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Sabine Glienke - One of the best experts on this subject based on the ideXlab platform.
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A new “microsaur” (Amphibia; Lepospondyli) from the Rotliegend of the Saar–Palatinate Region (Carboniferous/Permian transition; West Germany)
Paläontologische Zeitschrift, 2012Co-Authors: Sabine GlienkeAbstract:Altenglanerpeton schroederi n. sp. is documented by a skeleton preserved in dorsal view from the Altenglan Formation of the Saar–Nahe Basin. The only known species of this new genus has a massive skull that is slightly longer than wide with a more or less triangular outline, without traces of lateral-line canals, with a small round orbit, very wide Interorbital Region, and the jugal extending far in front of the orbit. The long, undifferentiated trunk Region comprises at least 30 lepospondylous presacral vertebrae. The pelvic girdle, hind limbs, and tail are not preserved. The forelimb is small and poorly ossified. The cladogram supports placement of Altenglanerpeton in the Recumbirostra. The new genus seems closest to Tambaroter , the Goniorhynchidae, and Brachystelechidae, with the largest number of morphological similarities shared with the Ostodolepidae, particularly with Micraroter and Pelodosotis . Altenglanerpeton schroederi n. sp. ist durch ein von der Dorsalseite erhaltenes Exemplar aus der Altenglan-Formation des Saar–Nahe-Beckens überliefert. Die einzige Art dieser neuen Gattung besitzt einen massiven Schädel, kaum länger als breit mit annähernd dreieckigem Umriss, ohne Anzeichen für Seitenlinien, mit kleiner rundlicher Orbita, sehr breiter InterorbitalRegion und bis weit vor die Orbita reichendem Jugale. Der lange undifferenzierte Rumpf umfasst mindestens 30 lepospondyle Präsakralwirbel. Becken, Hinterextremität und Schwanz sind nicht erhalten. Die Vorderextremität ist klein und schwach verknöchert. Das Kladogramm zeigt, dass Altenglanerpeton innerhalb der Recumbirostra dem Tambaroter sowie den Goniorhynchidae und Brachystelechidae am nächsten steht. Die meisten morphologischen Gemeinsamkeiten bestehen mit den Ostodolepiden Micraroter und Pelodosotis .
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A new “microsaur” (Amphibia; Lepospondyli) from the Rotliegend of the Saar–Palatinate Region (Carboniferous/Permian transition; West Germany)
Palaeontologische Zeitschrift, 2012Co-Authors: Sabine GlienkeAbstract:Altenglanerpetonschroederi n. sp. is documented by a skeleton preserved in dorsal view from the Altenglan Formation of the Saar–Nahe Basin. The only known species of this new genus has a massive skull that is slightly longer than wide with a more or less triangular outline, without traces of lateral-line canals, with a small round orbit, very wide Interorbital Region, and the jugal extending far in front of the orbit. The long, undifferentiated trunk Region comprises at least 30 lepospondylous presacral vertebrae. The pelvic girdle, hind limbs, and tail are not preserved. The forelimb is small and poorly ossified. The cladogram supports placement of Altenglanerpeton in the Recumbirostra. The new genus seems closest to Tambaroter, the Goniorhynchidae, and Brachystelechidae, with the largest number of morphological similarities shared with the Ostodolepidae, particularly with Micraroter and Pelodosotis.
Callum F. Ross - One of the best experts on this subject based on the ideXlab platform.
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In vivo function of the craniofacial haft: the Interorbital "pillar".
American Journal of Physical Anthropology, 2020Co-Authors: Callum F. RossAbstract:The craniofacial haft resists forces gener- ated in the face during feeding, but the importance of these forces for the form of the craniofacial haft remains to be determined. In vivo bone strain data were recorded from the medial orbital wall in an owl monkey (Aotus), rhesus macaques (Macaca mulatta), and a galago (Otole- mur) during feeding. These data were used to determine whether: the Interorbital Region can be modeled as a sim- ple beam under bending or shear; the face is twisting on the brain case during unilateral biting or mastication; the Interorbital "pillar" is being axially compressed during incisor loading and both axially compressed and laterally bent during mastication; and the Interorbital "pillar" transmits axial compressive forces from the toothrow to the braincase. The strain data reveal that the Interorbital Region can- not be modeled as a anteroposteriorly oriented beam bent superiorly in the sagittal plane during incision or masti- cation. The strain orientations recorded in the majority of experiments are concordant with those predicted for a short beam under shear, although the anthropoids dis- played evidence of multiple loading regimes in the medial orbital wall. Strain orientation data corroborate the hy- pothesis that the strepsirrhine face is twisted during mas- tication. The hypothesis that the Interorbital Region is a member in a rigid frame subjected to axial compression during mastication receives some support. The hypothesis that the Interorbital Region is a member in a rigid frame subjected to lateral bending during mastication is sup- ported by the e1/|e2| ratio data but not by the strain orientation data. The timing of peak shear strains in the medial orbital wall of anthropoids does not bear a consis- tent relationship to the timing of peak shear strain in the mandibular corpus, suggesting that bite force is not the only external force influencing the medial orbital wall. Strain orientation data suggest the existence of two dis- tinct loading regimes, possibly associated with masseter or medial pterygoid contraction. Regardless of the loading regime, all taxa showed low strain magnitudes in the medial orbital wall relative to the anterior root of the zygoma and the mandibular corpus. The strain gradients documented here and elsewhere suggest that, in anthro- poids at least, local effects of external forces are more important than a single global loading regime. The low strain magnitudes in the medial orbital wall and in other thin bony plates around the orbit suggest that these struc- tures are not optimally designed for resisting feeding forces. It is hypothesized that their function is to provide rigid support and protection for soft-tissue structures such as the nasal epithelium, the brain, meninges, and the eye and its adnexa. In contrast with the face of Otolemur, which appears to be subjected to a single predominant loading regime, anthropoids may experience different loading regimes in different parts of the face. This implies that the anthropoid and strepsirrhine facial skulls might be optimized for different functions. Am J Phys Anthropol 116:108 -139, 2001. © 2001 Wiley-Liss, Inc.
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In vivo and in vitro bone strain in the owl monkey circumorbital Region and the function of the postorbital septum.
American Journal of Physical Anthropology, 1996Co-Authors: Callum F. Ross, William L. HylanderAbstract:Anthropoids and tarsiers are the only vertebrates possessing a postorbital septum. This septum, formed by the frontal, alisphenoid, and zygomatic bones, separates the orbital contents from the temporal muscles. Three hypotheses suggest that the postorbital septum evolved to resist stresses acting on the skull during mastication or incision. The facial-torsion hypothesis posits that the septum resists twisting of the face about a rostrocaudal axis during unilateral mastication; the transverse-bending hypothesis argues that the septum resists caudally directed forces acting at the lateral orbital margin during mastication or incision; and the tension hypothesis suggests that the septum resists ventrally directed components of masseter muscle force during mastication and incision. This study evaluates these hypotheses using in vitro and in vivo bone strain data recorded from the circumorbital Region of owl monkeys. Incisor loading of an owl monkey skull in vitro bends the face upward in the sagittal plane, compressing the Interorbital Region rostrocaudally and buckling the lateral orbital walls. Unilateral loading of the toothrow in vitro also bends the face in the sagittal plane, compressing the Interorbital Region rostrocaudally and buckling the working side lateral orbital wall. When the lateral orbital wall is partially cut, so as to reduce the width of its attachment to the braincase, the following changes in circumorbital bone strain patterns occur. During loading of the incisors, lower bone strain magnitudes are recorded in the Interorbital Region and lateral orbital walls. In contrast, during unilateral loading of the P 3 , higher bone strain magnitudes are observed in the Interorbital Region, and generally lower bone strain magnitudes are observed in the lateral orbital walls. During unilateral loading of the M 2 , higher bone strain magnitudes are observed in both the Interorbital Region and in the lateral orbital wall ipsilateral to the loaded molar. Comparisons of the in vitro results with data gathered in vivo suggest that, during incision and unilateral mastication, the face is subjected to upward bending in the sagittal plane resulting in rostrocaudal compression of the Interorbital Region. Modeling the lateral orbital walls as curved plates suggests that during mastication the working side wall is buckled due to the dorsally directed component of the maxillary bite force which causes upward bending of the face in the sagittal plane. The balancing side lateral orbital wall may also be buckled due to upward bending of the face in the sagittal plane as well as being twisted by the caudoventrally directed components of the superficial masseter muscle force. The in vivo data do not exclude the possibility that the postorbital septum functions to improve the structural integrity of the postorbital bar during mastication. However, there is no reason to believe that a more robust postorbital bar could not also perform this function. Hypotheses stating that the postorbital septum originally evolved to reinforce the skull against routine masticatory loads must explain why, rather than evolving a postorbital septum, the stem anthropoids did not simply enlarge their postorbital bars.
Martin Pickford - One of the best experts on this subject based on the ideXlab platform.
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New reconstruction of the moroto hominoid snout and a reassessment of its affinities toAfropithecus turkanensis
Human Evolution, 2020Co-Authors: Martin PickfordAbstract:Two previous reconstructions of the Moroto hominoid palate and face made during the late 1960s suffer from several errors, in particular the angle at which the facial skeleton was hafted onto the palate, and the orientation of the canines, among others. A new reconstruction is based on the discovery that there is a good contact about 1cm logn between the palatal and facial pieces, which reveals that the snout was low and elongated as inAfropithecus turkanensis. Addition of a fragment of the right orbit reveals that the Interorbital Region was wide as inA. turkanensis. The remaining differences between the skulls from Moroto and Kalodirr are due to five factors:−1) pathology of the Moroto right premaxilla following ante-mortem loss of the right I1, which led to abnormal enlargement of the right half of the nasal cavity, 2) the incisive foramina of the Moroto palate are damaged, making them appear considerably larger than they were in life, 3) damage to the upper portions of the nasal aperture making it look higher than it would in life, 4) plastic deformation and crushing of the Kalodirr specimen has greatly reduced the width of the palate and has led to the cheek tooth rows converging to the rear, and 5) the slightly larger and ontogenetically older status of the Moroto individual.
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New reconstruction of the moroto hominoid snout and a reassessment of its affinities toAfropithecus turkanensis
Human Evolution, 2002Co-Authors: Martin PickfordAbstract:Two previous reconstructions of the Moroto hominoid palate and face made during the late 1960s suffer from several errors, in particular the angle at which the facial skeleton was hafted onto the palate, and the orientation of the canines, among others. A new reconstruction is based on the discovery that there is a good contact about 1cm logn between the palatal and facial pieces, which reveals that the snout was low and elongated as in Afropithecus turkanensis . Addition of a fragment of the right orbit reveals that the Interorbital Region was wide as in A. turkanensis . The remaining differences between the skulls from Moroto and Kalodirr are due to five factors:−1) pathology of the Moroto right premaxilla following ante-mortem loss of the right I^1, which led to abnormal enlargement of the right half of the nasal cavity, 2) the incisive foramina of the Moroto palate are damaged, making them appear considerably larger than they were in life, 3) damage to the upper portions of the nasal aperture making it look higher than it would in life, 4) plastic deformation and crushing of the Kalodirr specimen has greatly reduced the width of the palate and has led to the cheek tooth rows converging to the rear, and 5) the slightly larger and ontogenetically older status of the Moroto individual. Resemblances between the Moroto and Kalodirr specimens far outweight the purported or real differences and it is concluded that Morotopithecus bishopi is a junior subjective synonym of Afropithecus turkanensis . The sites of Moroto and Kalodirr are unlikely to differ greatly in age (certainly not as much as 4 Ma).
Ying-yong Wang - One of the best experts on this subject based on the ideXlab platform.
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Description of a new species of Gracixalus (Amphibia: Anura: Rhacophoridae) from Guangdong Province, southeastern China
Zootaxa, 2018Co-Authors: Jian Wang, Zhao-chi Zeng, Ying-yong WangAbstract:A new species of tree frog, G. guangdongensis sp nov., is described based on a series of specimens collected from Dawuling Forest Station, Mount Nankun and Nanling Nature Reserve of Guangdong Province, southeastern China. The new species is distinguished from all known congeners by a significant genetic divergence at the mitochondrial 16S rRNA gene fragment examined ( p -distance ≥ 4.6%) and the following combination of morphological characters: relatively small body size (SVL 26.1–34.7 mm in adult males, 34.9–35.4 mm in adult females); upper eyelid and dorsum lacking spines; supratympanic fold and tympanum distinct; dorsal and lateral surface rough, sparsely scattered with tubercles; ventral skin granular; tibiotarsal projection absent; toe-webbing moderately developed, finger webbing rudimentary; heels slightly overlapping when flexed hindlimbs are held at right angles to the body axis; brown to beige above, with an inverse Y-shaped dark brown marking extendeing from the Interorbital Region to the centre of the dorsum; males with a single subgular vocal sac and protruding nuptial pads with minute granules on the dorsal surface of the base of first finger. The discovery and description of Gracixalus guangdongensis sp. nov. represents the 14 th species known in this genus.
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A new species of the genus Gracixalus (Amphibia: Anura: Rhacophoridae) from Mount Jinggang, southeastern China
Zootaxa, 2017Co-Authors: Zhao-chi Zeng, Jian Zhao, Chun-quan Chen, Guoling Chen, Zhong Zhang, Ying-yong WangAbstract:A new species, Gracixalus jinggangensis sp. nov., is described based on a series of specimens collected from Mount Jinggang, Jiangxi Province, southeastern China. The new species is distinguished from all other known congeners by the following combination of morphological characters: relatively small body size, SVL 27.9–33.8 mm in nine males and 31.6 mm in a single female; upper eyelid and dorsum lacking spines; skin of dorsal and lateral surface of head, body and limbs rough with sparsely scattered with tubercles; ventral skin granular; tibiotarsal projection absent; finger webbing rudimentary; toes with moderately developed webbing; brown to beige above in life, with an inverse Y-shaped dark brown marking extending from the Interorbital Region to the middle of dorsum; males with a single, subgular vocal sac, barely visible nuptial pads with minute granules on the dorsal surface of the bases of first and second fingers. The new species is also genetically divergent from all other Gracixalus for which comparable 16S rRNA gene sequences are available. The discovery of Gracixalus jinggangensis sp. nov. represents the twelfth known species in the genus.
Joseph T. Eastman - One of the best experts on this subject based on the ideXlab platform.
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New species of Pogonophryne (Pisces, Artedidraconidae) from the Bellingshausen Sea, Antarctica
Polar Biology, 2008Co-Authors: Richard R. Eakin, Joseph T. Eastman, Jesús MatallanasAbstract:A new species of notothenioid fish, Pogonophryne bellingshausenensis n. sp., is described from the Bellingshausen Sea, Antarctica. The new species belongs to the dorsally-spotted “mentella” group of the genus and is characterized by having a short (about 13% SL) mental barbel with a short (about 16% of barbel length), narrow (barely wider than the stalk), and relatively inconspicuous terminal expansion composed of short, irregular, fingerlike processes. Compared to most other dorsally-spotted species of Pogonophryne (“barsukovi”, “marmorata”, and “mentella” groups), P . bellingshausenensis has a relatively wide (about 7% SL) Interorbital Region. An unspotted patch on the median dorsal surface of the head, posterior to the posttemporal ridges and anterior to the first dorsal fin, has not been observed previously in any dorsally-spotted species. The holotype was collected at 1,947 m, one of the deepest records for any species of Pogonophryne . A revised key to the ten species of the “mentella” group of Pogonophryne is also provided.
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New Species of Pogonophryne (Pisces, Artedidraconidae) from the Ross Sea, Antarctica
Copeia, 1998Co-Authors: Richard R. Eakin, Joseph T. EastmanAbstract:A new species of notothenioid fish, Pogonophryne cerebropogon n. sp., is described from the Ross Sea, Antarctica. The new species belongs to the dorsally spotted group of the genus and is characterized by having a brainlike terminal expansion on the long, bicolored mental barbel (23% SL, about twice as long as the barbels of other species with brainlike terminal expansions) and a very wide (7.6% SL vs about 47% SL for all other dorsally spotted species) Interorbital Region. This species has a greatly depressed head. The oral valves bear palmate papillae. The 7.6 m wide Marinovich Gulf Coast style trawl used in capturing this specimen was particularly effective compared to the small Blake trawls typically employed in the area. A REAS of the Southern Ocean thought to be well sampled, like the southwestern Ross Sea, continue to yield distinctive new species. Among the notothenioids collected during Cruise 96-6 of the R/V NATHANIEL B. PALMER is a specimen representing an undescribed species belonging to the dorsally spotted group of Pogonophryne (Artedidraconidae). A description of the new species is provided. The genus is currently under extensive revision (Balushkin and Eakin, 1998), and descriptions of additional species and keys are forthcoming.
