The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
Michelangelo Bisconti - One of the best experts on this subject based on the ideXlab platform.
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Taxonomic revision of Isocetus depauwi (Mammalia, Cetacea, Mysticeti) and the phylogenetic relationships of archaic ‘cetothere’ mysticetes
Palaeontology, 2013Co-Authors: Michelangelo Bisconti, Olivier Lambert, Mark BosselaersAbstract:: The taxonomic revision of Isocetus depauwi Van Beneden, 1880 was carried out through the description of a number of specimens assigned to this species by Van Beneden and Abel in the last decades of the 19th and the early decades of the 20th centuries. After detailed comparisons with the published record of archaic mysticetes, the genus and species are considered valid despite the incompleteness and poor preservation of the material. Diagnostic features are found in the morphology of the mandibular condyle, the angular process of the dentary and the thoracic vertebrae. The new species Parietobalaena campiniana is established based on a partial skeleton, including most of the skull and ear bones, previously assigned to Isocetus depauwi by Abel. Parietobalaena campiniana is described and compared in detail, and its phylogenetic relationships are assessed by a new large-scale cladistic analysis of 246 morphological characters scored for 46 taxa. The results support a basal position of the genus Parietobalaena in the radiation of Miocene ‘cetotheres’, the monophyly of Balaenoidea (Neobalaenidae and Balaenidae), Balaenopteroidea (Eschrichtiidae and Balaenopteridae), and Cetotheriidae and the paraphyly of ‘cetotheres’s.l. The new superfamily Thalassotherii is established based on high bootstrap support and a number of morphological characters; Thalassotherii includes Balaenopteridae, Eschrichtiidae, Cetotheriidae and the basal ‘cetothere’ mysticetes with the exclusion of Balaenoidea, Eomysticetoidea and toothed mysticetes.
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comparative osteology and phylogenetic relationships of miocaperea pulchra the first fossil pygmy right whale genus and species cetacea mysticeti Neobalaenidae
Zoological Journal of the Linnean Society, 2012Co-Authors: Michelangelo BiscontiAbstract:A fossil pygmy right whale (Cetacea, Mysticeti, Neobalaenidae) with exquisitely preserved baleen is described for the first time in the history of cetacean palaeontology, providing a wealth of information about the evolutionary history and palaeobiogeography of Neobalaenidae. This exquisitely preserved specimen is assigned to a new genus and species, Miocaperea pulchra gen. et sp. nov., and differs from Caperea marginata Gray, 1846, the only living taxon currently assigned to Neobalaenidae, in details of the temporal fossa and basicranium. A thorough comparative analysis of the skeleton of M. pulchra gen. et sp. nov. and C. marginata is also provided, and forms the basis of an extensive osteology-based phylogenetic analysis, confirming the placement of M. pulchra gen. et sp. nov. within Neobalaenidae as well as the monophyly of Neobalaenidae and Balaenidae; the phylogenetic results support the validity of the superfamily Balaenoidea. No relationship with Balaenopteroidea was found by the present study, and thus the balaenopterid-like morphological features observed in C. marginata must have resulted from parallel evolution. The presence of M. pulchra gen. et sp. nov. around 2000 km north from the northernmost sightings of C. marginata suggests that different ecological conditions were able to support pygmy right whale populations in what is now Peru, and that subsequent environmental change caused a southern shift in the distribution of the living neobalaenid whales. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166, 876–911.
R. Ewan Fordyce - One of the best experts on this subject based on the ideXlab platform.
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Disparate Heterochronic Processes in Baleen Whale Evolution
Evolutionary Biology, 2014Co-Authors: Cheng-hsiu Tsai, R. Ewan FordyceAbstract:Skulls of living baleen whales show distinctive patterns of heterochronic ontogenetic change with implications for mysticete evolution. Here, three baleen whale species are analysed and considered in a heterochronic context. Landmarks show that, during ontogeny, skull morphology changes significantly in the rorqual Balaenoptera borealis and humpback Megaptera novaeangliae (both Balaenopteridae), while the pygmy right whale Caperea marginata (Cetotheriidae: Neobalaeninae) retains an overall juvenile morphology from foetus to adult. Geometric morphometric analyses show that foetal and adult C . marginata are similar, whereas the balaenopterids are more disparate: foetal M . novaeangliae and B . borealis appear in one group, and adult M . novaeangliae and B . borealis are grouped closely. Heterochrony involves paedomorphosis for Caperea , and peramorphosis for the balaenopterids. Heterochrony might cause limited or released developmental constraints, leading to low taxonomic diversity in the single surviving species of neobalaenine, and higher diversity amongst balaenopterids.
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Mitochondrial Phylogenetics and Evolution of Mysticete Whales
Systematic Biology, 2005Co-Authors: Takeshi Sasaki, R. Ewan Fordyce, Masato Nikaido, Healy Hamilton, Mutsuo Goto, Hidehiro Kato, Naohisa Kanda, Luis A. Pastene, Masami HasegawaAbstract:The phylogenetic relationships among baleen whales (Order: Cetacea) remain uncertain despite extensive research in cetacean molecular phylogenetics and a potential morphological sample size of over 2 million animals harvested. Ques- tions remain regarding the number of species and the monophyly of genera, as well as higher order relationships. Here, we approach mysticete phylogeny with complete mitochondrial genome sequence analysis. We determined complete mtDNA sequences of 10 extant Mysticeti species, inferred their phylogenetic relationships, and estimated node divergence times. The mtDNA sequence analysis concurs with previous molecular studies in the ordering of the principal branches, with Balaenidae (right whales) as sister to all other mysticetes base, followed by Neobalaenidae (pygmy right whale), Eschrichtiidae (gray whale), and finally Balaenopteridae (rorquals + humpback whale). The mtDNA analysis further suggests that four lineages exist within the clade of Eschrichtiidae + Balaenopteridae, including a sister relationship between the humpback and fin whales, and a monophyletic group formed by the blue, sei, and Bryde's whales, each of which represents a newly recognized phylogenetic relationship in Mysticeti. We also estimated the divergence times of all extant mysticete species, accounting for evolutionary rate heterogeneity among lineages. When the mtDNA divergence estimates are compared with the mysticete fossil record, several lineages have molecular divergence estimates strikingly older than indicated by paleontological data. We suggest this discrepancy reflects both a large amount of ancestral polymorphism and long generation times of ances- tral baleen whale populations. (Ancestral polymorphism; baleen whale; evolution; mitochondrial DNA; molecular clock; phylogeny.)
Annalisa Berta - One of the best experts on this subject based on the ideXlab platform.
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Baleen Whales, Evolution
Encyclopedia of Marine Mammals, 2018Co-Authors: Annalisa Berta, Thomas A. DeméréAbstract:Summary The extant baleen whales of the Balaenidae, Neobalaenidae, Balaenopteridae, and Eschrichtiidae clades and their extinct sister taxa the Cetotheriidae are edentulous (without teeth) as adults, but possess fetal deciduous teeth that are resorbed prior to birth. Toothed mysticetes first evolved in the late Eocene or earliest Oligocene, diversified throughout the Oligocene, and appear to have been extinct before the Miocene began. It is likely that certain stem toothed mysticetes possessed some form of baleen in the upper jaw. This key filter feeding innovation permitted exploitation of a new niche and heralded the evolution of modern baleen whales, the largest animals on Earth.
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The Comparative Osteology of the Petrotympanic Complex (Ear Region) of Extant Baleen Whales (Cetacea: Mysticeti)
PLOS ONE, 2011Co-Authors: Eric G. Ekdale, Annalisa Berta, Thomas A. DeméréAbstract:Background Anatomical comparisons of the ear region of baleen whales (Mysticeti) are provided through detailed osteological descriptions and high-resolution photographs of the petrotympanic complex (tympanic bulla and petrosal bone) of all extant species of mysticete cetaceans. Salient morphological features are illustrated and identified, including overall shape of the bulla, size of the conical process of the bulla, morphology of the promontorium, and the size and shape of the anterior process of the petrosal. We place our comparative osteological observations into a phylogenetic context in order to initiate an exploration into petrotympanic evolution within Mysticeti. Principal Findings The morphology of the petrotympanic complex is diagnostic for individual species of baleen whale (e.g., sigmoid and conical processes positioned at midline of bulla in Balaenoptera musculus; confluence of fenestra cochleae and perilymphatic foramen in Eschrichtius robustus), and several mysticete clades are united by derived characteristics. Balaenids and neobalaenids share derived features of the bulla, such as a rhomboid shape and a reduced anterior lobe (swelling) in ventral aspect, and eschrichtiids share derived morphologies of the petrosal with balaenopterids, including loss of a medial promontory groove and dorsomedial elongation of the promontorium. Monophyly of Balaenoidea (Balaenidae and Neobalaenidae) and Balaenopteroidea (Balaenopteridae and Eschrichtiidae) was recovered in phylogenetic analyses utilizing data exclusively from the petrotympanic complex. Significance This study fills a major gap in our knowledge of the complex structures of the mysticete petrotympanic complex, which is an important anatomical region for the interpretation of the evolutionary history of mammals. In addition, we introduce a novel body of phylogenetically informative characters from the ear region of mysticetes. Our detailed anatomical descriptions, illustrations, and comparisons provide valuable data for current and future studies on the phylogenetic relationships, evolution, and auditory physiology of mysticetes and other cetaceans throughout Earth's history.
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Phylogeny of mysticete whales based on mitochondrial and nuclear data
Molecular Phylogenetics and Evolution, 2004Co-Authors: Amanda L. Rychel, Tod W. Reeder, Annalisa BertaAbstract:Mysticetes or baleen whales are comprised of four groups: Eschrichtiidae, Neobalaenidae, Balaenidae, and Balaenopteridae. Various phylogenetic hypotheses among these four groups have been proposed. Previous studies have not satisfactorily determined relationships among the four groups with a high degree of confidence. The objective of this study is to determine the relationships among the mysticete whales. Mitochondrial and nuclear DNA were sequenced for phylogenetic analysis. Most species relationships determined using these data were well resolved and congruent. Balaenidae is the most basal group and Neobalaenidae is the second most basal and sister group to the balaenopterid-eschrichtiid clade. In this phylogenetic study, the resolution of Eschrichtiidae with two main lineages of Balaenopteridae was problematic. Some data partitions placed this group within the balaenopterids, and other partitions placed it as a sister taxon to the balaenopterids. An additive likelihood approach was used to determine the most optimal trees. Although it was not found in the combined phylogenetic analyses, the "best" tree found under the additive likelihood approach was one with a monophyletic Balaenopteridae.
Thomas A. Deméré - One of the best experts on this subject based on the ideXlab platform.
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Baleen Whales, Evolution
Encyclopedia of Marine Mammals, 2018Co-Authors: Annalisa Berta, Thomas A. DeméréAbstract:Summary The extant baleen whales of the Balaenidae, Neobalaenidae, Balaenopteridae, and Eschrichtiidae clades and their extinct sister taxa the Cetotheriidae are edentulous (without teeth) as adults, but possess fetal deciduous teeth that are resorbed prior to birth. Toothed mysticetes first evolved in the late Eocene or earliest Oligocene, diversified throughout the Oligocene, and appear to have been extinct before the Miocene began. It is likely that certain stem toothed mysticetes possessed some form of baleen in the upper jaw. This key filter feeding innovation permitted exploitation of a new niche and heralded the evolution of modern baleen whales, the largest animals on Earth.
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The Comparative Osteology of the Petrotympanic Complex (Ear Region) of Extant Baleen Whales (Cetacea: Mysticeti)
PLOS ONE, 2011Co-Authors: Eric G. Ekdale, Annalisa Berta, Thomas A. DeméréAbstract:Background Anatomical comparisons of the ear region of baleen whales (Mysticeti) are provided through detailed osteological descriptions and high-resolution photographs of the petrotympanic complex (tympanic bulla and petrosal bone) of all extant species of mysticete cetaceans. Salient morphological features are illustrated and identified, including overall shape of the bulla, size of the conical process of the bulla, morphology of the promontorium, and the size and shape of the anterior process of the petrosal. We place our comparative osteological observations into a phylogenetic context in order to initiate an exploration into petrotympanic evolution within Mysticeti. Principal Findings The morphology of the petrotympanic complex is diagnostic for individual species of baleen whale (e.g., sigmoid and conical processes positioned at midline of bulla in Balaenoptera musculus; confluence of fenestra cochleae and perilymphatic foramen in Eschrichtius robustus), and several mysticete clades are united by derived characteristics. Balaenids and neobalaenids share derived features of the bulla, such as a rhomboid shape and a reduced anterior lobe (swelling) in ventral aspect, and eschrichtiids share derived morphologies of the petrosal with balaenopterids, including loss of a medial promontory groove and dorsomedial elongation of the promontorium. Monophyly of Balaenoidea (Balaenidae and Neobalaenidae) and Balaenopteroidea (Balaenopteridae and Eschrichtiidae) was recovered in phylogenetic analyses utilizing data exclusively from the petrotympanic complex. Significance This study fills a major gap in our knowledge of the complex structures of the mysticete petrotympanic complex, which is an important anatomical region for the interpretation of the evolutionary history of mammals. In addition, we introduce a novel body of phylogenetically informative characters from the ear region of mysticetes. Our detailed anatomical descriptions, illustrations, and comparisons provide valuable data for current and future studies on the phylogenetic relationships, evolution, and auditory physiology of mysticetes and other cetaceans throughout Earth's history.
Cheng-hsiu Tsai - One of the best experts on this subject based on the ideXlab platform.
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Disparate Heterochronic Processes in Baleen Whale Evolution
Evolutionary Biology, 2014Co-Authors: Cheng-hsiu Tsai, R. Ewan FordyceAbstract:Skulls of living baleen whales show distinctive patterns of heterochronic ontogenetic change with implications for mysticete evolution. Here, three baleen whale species are analysed and considered in a heterochronic context. Landmarks show that, during ontogeny, skull morphology changes significantly in the rorqual Balaenoptera borealis and humpback Megaptera novaeangliae (both Balaenopteridae), while the pygmy right whale Caperea marginata (Cetotheriidae: Neobalaeninae) retains an overall juvenile morphology from foetus to adult. Geometric morphometric analyses show that foetal and adult C . marginata are similar, whereas the balaenopterids are more disparate: foetal M . novaeangliae and B . borealis appear in one group, and adult M . novaeangliae and B . borealis are grouped closely. Heterochrony involves paedomorphosis for Caperea , and peramorphosis for the balaenopterids. Heterochrony might cause limited or released developmental constraints, leading to low taxonomic diversity in the single surviving species of neobalaenine, and higher diversity amongst balaenopterids.
