significant phylogenetic clustering in the combined humid forest and in the arboreal–humid, arboreal–dry and terricolous–humid communities, whereas the combined dry forest community was overdispersed. Among ant communities in Madagascar, overdispersion and competition therefore may be more prevalent in dry forest, and habitat filtering may be more dominant in humid forest. Excluding invasive ant species had little overall effect on community structure. All investigated traits showed low to intermediate conservatism; strong support for correlated evolution was found for increased eye size and an arboreal lifestyle. Habitat transitions from humid to dry and from terricolous to arboreal occurred more frequently, and ancestors of most lineages were predicted to be terricolous or humid‐forest adapted. We conclude that most Malagasy ant clades first colonized humid forests and subsequently transitioned into dry forests, indicating that previous hypotheses on the evolution of Madagascar's hyperdiverse biota may not apply to ants and other arthropods.

Like father, like son: assessment of the morphological affinities of A.L. 288-1 (A. afarensis), Sts 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) through a three-dimensional shape analysis of the shoulder joint.

The postcranial evidence for the Australopithecus genus indicates that australopiths were able bipeds; however, the morphology of the forelimbs and particularly that of the shoulder girdle suggests that they were partially adapted to an arboreal lifestyle. The nature of such arboreal adaptations is still unclear, as are the kind of arboreal behaviors in which australopiths might have engaged. In this study we analyzed the shape of the shoulder joint (proximal humerus and glenoid cavity of the scapula) of three australopith specimens: A.L. 288–1 (A. afarensis), Sts 7 (A. africanus) and Omo 119–73–2718 (Australopithecus sp.) with three-dimensional geometric morphometrics. The morphology of the specimens was compared with that of a wide array of living anthropoid taxa and some additional fossil hominins (the Homo erectus specimen KNM-WT 15000 and the H. neanderthalensis specimen Tabun 1). Our results indicate that A.L. 288–1 shows mosaic traits resembling H. sapiens and Pongo, whereas the Sts 7 shoulder is most similar to the arboreal apes and does not present affinities with H. sapiens. Omo 119–73–2718 exhibits morphological affinities with the more arboreal and partially suspensory New World monkey Lagothrix. The shoulder of the australopith specimens thus shows a combination of primitive and derived traits (humeral globularity, enhancement of internal and external rotation of the joint), related to use of the arm in overhead positions. The genus Homo specimens show overall affinities with H. sapiens at the shoulder, indicating full correspondence of these hominin shoulders with the modern human morphotype.

The coevolution of circumperineal color and terrestriality.

Old World monkeys (Cercopithecoidea) are unusual among primates for the high percentage of species exhibiting circumperineal coloration, as well as the large percentage of highly terrestrial species. Kingdon [1974, 1980] suggested that circumperineal skin coloration is functionally related to terrestriality, but this hypothesis has not been tested. From the literature, we collected data on habitat use (terrestrial/arboreal) and circumperineal coloration (present/absent) for 78 species. Indeed, among the 78 species surveyed here, 75% of them fall into either the category of colored circumperineals with terrestrial lifestyle, or of uncolored circumperineals with arboreal lifestyle (Χ(2)(1) = 19.550, P < 0.001). However, conventional statistical procedures assume all taxa are equally related-which is not usually the case in multispecies analyses-leading to higher rates of both type I and II statistical errors. We performed Bayesian trait coevolution analyses that show that models of dependent trait evolution are not significantly better than models assuming independent evolution of the two traits (log-likelihood ratio test P = 0.396, Bayes Factor = 1). Bayesian nodal reconstructions of the cercopithecoid phylogeny indicate that relatively few trait transitions are needed to account for the distributions of the two traits. Further, chi-squared distributional tests show that sub-family affiliation (i.e., Cercopithecinae, Colobinae) is an accurate predictor of trait status. The discordance of the analyses may represent the results of a few different evolutionary scenarios, but ultimately circumperineal coloration seems weakly linked to terrestrial ecology.

The genus Chironius (Serpentes, Colubridae) in Paraguay: composition, distribution, and morphology

Chironius is a genus of slender snakes adapted to a diurnal and arboreal life style, and is distributed from Honduras to Uruguay inhabiting different environments. Five species are present in Paraguay: C. bicarinatus, C. exoletus, C. flavolineatus, C. maculoventris, and C. quadricarinatus. In this work, we provide data on distribution, coloration, and morphological variation of 20 Paraguayan specimens housed in scientific collections. Our results fit with known parameters for the species referred in literature. A conclusion of this work is that, based on distribution and ecological preferences of the species in the region, Paraguay is poorly sampled. Here we extend the known pholidosis range of ventral scale for females of C. bicarinatus (154-170), and for C. maculoventris (143-157 for females and 154-161 for males), and the range of subcaudal scales for males of C. maculoventris (90-125), and females of C. quadricarinatus (91-123).

Motivation and manipulation capacities of the blue and yellow macaw and the tufted capuchin: A comparative approach

This study compared the motivation of the blue and yellow macaw (n=8) and the tufted capuchin (n=3) to manipulate objects that presented different features, their manipulative repertoires, and their ability to solve complex manipulation tasks. Results show that both species seem to be more motivated to manipulate objects that look like food items and that manipulative behavior may be considered as play behavior in the blue and yellow macaws, and would improve foraging motor skills. The tufted capuchins performed more different action styles than the macaws when manipulating objects, and performed substrate-use behavior – the object is put in relationship with a substrate – while the macaws did not. This is an interesting difference because these characteristics are supposed to be precursory of tool-use, behavior never observed in this macaw species. It may be due to the arboreal lifestyle of the macaw and its neophobic character that do not allow it to easily contact objects. Following the same method and using more individuals, further comparative studies should be conducted in order to test these hypotheses. Both species were able to solve complex manipulation tasks.

Jurassic archosaur is a non-dinosaurian bird

Re-examination utilizing Keyence 3D digital microscopy and low angled illumination of the fossil Scansoriopteryx, a problematic sparrow-size pre-Archaeopteryx specimen from the Jurassic Daohugou Biotas, provides new evidence which challenges the widely accepted hypothesis that birds are derived from dinosaurs in which avian flight originated from cursorial forms. Contrary to previous interpretations in which Scansoriopteryx was considered to be a coelurosaurian theropod dinosaur, the absence of fundamental dinosaurian characteristics demonstrates that it was not derived from a dinosaurian ancestry and should not be considered as a theropod dinosaur. Furthermore, the combination in which highly plesiomorphic non-dinosaurian traits are retained along with highly derived features, yet only the beginnings of salient birdlike characteristics, indicates that the basal origins of Aves stemmed from outside the Dinosauria and further back to basal archosaurs. Impressions of primitive elongate feathers on the forelimbs and hindlimbs suggest that Scansoriopteryx represents a basal form of “tetrapteryx” in which incipient aerodynamics involving parachuting or gliding was possible. Along with unique adaptations for an arboreal lifestyle, Scansoriopteryx fulfills predictions from the early twentieth century that the ancestors of birds did not evolve from dinosaurs, and instead were derived from earlier arboreal archosaurs which originated flight according to the traditional trees-down scenario.

A three-dimensional morphometric analysis of the locomotory ecology of Deccanolestes, a eutherian mammal from the Late Cretaceous of India

ABSTRACT The relationships and ecology of Deccanolestes, a eutherian mammal from the Late Cretaceous of India that is known only from isolated dental, mandibular, and postcranial elements, have been a topic of considerable interest and debate. A recent comprehensive phylogenetic analysis has placed this taxon within Adapisoriculidae, a clade of otherwise Paleocene arboreal mammals, but unexpectedly resolved this expanded Adapisoriculidae near the base of the eutherian tree. Deccanolestes has been described as having an arboreal or scansorial lifestyle based on its ankle morphology. Here, we present a geometric morphometric study of the astragalus to test hypotheses pertaining to the ecomorphological affinities of Deccanolestes. Shape analyses were performed on extant eutherians and marsupials displaying a range of different lifestyles, but predominantly sampling arboreal forms, as well as relevant Cretaceous to Eocene taxa. In addition, we constructed a neighbor-joining tree based on the shape variables to identify similarities among taxa in astragalar morphology. Our results show that Cretaceous and Paleocene taxa, including Deccanolestes, cluster most closely and form a separate group distinct from extant mammal clades, including extinct Primates. Strong phylogenetic signal in astragalar morphology among extant taxa, as well as apparent phylogenetic clustering of extant and extinct taxa, complicates a straightforward interpretation of the locomotor ecology of Deccanolestes, but our results suggest that the astragalar morphology of Deccanolestes has no analogue among the sampled living species. However, this morphology appears prevalent among Cretaceous and Paleocene eutherian mammals.

Previously unrecognized ornithuromorph bird diversity in the Early Cretaceous Changma Basin, Gansu Province, northwestern China.

Here we report on three new species of ornithuromorph birds from the Lower Cretaceous Xiagou Formation in the Changma Basin of Gansu Province, northwestern China: Yumenornis huangi gen. et sp. nov., Changmaornis houi gen. et sp. nov., and Jiuquanornis niui gen. et sp. nov.. The last of these is based on a previously published but unnamed specimen: GSGM-05-CM-021. Although incomplete, the specimens can be clearly distinguished from each other and from Gansus yumenensis Hou and Liu, 1984. Phylogenetic analysis resolves the three new taxa as basal ornithuromorphs. This study reveals previously unrecognized ornithuromorph diversity in the Changma avifauna, which is largely dominated by Gansus but with at least three other ornithuromorphs. Body mass estimates demonstrate that enantiornithines were much smaller than ornithuromorphs in the Changma avifauna. In addition, Changma enantiornithines preserve long and recurved pedal unguals, suggesting an arboreal lifestyle; in contrast, Changma ornithuromorphs tend to show terrestrial or even aquatic adaptions. Similar differences in body mass and ecology are also observed in the Jehol avifauna in northeastern China, suggesting niche partitioning between these two clades developed early in their evolutionary history.