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Bisconti M, Bosselaers M, Locatelli C, Carnevale G, Lambert O. The tympanoperiotic complex of the blue whale, Balaenoptera musculus. Anat Rec (Hoboken) 2024; 307:3041-3070. [PMID: 38297482 DOI: 10.1002/ar.25393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/08/2024] [Accepted: 01/10/2024] [Indexed: 02/02/2024]
Abstract
The tympanoperiotic complex of a blue whale Balaenoptera musculus is described and compared to the homologous structures in the other extant and fossil baleen whale species. The periotic and the tympanic bulla represent informative anatomical regions in both functional and phylogenetic studies and for this reason a micro-CT scan of the bones was performed in order to better characterize their external aspect and to reconstruct the inner structures. In particular, the cochlea, the semicircular canals and associated portions of the periotic are reconstructed so that these structures may be used in phylogenetic analyses. We observed that the blue whale periotic is characterized by the presence of a strong dorsal protrusion which is posteriorly bordered by a previously undescribed morphological character that we name the posterotransverse fossa. The peculiar shape of the anterior process and the en echelon organization of the posterior foramina of the pars cochlearis are also described and compared. From a phylogenetic perspective, the blue whale is confirmed to be closely related to the fin whale, Balaenoptera physalus, but it is suggested, based on ear bone characters only, that it diverged before the other balaenopterid species in the phylogeny of Balaenopteridae. This placement supports a series of morphological observations suggesting that the extant blue whale was an early-diverging member of Balaenoptera. Our results help to decipher the evolutionary origin of the blue whale, the largest living animal, by allowing new and more detailed morphological analyses of the balaenopterid fossil record.
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Affiliation(s)
- Michelangelo Bisconti
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
- Paleontology Department, San Diego Natural History Museum, San Diego, California, USA
| | - Mark Bosselaers
- D.O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
| | - Camille Locatelli
- Service scientifique Patrimoine, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
| | - Giorgio Carnevale
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italy
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
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2
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Werth AJ, Crompton AW. Cetacean tongue mobility and function: A comparative review. J Anat 2023; 243:343-373. [PMID: 37042479 PMCID: PMC10439401 DOI: 10.1111/joa.13876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023] Open
Abstract
Cetaceans are atypical mammals whose tongues often depart from the typical (basal) mammalian condition in structure, mobility, and function. Their tongues are dynamic, innovative multipurpose tools that include the world's largest muscular structures. These changes reflect the evolutionary history of cetaceans' secondary adaptation to a fully aquatic environment. Cetacean tongues play no role in mastication and apparently a greatly reduced role in nursing (mainly channeling milk ingestion), two hallmarks of Mammalia. Cetacean tongues are not involved in drinking, breathing, vocalizing, and other non-feeding activities; they evidently play no or little role in taste reception. Although cetaceans do not masticate or otherwise process food, their tongues retain key roles in food ingestion, transport, securing/positioning, and swallowing, though by different means than most mammals. This is due to cetaceans' aquatic habitat, which in turn altered their anatomy (e.g., the intranarial larynx and consequent soft palate alteration). Odontocetes ingest prey via raptorial biting or tongue-generated suction. Odontocete tongues expel water and possibly uncover benthic prey via hydraulic jetting. Mysticete tongues play crucial roles driving ram, suction, or lunge ingestion for filter feeding. The uniquely flaccid rorqual tongue, not a constant volume hydrostat (as in all other mammalian tongues), invaginates into a balloon-like pouch to temporarily hold engulfed water. Mysticete tongues also create hydrodynamic flow regimes and hydraulic forces for baleen filtration, and possibly for cleaning baleen. Cetacean tongues lost or modified much of the mobility and function of generic mammal tongues, but took on noteworthy morphological changes by evolving to accomplish new tasks.
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Affiliation(s)
- Alexander J Werth
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia, USA
| | - A W Crompton
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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3
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Bisconti M, Munsterman DK, Post K. A new balaenopterid whale from the late Miocene of the Southern North Sea Basin and the evolution of balaenopterid diversity (Cetacea, Mysticeti). PeerJ 2019; 7:e6915. [PMID: 31149399 PMCID: PMC6526909 DOI: 10.7717/peerj.6915] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/05/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Balaenopterid mysticetes represent the most successful family-rank group of this clade. Their evolutionary history is characterized by a rich fossil record but the origin of the living genera is still largely not understood. Recent discoveries in the southern border of the North Sea revealed a number of well preserved fossil balaenopterid whales that may help resolving this problem. In particular, skull NMR 14035 shares morphological characters with the living humpback whale, Megaptera novaeangliae and, for this reason, its characteristics are investigated here. METHODS The comparative anatomical analysis of the new specimen formed the basis of a new phylogenetic analysis of the Mysticeti based on a matrix including 350 morphological character states scored for 82 Operational Taxonomic Units. The stratigraphic age of the specimen was determined based on the analysis of the dinocyst assemblage recovered in the associated sediment. We assessed clade diversity in Balaenopteridae by counting the numbers of clades in given time intervals and then plotted the results. RESULTS Nehalaennia devossi n. gen. et sp. is described for the first time from the late Tortonian (8.7-8.1 Ma) of the Westerschelde (The Netherlands). This new taxon belongs to Balaenopteridae and shows a surprisingly high number of advanced characters in the skull morphology. Nehalaennia devossi is compared to a large sample of balaenopterid mysticetes and a phylogenetic analysis placed it as the sister group of a clade including the genus Archaebalaenoptera. The inclusion of this fossil allowed to propose a phylogenetic hypothesis for Balaenopteridae in which (1) Eschrichtiidae (gray whales) represents a family of its own, (2) Balaenopteridae + Eschrichtiidae form a monophyletic group (superfamily Balaenopteroidea), (3) Cetotheriidae is the sister group of Balaenopteroidea, (4) living Balaenoptera species form a monophyletic group and (5) living M. novaeangliae is the sister group of Balaenoptera. Our work reveals a complex phylogenetic history of Balaenopteridae and N. devossi informs us about the early morphological transformations in this family. Over time, this family experienced a number of diversity pulses suggesting that true evolutionary radiations had taken place. The paleoecological drivers of these pulses are then investigated.
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Affiliation(s)
- Michelangelo Bisconti
- Paleobiology Department, San Diego Natural History Museum, San Diego, CA, USA
- Dipartimento di Scienze della Terra, Università degli Studi di Torino, Torino, Italia
| | - Dirk K. Munsterman
- Toegepast Natuurwetenschappelijk Onderzoek (TNO-Netherlands Organization for Applied Scientific Research), Geological Survey of The Netherlands, Utrecht, The Netherlands
| | - Klaas Post
- Het Natuurhistorisch Museum, Rotterdam, The Netherlands
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4
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Roston RA, Roth VL. Cetacean Skull Telescoping Brings Evolution of Cranial Sutures into Focus. Anat Rec (Hoboken) 2019; 302:1055-1073. [DOI: 10.1002/ar.24079] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 10/12/2018] [Accepted: 10/21/2018] [Indexed: 01/09/2023]
Affiliation(s)
| | - V. Louise Roth
- Department of Biology; Duke University; Durham North Carolina
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5
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Marx FG, Post K, Bosselaers M, Munsterman DK. A large Late Miocene cetotheriid (Cetacea, Mysticeti) from the Netherlands clarifies the status of Tranatocetidae. PeerJ 2019; 7:e6426. [PMID: 30783574 PMCID: PMC6377596 DOI: 10.7717/peerj.6426] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/09/2019] [Indexed: 11/20/2022] Open
Abstract
Cetotheriidae are a group of small baleen whales (Mysticeti) that evolved alongside modern rorquals. They once enjoyed a nearly global distribution, but then largely went extinct during the Plio-Pleistocene. After languishing as a wastebasket taxon for more than a century, the concept of Cetotheriidae is now well established. Nevertheless, the clade remains notable for its variability, and its scope remains in flux. In particular, the recent referral of several traditional cetotheriids to a new and seemingly unrelated family, Tranatocetidae, has created major phylogenetic uncertainty. Here, we describe a new species of Tranatocetus, the type of Tranatocetidae, from the Late Miocene of the Netherlands. Tranatocetus maregermanicum sp. nov. clarifies several of the traits previously ascribed to this genus, and reveals distinctive auditory and mandibular morphologies suggesting cetotheriid affinities. This interpretation is supported by a large phylogenetic analysis, which mingles cetotheriids and tranatocetids within a unified clade. As a result, we suggest that both groups should be reintegrated into the single family Cetotheriidae.
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Affiliation(s)
- Felix G Marx
- Department of Geology, Université de Liège, Liège, Belgium.,Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Palaeontology, Museums Victoria, Melbourne, Victoria, Australia.,School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Klaas Post
- Natuurhistorisch Museum, Rotterdam, The Netherlands
| | - Mark Bosselaers
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Zeeland Royal Society of Sciences, Middelburg, The Netherlands
| | - Dirk K Munsterman
- Netherlands Institute of Applied Geoscience TNO - National Geological Survey, Utrecht, The Netherlands
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6
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Werth AJ, Potvin J, Shadwick RE, Jensen MM, Cade DE, Goldbogen JA. Filtration area scaling and evolution in mysticetes: trophic niche partitioning and the curious cases of sei and pygmy right whales. Biol J Linn Soc Lond 2018. [DOI: 10.1093/biolinnean/bly121] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Alexander J Werth
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA, USA
| | - Jean Potvin
- Department of Physics, Saint Louis University, St. Louis, MO, USA
| | - Robert E Shadwick
- Department of Zoology, University of British Columbia, Vancouver, B.C., Canada
| | - Megan M Jensen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - David E Cade
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Jeremy A Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
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7
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Marx FG, Park T, Fitzgerald EMG, Evans AR. A Miocene pygmy right whale fossil from Australia. PeerJ 2018; 6:e5025. [PMID: 29942692 PMCID: PMC6016540 DOI: 10.7717/peerj.5025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 05/31/2018] [Indexed: 11/28/2022] Open
Abstract
Neobalaenines are an enigmatic group of baleen whales represented today by a single living species: the pygmy right whale, Caperea marginata, found only in the Southern Hemisphere. Molecular divergence estimates date the origin of pygmy right whales to 22–26 Ma, yet so far there are only three confirmed fossil occurrences. Here, we describe an isolated periotic from the latest Miocene of Victoria (Australia). The new fossil shows all the hallmarks of Caperea, making it the second-oldest described neobalaenine, and the oldest record of the genus. Overall, the new specimen resembles C. marginata in its external morphology and details of the cochlea, but is more archaic in it having a hypertrophied suprameatal area and a greater number of cochlear turns. The presence of Caperea in Australian waters during the Late Miocene matches the distribution of the living species, and supports a southern origin for pygmy right whales.
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Affiliation(s)
- Felix G Marx
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Palaeontology, Museums Victoria, Melbourne, Victoria, Australia
| | - Travis Park
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Department of Life Sciences, Natural History Museum, London, United Kingdom
| | - Erich M G Fitzgerald
- Palaeontology, Museums Victoria, Melbourne, Victoria, Australia.,Department of Life Sciences, Natural History Museum, London, United Kingdom.,National Museum of Natural History, Smithsonian Institution, Washington, D.C., United States of America
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia.,Palaeontology, Museums Victoria, Melbourne, Victoria, Australia
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8
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Jensen MM, Saladrigas AH, Goldbogen JA. Comparative Three-Dimensional Morphology of Baleen: Cross-Sectional Profiles and Volume Measurements Using CT Images. Anat Rec (Hoboken) 2018; 300:1942-1952. [PMID: 28971628 PMCID: PMC5656919 DOI: 10.1002/ar.23648] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 06/14/2017] [Accepted: 06/17/2017] [Indexed: 12/29/2022]
Abstract
Baleen whales are obligate filter feeders, straining prey‐laden seawater through racks of keratinized baleen plates. Despite the importance of baleen to the ecology and natural history of these animals, relatively little work has been done on baleen morphology, particularly with regard to the three‐dimensional morphology and structure of baleen. We used computed tomography (CT) scanning to take 3D images of six baleen specimens representing five species, including three complete racks. With these images, we described the three‐dimensional shape of the baleen plates using cross‐sectional profiles from within the gum tissue to the tip of the plates. We also measured the percentage of each specimen that was composed of either keratinized plate material or was void space between baleen plates, and thus available for seawater flow. Baleen plates have a complex three‐dimensional structure with curvature that varies across the anterior‐posterior, proximal‐distal, and medial‐lateral (lingual‐labial) axes. These curvatures also vary with location along the baleen rack, and between species. Cross‐sectional profiles resemble backwards‐facing airfoils, and some specimens display S‐shaped, or reflexed, camber. Within a baleen specimen, the intra‐baleen void volume correlates with the average bristle diameter for a species, suggesting that essentially, thinner plates (with more space between them for flow) have thinner bristles. Both plate curvature and the relative proportions of plate and void volumes are likely to have implications for the mechanics of mysticete filtration, and future studies are needed to determine the particular functions of these morphological characters. Anat Rec, 300:1942–1952, 2017. © 2017 The Authors The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists
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Affiliation(s)
- Megan M Jensen
- Hopkins Marine Station of Stanford University, Pacific Grove, California, 93950
| | - Amalia H Saladrigas
- Hopkins Marine Station of Stanford University, Pacific Grove, California, 93950
| | - Jeremy A Goldbogen
- Hopkins Marine Station of Stanford University, Pacific Grove, California, 93950
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9
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Tsai CH, Fordyce RE. A new archaic baleen whale Toipahautea waitaki (early Late Oligocene, New Zealand) and the origins of crown Mysticeti. ROYAL SOCIETY OPEN SCIENCE 2018; 5:172453. [PMID: 29765689 PMCID: PMC5936954 DOI: 10.1098/rsos.172453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
A new genus and species of extinct baleen whale †Toipahautea waitaki (Late Oligocene, New Zealand) is based on a skull and associated bones, from the lower Kokoamu Greensand, about 27.5 Ma (local upper Whaingaroan Stage, early Chattian). The upper jaw includes a thin, elongate and apparently toothless maxilla, with evidence of arterial supply for baleen. Open sutures with the premaxilla suggest a flexible (kinetic) upper jaw. The blowhole is well forward. The mandible is bowed laterally and slightly dorsally; unlike the Eomysticetidae, there are no mandibular alveoli, and the coronoid process is tapered and curved laterally. Jaw structure is consistent with baleen-assisted gulp-feeding. The age of early Chattian makes †Toipahautea a very early, if not the oldest named, toothless and baleen-bearing mysticete, suggesting that the full transition from toothed to baleen-bearing probably occurred in the Early Oligocene. Late Oligocene mysticetes vary considerably in jaw form and kinesis, tooth form and function, and development of baleen, implying a wide range of raptorial, suctorial and filter-feeding behaviour. More study may elucidate the function of jaws, teeth and baleen in terms of opportunist/generalist feeding, as in modern gray whales, versus specialized feeding. We here propose that early mysticetes, when transitioned from toothed to baleen-bearing, were generalists and opportunists instead of specializing in any forms of feeding strategies. In addition, two different phylogenetic analyses placed †Toipahautea either in a polytomy including crown Mysticeti, or immediately basal to the crown, and above †Eomysticetidae in both cases. Because the †Toipahautea waitaki holotype is an immature individual, it may plot more basally in phylogeny than its true position.
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Affiliation(s)
- Cheng-Hsiu Tsai
- Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Department of Geology and Paleontology, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba 305-0005, Japan
| | - R. Ewan Fordyce
- Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7013, USA
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7013, USA
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10
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Marx FG, Lambert O, de Muizon C. A new Miocene baleen whale from Peru deciphers the dawn of cetotheriids. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170560. [PMID: 28989761 PMCID: PMC5627101 DOI: 10.1098/rsos.170560] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/17/2017] [Indexed: 06/07/2023]
Abstract
Cetotheriidae are an iconic, nearly extinct family of baleen whales (Mysticeti) with a highly distinct cranial morphology. Their origins remain a mystery, with even the most archaic species showing a variety of characteristic features. Here, we describe a new species of archaic cetotheriid, Tiucetus rosae, from the Miocene of Peru. The new material represents the first mysticete from the poorly explored lowest portion of the highly fossiliferous Pisco Formation (allomember P0), and appears to form part of a more archaic assemblage than observed at the well-known localities of Cerro Colorado, Cerro los Quesos, Sud-Sacaco and Aguada de Lomas. Tiucetus resembles basal plicogulans (crown Mysticeti excluding right whales), such as Diorocetus and Parietobalaena, but shares with cetotheriids a distinct morphology of the auditory region, including the presence of an enlarged paroccipital concavity. The distinctive morphology of Tiucetus firmly places Cetotheriidae in the context of the poorly understood 'cetotheres' sensu lato, and helps to resolve basal relationships within crown Mysticeti.
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Affiliation(s)
- Felix G. Marx
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, Victoria 3800, Australia
- Geosciences, Museum Victoria, Melbourne, Australia
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Olivier Lambert
- Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Christian de Muizon
- CR2P (MNHN, CNRS, UPMC, Sorbonne-Université), Département Origines et Évolution, Muséum national d'Histoire naturelle, Paris 75005, France
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11
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Bisconti M, Lambert O, Bosselaers M. Revision of " Balaena" belgica reveals a new right whale species, the possible ancestry of the northern right whale, Eubalaena glacialis, and the ages of divergence for the living right whale species. PeerJ 2017; 5:e3464. [PMID: 28663936 PMCID: PMC5490463 DOI: 10.7717/peerj.3464] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 05/24/2017] [Indexed: 12/03/2022] Open
Abstract
In 1941, Abel established Balaena belgica based on a series of fused cervical vertebrae and citing other cranial fragments from the late Neogene of the Antwerp harbor (northern Belgium). Later, Plisnier-Ladame & Quinet (1969) added a neurocranium and other skeletal remains from the same area to this species. Recently, the neurocranium was re-assigned to the genus Eubalaena thanks to newer phylogenetic analyses. Here, a new description is provided of materials previously assigned to “Balaena” belgica together with taxonomic revisions. Our work suggests that the cervical complex originally designated as the type of “Balaena” belgica is too poorly preserved to be used as such and is assigned to Balaenidae gen. et sp. indet., thus making “Balaena” belgica a nomen dubium. In addition to the neurocranium, the other remains consist in a fragment of maxilla assigned to Balaenidae gen. et sp. indet. and in a humerus assigned to Eubalaena sp. Discovered in the Kruisschans Sands Member of the Lillo Formation (3.2–2.8 Ma, Piacenzian, Late Pliocene), the neurocranium is designated as the holotype of the new species Eubalaena ianitrix. Our phylogenetic analysis supports a sister-group relationship of Eubalaena ianitrix and Eubalaena glacialis, and helps constraining the ages of origin for balaenid clades. Ecological and phylogenetic data suggest that Eubalaena ianitrix may represent the direct ancestor of Eubalaena glacialis, the latter having evolved through phyletic transformation including body size increase during the temperature decline of the Late Pliocene.
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Affiliation(s)
| | - Olivier Lambert
- Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Mark Bosselaers
- Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Zeeland Royal Society of Sciences, Middelburg, the Netherlands
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12
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Marx FG, Collareta A, Gioncada A, Post K, Lambert O, Bonaccorsi E, Urbina M, Bianucci G. How whales used to filter: exceptionally preserved baleen in a Miocene cetotheriid. J Anat 2017; 231:212-220. [PMID: 28542839 PMCID: PMC5522891 DOI: 10.1111/joa.12622] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2017] [Indexed: 11/30/2022] Open
Abstract
Baleen is a comb-like structure that enables mysticete whales to bulk feed on vast quantities of small prey, and ultimately allowed them to become the largest animals on Earth. Because baleen rarely fossilises, extremely little is known about its evolution, structure and function outside the living families. Here we describe, for the first time, the exceptionally preserved baleen apparatus of an entirely extinct mysticete morphotype: the Late Miocene cetotheriid, Piscobalaena nana, from the Pisco Formation of Peru. The baleen plates of P. nana are closely spaced and built around relatively dense, fine tubules, as in the enigmatic pygmy right whale, Caperea marginata. Phosphatisation of the intertubular horn, but not the tubules themselves, suggests in vivo intertubular calcification. The size of the rack matches the distribution of nutrient foramina on the palate, and implies the presence of an unusually large subrostral gap. Overall, the baleen morphology of Piscobalaena likely reflects the interacting effects of size, function and phylogeny, and reveals a previously unknown degree of complexity in modern mysticete feeding evolution.
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Affiliation(s)
- Felix G Marx
- School of Biological Sciences, Monash University, Clayton, Vic., Australia.,Geosciences, Museum Victoria, Melbourne, Vic., Australia.,D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
| | - Alberto Collareta
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy.,Dottorato Regionale in Scienze della Terra Pegaso, Pisa, Italy
| | - Anna Gioncada
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Klaas Post
- Natuurhistorisch Museum Rotterdam, Rotterdam, The Netherlands
| | - Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, Brussels, Belgium
| | - Elena Bonaccorsi
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
| | - Mario Urbina
- Departamento de Paleontología de Vertebrados, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima, Peru
| | - Giovanni Bianucci
- Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
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13
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Park T, Marx FG, Fitzgerald EMG, Evans AR. The cochlea of the enigmatic pygmy right whale Caperea marginata informs mysticete phylogeny. J Morphol 2017; 278:801-809. [PMID: 28333389 DOI: 10.1002/jmor.20674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 02/09/2017] [Accepted: 02/27/2017] [Indexed: 11/07/2022]
Abstract
The pygmy right whale, Caperea marginata, is the least understood extant baleen whale (Cetacea, Mysticeti). Knowledge on its basic anatomy, ecology, and fossil record is limited, even though its singular position outside both balaenids (right whales) and balaenopteroids (rorquals + grey whales) gives Caperea a pivotal role in mysticete evolution. Recent investigations of the cetacean cochlea have provided new insights into sensory capabilities and phylogeny. Here, we extend this advance to Caperea by describing, for the first time, the inner ear of this enigmatic species. The cochlea is large and appears to be sensitive to low-frequency sounds, but its hearing limit is relatively high. The presence of a well-developed tympanal recess links Caperea with cetotheriids and balaenopteroids, rather than balaenids, contrary to the traditional morphological view of a close Caperea-balaenid relationship. Nevertheless, a broader sample of the cetotheriid Herpetocetus demonstrates that the presence of a tympanal recess can be variable at the specific and possibly even the intraspecific level.
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Affiliation(s)
- Travis Park
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.,Geosciences, Museum Victoria, Melbourne, Victoria, Australia
| | - Felix G Marx
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.,Geosciences, Museum Victoria, Melbourne, Victoria, Australia.,Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Erich M G Fitzgerald
- Geosciences, Museum Victoria, Melbourne, Victoria, Australia.,National Museum of Natural History, Smithsonian Institution, Washington, DC.,Department of Vertebrate Zoology, Department of Life Sciences, Natural History Museum, London, United Kingdom
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.,Geosciences, Museum Victoria, Melbourne, Victoria, Australia
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