Pedal Digit Research Articles

New evidence from China for the nature of the pterosaur evolutionary transition

Pterosaurs are extinct flying reptiles, the first vertebrates to achieve powered flight. Our understanding of the evolutionary transition between basal, predominantly long-tailed forms to derived short-tailed pterodactyloids remained poor until the discovery of Wukongopterus and Darwinopterus in western Liaoning, China. In this paper we report on a new genus and species, Douzhanopterus zhengi, that has a reduced tail, 173% the length of the humerus, and a reduced fifth pedal digit, whose first phalange is ca. 20% the length of metatarsal III, both unique characters to Monofenestra. The morphological comparisons and phylogenetic analysis presented in this paper demonstrate that Douzhanopterus is the sister group to the ‘Painten pro-pterodactyloid’ and the Pterodactyloidea, reducing the evolutionary gap between long- and short-tailed pterosaurs.

Get a Grip: Substrate Orientation and Digital Grasping Pressures in Strepsirrhines

Skeletal functional morphology in primates underlies many fossil interpretations. Understanding the functional correlates of arboreal grasping is central to identifying locomotor signatures in extinct primates. We tested 3 predictions linking substrate orientation and digital grasping pressures: (1) below-branch pressures are greater than above-branch and vertical-branch pressures; (2) there is no difference in pressure exerted across digits within autopods at any substrate orientation, and (3) there is no difference in pressure exerted between homologous digits across autopods at any substrate orientation. Adult males and females from 3 strepsirrhine species crossed an artificial arboreal substrate oriented for above-, below- and vertical-branch locomotion. We compared digital pressures within and across behaviors via ANOVA and Tukey's Honest Significant Difference test. Results show limited support for all predictions: below-branch pressures exceeded vertical-branch pressures and above-branch pressures for some digits and species (prediction 1), lateral digits often exerted greater pressures than medial digits (prediction 2), and pedal digits occasionally exerted greater pressures than manual digits during above-branch and vertical orientations but less often for below-branch locomotion (prediction 3). We observed functional variability across autopods, substrate and species that could underlie morphological variation within and across primates. Future work should consider the complexity of arboreality when inferring locomotor modes in fossils.

Evolution of the hallux in non-avian theropod dinosaurs

ABSTRACTThe emergence of a reversed hallux (first pedal digit) in the theropod lineage is regarded as an important indicator of increasing grasping ability and possibly arboreality. However, functions of the pes with a plesiomorphic, non-reversed hallux in non-avian theropods, other than the major role in supporting and propelling the body during the stance phase, have not been fully addressed. To clarify hallucal function, 21 specimens of non-avian theropods were examined in this study. Ancestrally in Theropoda, the proximal end of the first metatarsal reached the ankle joint as in extant crocodilians. The size of the first metatarsal was then reduced, lost direct contact with the ankle joint, and shifted more plantarly in basal neotheropods. In articulated coelophysoid specimens, the proximal end of the first metatarsal attaches to the medioplantar margin of the second metatarsal, whereas the distal part of the first metatarsal and phalanges of the hallux lies on the plantar aspect of the pes. In four articulated specimens of the dromaeosaurid Velociraptor, preserved positions of the first metatarsal on the second metatarsal vary from the medial to plantar aspects, and correspondingly the rotational axis of the extension/flexion movement at its distal articulation ranges from mediolateral to dorsoplantar. Similar conditions are also observed in troodontid specimens, suggesting the presence of intermetatarsal mobility between the first and second metatarsals enabled by a convex proximal articular surface of the first metatarsal in deinonychosaurians similar to the one present in extant birds.Citation for this article: Hattori, S. 2016. Evolution of the hallux in non-avian theropod dinosaurs. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1116995.

Biostratigraphic significance of a new early sauropodomorph specimen from the Upper Triassic of southern Brazil

The Wachholz site (Caturrita Formation, Late Triassic), in Agudo, Rio Grande do Sul (RS), southern Brazil, has yielded several sauropodomorphs. This includes CAPPA/UFSM 0002, described here based on associated elements from the basalmost portion of the site. The specimen possesses a set of traits shared with typical ‘prosauropods’: a concave caudal margin of the trunk neural spines and a broadly convex proximal end of metacarpal V. However, it also retains some plesiomorphic features, for instance, the slender pedal digit I. Some bones closely resemble those of Unaysaurus tolentinoi, the other definitive sauropodomorph from the Caturrita Formation, an affinity corroborated by a new phylogenetic analysis. An updated biostratigraphic framework correlates the Wachholz, Água Negra (São Martinho da Serra/RS) and Botucaraí Hill (Candelária/RS) sites based on their sample of sauropodomorphs. In addition, the record of Jachaleria in the Botucaraí Hill site, a dicynodont also known from early Norian deposits of Argentina, indicates an equivalent age to deposits bearing U. tolentioni. Accordingly, a more constrained age is proposed for the Água Negra site. This is important as the early Norian marks the transition from an epoch of low sauropodomorphs representativeness to a period of extreme abundance of the group in Early-to-Middle Mesozoic ecosystems.

Effect of Intravenous Administration of Tramadol on the Minimum Alveolar Concentration of Isoflurane in Dogs

This study was aimed to evaluate the effects of tramadol hydrochloride on the minimum alveolar concentration of isoflurane (MAC ISO ) in dogs. Six healthy, female German shepherd dogs (aged 1-2 years) were used in this study. Anesthesia was induced by mask induction and maintained with isoflurane in oxygen. Mechanical ventilation maintained the end-tidal CO₂ partial pressure (P ET CO₂) from 35 to 45 mmHg throughout the study. A baseline MAC ISO (MAC ISO B) was determined starting 45 minutes after induction of anesthesia by clamping a pedal digit until gross purposeful movement was detected. After MAC ISO B determination, dogs received a tramadol loading dose of 3 mg/kg followed by a continuous rate infusion (CRI) of 2.6 mg/kg/h. The determination of MAC ISO after administration of tramadol (MAC ISO T) began 20 min after the start of the CRI. Arterial blood pressure and heart rate were recorded continuously and arterial blood samples for blood gas analysis were collected at the end of the equilibration period. Mean ± SD values for the MAC ISO B and MAC ISO T were 1.33 ± 0.04% and 1.23 ± 0.04%, respectively. The MAC ISO B decreased significantly by 7.5 ± 0.2% (P ISO without depression of cardiorespiratory function. Thus, the use of tramadol on inhalation anesthesia with isoflurane in dogs can improve the stability of anesthesia and the quality of recovery.

A diversified vertebrate ichnite fauna from the Feitianshan Formation (Lower Cretaceous) of southwestern Sichuan, China

The Bajiu tracksite exposed on a fine sandstone surface at the top of the Feitianshan Formation, close the contact with the overlying Xiaoba Formation, reveals a saurischian dominated ichnofauna consisting of four sauropod and at least eight theropod trackways. The sauropod trackways display a medium-wide gauge pattern characteristic of titanosauriforms, while the theropod trackways can be subdivided into two distinct morphotypes. One is similar to the ichnogenera Eubrontes and Megalosauripus, the other (cf. Dromaeopodus) appears to represent a functionally didactyl dromaeosaur where pedal digit II is represented only by an oval basal pad. A single swim track is possibly attributable to a turtle or crocodylian. Such sauropod-theropod dominated ichnofaunas are consistently typical of the red-bed tracksites in the region and useful for characterizing a fauna that is otherwise poorly known from body fossils. The stratigraphic position and late occurrence of the (typical Jurassic) Eubrontes-Megalosauripus morphotype is well known from other Cretaceous localities in China and seems to reflect a peculiarity in the theropod faunas of East Asia.

Distal phalanges of Eosimias and Hoanghonius

Seven primate distal phalanges have been identified from two middle Eocene fossil localities (Locality 1 and Nanbaotou) in the Yuanqu Basin, China, providing the first evidence of distal phalangeal morphology in Asian Eocene adapiform and eosimiid primates. The bones are best allocated to the basal anthropoid Eosimias centennicus and to hoanghoniine adapiforms. All distal phalangeal specimens display a morphology consistent with nail-bearing fingers and toes. The hallucal distal phalanx of the basal anthropoid Eosimias is more similar to that of primitive tarsiiforms than to crown group anthropoids. The adapiform distal phalanges from Locality 1 are allocated to Hoanghonius stehlini while those from Nanbaotou are tentatively assigned to an indeterminate hoanghoniine because dental remains of adapiforms have yet to be identified from this site. The distal phalangeal anatomy of hoanghoniines differs slightly from that documented for adapines and notharctines. One distal phalanx from Locality 1 shows a second pedal digit “grooming claw” morphology as noted for notharctines by Maiolino et al. (2012) and cercamoniines by Von Koenigswald et al. (2012).

The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod Balaur bondoc (Dinosauria, Maniraptora): dromaeosaurid or flightless bird?

The exceptionally well-preserved Romanian dinosaur Balaur bondoc is the most complete theropod known to date from the Upper Cretaceous of Europe. Previous studies of this remarkable taxon have included its phylogenetic interpretation as an aberrant dromaeosaurid with velociraptorine affinities. However, Balaur displays a combination of both apparently plesiomorphic and derived bird-like characters. Here, we analyse those features in a phylogenetic revision and show how they challenge its referral to Dromaeosauridae. Our reanalysis of two distinct phylogenetic datasets focusing on basal paravian taxa supports the reinterpretation of Balaur as an avialan more crownward than Archaeopteryx but outside of Pygostylia, and as a flightless taxon within a paraphyletic assemblage of long-tailed birds. Our placement of Balaur within Avialae is not biased by character weighting. The placement among dromaeosaurids resulted in a suboptimal alternative that cannot be rejected based on the data to hand. Interpreted as a dromaeosaurid, Balaur has been assumed to be hypercarnivorous and predatory, exhibiting a peculiar morphology influenced by island endemism. However, a dromaeosaurid-like ecology is contradicted by several details of Balaur’s morphology, including the loss of a third functional manual digit, the non-ginglymoid distal end of metatarsal II, and a non-falciform ungual on the second pedal digit that lacks a prominent flexor tubercle. Conversely, an omnivorous ecology is better supported by Balaur’s morphology and is consistent with its phylogenetic placement within Avialae. Our reinterpretation of Balaur implies that a superficially dromaeosaurid-like taxon represents the enlarged, terrestrialised descendant of smaller and probably volant ancestors.

A New Specimen of Carroll's Mystery Hupehsuchian from the Lower Triassic of China.

A new specimen of an enigmatic hupehsuchian genus is reported. The genus was first recognized by Robert L. Carroll and Zhi-ming Dong in 1991, who refrained from naming it because of the poor quality of the only specimen known at the time. After more than two decades, we finally report a second specimen of this genus, which remained unprepared until recently. The new specimen preserves most of the skeleton except the skull, allowing us to erect a new genus and species, Eretmorhipis carrolldongi. The new species shares many characters with Parahupehsuchus longus, including the strange axial skeleton that forms a bony body tube. However, the body tube is short in the new species, being limited to the pectoral region. The vertebral count and limb morphology considerably differ between the new species and P. longus. The forelimb of E. carrolldongi is markedly larger than its hind limb as in Hupehsuchus nanchangensis but unlike in P. longus. The new species is unique among hupehsuchians in a list of features. It has manual and pedal digits that spread radially, forming manus and pes that are almost as wide as long. The third-layer elements of the dermal armor are unusually large, spanning four vertebral segments, yet there are substantial gaps among them. With the addition of the unique paddle, it is now clear that Hupehsuchia had diverse forelimb morphologies spanning from paddles to flippers, unlike ichthyopterygians that were taxonomically more diverse yet only had flippers.

Reply to comment on “Primates in the Eocene” by Gilbert and Maiolino (2015)

My recent review titled BPrimates in the Eocene^ emphasised time as an essential variable in the study of primate evolution and primate phylogeny. The Eocene is important for primate evolution because this is the geological epoch when true primates (sometimes called euprimates) first appeared. The Eocene is interesting too because the earliest primates include two groups, Tarsioidea and Adapoidea, that are so similar early in their history that members of one group have often been mistaken for members of the other. Similarity in time, place, and morphology to the point of confusion is compelling—if not infallible—evidence of a close phylogenetic relationship. And still, in spite of this early linkage, some authors, such as Gilbert and Maiolino (2015), would classify Tarsioidea and Adapoidea in separate suborders, Haplorhini and Strepsirrhini respectively, in the order Primates. Maiolino et al. (2012) described the morphology of pedal distal phalanges in the early Eocene primate Notharctus tenebrosus and concluded that Notharctus had a grooming claw on the second toe, on pedal digit II. In their comment, Gilbert and Maiolino (2015) claim that pedal distal phalanges bearing grooming claws are readily separated from other ‘unguis’ forms on the basis of their facet-shaft angle (FSA), and volar feature length (VFL) as a proportion of total phalanx length (TPL). However, FSA and VFL/TPL are related to the positioning of distal phalanges in a grasping foot and by themselves indicate little about phalanx shape. As background it is important to note that Koenigswald, Habersetzer, and Gingerich (2012) described and analysed a broad range of primate distal phalanges, recognizing scutiform, falciform, piciform, and columnar distal phalanges on the basis of morphology, with scutiform phalanges interpreted as nail-bearing in prosimians, falciform phalanges interpreted as claw-bearing, piciform phalanges interpreted as bearing grooming claws, and columnar phalanges interpreted as nail-bearing in anthropoids. Our principal components analysis of pedal distal phalanx measurements indicated that Notharctus had grooming claws on digits II and III (von Koenigswald et al. 2012). Discriminant analysis of feet with and without grooming claws, analysed phalanx by phalanx, indicated that Notharctus lacked grooming claws. Discriminant analysis of feet with and without grooming claws, analysed foot by foot rather than phalanx by phalanx, indicated thatNotharctus falls in an ambiguous middle ground between primates with grooming claws and primates that lack them. Gilbert and Maiolino (2015) question my recent characterisation of the morphology of pedal distal phalanges in Notharctus as ‘ambiguous,’ arguing, as they did before (Maiolino et al. 2012), that morphology shows Notharctus to have had a grooming claw on pedal digit II. However, the strongest case for ‘ambiguity’ in the interpretation of Notharctus grooming claws is provided by Maiolino et al. (2012) in their figure 13 (reproduced here as Fig. 1). Notharctus pedal distal phalanges all have ‘SW-3/4/TPL’ values in the ungulae range, and most of these are beyond the tail of the grooming claw range. The one Notharctus ungule known to represent the pedal distal phalanx of digit II (arrows in Fig. 1) is far beyond the range of values observed for grooming claws. Gilbert and Maiolino (2015) can call the distal phalanx of pedal digit II in Notharctus a claw, but calling it a claw does not make it a claw—and it is not a claw unless it has the form of a claw in all three dimensions. A spoon looks like a fork in * Philip D. Gingerich gingeric@umich.edu

Limb and digit orientation during vertical clinging in Bibron's gecko, Chondrodactylus bibronii (A. Smith, 1846) and its bearing on the adhesive capabilities of geckos

AbstractGeckos with subdigital adhesive pads can scale smooth vertical surfaces in defiance of gravity. The deployment of the adhesive system is activated by the musculoskeletal system during active traverses of such surfaces, but adhesion on such substrata can also be achieved by passive means, with the body weight of the gecko applying tensile loading to the adhesive setae, maintaining prolonged, static contact with the surface. To investigate whether passively induced adhesion is employed by geckos holding station on smooth vertical surfaces, we investigated the magnitude of shear force generation for the manus and pes, and the positioning of the limb segments and digits in Chondrodactylus bibronii in freely selected resting postures (head‐up, head‐down and facing laterally to the left and right). Our results indicate that different subsets of digits occupy positions consistent with them being passively loaded in different body orientations. Limb segment and digit orientation are consistent within, and differ between, the resting postures, and relatively few of the 20 digits are positioned to take advantage of gravitationally induced loading in any posture. The pedal digits have greater adhesive potential than the manual ones and, more frequently, capitalize on passive loading than do manual digits. This is especially evident in the commonly adopted head‐down resting posture.

Comment to “Primates in the Eocene” by Gingerich (2012)

In his recent article BPrimates in the Eocene^, Gingerich (2012) presented a broad review of Eocene primate radiations and their place in the primate evolutionary tree, with a particular focus on Adapoidea. While synthetic reviews of early primate evolution are always welcome additions to the literature, within his larger analysis Gingerich (2012) specifically discussed two issues that deserve special comment, the first relating to the evolution of grooming claws within Adapoidea and the second relating to his phylogenetic interpretation of Darwinius and Adapoidea within the order Primates, which was supposedly based on a modification of our own final matrix inMaiolino et al. (2012). Unfortunately, as we will demonstrate below, in both cases the interpretations of Gingerich (2012) are unlikely to be correct. First, Gingerich (2012) characterises the morphology of Notharctus pedal distal phalanges as Bambiguous^. In fact, there is very little ambiguity involved. The analyses provided in Maiolino et al. (2012) demonstrate quite conclusively, both metrically and visually, that pedal distal phalanges bearing grooming claws are readily separated from other unguis forms (ungulae=nails, falculae=non-primate claws, and tegulae= claw-like ungues of callitrichins and aye-ayes) on the basis of facet-shaft angle (FSA), volar feature length (VFL), and other distinctive measures. Univariate and multivariate analyses including FSA and VFL clearly indicate that Notharctus tenebrosus possessed a grooming claw on pedal digit II (Maiolino et al. 2012). To illustrate this point further, a simple bivariate plot of FSA and VFL divided by total phalanx length (TPL) from 512 primate pedal distal phalanges shows the stark distinction between grooming claw and ungula-bearing distal phalanges (Fig. 1). Strepsirrhine and tarsier phalanges that bear grooming claws are well-separated from ungulaand tegula-bearing forms (Fig. 1, dotted line within convex hull surrounding all grooming claws). On the basis of FSA and VFL/TPL, Fig. 1 indicates that Notharctus venticolis (UM 102287), Cantius nuniensis (UM 102193), and Notharctus tenebrosus (AMNH 143612_3 and AMNH 129382) bore grooming claws, confirming the results of Maiolino et al. (2012) for Notharctus tenebrosus and extending them to notharctid pedal morphology, more generally. We note that Gingerich (2012) provides no compelling evidence to the contrary, and the discriminant analyses mentioned by Gingerich (2012) (see also von Koenigswald et al. (2012)) exclude FSA, VFL, VFL/TPL, and other distinctive measures. Until our results are contradicted by a proper study including diagnostic features such as FSA, VFL, and VFL/TPL, the analyses in Maiolino et al. (2012) remain the most comprehensive performed thus far and strongly Electronic supplementary material The online version of this article (doi:10.1007/s12549-015-0184-1) contains supplementary material, which is available to authorized users.

Anatomical investigation on the appendicular skeleton of the cattle egret (Bubulcus ibis)

Introduction: The Cattle Egret (Bubulcus ibis) is a cosmopolitan species of heron (family Ardeidae) found in the tropics, subtropics and warm temperate zones. It is the only member of the monotypic genus Bubulcus. Cattle egret is popular for its role in the bio-control of cattle parasites and land pests. Materials and Methods: The present study was conducted on five adult, apparently healthy, cattle egrets. The birds were euthanized and the skeletons were prepared by the cold maceration method. Results: The appendicular skeleton of the cattle egret consists of the pectoral (shoulder) girdle and appendage, and pelvic girdle and appendages. The pectoral girdle comprises the long flat scapula, coracoid bone, and the united paired clavicles. Canalis triosseum is a canal formed by the attachment of the three bones of the pectoral girdle. The furcula formed fi brous connection with the sternum. The radius and ulna have the same length. The wrist comprises two carpal bones, carpometacarpus and three digits. The pubic bones are not fused ventrally. The pes consists of tibiotarsus, tarsometatarsus and four pedal digits. The tibiotarsus is longer than the femur. The spur is not found in the male bird. Conclusion: The skeleton of the cattle egret has a unique conformation that accommodates its ability to flight as well as being an insectivorous animal.

Patterns of postcranial ossification and sequence heterochrony in bats: life histories and developmental trade-offs.

The recently increased interest in studies on sequence heterochrony has uncovered developmental variation between species. However, how changes in developmental program are related to shifts in life-history parameters remains largely unsolved. Here we provide the most comprehensive data to date on postcranial ossification sequence of bats and compare them to various boreoeutherian mammals with different locomotive modes. Given that bats are equipped with an elongated manus, we expected to detect characteristic heterochronies particularly related to wing development. Although heterochronies related to wing development were confirmed as predicted, unexpected heterochronies regarding the pedal digits were also found. The timing of ossification onset of pedal phalanges is earlier than other mammals. Particularly, bats deviate from others in that pedal phalanges initiate ossification earlier than manual phalanges. It is known that the foot size of new born bats is close to that of adults, and that it takes several weeks to month until the wing is developed for flight. Given that the foot is required to be firm and stable enough at the time of birth to allow continued attachment to the mother and/or cave walls, we suggest that the accelerated development of the hind foot is linked to their unique life history. Since the forelimb is not mature enough for flight at birth and requires extended postnatal time to be large enough to be fully functional, we postulate that bats invest in earlier development of the hindlimb. We conclud that energy allocation trade-offs can play a significant role in shaping the evolution of development.

A new robust enantiornithine bird from the Lower Cretaceous of China with scansorial adaptations

ABSTRACTWe describe a new enantiornithine bird, Fortunguavis xiaotaizicus, gen. et sp. nov, from the Lower Cretaceous lacustrine deposits of the Jiufotang Formation in northeastern China. The new taxon has a strongly dorsoventrally bowed furcula indicating that enantiornithines evolved furcular morphologies in parallel with ornithuromorphs. The new specimen has very robust limbs compared with other enantiornithines and has an unique foot morphology with metatarsal II much shorter than metatarsal IV, robust pedal digits, and strongly recurved pedal unguals. Although recurved unguals characterize Enantiornithes, the extreme curvature present in Fortunguavis suggests scansorial specialization in this species. These features hint at a unique ecology for this taxon and further increase the known diversity of body plans in Early Cretaceous enantiornithines.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at http://www.tandfonline.com/UJVP.

CLINICAL CHALLENGE: SYSTEMIC RHIZOPUS MICROSPORUS INFECTION WITH RENAL CAVITATION IN A GREY SEAL (HALICHOERUS GRYPUS)

A 22-yr-old, intact female grey seal (Halichoerus grypus) (wt: 155 kg) had limited prior medical history other than persistent perionychitis of the right pedal flipper. Four years before the current presentation, this problem had been resolved completely by skeletal amputation of the right pedal digit 3 distal phalanx. During that same year, and progressive over the following 3 yr, the seal developed cataracts and keratopathy including corneal vascularization, pigmentation, and edema. It was elected to perform cataract removal, corneal debridement, and placement of subconjunctival cyclosporine implants (Lux Biosciences Inc., Jersey City, New Jersey 07302, USA; lot# 47614, 0.75 inch). Postoperative treatment (Fig. 1) was initiated with systemic broadspectrum antibiotics, anti-inflammatory and antifungal medications, gastroprotectants, and topical ophthalmic care that included antibiotics and anti-inflammatory medications. After 6 mo of treatment, no substantial improvement to the seal’s ophthalmic status was noted. The corneal hyperpigmentation OU had recurred and a stromal abscess OD had developed. Additionally, the seal presented with non-

Xinghaiornis lini (Aves: Ornithothoraces) from the Early Cretaceous of Liaoning: An Example of Evolutionary Mosaic in Early Birds

Abstract:We describe a new species of Early Cretaceous bird from the Yixian Formation of Liaoning Province. Xinghaiornis lini gen. et sp. nov. is relatively large and characterized by a long, toothless rostrum and an elevated pedal digit I. The design of the skull and feet suggests that this bird was likely a mud‐prober. This discovery provides strong support indicating that this avian trophic specialization originated at least 125 million years ago.

A New Look at Morphological Variation in the IchnogenusAnomoepus, with Special Reference to Material from the Lower Jurassic Newark Supergroup: Implications for Ichnotaxonomy and Ichnodiversity

Numerous new trackways of the small, ornithischian dinosaurs ichnogenus Anomoepus were discovered in the Lower Jurassic (Hettangian) East Berlin Formation in Holyoke, Massachusetts. This new material consists of 16 trackways, on two bedding surfaces 1.5 cm apart, all in close proximity to each other. The abundant pedal and manual impressions have well-preserved digital pad impressions, and claw marks are often discernible also. An Osteometric analysis allows reconstruction of the pedal digits and weight-bearing portions of the metatarsals. On the basis of their small size, as well as distinctive features and proportions of both the manus and pes impressions, these prints are assigned to the ichnospecies Anomoepus lacertoideus (comb. nov.). Three ichnospecies of Anomoepus can be recognized in the Lower Jurassic of the Newark Supergroup: A. lacertoideus, A. scambus and A. crassus. The A. lacertoideus footprints described herein provide evidence that this small, ornithischian track maker engaged in a variety of locomotion-related behaviors. Trackways mostly consist of digitigrade pes prints, reflecting bipedal locomotion, but intervals of quadrupedal progression also are documented by metatarsal and manus imprints in seven trackways. The longest trackways, each consisting of 10 to 15 pes impressions, vary in morphology as a result of the presence or absence of an impression of the distal parts of metatarsals II and IV. The manus prints show two distinct digital divarication angles, 120° and 180°, depending on whether the animal was walking normally or stopping. Variations in substrate consistency influenced locomotor behavior, as shown by the variable pattern of body weight distributions on the pedal digits. Such differences are especially apparent in the longest trackways, which vary in stride and pace lengths. The trends of the abundant trackways at this site also suggest group behavior in Anomoepus, something previously unrecorded for this ichnogenus in the Connecticut River Valley. Evidence from the East Berlin Formation suggests that ichnogenus Anomoepus is not monospecific as some authors have suggested.

New Bird Remains from the Middle Eocene of Guangdong, China

We describe a new avian taxon (Sanshuiornis zhangi gen. et sp. nov.) from Middle Eocene black oil shales in the Huayong Formation of Guangdong Province, south China. The specimen consists of a distal tibiotarsus and a complete foot with tarsometatarsus and pedal digits in articulation. A preliminary phylogenetic analysis does not resolve the affinities of the fossil, but the bones show resemblances to some “ciconiiform” birds. The peculiar hypotarsus morphology, which is block-like and exhibits four cristae, resembles that of the early Eocene Rhynchaeites, which is a stem group representative of the Threskiornithidae. The new Chinese fossil has, however, proportionally longer legs than Rhynchaeites and its phylogenetic affinities probably cannot be resolved without further material.

Evidence for a grooming claw in a North American adapiform primate: implications for anthropoid origins.

Among fossil primates, the Eocene adapiforms have been suggested as the closest relatives of living anthropoids (monkeys, apes, and humans). Central to this argument is the form of the second pedal digit. Extant strepsirrhines and tarsiers possess a grooming claw on this digit, while most anthropoids have a nail. While controversial, the possible presence of a nail in certain European adapiforms has been considered evidence for anthropoid affinities. Skeletons preserved well enough to test this idea have been lacking for North American adapiforms. Here, we document and quantitatively analyze, for the first time, a dentally associated skeleton of Notharctus tenebrosus from the early Eocene of Wyoming that preserves the complete bones of digit II in semi-articulation. Utilizing twelve shape variables, we compare the distal phalanges of Notharctus tenebrosus to those of extant primates that bear nails (n = 21), tegulae (n = 4), and grooming claws (n = 10), and those of non-primates that bear claws (n = 7). Quantitative analyses demonstrate that Notharctus tenebrosus possessed a grooming claw with a surprisingly well-developed apical tuft on its second pedal digit. The presence of a wide apical tuft on the pedal digit II of Notharctus tenebrosus may reflect intermediate morphology between a typical grooming claw and a nail, which is consistent with the recent hypothesis that loss of a grooming claw occurred in a clade containing adapiforms (e.g. Darwinius masillae) and anthropoids. However, a cladistic analysis including newly documented morphologies and thorough representation of characters acknowledged to have states constituting strepsirrhine, haplorhine, and anthropoid synapomorphies groups Notharctus tenebrosus and Darwinius masillae with extant strepsirrhines rather than haplorhines suggesting that the form of pedal digit II reflects substantial homoplasy during the course of early primate evolution.