Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

New isolated petrosals from the Itaboraí beds of Brazil (late Palaeocene or early Eocene) are here described and referred to the early diverging litoptern Miguelsoria parayirunhor, based on phylogenetic, size, and abundance arguments. Both the external and internal anatomy of these specimens were investigated, which for the first time document many details of the auditory region of a Palaeogene litoptern. Our cladistic analysis, which included our new observations, failed to recover a monophyletic Litopterna but did not exclude it. A constrained analysis for the monophyly of this order showed that several features such as a (sub)quadrangular and anteroposteriorly elongated tensor tympani fossa and a large notch in the vicinity of the external opening of the cochlear canaliculus may constitute synapomorphies for Litopterna. The evolution of several other auditory characters amongst Litopterna is discussed and the relative dimensions of the inner ear and surrounding petrosal in the group were also investigated. This allowed detection of negative allometry of the bony labyrinth within the petrosal, which was confirmed by measurements and regression analysis across a larger sample of placental mammals. This scaling effect probably has an important influence on several characters of the bony labyrinth and petrosal, amongst which are the length of the vestibular aqueduct and cochlear canaliculus. It demonstrates that many aspects of the morphological variation of the bony labyrinth need to be thoroughly investigated before being incorporated into phylogenetic analyses. © 2015 The Linnean Society of London     

Cranial morphology of the early tertiary Phenacolemur and its bearing on primate phylogeny

An early Eocene skull of the paromomyid Phenacolemur, a plesiadapoid primate, is described with particular emphasis on the ear region. The auditory bulla is composed of the petrosal and of a large ectotympanic plate which is outside of the bulla. The preserved morphology of the middle ear is distinctly more primitive than that of the older Plesiadapis. It cannot be determined with certainty whether Phenacolemur had the carotid circulation enclosed in bony tubes or not. The auditory bulla of early primates and relevant living ones is discussed and it is suggested that an extrabullar ectotympanic, as seen in all non-lemuriform fossil and extant primates, was probably the primitive ordinal condition, rather than the intrabullar ring-like ectotympanic in the Lemuriformes. Aspects of the carotid circulation are discussed as they pertain to the relationship of early Tertiary primates, living Tarsiiformes, Lemuriformes and Lorisiformes.     

Comparative Anatomy of the Petrosal Bone of Dichobunoids,Early Members of Artiodactylamorpha (Mammalia)

Among Artiodactylamorpha, dichobunoids are some of the oldest fossil species that have been associated with Artiodactyla, the crown clade that includes hippopotamids, camelids, suoids, ruminants, and cetaceans. These important fossil species are known from early Eocene rocks of North America, Europe, and Asia, but their phylogenetic position has yet to be well resolved. Before generating such a phylogeny, it is first critical to document all of the anatomy of known dichobunoid fossils. Here we use CT scans to describe previously undescribed anatomy of the petrosal bone, a complex part of the mammalian skull that contains many variable and phylogenetically informative features. Results show that these extinct species share a number of features that are not documented in modern species including a lateral process of the epitympanic wing constituting the medial border of the piriform fenestra, and a tegmen tympani foramen that may have given passage to the ramus superior of the stapedial artery. Future comprehensive phylogenetic studies may show that many of these characters are plesiomophic for Artiodactylamopha. Some species (Diacodexis, Homacodon and ?Helohyus) exhibit a dorsolateral exposure of the mastoid region of the petrosal on the temporal part of the cranium. This uncommon feature has, to our knowledge, not been reported in another euungulate group.     

Synchrotron analysis of a ‘mummified’ salamander (Vertebrata: Caudata) from the Eocene of Quercy,France

An incomplete ‘mummy’ from the Phosphorites du Quercy (presumed Eocene) was identified as a salamander during the 19^th century. The specimen has now been computed tomography (CT) scanned, and this revealed the incomplete skeleton (with perfectly preserved bones) and soft tissues (lung). The fossil represents a new, well‐characterized taxon. Despite the absence of the skull, several features allow a phylogenetic analysis. The fossil belongs to pseudosaurian caudates; it is tentatively assigned to the Salamandridae, although affinities with Plethodontidae cannot be definitely ruled out.     

新疆吉木萨尔克拉玛依组副肯氏兽一新种

1963年在新疆阜康曾经发现过肯氏兽的材料,这批化石中有被称为“九龙壁”的一群个体。这些化石曾被归入副肯氏兽属,命名为短吻副肯氏兽(Parakannemeyeria brevirostris)(孙艾玲,1978)。最近依据这个种建立了一个新属：西域肯氏兽(Xiyukannemeyeria),于是新疆的肯氏兽与华北的肯氏兽就没有相同属了(刘俊、李锦玲,2003)。     

A well‐preserved ‘charadriiform‐like’ fossil bird from the Early Eocene Fur Formation of Denmark

Abstract: We describe a new, exceptionally well‐preserved fossil bird recovered from marine deposits of the Early Eocene Fur Formation of Denmark. Morsoravis sedilis gen. et sp. nov. is known by a single specimen that consists of a three‐dimensional skull, vertebral column, ribs, pelvis, and left hindlimb and associated parts of the right hindlimb. Comparisons based on overall morphology and particularly characters of the skull, vertebrae and pelvis indicate that the new specimen is morphologically similar to charadriiform birds (the shorebirds and relatives). This similarity is also expressed by a phylogenetic analysis of higher neornithine (modern birds) taxa, which supports a close relationship between the new fossil and modern charadriiforms. The morphology of the hindlimbs, in particular, shows that the new fossil corresponds to a new taxon that is distinguishable from modern charadriiform clades. One interesting aspect of its morphology is the presence of hindlimb specializations that are most commonly found among perching birds – these suggest that ecologically the new Danish fossil bird may have differed from the wading habits typical of most charadriiforms.     

Orientation of the lateral semicircular canal in Xenarthra and its links with head posture and phylogeny

The orientation of the semicircular canals of the inner ear in the skull of vertebrates is one of the determinants of the capacity of this system to detect a given rotational movement of the head. Past functional studies on the spatial orientation of the semicircular canals essentially focused on the lateral semicircular canal (LSC), which is supposedly held close to horizontal during rest and/or alert behaviors. However, they generally investigated this feature in only a few and distantly related taxa. Based on 3D‐models reconstructed from µCT‐scans of skulls, we examined the diversity of orientations of the LSC within one of the four major clades of placental mammals, that is, the superorder Xenarthra, with a data set that includes almost all extant genera and two extinct taxa. We observed a wide diversity of LSC orientations relative to the basicranium at both intraspecific and interspecific scales. The estimated phylogenetic imprint on the orientation of the LSC was significant but rather low within the superorder, though some phylogenetic conservatism was detected for armadillos that were characterized by a strongly tilted LSC. A convergence between extant suspensory sloths was also detected, both genera showing a weakly tilted LSC. Our preliminary analysis of usual head posture in extant xenarthrans based on photographs of living animals further revealed that the LSC orientation in armadillos is congruent with a strongly nose‐down head posture. It also portrayed a more complex situation for sloths and anteaters. Finally, we also demonstrate that the conformation of the cranial vault and nuchal crests as well as the orientation of the posterior part of the petrosal may covary with the LSC orientation in Xenarthra. Possible inferences for the head postures of extinct xenarthrans such as giant ground sloths are discussed in the light of these results.     

An Eocene tomistomine from peninsular Thailand

Skull and mandibular elements of a tomistomine crocodilian are described from the late Eocene to early Oligocene lignite seams of Krabi, peninsular Thailand. The Thai tomistomine is a longirostrine form characterized by a rostrum/skull ratio of about 0.6; a mandibular symphysis reaching the level of the eleventh alveolus; a deep participation of the splenial in the symphysis to the level of the ninth alveolus; an enlarged fifth maxillary alveolus; long nasals reaching the premaxillae at the level of the fifth maxillary alveolus but not contributing to the external nares; undivided posterior processes of premaxillae; a short prefrontal, excluded by a longer lacrimal from the posteromedial margin of maxillae; vomers visible on the palate. A phylogenetic analysis recovers the Thai specimen among derived tomistomines, on the stem lineage of the extant Tomistoma schlegelii, as a close ally of Maomingosuchus petrolica, a late Eocene tomistomine from southern China. The present recognition of Maomingosuchus sp. in late Eocene Thai deposits expands the distribution of Eocene tomistomines from southern China to the tropics. The origin of Tomistominae in Asia is briefly discussed.     

NEW GENUS OF DORUDONTINE ARCHAEOCETE (CETACEA) FROM THE MIDDLE-TO-LATE EOCENE OF SOUTH CAROLINA

A new archaeocete whale from the late middle or early late Eocene of South Carolina, Chrysocetus healyorum gen. et sp. nov., is described on the basis of a single subadult specimen. This individual includes: a partial skull; hyoid apparatus; lower jaws; teeth; all cervical, some thoracic and some lumbar vertebrae; ribs and sternum; left forelimb elements; and pelves. The specimen includes portions of much of the body, but while some of the bones are fairly complete, others are damaged, particularly the skull. The pelves resemble those of Basilosaurus , documenting a similar stage of hind limb reduction in dorudontines and suggesting that Chrysocetus was not able to support its body on land. The acetabulum for articulation of the femur is well formed and indicates that the hip joint was functional. Chrysocetus is distinguishable from other described dorudontines based on body size, characteristics of the teeth, and forelimb elements. Absence of deciduous teeth in a subadult individual of Chrysocetus may be indicative of an early stage of the evolution of monophyodonty.     

Eocene primates from Myanmar: Historical perspectives on the origin of Anthropoidea

The phylogenetic and geographic origins of the primate suborder Anthropoidea have long been major focal points in the study of primate evolution. Field work in Africa and Asia over the past forty years has produced a bewildering array of fossil primates, many having been linked in one way or another with the early origins of anthropoids. Asia recently has become fashionable in some circles as the ultimate geographic source of anthropoids, while Africa remains a viable alternative for others. In this paper we discuss the history of discovery of the Eocene primates of Myanmar and then offer our views on the current status of these Myanmar primates in the ongoing debate over anthropoid origins.     

Callistoe vincei, a new Proborhyaenidae (Borhyaenoidea, Metatheria, Mammalia) from the Early Eocene of Argentina

Callistoe vincei nov. gen., nov. sp. is a new South American carnivorous marsupial (Proborhyaenidae, Borhyaenoidea) from Salta Province (Argentina). It is preliminarily described and its phylogenetic relationships with other borhyaenoids are analyzed. The holotype is a complete skull with almost complete postcranial skeleton (missing the pelvis and the tail). It is from the Lumbrera Formation (Early Eocene of northwestern Argentina). It represents the most complete proborhyaenid specimen ever discovered and one of the best-preserved borhyaenoid. In the present paper we analyze the major cranial and dental features, the essential elements to compare C. vincei to Arminiheringia auceta, a Casamayoran proborhyaenid of Patagonia. C. vincei is smaller, much more gracile; its skull is narrower; its lower canines are not procumbent; the metacrista of M3 is U-shaped; the postmetacrista of M4 is present and the mandibular symphysis is shorter. This new material allows reconsideration of some dental traits proposed to diagnose the Proborhyaenidae such as the number of incisors and the open-rooted canines.     

An evaluation of the systematic value of skull morphology in the Trimeresurus radiation (Serpentes: Viperidae: Crotalinae) of Asian pitvipers

Trimeresurus (in its widest sense) is a very diverse and widespread radiation of Asian pitvipers, which has been subject to numerous taxonomic revisions, some of which have been based on characteristics of the skull. In order to evaluate the taxonomic utility of such characters, we conducted a comparison of the skulls of 57 specimens representing nine genera, and two currently unassigned species that are very closely related to each other. A canonical variate analysis reveals three distinct phenetic groups: the Protobothrops group, a group containing Ovophis monticola , ' Ovophis ' okinavensis , and ' Trimeresurus ' gracilis , and finally a group comprising the remaining species and characterized by considerable overlap between most genera with the exception of the monotypic Peltopelor and Himalayophis . Agreement between phenetic similarity based on skull characteristics and phylogenetic relationships based on molecular evidence varies between different groups: the morphological similarity of the skull of Protobothrops sieversorum to the other Protobothrops species is congruent with their recent synonymization while the phenetic similarity among the species within the second group does not reflect current molecular phylogenetic relationships and indicates that convergent or parallel evolution may be responsible for at least some of the phenetic similarity detected among skulls of the Asian pit vipers examined. A test of phylogenetic independence, however, indicates that there is still a significant phylogenetic signal that can be recovered from several skull characteristics. Thus, we conclude that skull morphology can contribute to an overall understanding of pitviper taxonomy, but that it would be unwise to rely on skull characteristics alone.     

The inner ear of <Emphasis Type="Italic">Protungulatum</Emphasis> (Pan-Euungulata,Mammalia)

We present new anatomical details about the bony labyrinth of Protungulatum based on micro CT-scan investigation of an isolated petrosal bone retrieved at the Puercan locality of Bug Creek Anthills and referred to Protungulatum sp. The exceptional state of preservation of the specimen allowed us to reconstruct the very fine details of the inside of the petrosal bone, including the bony labyrinth, the innervation of the vestibule and the innervation and vasculature of the cochlea. Estimation of the auditory capability of Protungulatum based on cochlear morphology indicate that Protungulatum was specialized for high-frequency hearing, with estimated low frequency limits above 1 KHz. Comparisons with Late Cretaceous non-placental eutherians and with early Tertiary pan-euungulates indicate that the bony labyrinth of Protungulatum is closer in general morphology to Mesozoic forms (low coiling and low aspect ratio of the cochlea, posterior orientation of the common crus, dorsal outpocketing of the cochlear fossula), and shares only a few characters with pan-euungulate and euungulate taxa. Interestingly, the bony labyrinth of Protungulatum also shares some morphological features with South American notoungulates and litopterns recently described from Itaboraí, Brazil. These new observations provide new morphological features of potential phylogenetic interest.     

利用面包虫制作小兽头骨标本方法的探讨

我们利用面包虫虫蚀制作小型兽类头骨标本,取得了较好的效果.采用分组对照的方法,依据蝙蝠头骨大小、标本浸制液种类、标本浸制时间、是否剔除舌、下颌软组织和颅骨两侧大片肌肉和标本清水浸泡处理时间等5个影响因素,设计蝙蝠头骨标本制作的实验（共27只蝙蝠头骨,分7个组）.结果表明,利用面包虫虫蚀制作的头骨标本完整、干净,头骨较小的标本虫蚀时间较短,酒精或甲醛浸制一定时间的标本比新鲜标本更适合用虫蚀方法制作头骨,剔除肌肉等组织以及清水浸泡处理和适当提高实验温度均可以提高标本的制作速度,温湿度对标本制作过程有较大影响.     

Ontogeny and cranial morphology of the tympanic region of the Tupaiidae, with special reference to Ptilocercus

The structure of the tympanic region of the skull of Ptilocercus lowii was studied in an embryo of 30 mm crown-rump length and in 5 osteocrania. As in Tupaia, the anterior wall of the bulla of Ptilocercus is not completed by a tympanic process of the alisphenoid, contrary to earlier reports. Ptilocercus resembles Tupaia in the following derived characters. The ventral wall of the tympanic cavity is formed by a rostral entotympanic and by a caudal tympanic process of the petrosal. The entotympanic develops in primary connection with the tubal cartilage. The tympanic aperture of the auditory tube is bordered by the entotympanic. The ring-shaped tympanicum is covered by the entotympanicum and is aphaneric. The musculus tensor tympani is lacking. Among mammals, these characters can be regarded as synapomorphic for the Tupaiidae, that is, to have been present in the common ancestor of the two subfamilies. From the evidence of the tympanic region, the Tupaiidae, therefore, form a monophyletic group. Besides these synapomorphies, there are remarkable differences between Ptilocercus and Tupaia in the structure of the bulla. In Ptilocercus the bulla is smaller and less pneumatized than in Tupaia. An anterior intrabullar septum, present in Tupaia, is lacking in Ptilocercus. The epitympanic wing of the alisphenoid is smaller in Ptilocercus than in Tupaia. A lateral prefacial commissure of the tegmen tympani is present in Ptilocercus, but absent in Tupaia. The caudal tympanic process of the petrosal is larger in Ptilocercus than in Tupaia. These characters are autapomorphic for the Ptilocercinae and for the Tupaiinae, respectively. They demonstrate that the auditory bulla of Ptilocercus and that of Tupaia have evolved independently to a considerable extent. An early phylogenetic separation of their respective ancestors seems likely. The tympanic region of the skull provides no evidence for close relationships of the tree shrews to the primates or to any other eutherians. The classification of the Tupaiidae in a separate order, Scandentia, is supported.     

The Evolution of Bat Vestibular Systems in the Face of Potential Antagonistic Selection Pressures for Flight and Echolocation

The vestibular system maintains the body’s sense of balance and, therefore, was probably subject to strong selection during evolutionary transitions in locomotion. Among mammals, bats possess unique traits that place unusual demands on their vestibular systems. First, bats are capable of powered flight, which in birds is associated with enlarged semicircular canals. Second, many bats have enlarged cochleae associated with echolocation, and both cochleae and semicircular canals share a space within the petrosal bone. To determine how bat vestibular systems have evolved in the face of these pressures, we used micro-CT scans to compare canal morphology across species with contrasting flight and echolocation capabilities. We found no increase in canal radius in bats associated with the acquisition of powered flight, but canal radius did correlate with body mass in bat species from the suborder Yangochiroptera, and also in non-echolocating Old World fruit bats from the suborder Yinpterochiroptera. No such trend was seen in members of the Yinpterochiroptera that use laryngeal echolocation, although canal radius was associated with wing-tip roundedness in this group. We also found that the vestibular system scaled with cochlea size, although the relationship differed in species that use constant frequency echolocation. Across all bats, the shape of the anterior and lateral canals was associated with large cochlea size and small body size respectively, suggesting differential spatial constraints on each canal depending on its orientation within the skull. Thus in many echolocating bats, it seems that the combination of small body size and enlarged cochlea together act as a principal force on the vestibular system. The two main groups of echolocating bats displayed different canal morphologies, in terms of size and shape in relation to body mass and cochlear size, thus suggesting independent evolutionary pathways and offering tentative support for multiple acquisitions of echolocation.     

New discoveries on the middle ear anatomy of Ignacius graybullianus (Paromomyidae,Primates) from ultra high resolution X-ray computed tomography

A skull of Ignacius graybullianus (USNM 421608) was studied using ultra high resolution X-ray computed tomography (uhrCT). The anatomy of the middle ear in this specimen was previously studied through partial removal of the auditory bulla on one side. The data now available allow for examination of the others unprepared ear, which is more completely preserved, as well as adding to the information available about the previously studied ear. Analysis of the relationships between the bones making up the auditory bulla confirms previous assertions that it is formed from the entotympanic, and not from the petrosal, basioccipital, or basisphenoid. Contrary to previous reconstructions of the middle ear anatomy in all known plesiadapiforms, this specimen exhibits a bony canal for the promontorial artery and/or internal carotid nerves running across the lateral extreme of the promontorium. The identification of this structure is confirmed by the clear presence of a lumen, and its origination at a posterior carotid foramen (pcf) in a position that corresponds to that identified in previous studies of the paromomyid basicranium (Am. J. Phys. Anthropol., 36 (1972) 59, Am. J. Phys. Anthropol., 89 (1992) 477). Remnants of this canal are present bilaterally in USNM 421608, which additionally supports its identification. The presence of bony canals for branches of the internal carotid artery and the internal carotid nerves is a feature seen in scandentians and euprimates that is missing in dermopterans. The unusual lateral route followed by the internal carotid nerves is a primitive euprimate feature missing in all other archontans. As such, this evidence is consistent with a close euprimate-paromomyid relationship, and the inclusion of the latter in the order Primates. The discovery of this feature in paromomyids after almost 30 years of study of the ear region of this family acts as a cautionary note to the interpretation of the middle ear in damaged specimens.     

Morphology of male genitalia in lice and their relatives and phylogenetic implications

Abstract.  Lice (Insecta: Phthiraptera) have long been considered to compose a monophyletic group of insects on the basis of external morphological characteristics. However, a recent phylogenetic analysis of 18S rDNA sequences suggested that 'Phthiraptera' have arisen twice within the order Psocoptera (booklice and barklice). The external features of lice are highly specialized to a parasitic lifestyle, and convergence may be frequent for such characters. To provide a further test between traditional and recent molecular-based phylogenetic hypotheses, a phylogenetic analysis of lice and relatives based on morphological characters that are independent from the selective pressures of a parasitic lifestyle is needed. Here, we examined the morphology of the male phallic organ in lice and relatives ('Psocoptera': suborders Troctomorpha and Psocomorpha) and detected some novel modifications that were stable within each group and useful for higher level phylogenetic reconstruction. Phylogenetic analysis based on these characters provided a concordant result with the 18S-based phylogeny. In particular, the apomorphic presence of articulations between the basal plate, mesomere and ventral plate (= sclerite on the permanently everted endophallus) is observed consistently throughout the psocid families Pachytroctidae and Liposcelididae and the louse suborder Amblycera, providing support for a clade composed of these three groups, although possible homoplasy was detected in some Ischnocera. This is the first study to provide morphological support for the polyphyly of lice.     

Another charadriiform-like bird from the lower Eocene of Denmark

We describe an exceptionally well-preserved partial skeleton of a new bird from the early Eocene Fur Formation of Denmark. Like other fossils from these marine deposits, the partial skeleton is three-dimensionally preserved and articulated. This new Danish specimen consists of a skull, vertebral column, ribs, pelvis, and hindlimbs. Concerning characters of the pelvis, tibiotarsus and tarsometatarsus, the new fossil bears morphological affinities to charadriiform birds (shorebirds and relatives). A phylogenetic analysis of higher neomithine (modern birds) taxa also supports a close relationship between the new specimen and modern Charadriiformes. The morphologies of the skull and vertebrae, however, distinguish the new fossil from all recent charadriiform families.