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Gaetano Odierna - One of the best experts on this subject based on the ideXlab platform.
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description of a new endemic species of mountain lizard from northwestern spain iberolacerta galani sp nov squamata lacertidae
Zootaxa, 2006Co-Authors: Oscar Arribas, Salvador Carranza, Gaetano OdiernaAbstract:A new species of Iberolacerta is described from the Montes de Leon (northwest Iberia). This new species, Iberolacerta galani sp. nov., is characterized by its relatively large size, high number of blue ocelli on the shoulders and the relatively frequent contact or near-contact between the supranasal and the first loreal scale, the fairly straight Squamosal Bone (only curved on its posterior part), a unique karyotype in Iberolacerta combining 2n=36 chromosomes, an L-type NOR and differentiated W and Z sex chromosomes, and unique mitochondrial DNA sequences for the cytochrome b and 12S rRNA genes. The correlation analyses show that morphology in general, but especially scalation, is strongly correlated with the amount of precipitation during the months of lizard activity, which suggests that these are not good taxonomic characters, and that other characters apparently independent of the climate like for instance osteological, karyological and DNA features are much more reliable in delimiting species boundaries in Iberolacerta. According to our phylogenetic analyses, I. galani nov. is part of a very well supported clade that originated around 2.5 mya and also includes I. monticola and I. martinezricai. Phylogeny suggests I.martinezricai might be the sister taxon to I. galani nov. from which it split approximately 2 mya, at the beginning of the Pleistocene. The clade containing I. galani nov., I. martinezricai and I. monticola was probably widely distributed across western Iberia during moderately cool and moist phases of the Pleistocene, but it was probably restricted to its present range as a result of the general temperature increase during the Holocene and competition with other lacertid lizards. Iberolacerta galani nov. is endemic to the Montes de Leon, where it is isolated from the other species of the “monticola-group” by the Duero and Mino-Sil Rivers, but particularly by the Bibei river valley.
Susa W Herring - One of the best experts on this subject based on the ideXlab platform.
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ontogeny of Bone strain the zygomatic arch in pigs
The Journal of Experimental Biology, 2005Co-Authors: Susa W Herring, Sco C Pederse, Xiaofeng HuangAbstract:SUMMARY At the time of weaning, infant animals have little experience with hard food, and thus their skulls are not likely to be epigenetically adapted for the loads imposed by mastication. We examined Bone strain in the zygomatic arch of 4-week-old weanling piglets. Functional strains in piglets differed from those previously reported for older pigs in that the Squamosal Bone was not bent in the horizontal plane and the principal tensile strain on the zygomatic Bone did not correspond to the direction of masseter muscle pull. Strain patterns were more variable in piglets than in older pigs. In older pigs, masticatory strains can be reproduced by stimulating the masseter muscles. When the piglet masseter was stimulated, strain patterns were more similar to those of older pigs, but shear strain magnitudes were the largest yet recorded from mammalian skull Bones, up to 4000 μϵ. To put these findings in the context of skeletal adaptation, 45 dry skulls, including some animals from the strain study, were measured. Reduced major axis regressions indicated that the infant arch was rounder in cross section and straighter than that of older animals. With growth, the arch became dorsoventrally higher, while mediolateral thickness decreased in the Squamosal Bone. Overall, these changes should make strain more predictable, explaining the lower variability in older animals. Other factors likely to be important in causing unique strain regimes in piglets include (1) unfamiliarity with hard food, (2) greater importance of muscles other than the same-side masseter and (3) greater proximity of molariform teeth to the arch. Collectively, these data indicate that the skeleton is not pre-adapted for specific functional loads.
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three dimensional loading and growth of the zygomatic arch
The Journal of Experimental Biology, 2000Co-Authors: Katherine L. Rafferty, Susa W Herring, Flavia ArteseAbstract:Despite a number of previous biomechanical studies on the zygomatic arch, unanswered questions remain about its three-dimensional loading and growth. Using young miniature swine, we have for the first time recorded strains from both the medial and lateral aspects of the Squamosal Bone during mastication and masseter muscle stimulation. Strains from the zygomatic Bone flange and zygomatic arch growth data were also obtained from the same animals. A second study on a younger group of animals examined the growth of the zygomatic flange following partial removal of the masseter. Strain data indicated that the Squamosal Bone is bent out-of-plane and that this pattern of loading is quite different from that of the adjacent zygomatic Bone, which experiences much lower strains with little evidence of out-of-plane bending. Surprisingly, strains were higher in the zygomatic flange during contralateral chews and contralateral masseter stimulations than during ipsilateral chews/stimulations. These strains proved to arise from movement of the condyle, explaining why partial removal of the masseter had little effect on the growth of the flange. Other growth results indicated an approximately threefold greater rate of subperiosteal deposition on the lateral surface of the Squamosal Bone than on the zygomatic Bone. This difference in growth rate is attributed to the presence of sutures that contribute to the lateral displacement of the zygomatic Bone but not the Squamosal Bone. This explanation does not exclude the possibility that the rapid apposition on the lateral Squamosal surface is regulated by the high surface strains that result from out-of-plane bending.
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stereological analysis of Bone architecture in the pig zygomatic arch
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 1997Co-Authors: Shengyi Teng, Susa W Herring, I W Choi, Joh M RensbergeAbstract:An understanding of stress distribution within Bones requires three-dimensional information on Bone strain and Bone material properties. Material properties can be relatively easily obtained by mechanical (Turner and Burr, 1993) or ultrasonic (Ashman et al., 1984; Dechow et al., 1993) techniques for locations that are predominantly cortical. Trabecular Bone is more difficult to assess, because the dimensions of the test samples strongly influence measured properties (Linde et al., 1992) and because failure at sample ends biases the overall results (Odgaard et al., 1989). These problems can be overcome if the sample of trabecular Bone is large enough to allow strain to be measured specifically from the central section (Ashman et al., 1987; Odgaard et al., 1989; Teng and Herring, 1996). Unfortunately, there are many cancellous areas in the irregularly shaped flat Bones of the craniofacial skeleton that are too small for an adequate sample. Moreover, the orientation of the trabeculae can vary greatly between adjacent areas, suggesting that regional differences, which cannot be assessed experimentally, may be of great significance in the overall architecture of the Bones. In such cases the best available technique is textural analysis of Bone structure using stereological methods (Cowin, 1985; Goldstein, 1992). Such an analysis of the mandibular condyle of the pig (Teng and Herring, 1995) provided an accurate prediction of actual mechanical properties (Teng and Herring, 1996). One location where analysis of trabecular architecture may help to elucidate loading is the zygomatic arch, a construct of two flat Bones (zygomatic and Squamosal) that are primarily cancellous in growing animals. In addition to providing the origin of the large masseter muscle, the arch mechanically links the tooth-bearing maxilla to the jaw joint and braincase. Loading in the arch is far from simple. A recent in vivo study of strain in the zygomatic arch of the pig (Herring et al., 1996) revealed the surprising finding that the lateral surfaces of the two component Bones are deformed to different degrees and in different directions. Specifically, strain magnitudes were substantially higher in the Squamosal Bone than in the zygomatic, and the axes of the principal strains were rotated approximately 50°. Reasons for this striking variation are not clear. The two Bones of the arch may be loaded differently. Specifically, the Squamosal Bone, but not the zygomatic Bone, may be bent out-of-plane such that its lateral surface becomes more convex. Because strain gauges can be installed only on the lateral surface it is difficult to assess out-of-plane bending. Another possibility is that a relatively less dense and more anisotropic architecture of the Squamosal Bone was responsible for increased and reoriented strain even in the face of the same applied load. The present study on trabecular architecture was undertaken to investigate these possibilities.
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patterns of Bone strain in the zygomatic arch
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 1996Co-Authors: Susa W Herring, Robert J. Mucci, Shengyi Teng, Xiaofeng Huang, Joh A FreemaAbstract:Background The transmission of force through the skull is complicated by the irregular form of the Bones, the interposed sutures, and the multiplicity of loads from the teeth, muscles, and environment. The in vivo relationship between Bone strain and muscle function in the mammalian skull is best investigated empirically. Methods We studied the zygomatic arch of pigs (Sus scrofa) by simultaneous strain gauge recording and electromyography. Seventeen juvenile animals were used, employing multiple strain gauges arranged either in rosettes or strips. Strain was recorded during mastication and muscle stimulations. Bony architecture was examined on sectioned specimens. Results Strain patterns were complex even in this beamlike structure. During masseteric contraction, the more anterior zygomatic Bone showed in-plane bending such that its lower border became more convex, and the major principal strain axis (tension) was parallel to the masseter muscle. The posterior Squamosal Bone was slightly bent in the opposite direction, and the major principal strain was rotated 45–60° from the masseteric line of action. Strain magnitudes in the Squamosal were larger than those in the zygomatic. Woven Bone composing the surface of the arch appeared denser in the zygomatic Bone, where its predominant orientation corresponded with compressive strain. In the Squamosal Bone trabeculae were more regularly arranged, but their orientation did not correspond with strain axes. Conclusions The magnitude differences are probably related to the different architecture of the zygomatic and Squamosal Bones, whereas the different strain patterns primarily reflect the influence of the sutures in selectively damping or transmitting loads. In particular, the zygomatic Bone may be loaded by three-point, distributed-load bending, whereas the Squamosal, loaded at only two points, may be sheared. We conclude that each cranial Bone functions in a unique strain environment, with the sutures serving to redirect loading. © 1996 Wiley-Liss, Inc.
Xiaofeng Huang - One of the best experts on this subject based on the ideXlab platform.
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ontogeny of Bone strain the zygomatic arch in pigs
The Journal of Experimental Biology, 2005Co-Authors: Susa W Herring, Sco C Pederse, Xiaofeng HuangAbstract:SUMMARY At the time of weaning, infant animals have little experience with hard food, and thus their skulls are not likely to be epigenetically adapted for the loads imposed by mastication. We examined Bone strain in the zygomatic arch of 4-week-old weanling piglets. Functional strains in piglets differed from those previously reported for older pigs in that the Squamosal Bone was not bent in the horizontal plane and the principal tensile strain on the zygomatic Bone did not correspond to the direction of masseter muscle pull. Strain patterns were more variable in piglets than in older pigs. In older pigs, masticatory strains can be reproduced by stimulating the masseter muscles. When the piglet masseter was stimulated, strain patterns were more similar to those of older pigs, but shear strain magnitudes were the largest yet recorded from mammalian skull Bones, up to 4000 μϵ. To put these findings in the context of skeletal adaptation, 45 dry skulls, including some animals from the strain study, were measured. Reduced major axis regressions indicated that the infant arch was rounder in cross section and straighter than that of older animals. With growth, the arch became dorsoventrally higher, while mediolateral thickness decreased in the Squamosal Bone. Overall, these changes should make strain more predictable, explaining the lower variability in older animals. Other factors likely to be important in causing unique strain regimes in piglets include (1) unfamiliarity with hard food, (2) greater importance of muscles other than the same-side masseter and (3) greater proximity of molariform teeth to the arch. Collectively, these data indicate that the skeleton is not pre-adapted for specific functional loads.
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patterns of Bone strain in the zygomatic arch
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 1996Co-Authors: Susa W Herring, Robert J. Mucci, Shengyi Teng, Xiaofeng Huang, Joh A FreemaAbstract:Background The transmission of force through the skull is complicated by the irregular form of the Bones, the interposed sutures, and the multiplicity of loads from the teeth, muscles, and environment. The in vivo relationship between Bone strain and muscle function in the mammalian skull is best investigated empirically. Methods We studied the zygomatic arch of pigs (Sus scrofa) by simultaneous strain gauge recording and electromyography. Seventeen juvenile animals were used, employing multiple strain gauges arranged either in rosettes or strips. Strain was recorded during mastication and muscle stimulations. Bony architecture was examined on sectioned specimens. Results Strain patterns were complex even in this beamlike structure. During masseteric contraction, the more anterior zygomatic Bone showed in-plane bending such that its lower border became more convex, and the major principal strain axis (tension) was parallel to the masseter muscle. The posterior Squamosal Bone was slightly bent in the opposite direction, and the major principal strain was rotated 45–60° from the masseteric line of action. Strain magnitudes in the Squamosal were larger than those in the zygomatic. Woven Bone composing the surface of the arch appeared denser in the zygomatic Bone, where its predominant orientation corresponded with compressive strain. In the Squamosal Bone trabeculae were more regularly arranged, but their orientation did not correspond with strain axes. Conclusions The magnitude differences are probably related to the different architecture of the zygomatic and Squamosal Bones, whereas the different strain patterns primarily reflect the influence of the sutures in selectively damping or transmitting loads. In particular, the zygomatic Bone may be loaded by three-point, distributed-load bending, whereas the Squamosal, loaded at only two points, may be sheared. We conclude that each cranial Bone functions in a unique strain environment, with the sutures serving to redirect loading. © 1996 Wiley-Liss, Inc.
Oscar Arribas - One of the best experts on this subject based on the ideXlab platform.
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description of a new endemic species of mountain lizard from northwestern spain iberolacerta galani sp nov squamata lacertidae
Zootaxa, 2006Co-Authors: Oscar Arribas, Salvador Carranza, Gaetano OdiernaAbstract:A new species of Iberolacerta is described from the Montes de Leon (northwest Iberia). This new species, Iberolacerta galani sp. nov., is characterized by its relatively large size, high number of blue ocelli on the shoulders and the relatively frequent contact or near-contact between the supranasal and the first loreal scale, the fairly straight Squamosal Bone (only curved on its posterior part), a unique karyotype in Iberolacerta combining 2n=36 chromosomes, an L-type NOR and differentiated W and Z sex chromosomes, and unique mitochondrial DNA sequences for the cytochrome b and 12S rRNA genes. The correlation analyses show that morphology in general, but especially scalation, is strongly correlated with the amount of precipitation during the months of lizard activity, which suggests that these are not good taxonomic characters, and that other characters apparently independent of the climate like for instance osteological, karyological and DNA features are much more reliable in delimiting species boundaries in Iberolacerta. According to our phylogenetic analyses, I. galani nov. is part of a very well supported clade that originated around 2.5 mya and also includes I. monticola and I. martinezricai. Phylogeny suggests I.martinezricai might be the sister taxon to I. galani nov. from which it split approximately 2 mya, at the beginning of the Pleistocene. The clade containing I. galani nov., I. martinezricai and I. monticola was probably widely distributed across western Iberia during moderately cool and moist phases of the Pleistocene, but it was probably restricted to its present range as a result of the general temperature increase during the Holocene and competition with other lacertid lizards. Iberolacerta galani nov. is endemic to the Montes de Leon, where it is isolated from the other species of the “monticola-group” by the Duero and Mino-Sil Rivers, but particularly by the Bibei river valley.
Odierna Gaetano - One of the best experts on this subject based on the ideXlab platform.
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FIGURE 6 in Description of a new endemic species of mountain lizard from Northwestern Spain: Iberolacerta galani sp. nov. (Squamata: Lacertidae)
2018Co-Authors: Arribas Oscar, Carranza Salvador, Odierna GaetanoAbstract:FIGURE 6. Morphology of the Squamosal Bone in Iberolacerta. Iberolacerta galani nov. (represented in black) has a fairly straight Squamosal in comparison with the more gradually incurved ones of the other Iberolacerta spp. 1) I. monticola (male) from Sª Estrela; 2) I. monticola (female) from Sª Estrela; 3) I. monticola (female) from Sª Caurel; 4) I. monticola (female) from Pto. de las Señales; 5) I. monticola (male) from Somiedo; 6) I. monticola (male) from Somiedo; 7) I. monticola (female) from Cabeza de Manzaneda. 8) I. galani nov. (male) from Sanabria; 9) I. galani nov. (female) from Sanabria. 10) I. cyreni (male) from Pto. de Navacerrada; 11) I. cyreni (male) from Gredos; 12) I. cyreni (male) from Gredos; 13) I. martinezricai (female) from Las Batuecas.; 14) I. martinezricai (female) from las Batuecas; 15) I. aurelioi (female) from Coma Pedrosa (Andorra); 16) I. bonnali (male) from Bigorre; 17) I. aranica (female) from Mauberme massif; 18) I. horvathi (female) from Udine (Italy)