1
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Arnold P, Janiszewska K, Li Q, O'Connor JK, Fostowicz-Frelik Ł. The Late Cretaceous eutherian Zalambdalestes reveals unique axis and complex evolution of the mammalian neck. Sci Bull (Beijing) 2024; 69:1767-1775. [PMID: 38702276 DOI: 10.1016/j.scib.2024.04.027] [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: 09/08/2023] [Revised: 03/24/2024] [Accepted: 03/26/2024] [Indexed: 05/06/2024]
Abstract
The typical mammalian neck consisting of seven cervical vertebrae (C1-C7) was established by the Late Permian in the cynodont forerunners of modern mammals. This structure is precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the clade including crown placentals, has a fossil record extending back more than 125 million years revealing significant morphological diversification in the Mesozoic. Yet very little is known concerning the early evolution of eutherian cervical morphology and its functional adaptations. A specimen of Zalambdalestes lechei from the Late Cretaceous of Mongolia boasts exceptional preservation of an almost complete series of cervical vertebrae (C2-C7) revealing a highly modified axis (C2). The significance of this cervical morphology is explored utilizing an integrated approach combining comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. We compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of the eutherian cervical morphology and suggest a feeding behavior similar to insectivores specialized in vermivory and defensive behaviors in Zalambdalestes akin to modern spiniferous mammals.
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Affiliation(s)
- Patrick Arnold
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam D-14476, Germany
| | - Katarzyna Janiszewska
- Environmental Paleobiology Department, Institute of Paleobiology, Polish Academy of Sciences, Warsaw 00-818, Poland
| | - Qian Li
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | | | - Łucja Fostowicz-Frelik
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago IL 60637, USA; Evolutionary Paleobiology Department, Institute of Paleobiology, Polish Academy of Sciences, Warsaw 00-818, Poland.
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2
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Wible JR. The ear region of the Philippine flying lemur Cynocephalus volans (Placentalia, Dermoptera). Anat Rec (Hoboken) 2023; 306:2853-2871. [PMID: 36897245 DOI: 10.1002/ar.25174] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 03/11/2023]
Abstract
The placental order Dermoptera, which includes two extant species, the Philippine and Sunda flying lemurs, Cynocephalus volans and Galeopterus variegatus, respectively, is generally held to be the sister group of Primates. Yet, little has been reported on their cranial anatomy. Here, the anatomy of the ear region is described and illustrated for a juvenile and adult C. volans based on CT scans. The inclusion of a juvenile is essential as nearly all cranial sutures are fused in the adult. Soft tissues are reconstructed based on sectioned histological pre- and postnatal specimens previously reported by the author. Numerous unusual features are identified, including: a small parasphenoid beneath the basisphenoid, a tensor tympani fossa on the epitympanic wing of the squamosal, a cavum supracochleare for the geniculate ganglion of the facial nerve that is not enclosed in the petrosal bone, a secondary facial foramen between the petrosal and squamosal, a secondary posttemporal foramen leading to the primary one, a subarcuate fossa that is floored in part by a large contribution from the squamosal, a body of the incus larger than the head of the malleus, and a crus longum of the incus that lacks an osseous connection to the lenticular process. Documentation of the anatomy of the Philippine flying lemur ear region is an essential first step in morphological phylogenetic analyses where features of the basicranium are widely sampled.
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Affiliation(s)
- John R Wible
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA
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3
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Wang H, Wang Y. Middle ear innovation in Early Cretaceous eutherian mammals. Nat Commun 2023; 14:6831. [PMID: 37884521 PMCID: PMC10603157 DOI: 10.1038/s41467-023-42606-7] [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: 03/07/2022] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
The middle ear ossicles in modern mammals are repurposed from postdentary bones in non-mammalian cynodonts. Recent discoveries by palaeontological and embryonic studies have developed different models for the middle ear evolution in mammaliaforms. However, little is known about the evolutionary scenario of the middle ear in early therians. Here we report a detached middle ear preserved in a new eutherian mammal from the Early Cretaceous Jehol Biota. The well-preserved articulation of the malleus and incus suggest that the saddle-shaped incudomallear joint is a major apomorphy of Early Cretaceous eutherians. By contrast to the distinct saddle-like incudomallear articulation in therians, differences between the overlapping versus the half-overlapping incudomallear joints in monotremes and stem mammals would be relatively minor. The middle ear belongs to the microtype by definition, indicating its adaptation to high-frequency hearing. Current evidence indicates that significant evolutionary innovations of the middle ear in modern therians evolved in Early Cretaceous.
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Affiliation(s)
- Haibing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 100044, Beijing, China.
| | - Yuanqing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 100044, Beijing, China.
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China.
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4
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Fostowicz-Frelik Ł, Cox PG, Li Q. Mandibular characteristics of early Glires (Mammalia) reveal mixed rodent and lagomorph morphotypes. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220087. [PMID: 37183896 PMCID: PMC10184241 DOI: 10.1098/rstb.2022.0087] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
Glires (rodents, lagomorphs and their fossil kin) is the most speciose and arguably most diversified clade of living placentals. Different lineages within the Glires evolved basically opposite chewing movements: a mostly transversal power stroke in lagomorphs, and a mostly proal power stroke in rodents, but the ancestral condition for Glires is still unclear. To address this knowledge gap, we studied the mandibles of Chinese Palaeocene Glires representing the duplicidentate (lagomorph-like; Mimotona) and simplicidentate (rodent-like; Eomylus and Heomys) lineages. To assess the mechanical resistance of mandibles to bending and torsion, we calculated the section modulus. The dentaries differ greatly in morphology and the region where the maximum grinding force was likely applied. The early Palaeocene Mimotona lii and the middle Palaeocene Mimotona robusta and Heomys orientalis all show a pattern of increasing strength moving posteriorly along the mandible, similar to sciurids and the mountain beaver. By contrast, the late Palaeocene Eomylus sp. mandible was strongest in the m1 region, a pattern seen in lagomorphs and the stem placental Zofialestes. Our results indicate the early diversification of mandible structure of Glires, demonstrate a mixture of duplicidentate and simplicidentate characters among the basal Glires and suggest an early occurrence of a lagomorph-like morphotype. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
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Affiliation(s)
- Łucja Fostowicz-Frelik
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
- Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland
| | - Philip G Cox
- Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Qian Li
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
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5
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Ruf I, Meng J, Fostowicz-Frelik Ł. Auditory region circulation in Lagomorpha: the internal carotid artery pattern revisited. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220088. [PMID: 37183894 PMCID: PMC10184246 DOI: 10.1098/rstb.2022.0088] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
The internal carotid artery (ICA) is one of the major vessels in the cranial circulation. Characters concerning the ICA, such as its course in the auditory region, have been employed frequently in phylogenetic analyses of mammals, including extinct taxa. In lagomorphs, however, our knowledge on vascular features of the auditory region has been based predominantly on living species, mostly on the European rabbit. We present the first survey on 11 out of 12 extant genera and key fossil taxa such as stem lagomorphs and early crown representatives (Archaeolagus and Prolagus). The ICA pattern shows a modified transpromontorial course in stem taxa (Litolagus, Megalagus and Palaeolagus) and Archaeolagus, which we propose as the ancestral character state for Lagomorpha, similar to that for the earliest rodents, plesiadapids and scandentians. The ICA pattern in leporids is perbullar, but shows structural similarities to stem taxa, whereas the extrabullar ICA course in Ochotona is apparently a highly derived condition. Prolagus shows a mixed character state between leporids and Ochotona in its ICA route. The persistence of the transpromontorial ICA course and similarities in the carotid canal structure among stem taxa and crown leporids support morphological conservatism in Lagomorpha, in contrast to their sister clade Rodentia. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
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Affiliation(s)
- Irina Ruf
- Abteilung Messelforschung und Mammalogie, Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, 60325 Frankfurt am Main, Germany
- Institut für Geowissenschaften, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main, Germany
| | - Jin Meng
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Łucja Fostowicz-Frelik
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
- Department of Evolutionary Paleobiology, Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland
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6
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Beck RM, Voss RS, Jansa SA. Craniodental Morphology and Phylogeny of Marsupials. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2022. [DOI: 10.1206/0003-0090.457.1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Robin M.D. Beck
- School of Science, Engineering and Environment University of Salford, U.K. School of Biological, Earth & Environmental Sciences University of New South Wales, Australia Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Robert S. Voss
- Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Sharon A. Jansa
- Bell Museum and Department of Ecology, Evolution, and Behavior University of Minnesota
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7
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Wang HB, Hoffmann S, Wang DC, Wang YQ. A new mammal from the Lower Cretaceous Jehol Biota and implications for eutherian evolution. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210042. [PMID: 35125007 PMCID: PMC8819371 DOI: 10.1098/rstb.2021.0042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Here we report on a new Early Cretaceous eutherian represented by a partial skeleton from the Jiufotang Formation at Sihedang site, Lingyuan City, Liaoning Province that fills a crucial gap between the earliest eutherians from the Yixian Formation and later Cretaceous eutherians. The new specimen reveals, to our knowledge for the first time in eutherians, that the Meckelian cartilage was ossified but reduced in size, confirming a complete detachment of the middle ear from the lower jaw. Seven hyoid elements, including paired stylohyals, epihyals and thyrohyals and the single basihyal are preserved. For the inner ear the ossified primary lamina, base of the secondary lamina, ossified cochlear ganglion and secondary crus commune are present and the cochlear canal is coiled through 360°. In addition, plesiomorphic features of the dentition include weak conules, lack of pre- and post-cingula and less expanded protocones on the upper molars and height differential between the trigonid and talonid, a large protoconid and a small paraconid on the lower molars. The new taxon displays an alternating pattern of tooth replacement with P3 being the last upper premolar to erupt similar to the basal eutherian Juramaia. Parsimony analysis places the new taxon with Montanalestes, Sinodelphys and Ambolestes as a sister group to other eutherians. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.
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Affiliation(s)
- Hai-Bing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People's Republic of China.,Centre for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, People's Republic of China.,Key State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, People's Republic of China
| | - Simone Hoffmann
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
| | - Dian-Can Wang
- Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology, 22 South Zhongguancun Avenue, Beijing, People's Republic of China
| | - Yuan-Qing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People's Republic of China.,Centre for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, People's Republic of China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, People's Republic of China
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8
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Velazco PM, Buczek AJ, Hoffman E, Hoffman DK, O'Leary MA, Novacek MJ. Combined data analysis of fossil and living mammals: a Paleogene sister taxon of Placentalia and the antiquity of Marsupialia. Cladistics 2022; 38:359-373. [PMID: 35098586 DOI: 10.1111/cla.12499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2022] [Indexed: 11/28/2022] Open
Abstract
The Cretaceous-Paleogene (KPg) boundary, one of Earth's five major extinction events, occurred just before the appearance of Placentalia in the fossil record. The Gobi Desert, Mongolia and the Western Interior of North America have important fossil mammals occurring just before and after the KPg boundary (e.g. Prodiacodon, Deltatheridium) that have yet to be phylogenetically tested in a character-rich context with molecular data. We present here phylogenetic analyses of >6000 newly scored anatomical observations drawn from six untested fossils and added to the largest existing morphological matrix for mammals. These data are combined with sequence data from 27 nuclear genes. Results show the existence of a new eutherian sister clade to Placentalia, which we name and characterize. The extinct clade Leptictidae is part of this placental sister clade, indicating that the sister clade survived the KPg event to co-exist in ancient ecosystems during the Paleogene radiation of placentals. Analysing the Cretaceous metatherian Deltatheridium in this character-rich context reveals it is a member of Marsupialia, a finding that extends the minimum age of Marsupialia before the KPg boundary. Numerous shared-derived features from multiple anatomical systems support the assignment of Deltatheridium to Marsupialia. Computed tomography scans of exquisite new specimens better document the marsupial-like dental replacement pattern of Deltatheridium. The new placental sister clade has both Asian and North American species, and is ancestrally characterized by shared derived features such as a hind limb modified for saltatorial locomotion.
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Affiliation(s)
- Paúl M Velazco
- Division of Paleontology, American Museum of Natural History, New York, NY, 10024, USA.,Department of Biology, Arcadia University, Glenside, PA, 19038, USA
| | - Alexandra J Buczek
- Division of Paleontology, American Museum of Natural History, New York, NY, 10024, USA
| | - Eva Hoffman
- Division of Paleontology, American Museum of Natural History, New York, NY, 10024, USA
| | - Devin K Hoffman
- Department of Geosciences, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Maureen A O'Leary
- Division of Paleontology, American Museum of Natural History, New York, NY, 10024, USA.,Department of Anatomical Sciences, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Michael J Novacek
- Division of Paleontology, American Museum of Natural History, New York, NY, 10024, USA
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9
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Head of the Class: John R. Wible’s Transformative Insights Into Mammalian Craniodental Anatomy. J MAMM EVOL 2021. [DOI: 10.1007/s10914-021-09587-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Mammalian face as an evolutionary novelty. Proc Natl Acad Sci U S A 2021; 118:2111876118. [PMID: 34716275 PMCID: PMC8673075 DOI: 10.1073/pnas.2111876118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/08/2021] [Indexed: 12/13/2022] Open
Abstract
The anterior end of the mammalian face is characteristically composed of a semimotile nose, not the upper jaw as in other tetrapods. Thus, the therian nose is covered ventrolaterally by the "premaxilla," and the osteocranium possesses only a single nasal aperture because of the absence of medial bony elements. This stands in contrast to those in other tetrapods in whom the premaxilla covers the rostral terminus of the snout, providing a key to understanding the evolution of the mammalian face. Here, we show that the premaxilla in therian mammals (placentals and marsupials) is not entirely homologous to those in other amniotes; the therian premaxilla is a composite of the septomaxilla and the palatine remnant of the premaxilla of nontherian amniotes (including monotremes). By comparing topographical relationships of craniofacial primordia and nerve supplies in various tetrapod embryos, we found that the therian premaxilla is predominantly of the maxillary prominence origin and associated with mandibular arch. The rostral-most part of the upper jaw in nonmammalian tetrapods corresponds to the motile nose in therian mammals. During development, experimental inhibition of primordial growth demonstrated that the entire mammalian upper jaw mostly originates from the maxillary prominence, unlike other amniotes. Consistently, cell lineage tracing in transgenic mice revealed a mammalian-specific rostral growth of the maxillary prominence. We conclude that the mammalian-specific face, the muzzle, is an evolutionary novelty obtained by overriding ancestral developmental constraints to establish a novel topographical framework in craniofacial mesenchyme.
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11
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Shelley SL, Bertrand OC, Brusatte SL, Williamson TE. Petrosal Anatomy of the Paleocene Eutherian Mammal Deltatherium fundaminis (Cope, 1881). J MAMM EVOL 2021; 28:1161-1180. [PMID: 34483638 PMCID: PMC8406390 DOI: 10.1007/s10914-021-09568-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2021] [Indexed: 12/04/2022]
Abstract
We describe the tympanic anatomy of the petrosal of Deltatherium fundaminis, an enigmatic Paleocene mammal based on cranial specimens recovered from New Mexico, U.S.A. Although the ear region of Deltatherium has previously been described, there has not been a comprehensive, well-illustrated contribution using current anatomical terminology. The dental and cranial anatomy of Deltatherium is a chimera, with morphological similarities to both ‘condylarth’ and ‘cimolestan’ taxa. As such, the phylogenetic relationships of this taxon have remained elusive since its discovery, and it has variably been associated with Arctocyonidae, Pantodonta and Tillodontia. The petrosal of Deltatherium is anteriorly bordered by an open space comprising a contiguous carotid opening and pyriform fenestra. The promontorium features both a small rostral tympanic process and small epitympanic wing but lacks well-marked sulci. A large ventral facing external aperture of the canaliculus cochleae is present and bordered posteriorly by a well-developed caudal tympanic process. The hiatus Fallopii opens on the ventral surface of the petrosal. The tegmen tympani is mediolaterally broad and anteriorly expanded, and its anterior margin is perforated by a foramen for the ramus superior of the stapedial artery. The tympanohyal is small but approximates the caudal tympanic process to nearly enclose the stylomastoid notch. The mastoid is widely exposed on the basicranium and bears an enlarged mastoid process, separate from the paraoccipital process. These new observations provide novel anatomical data corroborating previous hypotheses regarding the plesiomorphic eutherian condition but also reveal subtle differences among Paleocene eutherians that have the potential to help inform the phylogeny of Deltatherium.
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Affiliation(s)
- Sarah L Shelley
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom.,Carnegie Museum of Natural History, Pittsburgh, Pennsylvania United States of America
| | - Ornella C Bertrand
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom.,New Mexico Museum of Natural History and Science, Albuquerque, New Mexico United States of America
| | - Thomas E Williamson
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico United States of America
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12
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Abel P, Werneburg I. Morphology of the temporal skull region in tetrapods: research history, functional explanations, and a new comprehensive classification scheme. Biol Rev Camb Philos Soc 2021; 96:2229-2257. [PMID: 34056833 DOI: 10.1111/brv.12751] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 12/21/2022]
Abstract
The morphology of the temporal region in the tetrapod skull traditionally has been a widely discussed feature of vertebrate anatomy. The evolution of different temporal openings in Amniota (mammals, birds, and reptiles), Lissamphibia (frogs, salamanders, and caecilians), and several extinct tetrapod groups has sparked debates on the phylogenetic, developmental, and functional background of this region in the tetrapod skull. This led most famously to the erection of different amniote taxa based on the number and position of temporal fenestrae in their skulls. However, most of these taxa are no longer recognised to represent natural groupings and the morphology of the temporal region is not necessarily an adequate trait for use in the reconstruction of amniote phylogenies. Yet, new fossil finds, most notably of parareptiles and stem-turtles, as well as modern embryological and biomechanical studies continue to provide new insights into the morphological diversity of the temporal region. Here, we introduce a novel comprehensive classification scheme for the various temporal morphotypes in all Tetrapoda that is independent of phylogeny and previous terminology and may facilitate morphological comparisons in future studies. We then review the history of research on the temporal region in the tetrapod skull. We document how, from the early 19th century with the first recognition of differences in the temporal region to the first proposals of phylogenetic relationships and their assessment over the centuries, the phylogenetic perspective on the temporal region has developed, and we highlight the controversies that still remain. We also compare the different functional and developmental drivers proposed for the observed morphological diversity and how the effects of internal and external factors on the structure of the tetrapod skull have been interpreted.
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Affiliation(s)
- Pascal Abel
- Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) at Eberhard Karls Universität, Sigwartstraße 10, Tübingen, 72076, Germany.,Fachbereich Geowissenschaften der Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, Tübingen, 72074, Germany
| | - Ingmar Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) at Eberhard Karls Universität, Sigwartstraße 10, Tübingen, 72076, Germany.,Fachbereich Geowissenschaften der Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, Tübingen, 72074, Germany
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13
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Gomes Rodrigues H, Tabuce R, Asher RJ, Hautier L. Developmental origins and homologies of the hyracoid dentition. Evol Dev 2020; 22:323-335. [PMID: 32353920 DOI: 10.1111/ede.12337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 11/29/2022]
Abstract
Understanding the origins of morphological specializations in mammals is a key goal in evolutionary biology. It can be accomplished by studying dental homology, which is at the core of most evolutionary and developmental studies. Here, we focused on the evolution and development of the specialized dentition of hyraxes for which dental homologies have long been debated, and could have implications on early placental evolution. Specifically, we analysed dental mineralization sequences of the three living genera of hyraxes and 17 fossil species using X-ray computed microtomography. Our results point out the labile position of vestigial upper teeth on jaw bones in extant species, associated with the frequently unusual premolar shape of deciduous canines over 50 Ma of hyracoid evolution. We proposed two evolutionary and developmental hypotheses to explain these original hyracoid dental characteristics. (a) The presence of a vestigial teeth on the maxilla in front of a complex deciduous canine could be interpreted as extra-teeth reminiscent of early placental evolution or sirenians, an order phylogenetically close to hyracoids and showing five premolars. (b) These vestigial teeth could also correspond to third incisors with a position unusually shifted on the maxilla, which could be explained by the dual developmental origin of these most posterior incisors and their degenerated condition. This integrative study allows discussion on the current evolutionary and developmental paradigms associated with the mammalian dentition. It also highlights the importance of nonmodel species to understand dental homologies.
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Affiliation(s)
- Helder Gomes Rodrigues
- Centre de Recherche en Paléontologie-Paris (CR2P), UMR CNRS 7207, Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France.,Mécanismes adaptatifs et évolution (MECADEV), UMR 7179, CNRS, Funevol team, Muséum National d'Histoire Naturelle, Paris, France.,Institut des Sciences de l'Evolution, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Rodolphe Tabuce
- Institut des Sciences de l'Evolution, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Robert J Asher
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Lionel Hautier
- Institut des Sciences de l'Evolution, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Department of Zoology, University of Cambridge, Cambridge, UK.,Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
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14
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O'Brien HD. From Anomalous Arteries to Selective Brain Cooling: Parallel Evolution of the Artiodactyl Carotid Rete. Anat Rec (Hoboken) 2018; 303:308-317. [PMID: 30421534 DOI: 10.1002/ar.23987] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/19/2017] [Accepted: 01/08/2018] [Indexed: 11/05/2022]
Abstract
Terrestrial artiodactyls (even-toed ungulates) inhabit some of the world's most extreme environments, including arid deserts and high elevations. As medium-to-large-bodied mammals, artiodactyls have a suite of specialized physiologies to facilitate occupation of regions unavailable to other large mammals. One such physiology is selective brain cooling, wherein reduction of brain temperature below core body temperature has been demonstrated to reduce evaporative water loss. This physiology is enabled by an arterial heat-exchanger called the carotid rete. The ubiquity of the carotid rete throughout the clade, as well as its evolutionary history, is currently uninvestigated. Here, I use osteological correlates to survey clade-wide presence and morphology of the carotid rete, prior to conducting a preliminary evolutionary analysis. Nearly all living artiodactyls possess a carotid rete and are capable of selective brain cooling; however, major arteries supplying the rete are derived from different embryonic aortic arches on a suborder-specific basis. Ancestral character estimation infers this pattern of variation to be the result of independent evolutionary processes, suggesting carotid rete homoplasy arising via parallelism. This is a surprising finding given the role this structure plays in driving a physiology that has been implicated in mitigating artiodactylan responses to extreme environmental conditions. Future studies should incorporate extinct species represented in the fossil record to better parse between parallel and convergent mechanisms, as well as to better understand the relationship between the carotid rete, selective brain cooling, and survivorship of climate perturbation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:308-317, 2020. © 2018 American Association for Anatomy.
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Affiliation(s)
- Haley D O'Brien
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma
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15
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Cameron J, Shelley SL, Williamson TE, Brusatte SL. The Brain and Inner Ear of the Early Paleocene “Condylarth”
Carsioptychus coarctatus
: Implications for Early Placental Mammal Neurosensory Biology and Behavior. Anat Rec (Hoboken) 2018; 302:306-324. [DOI: 10.1002/ar.23903] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 04/04/2018] [Accepted: 04/16/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Joe Cameron
- School of GeoSciences University of Edinburgh, Grant Institute Edinburgh Scotland UK
| | - Sarah L. Shelley
- School of GeoSciences University of Edinburgh, Grant Institute Edinburgh Scotland UK
| | | | - Stephen L. Brusatte
- School of GeoSciences University of Edinburgh, Grant Institute Edinburgh Scotland UK
- New Mexico Museum of Natural History and Science Albuquerque New Mexico
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16
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Billet G, Bardin J. Serial Homology and Correlated Characters in Morphological Phylogenetics: Modeling the Evolution of Dental Crests in Placentals. Syst Biol 2018; 68:267-280. [DOI: 10.1093/sysbio/syy071] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/22/2018] [Indexed: 01/24/2023] Open
Affiliation(s)
- Guillaume Billet
- CR2P, UMR 7207, Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, 8 rue Buffon 75005 Paris, France
| | - Jérémie Bardin
- CR2P, UMR 7207, Sorbonne Université, MNHN, CNRS, T.46-56, E.5, case 104, 4 place Jussieu, 75252 Paris cedex 05, France
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17
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An Early Cretaceous eutherian and the placental–marsupial dichotomy. Nature 2018; 558:390-395. [DOI: 10.1038/s41586-018-0210-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 05/10/2018] [Indexed: 11/08/2022]
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Lopatin AV, Averianov AO. A New Stem Placental Mammal from the Early Cretaceous of Mongolia. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2018. [PMID: 29536398 DOI: 10.1134/s0012496618010027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A new taxon of stem placentals, Hovurlestes noyon gen. et sp. nov. from the Early Cretaceous of Mongolia (Höovör locality) is described. The new taxon differs from members of the genus Prokennalestes from Höovör in the single-rooted canine and the presence of cusp e, which is an enhancing interlocking between anterior molars (m1 and m2). Hovurlestes noyon gen. et sp. nov. is one of the rarest mammal taxa from Höovör, which expands morphological diversity of the earliest Eutheria.
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Affiliation(s)
- A V Lopatin
- Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647, Russia. .,Moscow State University, Moscow, 119991, Russia.
| | - A O Averianov
- Zoological Institute, Russian Academy of Sciences, St. Petersburg, 199034, Russia.,Kazan (Volga) Federal University, Kazan, Tatarstan, 420008, Russia
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19
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Gaudin TJ, Lyon LM. Cranial osteology of the pampathere Holmesina floridanus (Xenarthra: Cingulata; Blancan NALMA), including a description of an isolated petrosal bone. PeerJ 2017; 5:e4022. [PMID: 29250462 PMCID: PMC5729832 DOI: 10.7717/peerj.4022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 10/21/2017] [Indexed: 11/20/2022] Open
Abstract
The present study entails descriptions of several well-preserved skulls from the pampathere species Holmesina floridanus, recovered from Pliocene localities in central Florida and housed in the collections of the Florida Museum of Natural History. Bone by bone descriptions have allowed detailed reconstructions of cranial morphology. Cranial foramina are described and illustrated in detail, and their contents inferred. The first ever description of an isolated pampathere petrosal is also included. Cranial osteology of Holmesina floridanus is compared to that of Pleistocene species of Holmesina from both North and South America (Holmesina septentrionalis, Holmesina occidentalis), as well as to the other well-known pampathere genera, to closely related taxa among glyptodonts (Propalaehoplophorus), and to extinct and extant armadillos (Proeutatus, Euphractus). This study identifies a suite of apomorphic cranial features that serve to diagnose a putative, progressive series of more inclusive monophyletic groups, including the species Holmesina floridanus, the genus Holmesina, pampatheres, pampatheres plus glyptodonts, and a clade formed by pampatheres, glyptodonts, and Proeutatus. The study highlights the need for further anatomical investigations of pampathere cranial anatomy, especially those using modern scanning technology, and for analyses of pampathere phylogenetic relationships.
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Affiliation(s)
- Timothy J. Gaudin
- Department of Biology, Geology and Environmental Science, University of Tennessee—Chattanooga, Chattanooga, TN, USA
| | - Lauren M. Lyon
- Department of Geosciences and Don Sundquist Center of Excellence in Paleontology, East Tennessee State University, Johnson City, TN, USA
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20
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Halliday TJD, Upchurch P, Goswami A. Resolving the relationships of Paleocene placental mammals. Biol Rev Camb Philos Soc 2017; 92:521-550. [PMID: 28075073 PMCID: PMC6849585 DOI: 10.1111/brv.12242] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 10/28/2015] [Accepted: 11/04/2015] [Indexed: 01/25/2023]
Abstract
The 'Age of Mammals' began in the Paleocene epoch, the 10 million year interval immediately following the Cretaceous-Palaeogene mass extinction. The apparently rapid shift in mammalian ecomorphs from small, largely insectivorous forms to many small-to-large-bodied, diverse taxa has driven a hypothesis that the end-Cretaceous heralded an adaptive radiation in placental mammal evolution. However, the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters. We improve the resolution of the relationships of several enigmatic Paleocene clades, including families of 'condylarths'. Protungulatum is resolved as a stem eutherian, meaning that no crown-placental mammal unambiguously pre-dates the Cretaceous-Palaeogene boundary. Our results support an Atlantogenata-Boreoeutheria split at the root of crown Placentalia, the presence of phenacodontids as closest relatives of Perissodactyla, the validity of Euungulata, and the placement of Arctocyonidae close to Carnivora. Periptychidae and Pantodonta are resolved as sister taxa, Leptictida and Cimolestidae are found to be stem eutherians, and Hyopsodontidae is highly polyphyletic. The inclusion of Paleocene taxa in a placental phylogeny alters interpretations of relationships and key events in mammalian evolutionary history. Paleocene mammals are an essential source of data for understanding fully the biotic dynamics associated with the end-Cretaceous mass extinction. The relationships presented here mark a critical first step towards accurate reconstruction of this important interval in the evolution of the modern fauna.
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Affiliation(s)
- Thomas J. D. Halliday
- Department of Earth SciencesUniversity College LondonGower StreetLondonWC1E 6BTU.K.
- Department of Genetics, Evolution and EnvironmentUniversity College LondonGower StreetLondonWC1E 6BTU.K.
| | - Paul Upchurch
- Department of Earth SciencesUniversity College LondonGower StreetLondonWC1E 6BTU.K.
| | - Anjali Goswami
- Department of Earth SciencesUniversity College LondonGower StreetLondonWC1E 6BTU.K.
- Department of Genetics, Evolution and EnvironmentUniversity College LondonGower StreetLondonWC1E 6BTU.K.
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Martínez G, Dozo MT, Gelfo JN, Marani H. Cranial Morphology of the Late Oligocene Patagonian Notohippid Rhynchippus equinus Ameghino, 1897 (Mammalia, Notoungulata) with Emphases in Basicranial and Auditory Region. PLoS One 2016; 11:e0156558. [PMID: 27232883 PMCID: PMC4883762 DOI: 10.1371/journal.pone.0156558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 05/16/2016] [Indexed: 11/18/2022] Open
Abstract
"Notohippidae" is a probably paraphyletic family of medium sized notoungulates with complete dentition and early tendency to hypsodonty. They have been recorded from early Eocene to early Miocene, being particularly diverse by the late Oligocene. Although Rhynchippus equinus Ameghino is one of the most frequent notohippids in the fossil record, there are scarce data about cranial osteology other than the classical descriptions which date back to the early last century. In this context, we describe the exceptionally preserved specimen MPEF PV 695 (based on CT scanning technique and 3D reconstruction) with the aim of improving our knowledge of the species, especially regarding auditory region (petrosal, tympanic and surrounding elements), sphenoidal and occipital complexes. Besides a modular description of the whole skull, osteological correlates identified on the basicranium are used to infer some soft-tissue elements, especially those associated with vessels that supply the head, mainly intracranially. One of the most informative elements was the petrosal bone, whose general morphology matches that expected for a toxodont. The endocranial surface, together with the surrounding parietal, basisphenoid, occipital, and squamosal, enabled us to propose the location and communication of main venous sinuses of the lateral head wall (temporal, inferior and sigmoid sinuses), whereas the tympanic aspect and the identification of a posterior carotid artery canal provided strong evidence in support of an intratympanic course of the internal carotid artery, a controversial issue among notoungulates. Regarding the arrangement of tympanic and paratympanic spaces, the preservation of the specimen allowed us to appreciate the three connected spaces that constitute a heavily pneumatized middle ear; the epitympanic sinus, the tympanic cavity itself, and the ventral expansion of the tympanic cavity through the notably inflated bullae. We hope this study stimulates further inquires and provides potentially informative data for future research involving other representatives of the order.
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Affiliation(s)
- Gastón Martínez
- Instituto Patagónico de Geología y Paleontología, Centro Nacional Patagónico, CONICET, Puerto Madryn, Chubut, Argentina
- Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
- * E-mail:
| | - María Teresa Dozo
- Instituto Patagónico de Geología y Paleontología, Centro Nacional Patagónico, CONICET, Puerto Madryn, Chubut, Argentina
| | - Javier N. Gelfo
- División Paleontología Vertebrados, Museo de la Plata, CONICET, La Plata, Buenos Aires, Argentina
- Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Hernán Marani
- Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Puerto Madryn, Chubut, Argentina
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22
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Schmitt A, Gheerbrant E. The ear region of earliest known elephant relatives: new light on the ancestral morphotype of proboscideans and afrotherians. J Anat 2015; 228:137-52. [PMID: 26510535 DOI: 10.1111/joa.12396] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2015] [Indexed: 12/01/2022] Open
Abstract
One of the last major clades of placental mammals recognized was the Afrotheria, which comprises all main endemic African mammals. This group includes the ungulate-like paenungulates, and among them the elephant order Proboscidea. Among afrotherians, the petrosal anatomy remains especially poorly known in Proboscidea. We provide here the first comparative CT scan study of the ear region of the two earliest known proboscideans (and paenungulates), Eritherium and Phosphatherium, from the mid Palaeocene and early Eocene of Morocco. It is helpful to characterize the ancestral morphotype of Proboscidea to understand petrosal evolution within proboscideans and afrotherians. The petrosal structure of these two taxa shows several differences. Eritherium is more primitive than Phosphatherium and closer to the basal paenungulate Ocepeia in several traits (inflated tegmen tympani, very deep fossa subarcuata and ossified canal for ramus superior of stapedial artery). Phosphatherium, however, retains plesiomorphies such as a true crus commune secundaria. A cladistic analysis of petrosal traits of Eritherium and Phosphatherium among Proboscidea results in a single tree with a low level of homoplasy in which Eritherium, Phosphatherium and Numidotherium are basal. This contrasts with previous phylogenetic studies showing homoplasy in petrosal evolution among Tethytheria. It suggests that evolutionary modalities of petrosal characters differ with the taxonomic level among Afrotheria: noticeable convergences occurred among the paenungulate orders, whereas little homoplasy seems to have occurred at intra-ordinal level in orders such as Proboscidea. Most petrosal features of both Eritherium and Phosphatherium are primitive. The ancestral petrosal morphotype of Proboscidea was not specialized but was close to the generalized condition of paenungulates, afrotherians, and even eutherians. This is consistent with cranial and dental characters of Eritherium, suggesting that the ancestral morphotypes of the different paenungulate orders were close to each other. Specializations occurred rapidly after the ordinal radiation of Paenungulata.
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Affiliation(s)
- Arnaud Schmitt
- CR2P - Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207, CNRS, MNHN, UPMC, Sorbonne Universités, Paris, France
| | - Emmanuel Gheerbrant
- CR2P - Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207, CNRS, MNHN, UPMC, Sorbonne Universités, Paris, France.
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23
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Averianov AO, Archibald JD. Evolutionary transition of dental formula in Late Cretaceous eutherian mammals. Naturwissenschaften 2015; 102:56. [PMID: 26319573 DOI: 10.1007/s00114-015-1308-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/01/2015] [Accepted: 08/19/2015] [Indexed: 01/02/2023]
Abstract
Kulbeckia kulbecke, stem placental mammal from the Late Cretaceous of Uzbekistan, shows a transitional stage of evolution in the dental formula from five to four premolars. A non-replaced dP3/dp3 may occur as individual variation. In other specimens, the lower premolars are crowded with no space for development of dp3. As is evident from the CT scanning of one juvenile specimen, the development of dp3 started in a late ontogenetic stage and was confined to the pulp cavity of the developing p2. This dp3 would have been resorbed in a later ontogenetic stage, as the roots of p2 formed. The initial stage of reduction of the third premolar can be traced to stem therians (Juramaia and Eomaia), which have both dP3 and P3 present in the adult dentition. Further delay in the development of dP3/dp3 led to the loss of the permanent P3/p3 (a possible synapomorphy for Eutheria). The dP3/dp3 was present during most of the adult stages in the Late Cretaceous stem placentals Zhelestidae and Gypsonictops. This tooth is totally absent in basal taxa of Placentalia, which normally have at most four premolars.
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Billet G, de Muizon C, Schellhorn R, Ruf I, Ladevèze S, Bergqvist L. Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia). Zool J Linn Soc 2015. [DOI: 10.1111/zoj.12219] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Guillaume Billet
- Steinmann-Institut für Geologie; Mineralogie und Paläontologie; Rheinische Friedrich-Wilhelms-Universität Bonn; Nussallee 8 53115 Bonn Germany
- CR2P - UMR 7207 CNRS; MNHN; Univ Paris 06 - Muséum national d'Histoire naturelle; 8 rue Buffon CP 38 75005 Paris France
| | - Christian de Muizon
- CR2P - UMR 7207 CNRS; MNHN; Univ Paris 06 - Muséum national d'Histoire naturelle; 8 rue Buffon CP 38 75005 Paris France
| | - Rico Schellhorn
- Steinmann-Institut für Geologie; Mineralogie und Paläontologie; Rheinische Friedrich-Wilhelms-Universität Bonn; Nussallee 8 53115 Bonn Germany
| | - Irina Ruf
- Steinmann-Institut für Geologie; Mineralogie und Paläontologie; Rheinische Friedrich-Wilhelms-Universität Bonn; Nussallee 8 53115 Bonn Germany
- Senckenberg Forschungsinstitut und Naturmuseum Frankfurt; Abteilung Paläoanthropologie und Messelforschung; Senckenberganlage 25 60325 Frankfurt am Main Germany
| | - Sandrine Ladevèze
- CR2P - UMR 7207 CNRS; MNHN; Univ Paris 06 - Muséum national d'Histoire naturelle; 8 rue Buffon CP 38 75005 Paris France
| | - Lilian Bergqvist
- Avenida Athos da Silveira Ramos; 274, bloco G; Centro de Ciências Matemáticas e da Natureza; Universidade Federal do Rio de Janeiro; Rio de Janeiro 21941-916 Brasil
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25
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Averianov AO, Lopatin AV. High-level systematics of placental mammals: Current status of the problem. BIOL BULL+ 2014. [DOI: 10.1134/s1062359014090039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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26
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Kirk EC, Daghighi P, Macrini TE, Bhullar BAS, Rowe TB. Cranial anatomy of the Duchesnean primate Rooneyia viejaensis : New insights from high resolution computed tomography. J Hum Evol 2014; 74:82-95. [DOI: 10.1016/j.jhevol.2014.03.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 02/28/2014] [Accepted: 03/13/2014] [Indexed: 11/16/2022]
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27
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Rougier GW, Sheth AS, Carpenter K, Appella-Guiscafre L, Davis BM. A New Species of Docodon (Mammaliaformes: Docodonta) from the Upper Jurassic Morrison Formation and a Reassessment of Selected Craniodental Characters in Basal Mammaliaforms. J MAMM EVOL 2014. [DOI: 10.1007/s10914-014-9263-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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28
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Gheerbrant E, Amaghzaz M, Bouya B, Goussard F, Letenneur C. Ocepeia (Middle Paleocene of Morocco): the oldest skull of an afrotherian mammal. PLoS One 2014; 9:e89739. [PMID: 24587000 PMCID: PMC3935939 DOI: 10.1371/journal.pone.0089739] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 01/21/2014] [Indexed: 11/19/2022] Open
Abstract
While key early(iest) fossils were recently discovered for several crown afrotherian mammal orders, basal afrotherians, e.g., early Cenozoic species that comprise sister taxa to Paenungulata, Afroinsectiphilia or Afrotheria, are nearly unknown, especially in Africa. Possible stem condylarth-like relatives of the Paenungulata (hyraxes, sea-cows, elephants) include only Abdounodus hamdii and Ocepeia daouiensis from the Selandian of Ouled Abdoun Basin, Morocco, both previously only documented by lower teeth. Here, we describe new fossils of Ocepeia, including O.grandis n. sp., and a sub-complete skull of O. daouiensis, the first known before the Eocene for African placentals. O.daouiensis skull displays a remarkable mosaic of autapomophic, ungulate-like and generalized eutherian-like characters. Autapomorphies include striking anthropoid-like characters of the rostrum and dentition. Besides having a basically eutherian-like skull construction, Ocepeia daouiensis is characterized by ungulate-like, and especially paenungulate-like characters of skull and dentition (e.g., selenodonty). However, some plesiomorphies such as absence of hypocone exclude Ocepeia from crown Paenungulata. Such a combination of plesiomorphic and derived characters best fits with a stem position of Ocepeia relative to Paenungulata. In our cladistic analyses Ocepeia is included in Afrotheria, but its shared derived characters with paenungulates are not optimized as exclusive synapomorphies. Rather, within Afrotheria Ocepeia is reconstructed as more closely related to insectivore-like afroinsectiphilians (i.e., aardvarks, sengis, tenrecs, and golden moles) than to paenungulates. This results from conflict with undetected convergences of Paenungulata and Perissodactyla in our cladistic analysis, such as the shared bilophodonty. The selenodont pattern best supports the stem paenungulate position of Ocepeia; that, however, needs further support. The remarkable character mosaic of Ocepeia makes it the first known "transitional fossil" between insectivore-like and ungulate-like afrotherians. In addition, the autapomorphic family Ocepeiidae supports the old--earliest Tertiary or Cretaceous--endemic evolution of placentals in Africa, in contrast to hypotheses rooting afrotherians in Paleogene Laurasian "condylarths".
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Affiliation(s)
- Emmanuel Gheerbrant
- Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, CNRS-MNHN-UPMC, Muséum National d'Histoire Naturelle, Dpnt Histoire de la Terre, Paris, France
| | - Mbarek Amaghzaz
- Office Chérifien des Phosphates (OCP SA), Centre Minier de Khouribga, Khouribga, Morocco
| | - Baadi Bouya
- Office Chérifien des Phosphates (OCP SA), Centre Minier de Khouribga, Khouribga, Morocco
| | - Florent Goussard
- Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, CNRS-MNHN-UPMC, Muséum National d'Histoire Naturelle, Dpnt Histoire de la Terre, Paris, France
| | - Charlène Letenneur
- Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, CNRS-MNHN-UPMC, Muséum National d'Histoire Naturelle, Dpnt Histoire de la Terre, Paris, France
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Beck RMD, Travouillon KJ, Aplin KP, Godthelp H, Archer M. The Osteology and Systematics of the Enigmatic Australian Oligo-Miocene Metatherian Yalkaparidon (Yalkaparidontidae; Yalkaparidontia; ?Australidelphia; Marsupialia). J MAMM EVOL 2013. [DOI: 10.1007/s10914-013-9236-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Macrini TE, Flynn JJ, Ni X, Croft DA, Wyss AR. Comparative study of notoungulate (Placentalia, Mammalia) bony labyrinths and new phylogenetically informative inner ear characters. J Anat 2013; 223:442-61. [PMID: 24102069 DOI: 10.1111/joa.12108] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2013] [Indexed: 11/30/2022] Open
Abstract
The phylogenetic relationships of notoungulates, an extinct group of predominantly South American herbivores, remain poorly resolved with respect to both other placental mammals and among one another. Most previous phylogenetic analyses of notoungulates have not included characters of the internal cranium, not least because few such features, including the bony labyrinth, have been described for members of the group. Here we describe the inner ears of the notoungulates Altitypotherium chucalensis (Mesotheriidae), Pachyrukhos moyani (Hegetotheriidae) and Cochilius sp. (Interatheriidae) based on reconstructions of bony labyrinths obtained from computed tomography imagery. Comparisons of the bony labyrinths of these taxa with the basally diverging notoungulate Notostylops murinus (Notostylopidae), an isolated petrosal from Itaboraí, Brazil, referred to Notoungulata, and six therian outgroups, yielded an inner ear character matrix of 25 potentially phylogenetically informative characters, 14 of them novel to this study. Two equivocally optimized character states potentially support a pairing of Mesotheriidae and Hegetotheriidae, whereas four others may be diagnostic of Notoungulata. Three additional characters are potentially informative for diagnosing more inclusive clades: one for crown Placentalia; another for a clade containing Kulbeckia, Zalambdalestes, and Placentalia; and a third for Eutheria (crown Placentalia plus stem taxa). Several other characters are apomorphic for at least one notoungulate in our study and are of potential interest for broader taxonomic sampling within Notoungulata to clarify currently enigmatic interrelationships. Measures of the semicircular canals were used to infer agility (e.g. capable of quick movements vs. lethargic movements) of these taxa. Agility scores calculated from these data generally corroborate interpretations based on postcranial remains of these or closely related species. We provide estimates of the low-frequency hearing limits in notoungulates based on the ratio of radii of the apical and basal turns of the cochlea. These limits range from 15 Hz in Notostylops to 149 Hz in Pachyrukhos, values comparable to the Asian elephant (Elephas maximus) and the California sea lion (Zalophus californianus) when hearing in air, respectively.
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Affiliation(s)
- Thomas E Macrini
- Department of Biological Sciences, St Mary's University, San Antonio, TX, USA; Department of Vertebrate Paleontology, Division of Paleontology, American Museum of Natural History, New York, NY, USA
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Kusuhashi N, Tsutsumi Y, Saegusa H, Horie K, Ikeda T, Yokoyama K, Shiraishi K. A new Early Cretaceous eutherian mammal from the Sasayama Group, Hyogo, Japan. Proc Biol Sci 2013; 280:20130142. [PMID: 23536594 DOI: 10.1098/rspb.2013.0142] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We here describe a new Early Cretaceous (early Albian) eutherian mammal, Sasayamamylos kawaii gen. et sp. nov., from the 'Lower Formation' of the Sasayama Group, Hyogo Prefecture, Japan. Sasayamamylos kawaii is characterized by a robust dentary, a distinct angle on the ventral margin of the dentary at the posterior end of the mandibular symphysis, a lower dental formula of 3-4 : 1 : 4 : 3, a robust lower canine, a non-molariform lower ultimate premolar, and a secondarily reduced entoconid on the molars. To date, S. kawaii is the earliest known eutherian mammal possessing only four premolars, which demonstrates that the reduction in the premolar count in eutherians started in the late Early Cretaceous. The occurrence of S. kawaii implies that the relatively rapid diversification of eutherians in the mid-Cretaceous had already started by the early Albian.
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Affiliation(s)
- Nao Kusuhashi
- Department of Earth's Evolution and Environment, Graduate School of Science and Engineering, Ehime University, Ehime 790-8577, Japan.
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O'Leary MA, Bloch JI, Flynn JJ, Gaudin TJ, Giallombardo A, Giannini NP, Goldberg SL, Kraatz BP, Luo ZX, Meng J, Ni X, Novacek MJ, Perini FA, Randall ZS, Rougier GW, Sargis EJ, Silcox MT, Simmons NB, Spaulding M, Velazco PM, Weksler M, Wible JR, Cirranello AL. The placental mammal ancestor and the post-K-Pg radiation of placentals. Science 2013; 339:662-7. [PMID: 23393258 DOI: 10.1126/science.1229237] [Citation(s) in RCA: 622] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated with fossils, shows that crown clade Placentalia and placental orders originated after the K-Pg boundary. Many nodes discovered using molecular data are upheld, but phenomic signals overturn molecular signals to show Sundatheria (Dermoptera + Scandentia) as the sister taxon of Primates, a close link between Proboscidea (elephants) and Sirenia (sea cows), and the monophyly of echolocating Chiroptera (bats). Our tree suggests that Placentalia first split into Xenarthra and Epitheria; extinct New World species are the oldest members of Afrotheria.
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Affiliation(s)
- Maureen A O'Leary
- Department of Anatomical Sciences, School of Medicine, HSC T-8 (040), Stony Brook University, Stony Brook, NY 11794-8081, USA.
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LUO ZHEXI, RUF IRINA, MARTIN THOMAS. The petrosal and inner ear of the Late Jurassic cladotherian mammalDryolestes leiriensisand implications for ear evolution in therian mammals. Zool J Linn Soc 2012. [DOI: 10.1111/j.1096-3642.2012.00852.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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ARCHIBALD JDAVID, AVERIANOV ALEXANDER. Phylogenetic analysis, taxonomic revision, and dental ontogeny of the Cretaceous Zhelestidae (Mammalia: Eutheria). Zool J Linn Soc 2012. [DOI: 10.1111/j.1096-3642.2011.00771.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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35
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Conrad JL, Rieppel O, Gauthier JA, Norell MA. Osteology of Gobiderma pulchrum (Monstersauria, Lepidosauria, Reptilia). BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2011. [DOI: 10.1206/740.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Soares MB, Schultz CL, Horn BLD. New information on Riograndia guaibensis Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications. AN ACAD BRAS CIENC 2011; 83:329-54. [PMID: 21437390 DOI: 10.1590/s0001-37652011000100021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 01/24/2010] [Indexed: 11/21/2022] Open
Abstract
The tritheledontid Riograndia guaibensis was the first cynodont described for the "Caturrita Formation" fauna from the Late Triassic of southern Brazil (Santa Maria 2 Sequence). The type materials did not preserve anatomical information regarding braincase, occiput, basicranium, zygomatic arch, postdentary bones and craniomandibular joint. Here new materials are described and supply the missing information. Riograndia shows a suite of important anatomical features quite derived among the non-mammaliaform eucynodonts, such as the partial closure of the medial orbital wall and braincase, extensive secondary osseous palate, wide primary palate, basicranium with jugular foramen separated from the periphery of fenestra rotunda, narrow zygomatic arch and much reduced postdentary bones. Many of these features constitute synapomorphies shared only with the other members of mammaliamorpha. Thus, the almost complete cranial, mandibular and dental information from the new fossils of Riograndia can bring a significant improve in the understanding of the anatomy and phylogenetic relationships of the tritheledontids and help to elucidate the transformational steps involved in the cynodont-mammal transition. Additionally, Riograndia is a key taxon in refining the "Caturrita Formation" biostratigraphy, enabling the connection of several fossiliferous outcrops that have a rich tetrapod fauna that can be correlated with other Triassic faunas from Gondwana and Laurasia.
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Affiliation(s)
- Marina B Soares
- Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS, Brazil.
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The comparative osteology of the petrotympanic complex (ear region) of extant baleen whales (Cetacea: Mysticeti). PLoS One 2011; 6:e21311. [PMID: 21731700 PMCID: PMC3120854 DOI: 10.1371/journal.pone.0021311] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 05/30/2011] [Indexed: 11/19/2022] Open
Abstract
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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SILCOX MARYT, BLOCH JONATHANI, BOYER DOUGM, HOUDE PETER. Cranial anatomy of Paleocene and Eocene Labidolemur kayi (Mammalia: Apatotheria), and the relationships of the Apatemyidae to other mammals. Zool J Linn Soc 2010. [DOI: 10.1111/j.1096-3642.2009.00614.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kraatz BP, Meng J, Weksler M, Li C. Evolutionary patterns in the dentition of duplicidentata (mammalia) and a novel trend in the molarization of premolars. PLoS One 2010; 5:e12838. [PMID: 20877465 PMCID: PMC2942898 DOI: 10.1371/journal.pone.0012838] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 08/20/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The cusp homology of Lagomorpha has long been problematic largely because their teeth are highly derived relative to their more typically tribosphenic ancestors. Within this context, the lagomorph central cusp has been particularly difficult to homologize with other tribosphenic cusps; authors have previously considered it the paracone, protocone, metacone, amphicone, or an entirely new cusp. METHODOLOGY/PRINCIPAL FINDINGS Here we present newly described fossil duplicidentates (Lagomorpha and Mimotonidae) in the context of a well-constrained phylogeny to establish a nomenclatural system for cusps based on the tribosphenic pattern. We show that the central cusp of lagomorphs is homologous with the metaconule of other mammals. We also show that the buccal acquisition of a second cusp on the premolars (molarization) within duplicidentates is atypical with respect to other mammalian lineages; within the earliest lagomorphs, a second buccal cusp is added mesially to an isolated buccal cusp. CONCLUSIONS/SIGNIFICANCE The distal shift of the 'ancestral' paracone within early duplicidentates amounts to the changing of a paracone into a metacone in these lineages. For this reason, we support a strictly topological approach to cusp names, and suggest a discontinuity in nomenclature to capture the complexity of the interplay between evolutionary history and the developmental process that have produced cusp patterns in duplicidentates.
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Affiliation(s)
- Brian P Kraatz
- Department of Anatomy, Western University of Health Sciences, Pomona, California, USA.
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Silcox MT, Benham AE, Bloch JI. Endocasts of Microsyops (Microsyopidae, Primates) and the evolution of the brain in primitive primates. J Hum Evol 2010; 58:505-21. [PMID: 20444495 DOI: 10.1016/j.jhevol.2010.03.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 03/18/2010] [Accepted: 03/23/2010] [Indexed: 11/24/2022]
Abstract
We describe a virtual endocast produced from ultra high resolution X-ray computed tomography (CT) data for the microsyopid, Microsyops annectens (middle Eocene, Wyoming). It is the most complete and least distorted endocast known for a plesiadapiform primate and because of the relatively basal position of Microsyopidae, has particular importance to reconstructing primitive characteristics for Primates. Cranial capacity is estimated at 5.9 cm(3), yielding encephalization quotients (EQ) of 0.26-0.39 (Jerison's equation) and 0.32-0.52 (Eisenberg's equation), depending on the body mass estimate. Even the lowest EQ estimate for M. annectens is higher than that for Plesiadapis cookei, while the range of estimates overlaps with that of Ignacius graybullianus and with the lower end of the range of estimates for fossil euprimates. As in other plesiadapiforms, the olfactory bulbs of M. annectens are large. The cerebrum does not extend onto the cerebellum or form a ventrally protruding temporal lobe with a clear temporal pole, suggesting less development of the visual sense and a greater emphasis on olfaction than in euprimates. Contrasts between the virtual endocast of M. annectens, and both a natural endocast of the same species and a partial endocast from the earlier-occurring Microsyops sp., cf. Microsyops elegans, suggest that the coverage of the caudal colliculi by the cerebrum evolved within the Microsyops lineage. This implies that microsyopids expanded their cerebra and perhaps evolved an improved visual sense independent of euprimates. With a growing body of data on the morphology of the brain in primitive primates, it is becoming clear that many of the characteristics of the brain common to euprimates evolved after the divergence of stem primates from other euarchontans and likely in parallel in different lineages. These new data suggest a different model for the ancestors of euprimates than has been assumed based on the anatomy of the brain in visually specialized diurnal tree shrews.
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Affiliation(s)
- Mary T Silcox
- Department of Anthropology, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB R3B 2E9, Canada.
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Jeffery N, Cox PG. Do agility and skull architecture influence the geometry of the mammalian vestibulo-ocular reflex? J Anat 2010; 216:496-509. [PMID: 20210819 DOI: 10.1111/j.1469-7580.2010.01211.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The spatial arrangement of the semicircular canals and extraocular muscles of the eye has been of considerable interest, particularly to researchers working on adaptations of the vestibulo-ocular reflex. Here we offer the first, extensive comparative analysis of the spatial relationships between each extraocular muscle and the canal providing its primary excitatory stimulus. The sample consisted of 113 specimens, representing 51 extant mammalian species. Hypotheses tested included that variations in the spatial alignments are linked with differences of skull morphology and with differences of agility during locomotion. Internal morphologies were visualized with magnetic resonance imaging and were measured with landmark-based vectors and planes. Values for body mass and agility were taken from the existing literature. Data were investigated for trends and associations with standard bivariate and multivariate statistical methods as well as with phylogenetically adjusted bivariate methods. The findings clearly show that species differences in the alignment of each extraocular muscle relative to the canal providing its primary excitatory stimulus are closely associated with changes of orbit morphology. The results also indicate that the actions of the oblique muscles interchange with those of the superior and inferior recti muscles when comparing lateral-eyed (rabbit) with frontal-eyed species (cat). There was only weak evidence to support the notion that canal-muscle alignments differ significantly among species according to how agile they are. The results suggest that semicircular canal morphology is arranged primarily for detecting head movements and then secondarily, if at all, for diminishing the burden of transforming vestibulo-ocular reflex signals in the most agile species.
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Affiliation(s)
- Nathan Jeffery
- Division of Human Anatomy and Cell Biology, School of Biomedical Sciences, University of Liverpool, Liverpool, UK.
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Hu Y, Meng J, Li C, Wang Y. New basal eutherian mammal from the Early Cretaceous Jehol biota, Liaoning, China. Proc Biol Sci 2010; 277:229-36. [PMID: 19419990 PMCID: PMC2842663 DOI: 10.1098/rspb.2009.0203] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 04/15/2009] [Indexed: 11/12/2022] Open
Abstract
A new genus and species of eutherian mammal, Acristatherium yanensis gen. et sp. nov., is described from the Early Cretaceous Jehol biota, China. The new taxon is based on a partial skull that is preserved in three dimensions from the Lujiatun bed of the Yixian Formation and dated 123.2+/-1.0 Ma. Its right upper and lower dentitions are nearly complete and it has a dental formula 4.1.5.3/3.1.5.3. The new mammal reveals several craniodental characteristics of Early Cretaceous eutherians previously unknown in fossil records of therians, such as a possible vestige of the septomaxilla. The craniodental features of the new taxon are compared with those of relevant Early Cretaceous eutherians and therians. Phylogenetic analyses based on a data matrix containing 70 taxa and 408 characters place A. yanensis as the most basal eutherian in the selected group. The morphological differences between Acristatherium and Eomaia indicate that eutherians already had a significant degree of generic diversification ca 125 Ma.
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Affiliation(s)
- Yaoming Hu
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
| | - Jin Meng
- Paleontology, American Museum of Natural History, Central Park West at 79 Street, New York, NY 10024, USA
| | - Chuankui Li
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
| | - Yuanqing Wang
- Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
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Billet G. New Observations on the Skull of Pyrotherium (Pyrotheria, Mammalia) and New Phylogenetic Hypotheses on South American Ungulates. J MAMM EVOL 2009. [DOI: 10.1007/s10914-009-9123-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Wible JR. The Ear Region of the Pen-tailed Treeshrew, Ptilocercus lowii Gray, 1848 (Placentalia, Scandentia, Ptilocercidae). J MAMM EVOL 2009. [DOI: 10.1007/s10914-009-9116-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ruf I, Luo ZX, Wible JR, Martin T. Petrosal anatomy and inner ear structures of the Late Jurassic Henkelotherium (Mammalia, Cladotheria, Dryolestoidea): insight into the early evolution of the ear region in cladotherian mammals. J Anat 2009; 214:679-93. [PMID: 19438763 PMCID: PMC2707092 DOI: 10.1111/j.1469-7580.2009.01059.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2009] [Indexed: 11/29/2022] Open
Abstract
The petrosal anatomy and inner ear structure of Jurassic cladotherian mammals represent the ancestral morphological conditions (groundplan) from which modern therian mammals (marsupials and placentals) have evolved. We present the reconstruction of the petrosal and inner ear features of the Late Jurassic dryolestoid mammal Henkelotherium guimarotae from high-resolution computed tomography and three-dimensional imaging analysis. This study of Henkelotherium revealed a combination of derived and primitive features, including: cladotherian apomorphies, such as the promontorial sulcus for the internal carotid artery and reduced lateral trough; trechnotherian characters, such as an enclosed cochlear canaliculus for the perilymphatic duct, post-promontorial tympanic sinus and caudal tympanic process; in addition to plesiomorphic mammalian features, such as the cavum supracochleare and prootic canal. The inner ear of Henkelotherium shows a division between the utricle and saccule, a cochlear canal coiled through at least 270 degrees, a distinctive primary bony lamina for the basilar membrane, and a secondary bony lamina. The development of the primary and secondary bony laminae in the cochlear canal is suggested here to be correlated with the concurrent coiling of the bony canal and membranous duct of the inner ear cochlea, apomorphies of the more inclusive cladotherian clade that also represent the ancestral morphotype of modern therian mammals. Because these features are crucial for high-frequency hearing in extant therian mammals, their early appearance in Late Jurassic cladotherians suggests a more ancient origination for high-frequency hearing in mammalian history than previously thought.
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Affiliation(s)
- Irina Ruf
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Bereich Paläontologie, Universität Bonn, Bonn, Germany.
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Cranial Morphology of a Pantolestid Eutherian Mammal from the Eocene Bridger Formation, Wyoming, USA: Implications for Relationships and Habitat. J MAMM EVOL 2007. [DOI: 10.1007/s10914-007-9055-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Wible JR, Rougier GW, Novacek MJ, Asher RJ. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature 2007; 447:1003-6. [PMID: 17581585 DOI: 10.1038/nature05854] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 04/17/2007] [Indexed: 11/09/2022]
Abstract
Estimates of the time of origin for placental mammals from DNA studies span nearly the duration of the Cretaceous period (145 to 65 million years ago), with a maximum of 129 million years ago and a minimum of 78 million years ago. Palaeontologists too are divided on the timing. Some support a deep Cretaceous origin by allying certain middle Cretaceous fossils (97-90 million years old) from Uzbekistan with modern placental lineages, whereas others support the origin of crown group Placentalia near the close of the Cretaceous. This controversy has yet to be addressed by a comprehensive phylogenetic analysis that includes all well-known Cretaceous fossils and a wide sample of morphology among Tertiary and recent placentals. Here we report the discovery of a new well-preserved mammal from the Late Cretaceous of Mongolia and a broad-scale phylogenetic analysis. Our results exclude Cretaceous fossils from Placentalia, place the origin of Placentalia near the Cretaceous/Tertiary (K/T) boundary in Laurasia rather than much earlier within the Cretaceous in the Southern Hemisphere, and place afrotherians and xenarthrans in a nested rather than a basal position within Placentalia.
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Affiliation(s)
- J R Wible
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania 15206, USA.
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Macrini TE, Rougier GW, Rowe T. Description of a Cranial Endocast from the Fossil MammalVincelestes neuquenianus (Theriiformes) and its Relevance to the Evolution of Endocranial Characters in Therians. Anat Rec (Hoboken) 2007; 290:875-92. [PMID: 17506058 DOI: 10.1002/ar.20551] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We generated a digital cranial endocast (infilling of the braincase) of Vincelestes neuquenianus, a Cretaceous theriiform mammal from Argentina, to achieve two goals. First, we described this endocast of Vincelestes to reconstruct the brain, associated soft-tissue structures, and internal osteological features. This report represents the first description of an endocast from a stem therian that is near crown group Theria (marsupials, placentals, and all descendants of that ancestor). Second, we examined 21 morphological characters related to the morphology of endocasts and endocranial osteology across 19 taxa (including Vincelestes) in the context of a current hypothesis about mammal phylogeny to identify potential synapomorphies for Theria. The digital endocast of Vincelestes is mostly complete, facilitating description in all views and allowing collection of accurate linear and volumetric measurements. However, it is unclear if the midbrain is exposed on the dorsal surface of the brain because of damage to this region of the endocast. Other portions of this specimen are extraordinarily well preserved, allowing identification of the accessory olfactory bulbs on the endocast, an ossified falx cerebri, and an osseous tentorium. The encephalization quotient (EQ) calculated for Vincelestes falls within the range of EQs of crown therians. Comparison of the endocranial characters across different mammalian taxa did not reveal any new synapomorphies for the clade Theria.
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Affiliation(s)
- Thomas E Macrini
- Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA.
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Hunter JP, Janis CM. Spiny Norman in the Garden of Eden? Dispersal and early biogeography of Placentalia. J MAMM EVOL 2006. [DOI: 10.1007/s10914-006-9006-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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