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Harano T, Asahara M. The anteriorization of tooth position underlies the atavism of tooth morphology: Insights into the morphogenesis of mammalian molars. Evolution 2022; 76:2986-3000. [PMID: 36200621 DOI: 10.1111/evo.14637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 08/29/2022] [Accepted: 09/15/2022] [Indexed: 01/22/2023]
Abstract
The evolution and development of complex molars as a key innovation in mammals have long been of interest yet remain poorly understood. With reference to century-old theories and modern findings, we focused on the teeth of pinnipeds (Carnivora) and cetaceans (Cetartiodactyla), which are morphologically simple compared with those of other mammals, and thus can be considered a reversal toward the ancestral state of nonmammalian synapsids. By reconstructing the evolutionary history of tooth complexity for the phylogenies of Carnivora and Cetartiodactyla, we established that a secondary evolution of simple teeth from more complex molars has occurred independently multiple times. Our phylogenetic comparative analyses showed that a simplification in tooth morphology was correlated with a more anterior dentition position relative to the component bones of the upper jaw in both Carnivora and Cetartiodactyla. These results suggest that the anterior shift of tooth position relative to the morphogenetic fields present in the jaw contributed to the evolutionary simplification in molar morphology. Our findings provide insights into the developmental basis of complex mammalian dentition.
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Affiliation(s)
- Tomohiro Harano
- Division of Liberal Arts and Sciences, Aichi Gakuin University, Nisshin, 470-0195, Japan
| | - Masakazu Asahara
- Division of Liberal Arts and Sciences, Aichi Gakuin University, Nisshin, 470-0195, Japan
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2
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Peredo CM, Ingle DN, Marshall CD. Puncture performance tests reveal distinct feeding modes in pinniped teeth. J Exp Biol 2022; 225:275668. [PMID: 35582832 DOI: 10.1242/jeb.244296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 05/12/2022] [Indexed: 11/20/2022]
Abstract
Marine mammals underwent a dramatic series of morphological transformations throughout their evolutionary history that facilitated their ecological transition to life in the water. Pinnipeds are a diverse clade of marine mammals that evolved from terrestrial carnivorans in the Oligocene (∼27 Ma). However, pinnipeds have secondarily lost the dental innovations emblematic of mammalian and carnivoran feeding, such as a talonid basin or shearing carnassials. Modern pinnipeds do not masticate their prey, but can reduce prey size through chopping behavior. Typically, small prey are swallowed whole. Nevertheless, pinnipeds display a wide breadth of morphology of the post-canine teeth. We investigated the relationship between dental morphologies and pinniped feeding by measuring the puncture performance of the cheek-teeth of seven extant pinniped genera. Puncture performance was measured as the maximum force and the maximum energy required to puncture a standardized prey item (Loligo sp). We report signficant differences in the puncture performance values across the seven genera, and identify three distinct categories based on cheek-teeth morphology and puncture performance: effective, ineffective, and moderate puncturers. In addition, we measured the overall complexity of the tooth row using two different metrics, Orientation Patch Count Rotated (OPCR) and Relif Index (RFI). Neither metric of complexity predicted puncture performance. Finally, we discuss these results in the broader context of known pinniped feeding strategies and lay the groundwork for subsequent efforts to explore the ecological variation of specific dental morphologies.
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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 Campus, Galveston, TX, USA.,Department of Paleobiology, National Museum of Natural History, Washington D.C., USA
| | - Danielle N Ingle
- Department of Marine Biology, Texas A&M University, Galveston Campus, Galveston, TX, USA
| | - Christopher D Marshall
- Department of Marine Biology, Texas A&M University, Galveston Campus, Galveston, TX, USA.,Department of Paleobiology, National Museum of Natural History, Washington D.C., USA.,Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, USA
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3
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Rule JP, Adams JW, Rovinsky DS, Hocking DP, Evans AR, Fitzgerald EMG. A new large-bodied Pliocene seal with unusual cutting teeth. ROYAL SOCIETY OPEN SCIENCE 2020; 7:201591. [PMID: 33391813 PMCID: PMC7735334 DOI: 10.1098/rsos.201591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/14/2020] [Indexed: 05/24/2023]
Abstract
Today, monachine seals display the largest body sizes in pinnipeds. However, the evolution of larger body sizes has been difficult to assess due to the murky taxonomic status of fossil seals, including fossils referred to Callophoca obscura, a species thought to be present on both sides of the North Atlantic during the Neogene. Several studies have recently called into question the taxonomic validity of these fossils, especially those from the USA, as the fragmentary lectotype specimen from Belgium is of dubious diagnostic value. We find that the lectotype isolated humerus of C. obscura is too uninformative; thus, we designate C. obscura as a nomen dubium. More complete cranial and postcranial specimens from the Pliocene Yorktown Formation are described as a new taxon, Sarcodectes magnus. The cranial specimens display adaptations towards an enhanced ability to cut or chew prey that are unique within Phocidae, and estimates indicate S. magnus to be around 2.83 m in length. A parsimony phylogenetic analysis found S. magnus is a crown monachine. An ancestral state estimation of body length indicates that monachines did not have a remarkable size increase until the evolution of the lobodontins and miroungins.
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Affiliation(s)
- James P. Rule
- Department of Anatomy and Developmental Biology, Melbourne, Victoria 3800, Australia
- Palaeontology, Museums Victoria, Melbourne, Victoria 3001, Australia
| | - Justin W. Adams
- Department of Anatomy and Developmental Biology, Melbourne, Victoria 3800, Australia
| | - Douglass S. Rovinsky
- Department of Anatomy and Developmental Biology, Melbourne, Victoria 3800, Australia
| | - David P. Hocking
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
- Palaeontology, Museums Victoria, Melbourne, Victoria 3001, Australia
| | - Alistair R. Evans
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
- Palaeontology, Museums Victoria, Melbourne, Victoria 3001, Australia
| | - Erich M. G. Fitzgerald
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
- Palaeontology, Museums Victoria, Melbourne, Victoria 3001, Australia
- National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
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Paterson RS, Rybczynski N, Kohno N, Maddin HC. A Total Evidence Phylogenetic Analysis of Pinniped Phylogeny and the Possibility of Parallel Evolution Within a Monophyletic Framework. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2019.00457] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Morphological integration and modularity are important for understanding phenotypic evolution because they constrain variation subjected to selection and enable independent evolution of functional and developmental units. We report dental integration and modularity in representative otariid (Eumetopias jubatus, Callorhinus ursinus) and phocid (Phoca largha, Histriophoca fasciata) species of Pinnipedia. This is the first study of integration and modularity in a secondarily simplified dentition with simple occlusion. Integration was stronger in both otariid species than in either phocid species and related positively to dental occlusion and negatively to both modularity and tooth-size variability across all the species. The canines and third upper incisor were most strongly integrated, comprising a module that likely serves as occlusal guides for the postcanines. There was no or weak modularity among tooth classes. The reported integration is stronger than or similar to that in mammals with complex dentition and refined occlusion. We hypothesise that this strong integration is driven by dental occlusion, and that it is enabled by reduction of modularity that constrains overall integration in complex dentitions. We propose that modularity was reduced in pinnipeds during the transition to aquatic life in association with the origin of pierce-feeding and loss of mastication caused by underwater feeding.
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Hocking DP, Marx FG, Park T, Fitzgerald EMG, Evans AR. A behavioural framework for the evolution of feeding in predatory aquatic mammals. Proc Biol Sci 2018; 284:rspb.2016.2750. [PMID: 28250183 DOI: 10.1098/rspb.2016.2750] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/09/2017] [Indexed: 11/12/2022] Open
Abstract
Extant aquatic mammals are a key component of aquatic ecosystems. Their morphology, ecological role and behaviour are, to a large extent, shaped by their feeding ecology. Nevertheless, the nature of this crucial aspect of their biology is often oversimplified and, consequently, misinterpreted. Here, we introduce a new framework that categorizes the feeding cycle of predatory aquatic mammals into four distinct functional stages (prey capture, manipulation and processing, water removal and swallowing), and details the feeding behaviours that can be employed at each stage. Based on this comprehensive scheme, we propose that the feeding strategies of living aquatic mammals form an evolutionary sequence that recalls the land-to-water transition of their ancestors. Our new conception helps to explain and predict the origin of particular feeding styles, such as baleen-assisted filter feeding in whales and raptorial 'pierce' feeding in pinnipeds, and informs the structure of present and past ecosystems.
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Affiliation(s)
- David P Hocking
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia .,Geosciences, Museums Victoria, Melbourne, Australia
| | - Felix G Marx
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.,Geosciences, Museums Victoria, Melbourne, Australia.,Directorate of Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Travis Park
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.,Geosciences, Museums Victoria, Melbourne, Australia
| | - Erich M G Fitzgerald
- Geosciences, Museums Victoria, Melbourne, Australia.,National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Department of Life Sciences, Natural History Museum, London, UK
| | - Alistair R Evans
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.,Geosciences, Museums Victoria, Melbourne, Australia
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Boessenecker RW, Churchill M. The last of the desmatophocid seals: a new species of Allodesmus from the upper Miocene of Washington, USA, and a revision of the taxonomy of Desmatophocidae. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zlx098] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Robert W Boessenecker
- Department of Geology and Environmental Geosciences, College of Charleston, Charleston, SC, USA
- University of California Museum of Paleontology, University of California, Berkeley, CA, USA
| | - Morgan Churchill
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI, USA
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Loch C, Boessenecker RW, Churchill M, Kieser J. Enamel ultrastructure of fossil and modern pinnipeds: evaluating hypotheses of feeding adaptations in the extinct walrus Pelagiarctos. Naturwissenschaften 2016; 103:44. [DOI: 10.1007/s00114-016-1366-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/12/2016] [Accepted: 04/15/2016] [Indexed: 01/05/2023]
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