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Ekdale EG, El Adli JJ, McGowen MR, Deméré TA, Lanzetti A, Berta A, Springer MS, Boessenecker RW, Gatesy J. Lateral palatal foramina are not widespread in Artiodactyla and imply baleen in extinct mysticetes. Sci Rep 2024; 14:10174. [PMID: 38702346 PMCID: PMC11068900 DOI: 10.1038/s41598-024-60673-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 04/25/2024] [Indexed: 05/06/2024] Open
Affiliation(s)
- Eric G Ekdale
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182, USA.
- Department of Paleontology, San Diego Natural History Museum, 1788 El Prado, San Diego, CA, 92101, USA.
| | - Joseph J El Adli
- Department of Paleontology, San Diego Natural History Museum, 1788 El Prado, San Diego, CA, 92101, USA
- Paleontology Department, Bargas Environmental Consulting, 3111 Camino del Rio N, Suite 400, San Diego, CA, 92108, USA
| | - Michael R McGowen
- Department of Vertebrate Zoology, Smithsonian National Museum of Natural History, MRC 108, PO Box 37012, Washington, DC, 20013-7012, USA
| | - Thomas A Deméré
- Department of Paleontology, San Diego Natural History Museum, 1788 El Prado, San Diego, CA, 92101, USA
| | - Agnese Lanzetti
- Imaging and Analysis Center, The Natural History Museum, London, SW7 5BD, UK
- School of Geography, Earth and Environmental Science, University of Birmingham, Birmingham, UK
| | - Annalisa Berta
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182, USA
| | - Mark S Springer
- Department of Evolution, Ecology, and Organismal Biology, University of California-Riverside, Riverside, CA, 92521, USA
| | - Robert W Boessenecker
- University of California Museum of Paleontology, University of California, Berkeley, CA, 94720, USA
| | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA
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2
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Lambert O. Whale evolution: Ancient toothed relative of baleen whales breaches northward. Curr Biol 2024; 34:R328-R330. [PMID: 38653203 DOI: 10.1016/j.cub.2024.03.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
The mysticetes - baleen whales and their toothed ancestors - have a long evolutionary history that, despite many recent paleontological discoveries, remains highly debated. The description of a new mysticete from the latest Eocene of North America opens promising new research directions.
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Affiliation(s)
- Olivier Lambert
- D.O. Terre et Histoire de la Vie, Institut Royal des Sciences Naturelles de Belgique, 29 rue Vautier, 1000 Brussels, Belgium.
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3
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Hautier L, Gomes Rodrigues H, Ferreira-Cardoso S, Emerling CA, Porcher ML, Asher RJ, Portela Miguez R, Delsuc F. From teeth to pad: tooth loss and development of keratinous structures in sirenians. Proc Biol Sci 2023; 290:20231932. [PMID: 38018114 PMCID: PMC10685118 DOI: 10.1098/rspb.2023.1932] [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: 08/29/2023] [Accepted: 11/03/2023] [Indexed: 11/30/2023] Open
Abstract
Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used μ-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.
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Affiliation(s)
- Lionel Hautier
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Helder Gomes Rodrigues
- Centre de Recherche en Paléontologie—Paris (CR2P), UMR CNRS 7207, Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France
| | - Sérgio Ferreira-Cardoso
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | | | - Marie-Lou Porcher
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | - Robert J. Asher
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Roberto Portela Miguez
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Frédéric Delsuc
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
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4
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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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5
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Fang ZC, Li JL, Yan CB, Zou YR, Tian L, Zhao B, Benton MJ, Cheng L, Lai XL. First filter feeding in the Early Triassic: cranial morphological convergence between Hupehsuchus and baleen whales. BMC Ecol Evol 2023; 23:36. [PMID: 37550649 PMCID: PMC10408079 DOI: 10.1186/s12862-023-02143-9] [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: 04/01/2023] [Accepted: 07/11/2023] [Indexed: 08/09/2023] Open
Abstract
Modern baleen whales are unique as large-sized filter feeders, but their roles were replicated much earlier by diverse marine reptiles of the Mesozoic. Here, we investigate convergence in skull morphology between modern baleen whales and one of the earliest marine reptiles, the basal ichthyosauromorph Hupehsuchus nanchangensis, from the Early Triassic, a time of rapid recovery of life following profound mass extinction. Two new specimens reveal the skull morphology especially in dorsal view. The snout of Hupehsuchus is highly convergent with modern baleen whales, as shown in a morphometric analysis including 130 modern aquatic amniotes. Convergences in the snout include the unfused upper jaw, specialized intermediate space in the divided premaxilla and grooves around the labial margin. Hupehsuchus had enlarged its buccal cavity to enable efficient filter feeding and probably used soft tissues like baleen to expel the water from the oral cavity. Coordinated with the rigid trunk and pachyostotic ribs suggests low speeds of aquatic locomotion, Hupehsuchus probably employed continuous ram filter feeding as in extant bowhead and right whales. The Early Triassic palaeoenvironment of a restrictive lagoon with low productivity drove Hupehsuchus to feed on zooplankton, which facilitated ecosystem recovery in the Nanzhang-Yuan'an Fauna at the beginning of the Mesozoic.
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Affiliation(s)
- Zi-Chen Fang
- School of Earth Sciences, China University of Geosciences, Wuhan, 430074, P. R. China
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, 430205, P. R. China
| | - Jiang-Li Li
- Hubei Institute of Geosciences, Hubei Geological Bureau, Wuhan, 430034, P. R. China
| | - Chun-Bo Yan
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, 430205, P. R. China
| | - Ya-Rui Zou
- Hubei Institute of Geosciences, Hubei Geological Bureau, Wuhan, 430034, P. R. China
| | - Li Tian
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, P. R. China
| | - Bi Zhao
- Hubei Institute of Geosciences, Hubei Geological Bureau, Wuhan, 430034, P. R. China
| | - Michael J Benton
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Long Cheng
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, 430205, P. R. China.
| | - Xu-Long Lai
- School of Earth Sciences, China University of Geosciences, Wuhan, 430074, P. R. China
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6
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Vandenberg ML, Cohen KE, Rubin RD, Goldbogen JA, Summers AP, Paig-Tran EWM, Kahane-Rapport SR. Formation of a fringe: A look inside baleen morphology using a multimodal visual approach. J Morphol 2023; 284:e21574. [PMID: 36807194 DOI: 10.1002/jmor.21574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/22/2022] [Accepted: 12/26/2022] [Indexed: 02/23/2023]
Abstract
Filter-feeding has been present for hundreds of millions of years, independently evolving in aquatic vertebrates' numerous times. Mysticete whales are a group of gigantic, marine filter-feeders that are defined by their fringed baleen and are divided into two groups: balaenids and rorquals. Recent studies have shown that balaenids likely feed using a self-cleaning, cross-flow filtration mechanism where food particles are collected and then swept to the esophagus for swallowing. However, it is unclear how filtering is achieved in the rorquals (Balaenopteridae). Lunging rorqual whales engulf enormous masses of both prey and water; the prey is then separated from the water through baleen plates lining the length of their upper jaw and positioned perpendicular to flow. Rorqual baleen is composed of both major (larger) and minor (smaller) keratin plates containing embedded fringe that extends into the whale's mouth, forming a filtering fringe. We used a multimodal approach, including microcomputed tomography (µCT) and scanning electron microscopy (SEM), to visualize and describe the variability in baleen anatomy across five species of rorqual whales, spanning two orders of magnitude in body length. For most morphological measurements, larger whales exhibited hypoallometry relative to body length. µCT and SEM revealed that the major and minor plates break away from the mineralized fringes at variable distances from the gums. We proposed a model for estimating the effective pore size to determine whether flow scales with body length or prey size across species. We found that pore size is likely not a proxy for prey size but instead, may reflect changes in resistance through the filter that affect fluid flow.
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Affiliation(s)
- Megan L Vandenberg
- Department of Biology, University of Washington, Seattle, Washington, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington, USA
| | - Karly E Cohen
- Department of Biology, University of Washington, Seattle, Washington, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington, USA
| | | | - Jeremy A Goldbogen
- Hopkins Marine Station, Stanford University, Pacific Grove, California, USA
| | - Adam P Summers
- Department of Biology, University of Washington, Seattle, Washington, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington, USA
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7
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Marx FG, Hocking DP, Park T, Pollock TI, Parker WMG, Rule JP, Fitzgerald EMG, Evans AR. Suction causes novel tooth wear in marine mammals, with implications for feeding evolution in baleen whales. J MAMM EVOL 2023. [DOI: 10.1007/s10914-022-09645-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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8
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Young MT, Bowman CIW, Erb A, Schwab JA, Witmer LM, Herrera Y, Brusatte SL. Evidence for a novel cranial thermoregulatory pathway in thalattosuchian crocodylomorphs. PeerJ 2023; 11:e15353. [PMID: 37151298 PMCID: PMC10162039 DOI: 10.7717/peerj.15353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/13/2023] [Indexed: 05/09/2023] Open
Abstract
Thalattosuchian crocodylomorphs were a diverse clade that lived from the Early Jurassic to the Early Cretaceous. The subclade Metriorhynchoidea underwent a remarkable transition, evolving from semi-aquatic ambush predators into fully aquatic forms living in the open oceans. Thalattosuchians share a peculiar palatal morphology with semi-aquatic and aquatic fossil cetaceans: paired anteroposteriorly aligned grooves along the palatal surface of the bony secondary palate. In extant cetaceans, these grooves are continuous with the greater palatine artery foramina, arteries that supply their oral thermoregulatory structures. Herein, we investigate the origins of thalattosuchian palatal grooves by examining CT scans of six thalattosuchian species (one teleosauroid, two early-diverging metriorhynchoids and three metriorhynchids), and CT scans of eleven extant crocodylian species. All thalattosuchians had paired osseous canals, enclosed by the palatines, that connect the nasal cavity to the oral cavity. These osseous canals open into the oral cavity via foramina at the posterior terminus of the palatal grooves. Extant crocodylians lack both the external grooves and the internal canals. We posit that in thalattosuchians these novel palatal canals transmitted hypertrophied medial nasal vessels (artery and vein), creating a novel heat exchange pathway connecting the palatal vascular plexus to the endocranial region. Given the general hypertrophy of thalattosuchian cephalic vasculature, and their increased blood flow and volume, thalattosuchians would have required a more extensive suite of thermoregulatory pathways to maintain stable temperatures for their neurosensory tissues.
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Affiliation(s)
- Mark T. Young
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
- LWL-Museum für Naturkunde, Münster, Germany
| | | | - Arthur Erb
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Julia A. Schwab
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, United Kingdom
| | - Lawrence M. Witmer
- Department of Biomedical Sciences, Ohio University, Athens, Ohio, United States
| | - Yanina Herrera
- Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina
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9
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Anatomical, Ontogenetic, and Genomic Homologies Guide Reconstructions of the Teeth-to-Baleen Transition in Mysticete Whales. J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09614-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Peredo CM, Pyenson ND, Uhen MD. Lateral palatal foramina do not indicate baleen in fossil whales. Sci Rep 2022; 12:11448. [PMID: 35794235 PMCID: PMC9259611 DOI: 10.1038/s41598-022-15684-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 06/28/2022] [Indexed: 11/19/2022] Open
Abstract
Today's mysticetes filter-feed using baleen, a novel integumentary structure with no apparent homolog in any living mammal. The origins of filter-feeding and baleen can be informed by the fossil record, including rare instances of soft tissue preservation of baleen and also by potential osteological correlates of baleen. Lateral palatal foramina on the roof of the mouth have been proposed as potential osteological correlates of baleen and their presence in some tooth-bearing stem mysticetes has led to the hypothesis that these early mysticetes possessed both teeth and incipient baleen. Here, we test this hypothesis by examining lateral palatal foramina in both filter-feeding and non-filter-feeding cetaceans, including crown and stem odontocetes and in stem cetaceans (or archaeocetes). We also confirm the presence of lateral palatal foramina in 61 species of terrestrial artiodactyls. CT scanning demonstrates consistent internal morphology across all observed taxa, suggesting that the lateral palatal foramina observed in extant mysticetes are homologous to those of terrestrial artiodactyls. The presence of lateral palatal foramina in terrestrial artiodactyls and non-filter-feeding whales (odontocetes and archaeocetes) suggests that these structures are not unique predictors for the presence of baleen in fossil whales; instead, these structures are more probably associated with gingiva or other oral tissue.
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Affiliation(s)
- Carlos Mauricio Peredo
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA.
- Department of Marine Biology, Texas A&M University, Galveston, TX, USA.
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA.
| | - Nicholas D Pyenson
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Departments of Mammalogy and Paleontology, Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Mark D Uhen
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
- Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA, USA
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11
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Randall JG, Gatesy J, Springer MS. Molecular evolutionary analyses of tooth genes support sequential loss of enamel and teeth in baleen whales (Mysticeti). Mol Phylogenet Evol 2022; 171:107463. [PMID: 35358696 DOI: 10.1016/j.ympev.2022.107463] [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: 10/29/2021] [Revised: 12/16/2021] [Accepted: 03/01/2022] [Indexed: 10/18/2022]
Abstract
The loss of teeth and evolution of baleen racks in Mysticeti was a profound transformation that permitted baleen whales to radiate and diversify into a previously underutilized ecological niche of bulk filter-feeding on zooplankton and other small prey. Ancestral state reconstructions suggest that postnatal teeth were lost in the common ancestor of crown Mysticeti. Genomic studies provide some support for this hypothesis and suggest that the genetic toolkit for enamel production was inactivated in the common ancestor of living baleen whales. However, molecular studies to date have not provided direct evidence for the complete loss of teeth, including their dentin component, on the stem mysticete branch. Given these results, several questions remain unanswered: (1) Were teeth lost in a single step or did enamel loss precede dentin loss? (2) Was enamel lost early or late on the stem mysticete branch? (3) If enamel and dentin/tooth loss were decoupled in the ancestry of baleen whales, did dentin loss occur on the stem mysticete branch or independently in different crown mysticete lineages? To address these outstanding questions, we compiled and analyzed complete protein-coding sequences for nine tooth-related genes from cetaceans with available genome data. Seven of these genes are associated with enamel formation (ACP4, AMBN, AMELX, AMTN, ENAM, KLK4, MMP20) whereas two other genes are either dentin-specific (DSPP) or tooth-specific (ODAPH) but not enamel-specific. Molecular evolutionary analyses indicate that all seven enamel-specific genes have inactivating mutations that are scattered across branches of the mysticete tree. Three of the enamel genes (ACP4, KLK4, MMP20) have inactivating mutations that are shared by all mysticetes. The two genes that are dentin-specific (DSPP) or tooth-specific (ODAPH) do not have any inactivating mutations that are shared by all mysticetes, but there are shared mutations in Balaenidae as well as in Plicogulae (Neobalaenidae + Balaenopteroidea). These shared mutations suggest that teeth were lost at most two times. Shared inactivating mutations and dN/dS analyses, in combination with cetacean divergence times, were used to estimate inactivation times of genes and by proxy enamel and tooth phenotypes at ancestral nodes. The results of these analyses are most compatible with a two-step model for the loss of teeth in the ancestry of living baleen whales: enamel was lost very early on the stem Mysticeti branch followed by the independent loss of dentin (and teeth) in the common ancestors of Balaenidae and Plicogulae, respectively. These results imply that some stem mysticetes, and even early crown mysticetes, may have had vestigial teeth comprised of dentin with no enamel. Our results also demonstrate that all odontocete species (in our study) with absent or degenerative enamel have inactivating mutations in one or more of their enamel genes.
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Affiliation(s)
- Jason G Randall
- Department of Evolution, Ecology, and Evolutionary Biology, University of California, Riverside, CA 92521, USA.
| | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA.
| | - Mark S Springer
- Department of Evolution, Ecology, and Evolutionary Biology, University of California, Riverside, CA 92521, USA.
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12
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Abstract
Innovations relating to the consumption of hard prey are implicated in ecological shifts in marine ecosystems as early as the mid-Paleozoic. Lungfishes represent the first and longest-ranging lineage of durophagous vertebrates, but how and when the various feeding specializations of this group arose remain unclear. Two exceptionally preserved fossils of the Early Devonian lobe-finned fish Youngolepis reveal the origin of the specialized lungfish feeding mechanism. Youngolepis has a radically restructured palate, reorienting jaw muscles for optimal force transition, coupled with radiating entopterygoid tooth rows like those of lungfish toothplates. This triturating surface occurs in conjunction with marginal dentition and blunt coronoid fangs, suggesting a role in crushing rather than piercing prey. Bayesian tip-dating analyses incorporating these morphological data indicate that the complete suite of lungfish feeding specializations may have arisen in as little as 7 million years, representing one of the most striking episodes of innovation during the initial evolutionary radiations of bony fishes. It is unclear how Lungfishes evolved durophagy, the consumption of hard prey, despite being the longest lineage of vertebrates with this feeding mechanism. Here, the authors describe exceptionally preserved fossils of Youngolepis from the Early Devonian, showing early adaptations to durophagy.
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