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Scott CS. Horolodectidae: a new family of unusual eutherians (Mammalia: Theria) from the Palaeocene of Alberta, Canada. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zly040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Craig S Scott
- Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada
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Phillips MJ, Fruciano C. The soft explosive model of placental mammal evolution. BMC Evol Biol 2018; 18:104. [PMID: 29969980 PMCID: PMC6029115 DOI: 10.1186/s12862-018-1218-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 06/19/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Recent molecular dating estimates for placental mammals echo fossil inferences for an explosive interordinal diversification, but typically place this event some 10-20 million years earlier than the Paleocene fossils, among apparently more "primitive" mammal faunas. RESULTS However, current models of molecular evolution do not adequately account for parallel rate changes, and result in dramatic divergence underestimates for large, long-lived mammals such as whales and hominids. Calibrating among these taxa shifts the rate model errors deeper in the tree, inflating interordinal divergence estimates. We employ simulations based on empirical rate variation, which show that this "error-shift inflation" can explain previous molecular dating overestimates relative to fossil inferences. Molecular dating accuracy is substantially improved in the simulations by focusing on calibrations for taxa that retain plesiomorphic life-history characteristics. Applying this strategy to the empirical data favours the soft explosive model of placental evolution, in line with traditional palaeontological interpretations - a few Cretaceous placental lineages give rise to a rapid interordinal diversification following the 66 Ma Cretaceous-Paleogene boundary mass extinction. CONCLUSIONS Our soft explosive model for the diversification of placental mammals brings into agreement previously incongruous molecular, fossil, and ancestral life history estimates, and closely aligns with a growing consensus for a similar model for bird evolution. We show that recent criticism of the soft explosive model relies on ignoring both experimental controls and statistical confidence, as well as misrepresentation, and inconsistent interpretations of morphological phylogeny. More generally, we suggest that the evolutionary properties of adaptive radiations may leave current molecular dating methods susceptible to overestimating the timing of major diversification events.
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Affiliation(s)
- Matthew J. Phillips
- School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Australia
| | - Carmelo Fruciano
- School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Australia
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Springer MS, Murphy WJ, Roca AL. Appropriate fossil calibrations and tree constraints uphold the Mesozoic divergence of solenodons from other extant mammals. Mol Phylogenet Evol 2018; 121:158-165. [PMID: 29331683 DOI: 10.1016/j.ympev.2018.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 12/27/2017] [Accepted: 01/09/2018] [Indexed: 11/30/2022]
Abstract
The mammalian order Eulipotyphla includes four extant families of insectivorans: Solenodontidae (solenodons); Talpidae (moles); Soricidae (shrews); and Erinaceidae (hedgehogs). Of these, Solenodontidae includes only two extant species, which are endemic to the largest islands of the Greater Antilles: Cuba and Hispaniola. Most molecular studies suggest that eulipotyphlan families diverged from each other across several million years, with the basal split between Solenodontidae and other families occurring in the Late Cretaceous. By contrast, Sato et al. (2016) suggest that eulipotyphlan families diverged from each other in a polytomy ∼58.6 million years ago (Mya). This more recent divergence estimate for Solenodontidae versus other extant eulipotyphlans suggests that solenodons must have arrived in the Greater Antilles via overwater dispersal rather than vicariance. Here, we show that the young timetree estimates for eulipotyphlan families and the polytomy are due to an inverted ingroup-outgroup arrangement of the tree, the result of using Tracer rather than TreeAnnotator to compile interfamilial divergence times, and of not enforcing the monophly of well-established clades such as Laurasiatheria and Eulipotyphla. Finally, Sato et al.'s (2016) timetree includes several zombie lineages where estimated divergence times are much younger than minimum ages that are implied by the fossil record. We reanalyzed Sato et al.'s (2016) original data with enforced monophyly for well-established clades and updated fossil calibrations that eliminate the inference of zombie lineages. Our resulting timetrees, which were compiled with TreeAnnotator rather than Tracer, produce dates that are in good agreement with other recent studies and place the basal split between Solenodontidae and other eulipotyphlans in the Late Cretaceous.
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Affiliation(s)
- Mark S Springer
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA.
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
| | - Alfred L Roca
- Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA
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5
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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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6
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Gould FDH. Testing the Role of Cursorial Specializations as Adaptive Key Innovations in Paleocene-Eocene Ungulates of North America. J MAMM EVOL 2016. [DOI: 10.1007/s10914-016-9359-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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7
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Springer MS, Emerling CA, Meredith RW, Janečka JE, Eizirik E, Murphy WJ. Waking the undead: Implications of a soft explosive model for the timing of placental mammal diversification. Mol Phylogenet Evol 2016; 106:86-102. [PMID: 27659724 DOI: 10.1016/j.ympev.2016.09.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 09/15/2016] [Accepted: 09/18/2016] [Indexed: 02/06/2023]
Abstract
The explosive, long fuse, and short fuse models represent competing hypotheses for the timing of placental mammal diversification. Support for the explosive model, which posits both interordinal and intraordinal diversification after the KPg mass extinction, derives from morphological cladistic studies that place Cretaceous eutherians outside of crown Placentalia. By contrast, most molecular studies favor the long fuse model wherein interordinal cladogenesis occurred in the Cretaceous followed by intraordinal cladogenesis after the KPg boundary. Phillips (2016) proposed a soft explosive model that allows for the emergence of a few lineages (Xenarthra, Afrotheria, Euarchontoglires, Laurasiatheria) in the Cretaceous, but otherwise agrees with the explosive model in positing the majority of interordinal diversification after the KPg mass extinction. Phillips (2016) argues that rate transference errors associated with large body size and long lifespan have inflated previous estimates of interordinal divergence times, and further suggests that most interordinal divergences are positioned after the KPg boundary when rate transference errors are avoided through the elimination of calibrations in large-bodied and/or long lifespan clades. Here, we show that rate transference errors can also occur in the opposite direction and drag forward estimated divergence dates when calibrations in large-bodied/long lifespan clades are omitted. This dragging forward effect results in the occurrence of more than half a billion years of 'zombie lineages' on Phillips' preferred timetree. By contrast with ghost lineages, which are a logical byproduct of an incomplete fossil record, zombie lineages occur when estimated divergence dates are younger than the minimum age of the oldest crown fossils. We also present the results of new timetree analyses that address the rate transference problem highlighted by Phillips (2016) by deleting taxa that exceed thresholds for body size and lifespan. These analyses recover all interordinal divergence times in the Cretaceous and are consistent with the long fuse model of placental diversification. Finally, we outline potential problems with morphological cladistic analyses of higher-level relationships among placental mammals that may account for the perceived discrepancies between molecular and paleontological estimates of placental divergence times.
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Affiliation(s)
- Mark S Springer
- Department of Biology, University of California, Riverside, CA 92521, USA.
| | | | - Robert W Meredith
- Department of Biology and Molecular Biology, Montclair State University, Montclair, NJ 07043, USA
| | - Jan E Janečka
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - Eduardo Eizirik
- Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, RS 90619-900, Brazil
| | - William J Murphy
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA
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Gheerbrant E, Filippo A, Schmitt A. Convergence of Afrotherian and Laurasiatherian Ungulate-Like Mammals: First Morphological Evidence from the Paleocene of Morocco. PLoS One 2016; 11:e0157556. [PMID: 27384169 PMCID: PMC4934866 DOI: 10.1371/journal.pone.0157556] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 02/04/2023] Open
Abstract
Molecular-based analyses showed that extant "ungulate" mammals are polyphyletic and belong to the two main clades Afrotheria (Paenungulata) and Laurasiatheria (Euungulata: Cetartiodactyla-Perissodactyla). However, paleontological and neontological studies hitherto failed to demonstrate the morphological convergence of African and Laurasian "ungulate" orders. They support an "Altungulata" group including the Laurasian order Perissodactyla and the African superorder Paenungulata and characterized especially by quadritubercular and bilophodont molars adapted for a folivorous diet. We report new critical fossils of one of the few known African condylarth-like mammal, the enigmatic Abdounodus from the middle Paleocene of Morocco. They show that Abdounodus and Ocepeia display key intermediate morphologies refuting the homology of the fourth main cusp of upper molars in Paenungulata and Perissodactyla: Paenungulates unexpectedly have a metaconule-derived pseudohypocone, instead of a cingular hypocone. Comparative and functional dental anatomy of Abdounodus demonstrates indeed the convergence of the quadritubercular and bilophodont pattern in "ungulates". Consistently with our reconstruction of the structural evolution of paenungulate bilophodonty, the phylogenetic analysis relates Abdounodus and Ocepeia to Paenungulata as stem taxa of the more inclusive new clade Paenungulatomorpha which is distinct from the Perissodactyla and Anthracobunidae. Abdounodus and Ocepeia help to identify the first convincing synapomorphy within the Afrotheria-i.e., the pseudohypocone-that demonstrates the morphological convergence of African and Laurasian ungulate-like placentals, in agreement with molecular phylogeny. Abdounodus and Ocepeia are the only known representatives of the early African ungulate radiation predating the divergence of extant paenungulate orders. Paenungulatomorpha evolved in Africa since the early Tertiary independently from laurasiatherian euungulates and "condylarths" such as apheliscids. The rapid early Tertiary radiation of the Afrotheria and Paenungulatomorpha, as illustrated by the Paleocene Moroccan mammals, is concurrent with that of the Laurasiatheria in a general, explosive mammal evolution in both the South and North Tethyan continents following the K/Pg event.
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Affiliation(s)
- Emmanuel Gheerbrant
- CR2P –Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207, Muséum National d'Histoire Naturelle, CNRS, UPMC, Sorbonne Universités. MNHN, CP38, Paris, France
| | - Andrea Filippo
- CR2P –Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207, Muséum National d'Histoire Naturelle, CNRS, UPMC, Sorbonne Universités. MNHN, CP38, Paris, France
| | - Arnaud Schmitt
- CR2P –Centre de Recherches sur la Paléobiodiversité et les Paléoenvironnements, UMR 7207, Muséum National d'Histoire Naturelle, CNRS, UPMC, Sorbonne Universités. MNHN, CP38, Paris, France
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9
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Puttick MN, Thomas GH, Benton MJ. Dating placentalia: Morphological clocks fail to close the molecular fossil gap. Evolution 2016; 70:873-86. [PMID: 26990798 PMCID: PMC5071738 DOI: 10.1111/evo.12907] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 02/22/2016] [Accepted: 03/07/2016] [Indexed: 11/27/2022]
Abstract
Dating the origin of Placentalia has been a contentious issue for biologists and paleontologists. Although it is likely that crown‐group placentals originated in the Late Cretaceous, nearly all molecular clock estimates point to a deeper Cretaceous origin. An approach with the potential to reconcile this discrepancy could be the application of a morphological clock. This would permit the direct incorporation of fossil data in node dating, and would break long internal branches of the tree, so leading to improved estimates of node ages. Here, we use a large morphological dataset and the tip‐calibration approach of MrBayes. We find that the estimated date for the origin of crown mammals is much older, ∼130–145 million years ago (Ma), than fossil and molecular clock data (∼80–90 Ma). Our results suggest that tip calibration may result in estimated dates that are more ancient than those obtained from other sources of data. This can be partially overcome by constraining the ages of internal nodes on the tree; however, when this was applied to our dataset, the estimated dates were still substantially more ancient than expected. We recommend that results obtained using tip calibration, and possibly morphological dating more generally, should be treated with caution.
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Affiliation(s)
- Mark N Puttick
- School of Earth Sciences, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol, BS8 1TQ, United Kingdom.
| | - Gavin H Thomas
- Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Western Bank, Sheffield, S10 2TN, United Kingdom
| | - Michael J Benton
- School of Earth Sciences, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol, BS8 1TQ, United Kingdom
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A New Early Eocene (Ypresian) Bat from Pourcy, Paris Basin, France, with Comments on Patterns of Diversity in the Earliest Chiropterans. J MAMM EVOL 2015. [DOI: 10.1007/s10914-015-9286-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Systematics and Phylogeny of Paleocene-Eocene Nyctitheriidae (Mammalia, Eulipotyphla?) with Description of a new Species from the Late Paleocene of the Clarks Fork Basin, Wyoming, USA. J MAMM EVOL 2014. [DOI: 10.1007/s10914-014-9284-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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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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Anthracobunids from the middle eocene of India and pakistan are stem perissodactyls. PLoS One 2014; 9:e109232. [PMID: 25295875 PMCID: PMC4189980 DOI: 10.1371/journal.pone.0109232] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 08/20/2014] [Indexed: 11/19/2022] Open
Abstract
Anthracobunidae is an Eocene family of large mammals from south Asia that is commonly considered to be part of the radiation that gave rise to elephants (proboscideans) and sea cows (sirenians). We describe a new collection of anthracobunid fossils from Middle Eocene rocks of Indo-Pakistan that more than doubles the number of known anthracobunid fossils and challenges their putative relationships, instead implying that they are stem perissodactyls. Cranial, dental, and postcranial elements allow a revision of species and the recognition of a new anthracobunid genus. Analyses of stable isotopes and long bone geometry together suggest that most anthracobunids fed on land, but spent a considerable amount of time near water. This new evidence expands our understanding of stem perissodactyl diversity and sheds new light on perissodactyl origins.
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Smith T, Quesnel F, De Plöeg G, De Franceschi D, Métais G, De Bast E, Solé F, Folie A, Boura A, Claude J, Dupuis C, Gagnaison C, Iakovleva A, Martin J, Maubert F, Prieur J, Roche E, Storme JY, Thomas R, Tong H, Yans J, Buffetaut E. First Clarkforkian equivalent Land Mammal Age in the latest Paleocene basal Sparnacian facies of Europe: fauna, flora, paleoenvironment and (bio)stratigraphy. PLoS One 2014; 9:e86229. [PMID: 24489703 PMCID: PMC3906055 DOI: 10.1371/journal.pone.0086229] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 12/07/2013] [Indexed: 11/19/2022] Open
Abstract
The Paleocene-Eocene Thermal Maximum (PETM) is correlated with the first occurrences of earliest modern mammals in the Northern Hemisphere. The latest Paleocene Clarkforkian North American Land Mammal Age, that has yielded rodents and carnivorans, is the only exception to this rule. However, until now no pre-PETM localities have yielded modern mammals in Europe or Asia. We report the first Clarkforkian equivalent Land Mammal Age in the latest Paleocene deposits of the basal Sparnacian facies at Rivecourt, in the north-central part of the Paris Basin. The new terrestrial vertebrate and macroflora assemblages are analyzed through a multidisciplinary study including sedimentologic, stratigraphic, isotopic, and palynological aspects in order to reconstruct the paleoenvironment and to evaluate biochronologic and paleogeographic implications. The mammals are moderately diverse and not abundant, contrary to turtles and champsosaurs. The macroflora is exceptional in preservation and diversity with numerous angiosperms represented by flowers, fruits, seeds and wood preserved as lignite material, revealing an abundance of Arecaceae, Betulaceae, Icacinaceae, Menispermaceae, Vitaceae and probably Cornaceae. Results indicate a Late Paleocene age based on carbon isotope data, palynology and vertebrate occurrences such as the choristoderan Champsosaurus, the arctocyonid Arctocyon, and the plesiadapid Plesiadapis tricuspidens. However, several mammal species compare better with the earliest Eocene. Among these, the particular louisinid Teilhardimys musculus, also recorded from the latest Paleocene of the Spanish Pyrenees, suggests a younger age than the typical MP6 reference level. Nevertheless, the most important aspect of the Rivecourt fauna is the presence of dental remains of a rodent and a “miacid” carnivoran, attesting to the presence of two modern mammalian orders in the latest Paleocene of Europe. Interestingly, these two groups are also the only modern groups recorded from the latest Paleocene of North America, making Rivecourt the first direct equivalent to the Clarkforkian Land Mammal Age outside of North America.
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Affiliation(s)
- Thierry Smith
- Direction Opérationnelle Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
- * E-mail:
| | - Florence Quesnel
- DGR/GAT, Bureau de Recherches Géologiques et Minières (French Geological Survey) et UMR 7327 CNRS-Université d'Orléans-BRGM, Orléans, France
| | - Gaël De Plöeg
- Centre Permanent d'Initiatives pour l'Environnement des Pays de l'Oise, Verberie, France
| | - Dario De Franceschi
- Centre de recherche sur la paléobiodiversité et les paléoenvironnements (UMR7207 CNRS-MNHN-UPMC), Muséum National d'Histoire Naturelle et Université Pierre et Marie Curie, Paris, France
| | - Grégoire Métais
- Centre de recherche sur la paléobiodiversité et les paléoenvironnements (UMR7207 CNRS-MNHN-UPMC), Muséum National d'Histoire Naturelle et Université Pierre et Marie Curie, Paris, France
| | - Eric De Bast
- Direction Opérationnelle Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
| | - Floréal Solé
- Direction Opérationnelle Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
| | - Annelise Folie
- Direction Opérationnelle Terre et Histoire de la Vie, Institut royal des Sciences naturelles de Belgique, Bruxelles, Belgium
| | - Anaïs Boura
- Centre de recherche sur la paléobiodiversité et les paléoenvironnements (UMR7207 CNRS-MNHN-UPMC), Muséum National d'Histoire Naturelle et Université Pierre et Marie Curie, Paris, France
| | - Julien Claude
- Institut des Sciences de l'Évolution de Montpellier, Université de Montpellier 2, Montpellier, France
| | - Christian Dupuis
- Géologie GFA, Faculté Polytechnique, Université de Mons, Mons, Belgium
| | | | - Alina Iakovleva
- Geological Institute, Russian Academy of Sciences, Moscow, Russia
| | - Jeremy Martin
- School of Earth Sciences, University of Bristol, Bristol, United Kingdom
| | | | - Judicaël Prieur
- Centre Permanent d'Initiatives pour l'Environnement des Pays de l'Oise, Verberie, France
| | - Emile Roche
- Département de Géologie, Université de Liège, Liège, Belgium
| | | | - Romain Thomas
- Centre de recherche sur la paléobiodiversité et les paléoenvironnements (UMR7207 CNRS-MNHN-UPMC), Muséum National d'Histoire Naturelle et Université Pierre et Marie Curie, Paris, France
| | - Haiyan Tong
- Palaeontological Research and Education Centre, Mahasarakham University, Kantarawichai, Thailand
| | - Johan Yans
- Département de Géologie, Université de Namur, Namur, Belgium
| | - Eric Buffetaut
- CNRS (UMR 8538), Laboratoire de Géologie, Ecole Normale Supérieure, Paris, France
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Abstract
Summary
In this study we report on the evolution of micro-cursoriality, a unique case of cursoriality in mammals smaller than 1 kg. We obtained new running speed and limb morphology data for two species of elephant-shrews (Elephantulus spp., Macroscelidae) from Namaqualand, South Africa, which we compared with published data for other mammals. Elephantulus maximum running speeds were higher than most mammals smaller than 1 kg. Elephantulus also possess exceptionally high metatarsal:femur ratios (1.07) that are typically associated with fast unguligrade cursors. Cursoriality evolved in the Artiodactyla, Perissodactyla, and Carnivora coincident with global cooling and the replacement of forests with open landscapes in the Oligocene and Miocene. The majority of mammal species, though, remained non-cursorial, plantigrade, and small (< 1 kg). The extraordinary running speed and digitigrady of elephant-shrews was established in the Early Eocene in the earliest macroscelid Prodiacodon, but was probably inherited from Paleocene, Holarctic stem macroscelids. Micro-cursoriality in macroscelids evolved from the plesiomorphic plantigrade foot of the possum-like ancestral mammal earlier than in other mammalian crown groups. Micro-cursoriality evolved first in forests, presumably in response to selection for rapid running speeds facilitated by local knowledge, in order to avoid predators. During the Miocene, micro-cursoriality was pre-adaptive to open, arid habitats, and became more derived in the newly-evolved Elephantulus and Macroscelides elephant-shrews with trail running.
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