Topic
Manus
About: Manus is a research topic. Over the lifetime, 128 publications have been published within this topic receiving 2295 citations.
Papers published on a yearly basis
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Papers
TL;DR: A new phylogenetic analysis indicates that several early fossil bats are consecutive sister taxa to the extant crown group (including megabats), and suggests a single origin for the order, at least by the late Paleocene.
Abstract: The phylogenetic and geographic origins of bats (Chiroptera) remain unknown. The earliest confirmed records of bats date from the early Eocene (approximately 51 Ma) in North America with other early Eocene bat taxa also being represented from Europe, Africa, and Australia. Where known, skeletons of these early taxa indicate that many of the anatomical specializations characteristic of bats had already been achieved by the early Eocene, including forelimb and manus elongation in conjunction with structural changes in the pectoral skeleton, hind limb reorientation, and the presence of rudimentary echolocating abilities. By the middle Eocene, the diversification of bats was well underway with many modern families being represented among fossil forms. A new phylogenetic analysis indicates that several early fossil bats are consecutive sister taxa to the extant crown group (including megabats), and suggests a single origin for the order, at least by the late Paleocene. Although morphological studies have long placed bats in the Grandorder Archonta, (along with primates dermopterans, and tree shrews), recent molecular studies have refuted this hypothesis, instead strongly supporting placement of bats in Laurasiatheria. Primitively, proto-bats were likely insectivorous, under-branch hangers and elementary gliders that exploited terminal branch habitats. Recent work has indicated that a number of other mammalian groups began to exploit similar arboreal, terminal branch habitats in the Paleocene, including multituberculates, eulipotyphlans, dermopterans, and plesiadapiforms. This may offer an ecological explanation for morphological convergences that led to the erroneous inclusion of bats within Archonta: ancestral archontan groups as well as proto-bats apparently were exploiting similar arboreal habitats, which may have led to concurrent development of homoplasic morphological attributes.
205 citations
TL;DR: Pederpes is the earliest-known tetrapod to show the beginnings of terrestrial locomotion and was at least functionally pentadactyl, bridging the temporal, morphological and phylogenetic gaps that have hitherto separated Late Devonian and mid-Carboniferous tetrapOD faunas.
Abstract: The fossil record of early tetrapods has been increased recently by new finds from the Devonian period1 and mid–late Early Carboniferous period2. Despite this, understanding of tetrapod evolution has been hampered by a 20-million-year gap (‘Romer's Gap’3) that covers the crucial, early period when many key features of terrestrial tetrapods were acquired. Here I describe the only articulated skeleton of a tetrapod, Pederpes, yet found from the Tournaisian epoch (354–344 million years ago (Myr)). The new taxon includes a pes with five robust digits, but a very small, possibly supernumerary digit preserved on the manus suggests the presence of polydactyly. Polydactylous early tetrapods may have survived beyond the end of the Devonian and pentadactyly cannot be assumed for the pes. However, the pes has characteristics that distinguish it from the paddle-like feet of the Devonian forms and resembles the feet of later, more terrestrially adapted Carboniferous forms. Pederpes is the earliest-known tetrapod to show the beginnings of terrestrial locomotion and was at least functionally pentadactyl. With its later American sister-genus, Whatcheeria4,5, it represents the next most primitive tetrapod clade after those of the Late Devonian, bridging the temporal, morphological and phylogenetic gaps that have hitherto separated Late Devonian and mid-Carboniferous tetrapod faunas.
137 citations
TL;DR: Morphological evidence presented here suggests a semi-tubular manus was an exaptation that ultimately functioned as a weight-distributing structure, and that this unique morphology may have been present in basal sauropods.
Abstract: Sauropods have a unique digitigrade and semi-tubular manus whose shape has been used as a synapomorphy that unites most sauropod taxa. The vertical orientation and semi-tubular arrangement of the metacarpale suggest the sauropod manus improved the mechanical ability of the forelimb to support great weight. However, the evolutionary mechanism responsible for modifying the relatively flat metacarpus of basal saurischians into a semi-tubular arrangement has remained uninvestigated. Furthermore, trackway evidence shows that manus pronation was more developed in sauropods than other saurischians. However, because the radius and ulna do not cross completely in sauropods, reconciling manus print orientation with forelimb osteology has been difficult. Restudy of North American neosauropod appendicular osteology and anatomy suggests that the unique manus shape of sauropods is linked temporally with reversion to a quadrupedal posture and the necessity of manus pronation. Articulation and manipulation of ne...
132 citations
TL;DR: The nature of the Upper Permian sediments in Madagascar and the tectonic environment of their deposition indicate accumulation in deep rift valleys, some parts of which were open to the sea, and the presence of oolites replaced with collophane suggests a rich phosphate source such as deep marine upwellings.
Abstract: Numerus well preserved fossils from the Upper Permian of Madagascar are structurally intermediate between primitive diapsid reptiles and nothosaurs and plesiosaurs. Claudiosaurus germaini (gen.nov., sp.nov.) is similar in its basic anatomy to eosuchian reptiles such as Thadeosaurus colcanapi (gen.nov., sp.nov.), but the absence of a lower temporal bar and the closure of the palate are characteristics of sauropterygian reptiles. Claudiosaurus shows the initiation of aquatic adaptations in the proportions and reduced ossification of the carpus and manus. A third pair of sacral ribs is partially incorporated. The small size of the skull, the nature of the palate and marginal dentition and the long neck are suggestive of aquatic feeding habits. Claudiosaurus does not, however, show the specific adaptations for aquatic locomotion seen in either nothosaurs or plesiosaurs. Even the most primitive known species of nothosaurs and plesiosaurs are too specialized in the postcranial skeleton for direct comparison with Claudiosaurs , although the similarities to the skull roof of primitive nothosaurs are very close. The configuration of the cheek in nothosaurs almost certainly resulted from the loss of the lower temporal bar from a pattern like that of Youngina , rather than from the ventral emargination of the cheek. The nature of the Upper Permian sediments in Madagascar and the tectonic environment of their deposition indicate accumulation in deep rift valleys, some parts of which were open to the sea. The presence of oolites replaced with collophane suggests a rich phosphate source such as deep marine upwellings. Similar upwellings of phosphate have also been associated with the evolution of the marine iguanas on the Pacific coast of South America. The concept of the derivation of nothosaurs from protorosaurs or araeosceloids may be traced to misunderstandings of the nature of the cheek in both Nothosaurus and Protorosaurus . Araeoscelis , despite the possession of a solid cheek, is closely related to Petrolacosaurus , an ancestral diapsid.
110 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2026 | 1 |
| 2025 | 33 |
| 2024 | 40 |
| 2023 | 53 |
| 2022 | 78 |
| 2021 | 24 |