24 research outputs found
The axial biomechanics of Trigonosaurus pricei (Neosauropoda: Titanosauria) and the importance of the cervical–dorsal region to sauropod high-browser feeding strategy
Trigonosaurus pricei is a small to medium-sized sauropod dinosaur (Sauropoda: Titanosauria) from the Late Cretaceous Bauru Group of Brazil that is known from a significant amount of recovered axial elements [four cervical vertebrae, 10 dorsal vertebrae, sacrum (MCT 1488-R), and 10 caudal vertebrae (MCT 1719-R)]. In this biomechanical work, we approach the hypothesis of the cartilaginous neutral pose and the range of motion of the axial series of Trigonosaurus. The results show that this sauropod could be capable of high elevation of the neck resulting from morphological adaptations of the cervicodorsal region on dorsal (D) vertebrae D2 and D3 (e.g. postzygapophyses of D2 positioned over the vertebral centrum and prezygapophyses of D3 over the anterior vertebral centrum). This implies that D2 articulates (cartilaginous neutral posture) with D3 only at a strong dorsally directed angle, resulting in a shift in the direction of the neck to a more elevated posture. Furthermore, the tail attributed to Trigonosaurus as a paratype could be oriented in the horizontal ‘direction’ and presented a sigmoidal ‘shape’. This work contributes generally to the understanding of variation in the body plan of sauropods and, more specifically, to the feeding strategy of small and medium-sized titanosaurs from semi-arid regions of Gondwana
LaMMos - Latching Mechanism based on Motorized-screw for Reconfigurable Robots and Exoskeleton Suits
Reconfigurable robots refer to a category of robots that their components
(individual joints and links) can be assembled in multiple configurations and
geometries. Most of existing latching mechanisms are based on physical tools
such as hooks, cages or magnets, which limit the payload capacity. Therefore,
robots re- quire a latching mechanism which can help to reconfigure itself
without sacrificing the payload capability. This paper presents a latching
mechanism based on the flexible screw attaching principle. In which, actuators
are used to move the robot links and joints while connecting them with a
motorized-screw and dis- connecting them by unfastening the screw. The brackets
used in our mechanism configuration helps to hold maximum force up to 5000N.
The LaMMos - Latching Mechanism based on Motorized- screw has been applied to
the DeWaLoP - Developing Water Loss Prevention in-pipe robot. It helps the
robot to shrink its body to crawl into the pipe with minimum diameter, by
recon- figuring the leg positions. And it helps to recover the legs positions
to original status once the robot is inside the pipe. Also, LaMMos add
stiffness to the robot legs by dynamically integrate them to the structure.
Additionally, we present an application of the LaMMos mechanism to exoskeleton
suits, for easing the mo- tors from the joints when carrying heavy weights for
long periods of time. This mechanism offers many interesting opportunities for
robotics research in terms of functionality, pay- load and size.Comment: 14 pages, 15 figure
Revisiting the Intertropical Brazilian Species Hoplophorus euphractus (Cingulata, Glyptodontoidea) and the Phylogenetic Affinities of Hoplophorus
The genus Hoplophorus is one of the most distinctive glyptodonts from the Quaternary deposits of the intertropical area of Brazil. In this paper, we redescribe cranial and postcranial elements and describe some new tarsal elements belonging to the species Hoplophorus euphractus from caves from Minas Gerais state, southern Brazil, in order to provide a better diagnosis for the genus. The material examined shows several striking, distinctive characters relative to Neosclerocalyptus, besides those previously reported, reinforcing the validity of Hoplophorus. On the other hand, we find that the postcrania of Hoplophorus presents striking, unreported resemblances with Panochthus (e.g., more lateromedially elongated cuboid facet of navicular and caudal tube with large lateral figures separated from the terminal ones by a wide space). In order to infer the relationships of Hoplophorus and to reevaluate the monophyly of the tribe Hoplophorini and the subfamily Hoplophorinae (in which Hoplophorus was previously allocated), we carried out a cladistic analysis of 18 taxa, including 13 glyptodont genera and five cingulate outgroups, scored for 151 cranial, dental, and postcranial characters. The most parsimonious tree shows that Hoplophorinae and Hoplophorini are both paraphyletic and has Hoplophorus as the sister group to Panochthus based mostly on synapomorphies of the caudal tube. We propose: (1) restricting the definition of the tribe Hoplophorini to the lineage represented by Hoplophorus, making it the sister group to Panochthini within Panochthinae (= Hoplophorus + Panochthus); and (2) a new subfamily, Neosclerocalyptinae, represented by Neosclerocalyptus, the sister group to Panochthinae.Fil: Porpino, Kleberson de O.. Universidade Federal do Rio Grande do Norte; BrasilFil: Fernicola, Juan Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Bergqvist, Lílian P.. Universidade Federal do Rio de Janeiro; Brasi
New material of Carolocoutoia ferigoloi (Mammalia, Marsupialia, Didelphimorphia): Systematic affinities and dietary inferences
Carolocoutoia ferigoloi is one of the largest metatherians of the Itaboraí fauna (Early Eocene, Southeastern Brazil). It was originally identified from a single upper molar with a markedly bunodont crown, wrinkled enamel, and a robust protocone. Here, we describe a nearly complete right dentary of C. ferigoloi with the alveoli of the premolars and first lower molar, a very worn second lower molar, complete third and fourth lower molars, and a right second upper molar. Carolocoutoia differs from other protodidelphids in having inflated, conical trigonid cusps, a more flattened entoconid, a developed entocristid, and a supernumerary cusp labial to the entoconid. Carolocoutoia was recovered in our phylogenetic analysis as the sister taxon of Protodidelphis ), since both share the presence of an anteriorly recurved dentary, wrinkled enamel, and a sinuous crest between stylar cusps B and D. The inflated, conical trigonid cusps of Carolocoutoia represent an evolutionary convergence with other South American Paleogene mammals, such as some ungulates, and the polydolopimorphian Roberthoffstetteria. We also present the second record of a pathology (molar extrusion) in a metatherian from Itaboraí. Based on its molar crown morphology, Carolocoutoia ferigoloi was a specialized frugivorous metatherian. The occurrence of a specialized frugivorous protodidelphid in the Itaboraí fauna is in line with the well-established increase in global temperatures and the expansion of tropical forests after the Paleocene-Eocene Thermal Maximum (around 55.5–55.3 million years ago).Fil: Carneiro, Leonardo M.. Universidade Federal de Pernambuco. Centro de Tecnología E Geociências; BrasilFil: Zanesco, Tábata. Universidade Federal do Rio de Janeiro; BrasilFil: Bergqvist, Lílian P.. Universidade Federal do Rio de Janeiro; BrasilFil: Goin, Francisco Javier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Guedes, Fábio R.. Universidade Federal do Rio de Janeiro; BrasilFil: Agnes, Ágatha. Universidade Federal do Rio de Janeiro; BrasilFil: Oliveira, Édison V.. Universidade Federal de Pernambuco. Centro de Tecnología E Geociências; Brasi
A new <i>Eocaiman</i> (Alligatoridae, Crocodylia) from the Itaboraí Basin, Paleogene of Rio de Janeiro, Brazil
<div><p>A new small species of <i>Eocaiman</i> is described on the basis of three anterior left mandibular rami and one isolated tooth. The specimens came from the middle-upper Paleocene Itaboraí Basin (Rio de Janeiro State, Brazil; Itaboraian South American Land Mammal Age). The new taxon differs from the other two <i>Eocaiman</i> species, such as its small size, likely participation of the splenial in the mandibular symphysis, a reduced angle between the longitudinal axis of the symphysis and the mandibular ramus, and enlarged ninth and tenth dentary teeth (in addition to the large first and fourth dentary teeth). The participation of the splenial in the mandibular symphysis is a unique character among caimanines (with the only possible exception being <i>Tsoabichi greenriverensis</i>). The new taxon provides new information on the taxonomic and anatomical diversity of the genus <i>Eocaiman</i>, a taxon of prime importance to understand the evolutionary origins of caimans given its position as the basalmost member of Caimaninae. Furthermore, the new taxon has a relatively small body size in comparison with other species of <i>Eocaiman</i>, a case paralleled by other Itaboraian reptilian groups (e.g. snakes), suggesting that this ecosystem provides critical data to test the relationship between reptilian body size and climate. </p> <p> </p> <p><a href="http://zoobank.org/83636F22-D121-4A77-9141-BE68987B6CBF" target="_blank">http://zoobank.org/83636F22-D121-4A77-9141-BE68987B6CBF</a></p>
</div
Cross-section of correlation of vertical profile composites of the Bauru Group.
<p>Showing the sequence stratigraphic framework at facies association level of the Bauru Group.</p
Details of the lingual crown surfaces, showing multicrenulate longitudinal ridges, from <i>Roxochampsa paulistanus</i> comb. nov. specimens.
<p>A- DGM 259-R; B- d12 of UFRJ-DG 451-R; C- d12 of UFRJ-DG 501-R. Each scale bar = 1 mm.</p
<i>Roxochampsa paulistanus</i> comb. nov. UFRJ-DG 451-R, d12 multicrenulate tooth features.
<p>A- detail of the basal region, showing multicrenulated high relief enamel ridges; B- detail of apical region, showing granulated protuberances “scaly-forms”; C- detail of mid-apex region, showing overlapping projections; D- section of distal and crenulated carena. Scale bar for the tooth = 10 mm; in A, C and D scale bars = 1 mm; in B scale bar = 0.1mm.</p