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Juan Luis Arsuaga - One of the best experts on this subject based on the ideXlab platform.
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the Bony Labyrinth in the aroeira 3 middle pleistocene cranium
Journal of Human Evolution, 2018Co-Authors: Mercedes Condevalverde, Ignacio Martínez, Juan Luis Arsuaga, Rolf Quam, Joan Daura, Montserrat Sanz, Joao ZilhaoAbstract:Abstract The discovery of a partial cranium at the site of Aroeira (Portugal) dating to 389–436 ka augments the current sample of Middle Pleistocene European crania and makes this specimen penecontemporaneous with the fossils from the geographically close Atapuerca Sima de los Huesos (SH) and Arago sites. A recent study of the cranium documented a unique combination of primitive and derived features. The Aroeira 3 cranium preserves the right temporal bone, including the petrosal portion. Virtual reconstruction of the Bony Labyrinth from μCT scans provides an opportunity to examine its morphology. A series of standard linear and angular measures of the semicircular canals and cochlea in Aroeira 3 were compared with other fossil hominins and recent humans. Our analysis has revealed the absence of derived Neandertal features in Aroeira 3. In particular, the specimen lacks both the derived canal proportions and the low position of the posterior canal, two of the most diagnostic features of the Neandertal Bony Labyrinth, and Aroeira 3 is more primitive in these features than the Atapuerca (SH) sample. One potentially derived feature (low shape index of the cochlear basal turn) is shared between Aroeira 3 and the Atapuerca (SH) hominins, but is absent in Neandertals. The results of our study provide new insights into Middle Pleistocene population dynamics close to the origin of the Neandertal clade. In particular, the contrasting inner ear morphology between Aroeira 3 and the Atapuerca (SH) hominins suggests a degree of demographic isolation, despite the close geographic proximity and similar age of these two sites.
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The Bony Labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain)
Journal of Human Evolution, 2016Co-Authors: Rolf Quam, Ana Gracia-téllez, Ignacio Martínez, Carlos Lorenzo, Juan Luis ArsuagaAbstract:We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm < APA), posterior surface of the petrous pyramid (LSCm > PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
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the Bony Labyrinth of the middle pleistocene sima de los huesos hominins sierra de atapuerca spain
Journal of Human Evolution, 2016Co-Authors: Ignacio Martínez, Rolf Quam, Carlos Lorenzo, Ana Graciatellez, Juan Luis ArsuagaAbstract:Abstract We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm PPp), and third part of the facial canal (LSCm Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
Rolf Quam - One of the best experts on this subject based on the ideXlab platform.
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the Bony Labyrinth in the aroeira 3 middle pleistocene cranium
Journal of Human Evolution, 2018Co-Authors: Mercedes Condevalverde, Ignacio Martínez, Juan Luis Arsuaga, Rolf Quam, Joan Daura, Montserrat Sanz, Joao ZilhaoAbstract:Abstract The discovery of a partial cranium at the site of Aroeira (Portugal) dating to 389–436 ka augments the current sample of Middle Pleistocene European crania and makes this specimen penecontemporaneous with the fossils from the geographically close Atapuerca Sima de los Huesos (SH) and Arago sites. A recent study of the cranium documented a unique combination of primitive and derived features. The Aroeira 3 cranium preserves the right temporal bone, including the petrosal portion. Virtual reconstruction of the Bony Labyrinth from μCT scans provides an opportunity to examine its morphology. A series of standard linear and angular measures of the semicircular canals and cochlea in Aroeira 3 were compared with other fossil hominins and recent humans. Our analysis has revealed the absence of derived Neandertal features in Aroeira 3. In particular, the specimen lacks both the derived canal proportions and the low position of the posterior canal, two of the most diagnostic features of the Neandertal Bony Labyrinth, and Aroeira 3 is more primitive in these features than the Atapuerca (SH) sample. One potentially derived feature (low shape index of the cochlear basal turn) is shared between Aroeira 3 and the Atapuerca (SH) hominins, but is absent in Neandertals. The results of our study provide new insights into Middle Pleistocene population dynamics close to the origin of the Neandertal clade. In particular, the contrasting inner ear morphology between Aroeira 3 and the Atapuerca (SH) hominins suggests a degree of demographic isolation, despite the close geographic proximity and similar age of these two sites.
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The Bony Labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain)
Journal of Human Evolution, 2016Co-Authors: Rolf Quam, Ana Gracia-téllez, Ignacio Martínez, Carlos Lorenzo, Juan Luis ArsuagaAbstract:We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm < APA), posterior surface of the petrous pyramid (LSCm > PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
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the Bony Labyrinth of the middle pleistocene sima de los huesos hominins sierra de atapuerca spain
Journal of Human Evolution, 2016Co-Authors: Ignacio Martínez, Rolf Quam, Carlos Lorenzo, Ana Graciatellez, Juan Luis ArsuagaAbstract:Abstract We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm PPp), and third part of the facial canal (LSCm Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
Loic Costeur - One of the best experts on this subject based on the ideXlab platform.
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the Bony Labyrinth of toothed whales reflects both phylogeny and habitat preferences
Scientific Reports, 2018Co-Authors: Loic Costeur, Eric G. Ekdale, Camille Grohé, Bert Muller, Georg Schulz, Gabriel Aguirrefernandez, Bastien MennecartAbstract:The inner ear of toothed whales (odontocetes) is known to have evolved particular shapes related to their abilities to echolocate and move under water. While the origin of these capacities is now more and more examined, thanks to new imaging techniques, little is still known about how informative inner ear shape could be to tackle phylogenetic issues or questions pertaining to the habitat preferences of extinct species. Here we show that the shape of the Bony Labyrinth of toothed whales provides key information both about phylogeny and habitat preferences (freshwater versus coastal and fully marine habitats). Our investigation of more than 20 species of extinct and modern odontocetes shows that the semi-circular canals are not very informative, in contrast to baleen whales, while the cochlea alone bears a strong signal. Inner ear shape thus provides a novel source of information to distinguish between morphologically convergent lineages (e.g. river dolphins).
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The first French tragulid skull (Mammalia, Ruminantia, Tragulidae) and associated tragulid remains from the Middle Miocene of Contres (Loir-et-Cher, France)
Comptes Rendus Palevol, 2017Co-Authors: Bastien Mennecart, Gertrud E Rossner, Adrien De Perthuis, Jonathan A. Guzmán, Loic CosteurAbstract:Abstract The Faluns Auger quarry (Contres, France) is famous for its Langhian mammal fauna (MN5) and tragulid remains have been identified as Dorcatherium sp. New excavations provided a fragmented skull of a tragulid, dental remains, and a metapodium which we describe here. Based on morphological and morphometrical characters, these specimens are attributed to Dorcatherium crassum. CT-scans provide insight in the petrosal bone and Bony Labyrinth. We prove intra-population variability of the p4 and intra-specific variability of the Bony Labyrinth. Nevertheless, we can demonstrate that the Bony Labyrinth is useful for systematics. Thus, we confirm the presence of D. crassum in the Pontlevoy–Thenay and Savigne-sur-Lathan Faluns Basins as reported already prior to our study. Yet, we cannot confirm evidence for Dorcatherium naui. D. naui specimens reported from these basins may belong to another species. D. naui should be absent from the Faluns before MN7, such as in the rest of Europe.
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A Dolphin Fossil Ear Bone from the Northern Neotropics—Insights into Habitat Transitions in Iniid Evolution
Journal of Vertebrate Paleontology, 2017Co-Authors: Gabriel Aguirre-fernández, Marcelo R. Sánchez-villagra, Bastien Mennecart, Rodolfo Sánchez, Loic CosteurAbstract:ABSTRACTAn iniid fossil (Cetacea, Odontoceti) is reported based on a periotic found in the Codore Formation (late Miocene to middle Pliocene) of northwestern Venezuela. The marine sediments where the Codore dolphin was collected have yielded another cetacean and a diverse elasmobranch fauna. Cladistic analysis indicates a close relationship between the Codore dolphin and the extant Amazon River dolphin (Inia geoffrensis); key characteristics include a large cochlear portion that is dorsoventrally compressed and the extremely small size of the posterior process. High-resolution micro-computed tomography scans were used for the description and analysis of the Bony Labyrinth endocast. Geometric morphometric analysis of the Bony Labyrinth endocast places the Codore dolphin as intermediate between the La Plata dolphin (Pontoporia blainvillei) and Inia geoffrensis (principal component 1), but distinctive from both extant species (principal component 2). Comparisons of the depositional environment with cladistic...
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prenatal growth stages show the development of the ruminant Bony Labyrinth and petrosal bone
Journal of Anatomy, 2017Co-Authors: Loic Costeur, Bastien Mennecart, Bert Muller, Georg SchulzAbstract:: Foetuses are a source of scientific information to understand the development and evolution of anatomical structures. The Bony Labyrinth, surrounding the organ of balance and hearing, is a phylogenetically and ecologically informative structure for which still little concerning growth and shape variability is known in many groups of vertebrates. Except in humans, it is poorly known in many other placentals and its prenatal growth has almost never been studied. Ruminants are a diversified group of placentals and represent an interesting case study to understand the prenatal growth of the ear region. We computed tomography -scanned five cow foetuses and an adult petrosal bone (Bos taurus, Artiodactyla, Mammalia), and describe the Bony Labyrinth when already ossified. The foetuses encompass the second half of the 9.3-month-long gestation period of the cow. They were sampled at different ontogenetic stages to understand how and when the petrosal bone and Bony Labyrinth ossify in ruminants. The petrosal bone and Bony Labyrinth ossify within about 20 days in the fourth month of gestation. The Bony Labyrinth is already fully ossified at least in the 6th month, while only the cochlea, most of the vestibule and the common crus are already ossified at the beginning of the 4th month. The pars canalicularis of the petrosal thus ossifies at last. The size and volume of the Bony Labyrinth stay similar from the 6th month (possibly even from the 5th). From the end of the 4th month of gestation, a progressive lengthening of the cochlear aqueduct and endolymphatic sac occurs, culminating in the adult form and partly explaining the larger volume of the later. The inner ear in the cow ossifies quickly during the gestation period, being fully ossified around mid-gestation time, as in humans. The adult size and most of its volume are reached by mid-gestation time while the petrosal bone and skull still grow. A negative ontogenetic allometry between the Bony Labyrinth and the petrosal bone and skull is thus observed. It matches the evolutionary negative allometry of the structure observed in earlier studies. Few changes occur after ossification is achieved; only open structures (i.e. cochlear aqueduct and endolymphatic sac) continue to grow after birth and reflect size increase of the petrosal bone.
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the petrosal bone and Bony Labyrinth of early to middle miocene european deer mammalia cervidae reveal their phylogeny
Journal of Morphology, 2016Co-Authors: Bastien Mennecart, Bert Muller, Georg Schulz, Daniel Demiguel, Gertrud E Rossner, Gregoire Metais, Loic CosteurAbstract:Deer (Cervidae) have a long evolutionary history dating back to the Early Miocene, around 19 million years ago. The best known fossils to document this history belong to European taxa, which all bear cranial appendages more or less similar to today's deer antlers. Despite the good fossil record, relationships of the earliest stem deer and earliest crown deer are much debated. This hampers precise calibration against the independent evidence of the fossil record in molecular clock analyses. While much has been written on the Early and Middle Miocene deer, only two phylogenetic analyses have been performed on these taxa to date mostly based on cranial appendage characters. Because the petrosal bone and Bony Labyrinth have been shown to be relevant for phylogeny in ruminants, we describe for the first time these elements for four iconic early cervids from Europe (Procervulus dichotomus, Heteroprox larteti, Dicrocerus elegans and Euprox furcatus) and include them in a phylogenetic analysis based on the ear region exclusively. The analysis recovered E. furcatus in a sister position to the living red deer (Cervus elaphus). Further, it placed D. elegans in a sister position to Euprox+Cervus and a clade Procervulinae that includes P. dichotomus and H. larteti, in sister position to all other deer. The inclusion of E. furcatus in crown Cervidae, which was previously suggested based on antler morphology, cannot be ruled out here but needs a more comprehensive comparison to other crown deer to be confirmed. J. Morphol. 277:1329-1338, 2016. (c) 2016 Wiley-Blackwell.
Bastien Mennecart - One of the best experts on this subject based on the ideXlab platform.
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the Bony Labyrinth of toothed whales reflects both phylogeny and habitat preferences
Scientific Reports, 2018Co-Authors: Loic Costeur, Eric G. Ekdale, Camille Grohé, Bert Muller, Georg Schulz, Gabriel Aguirrefernandez, Bastien MennecartAbstract:The inner ear of toothed whales (odontocetes) is known to have evolved particular shapes related to their abilities to echolocate and move under water. While the origin of these capacities is now more and more examined, thanks to new imaging techniques, little is still known about how informative inner ear shape could be to tackle phylogenetic issues or questions pertaining to the habitat preferences of extinct species. Here we show that the shape of the Bony Labyrinth of toothed whales provides key information both about phylogeny and habitat preferences (freshwater versus coastal and fully marine habitats). Our investigation of more than 20 species of extinct and modern odontocetes shows that the semi-circular canals are not very informative, in contrast to baleen whales, while the cochlea alone bears a strong signal. Inner ear shape thus provides a novel source of information to distinguish between morphologically convergent lineages (e.g. river dolphins).
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The first French tragulid skull (Mammalia, Ruminantia, Tragulidae) and associated tragulid remains from the Middle Miocene of Contres (Loir-et-Cher, France)
Comptes Rendus Palevol, 2017Co-Authors: Bastien Mennecart, Gertrud E Rossner, Adrien De Perthuis, Jonathan A. Guzmán, Loic CosteurAbstract:Abstract The Faluns Auger quarry (Contres, France) is famous for its Langhian mammal fauna (MN5) and tragulid remains have been identified as Dorcatherium sp. New excavations provided a fragmented skull of a tragulid, dental remains, and a metapodium which we describe here. Based on morphological and morphometrical characters, these specimens are attributed to Dorcatherium crassum. CT-scans provide insight in the petrosal bone and Bony Labyrinth. We prove intra-population variability of the p4 and intra-specific variability of the Bony Labyrinth. Nevertheless, we can demonstrate that the Bony Labyrinth is useful for systematics. Thus, we confirm the presence of D. crassum in the Pontlevoy–Thenay and Savigne-sur-Lathan Faluns Basins as reported already prior to our study. Yet, we cannot confirm evidence for Dorcatherium naui. D. naui specimens reported from these basins may belong to another species. D. naui should be absent from the Faluns before MN7, such as in the rest of Europe.
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Bony Labyrinth morphology clarifies the origin and evolution of deer
Scientific Reports, 2017Co-Authors: Bastien Mennecart, Georg Schulz, Daniel Demiguel, Faysal Bibi, Gertrud E Rossner, Gregoire Metais, James M Neenan, Shiqi Wang, Bert MullerAbstract:Deer are an iconic group of large mammals that originated in the Early Miocene of Eurasia (ca. 19 Ma). While there is some consensus on key relationships among their members, on the basis of molecular- or morphology-based analyses, or combined approaches, many questions remain, and the Bony Labyrinth has shown considerable potential for the phylogenetics of this and other groups. Here we examine its shape in 29 species of living and fossil deer using 3D geometric morphometrics and cladistics. We clarify several issues of the origin and evolution of cervids. Our results give new age estimates at different nodes of the tree and provide for the first time a clear distinction of stem and crown Cervidae. We unambiguously attribute the fossil Euprox furcatus (13.8 Ma) to crown Cervidae, pushing back the origin of crown deer to (at least) 4 Ma. Furthermore, we show that Capreolinae are more variable in Bony Labyrinth shape than Cervinae and confirm for the first time the monophyly of the Old World Capreolinae (including the Chinese water deer Hydropotes) based on morphological characters only. Finally, we provide evidence to support the sister group relationship of Megaloceros giganteus with the fallow deer Dama.
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A Dolphin Fossil Ear Bone from the Northern Neotropics—Insights into Habitat Transitions in Iniid Evolution
Journal of Vertebrate Paleontology, 2017Co-Authors: Gabriel Aguirre-fernández, Marcelo R. Sánchez-villagra, Bastien Mennecart, Rodolfo Sánchez, Loic CosteurAbstract:ABSTRACTAn iniid fossil (Cetacea, Odontoceti) is reported based on a periotic found in the Codore Formation (late Miocene to middle Pliocene) of northwestern Venezuela. The marine sediments where the Codore dolphin was collected have yielded another cetacean and a diverse elasmobranch fauna. Cladistic analysis indicates a close relationship between the Codore dolphin and the extant Amazon River dolphin (Inia geoffrensis); key characteristics include a large cochlear portion that is dorsoventrally compressed and the extremely small size of the posterior process. High-resolution micro-computed tomography scans were used for the description and analysis of the Bony Labyrinth endocast. Geometric morphometric analysis of the Bony Labyrinth endocast places the Codore dolphin as intermediate between the La Plata dolphin (Pontoporia blainvillei) and Inia geoffrensis (principal component 1), but distinctive from both extant species (principal component 2). Comparisons of the depositional environment with cladistic...
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prenatal growth stages show the development of the ruminant Bony Labyrinth and petrosal bone
Journal of Anatomy, 2017Co-Authors: Loic Costeur, Bastien Mennecart, Bert Muller, Georg SchulzAbstract:: Foetuses are a source of scientific information to understand the development and evolution of anatomical structures. The Bony Labyrinth, surrounding the organ of balance and hearing, is a phylogenetically and ecologically informative structure for which still little concerning growth and shape variability is known in many groups of vertebrates. Except in humans, it is poorly known in many other placentals and its prenatal growth has almost never been studied. Ruminants are a diversified group of placentals and represent an interesting case study to understand the prenatal growth of the ear region. We computed tomography -scanned five cow foetuses and an adult petrosal bone (Bos taurus, Artiodactyla, Mammalia), and describe the Bony Labyrinth when already ossified. The foetuses encompass the second half of the 9.3-month-long gestation period of the cow. They were sampled at different ontogenetic stages to understand how and when the petrosal bone and Bony Labyrinth ossify in ruminants. The petrosal bone and Bony Labyrinth ossify within about 20 days in the fourth month of gestation. The Bony Labyrinth is already fully ossified at least in the 6th month, while only the cochlea, most of the vestibule and the common crus are already ossified at the beginning of the 4th month. The pars canalicularis of the petrosal thus ossifies at last. The size and volume of the Bony Labyrinth stay similar from the 6th month (possibly even from the 5th). From the end of the 4th month of gestation, a progressive lengthening of the cochlear aqueduct and endolymphatic sac occurs, culminating in the adult form and partly explaining the larger volume of the later. The inner ear in the cow ossifies quickly during the gestation period, being fully ossified around mid-gestation time, as in humans. The adult size and most of its volume are reached by mid-gestation time while the petrosal bone and skull still grow. A negative ontogenetic allometry between the Bony Labyrinth and the petrosal bone and skull is thus observed. It matches the evolutionary negative allometry of the structure observed in earlier studies. Few changes occur after ossification is achieved; only open structures (i.e. cochlear aqueduct and endolymphatic sac) continue to grow after birth and reflect size increase of the petrosal bone.
Ignacio Martínez - One of the best experts on this subject based on the ideXlab platform.
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the Bony Labyrinth in the aroeira 3 middle pleistocene cranium
Journal of Human Evolution, 2018Co-Authors: Mercedes Condevalverde, Ignacio Martínez, Juan Luis Arsuaga, Rolf Quam, Joan Daura, Montserrat Sanz, Joao ZilhaoAbstract:Abstract The discovery of a partial cranium at the site of Aroeira (Portugal) dating to 389–436 ka augments the current sample of Middle Pleistocene European crania and makes this specimen penecontemporaneous with the fossils from the geographically close Atapuerca Sima de los Huesos (SH) and Arago sites. A recent study of the cranium documented a unique combination of primitive and derived features. The Aroeira 3 cranium preserves the right temporal bone, including the petrosal portion. Virtual reconstruction of the Bony Labyrinth from μCT scans provides an opportunity to examine its morphology. A series of standard linear and angular measures of the semicircular canals and cochlea in Aroeira 3 were compared with other fossil hominins and recent humans. Our analysis has revealed the absence of derived Neandertal features in Aroeira 3. In particular, the specimen lacks both the derived canal proportions and the low position of the posterior canal, two of the most diagnostic features of the Neandertal Bony Labyrinth, and Aroeira 3 is more primitive in these features than the Atapuerca (SH) sample. One potentially derived feature (low shape index of the cochlear basal turn) is shared between Aroeira 3 and the Atapuerca (SH) hominins, but is absent in Neandertals. The results of our study provide new insights into Middle Pleistocene population dynamics close to the origin of the Neandertal clade. In particular, the contrasting inner ear morphology between Aroeira 3 and the Atapuerca (SH) hominins suggests a degree of demographic isolation, despite the close geographic proximity and similar age of these two sites.
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The Bony Labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain)
Journal of Human Evolution, 2016Co-Authors: Rolf Quam, Ana Gracia-téllez, Ignacio Martínez, Carlos Lorenzo, Juan Luis ArsuagaAbstract:We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm < APA), posterior surface of the petrous pyramid (LSCm > PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
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the Bony Labyrinth of the middle pleistocene sima de los huesos hominins sierra de atapuerca spain
Journal of Human Evolution, 2016Co-Authors: Ignacio Martínez, Rolf Quam, Carlos Lorenzo, Ana Graciatellez, Juan Luis ArsuagaAbstract:Abstract We performed 3D virtual reconstructions based on CT scans to study the Bony Labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal Labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm PPp), and third part of the facial canal (LSCm Principal components analysis largely confirms these observations. While not fully resolved, the low placement of the posterior canal in Neandertals may be related to some combination of absolutely large brain size, a wide cranial base, and an archaic pattern of brain allometry. This more general explanation would not necessarily follow taxonomic lines, even though this morphology of the Bony Labyrinth occurs at high frequencies among Neandertals. While a functional interpretation of the relatively small vertical canals in the Neandertal clade remains elusive, the relative proportions of the semicircular canals is one of several derived Neandertal features in the Atapuerca (SH) crania. Examination of additional European middle Pleistocene specimens suggests that the full suite of Neandertal features in the Bony Labyrinth did not emerge in Europe until perhaps
