Michel Laurin | Muséum National d'Histoire Naturelle (original) (raw)

Papers by Michel Laurin

Acta Palaeontologica Polonica, 2024

Comptes rendus. Palévol/Comptes rendus Palévol, Feb 26, 2024

révisions linguistiques Des textes anglais / english language revisions : Kevin Padian (Universit... more révisions linguistiques Des textes anglais / english language revisions : Kevin Padian (University of California at Berkeley) réDacteurs associés / associate editors (*, took charge of the editorial process of the article/a pris en charge le suivi éditorial de l'article) :

PeerJ, Oct 3, 2017

Fossils are almost always represented by hard tissues but we present here the exceptional case of... more Fossils are almost always represented by hard tissues but we present here the exceptional case of a three-dimensionally preserved specimen that was 'mummified' (likely between 40 and 34 million years ago) in a terrestrial karstic environment. This fossil is the incomplete body of a salamander, Phosphotriton sigei, whose skeleton and external morphology are well preserved, as revealed by phase-contrast synchrotron X-ray microtomography. In addition, internal structures composed of soft tissues preserved in three dimensions are now identified: a lung, the spinal cord, a lumbosacral plexus, the digestive tract, muscles and urogenital organs that may be cloacal glands. These are among the oldest known cases of three-dimensional preservation of these organs in vertebrates and shed light on the ecology of this salamander. Indeed, the digestive tract contains remains of a frog, which represents the only known case of an extinct salamander that fed on a frog, an extremely rare type of predation in extant salamanders. These new data improve our scarce knowledge on soft tissue anatomy of early urodeles and should prove useful for future biologists and palaeontologists working on urodele evolutionary biology. We also suggest that the presence of bat guano and carcasses represented a close source of phosphorus, favouring preservation of soft tissues. Bone microanatomy indicates that P. sigei was likely amphibious or terrestrial, and was probably not neotenic.

Journal of Natural History, Oct 28, 2005

Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content")... more Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.

Systematic Biology, Oct 11, 2010

Some of the most basic questions about the history of life concern evolutionary trends. These inc... more Some of the most basic questions about the history of life concern evolutionary trends. These include determining whether or not metazoans have become more complex over time, whether or not body size tends to increase over time (the Cope-Depéret rule), or whether or not brain size has increased over time in various taxa, such as mammals and birds. Despite the proliferation of studies on such topics, assessment of the reliability of results in this field is hampered by the variability of techniques used and the lack of statistical validation of these methods. To solve this problem, simulations are performed using a variety of evolutionary models (gradual Brownian motion, speciational Brownian motion, and Ornstein-Uhlenbeck), with or without a drift of variable amplitude, with variable variance of tips, and with bounds placed close or far from the starting values and final means of simulated characters. These are used to assess the relative merits (power, Type I error rate, bias, and mean absolute value of error on slope estimate) of several statistical methods that have recently been used to assess the presence of evolutionary trends in comparative data. Results show widely divergent performance of the methods. The simple, nonphylogenetic regression (SR) and variance partitioning using phylogenetic eigenvector regression (PVR) with a broken stick selection procedure have greatly inflated Type I error rate (0.123-0.180 at a 0.05 threshold), which invalidates their use in this context. However, they have the greatest power. Most variants of Felsenstein's independent contrasts (FIC; five of which are presented) have adequate Type I error rate, although two have a slightly inflated Type I error rate with at least one of the two reference trees (0.064-0.090 error rate at a 0.05 threshold). The power of all contrastbased methods is always much lower than that of SR and PVR, except under Brownian motion with a strong trend and distant bounds. Mean absolute value of error on slope of all FIC methods is slightly higher than that of phylogenetic generalized least squares (PGLS), SR, and PVR. PGLS performs well, with low Type I error rate, low error on regression coefficient, and power comparable with some FIC methods. Four variants of skewness analysis are examined, and a new method to assess significance of results is presented. However, all have consistently low power, except in rare combinations of trees, trend strength, and distance between final means and bounds. Globally, the results clearly show that FIC-based methods and PGLS are globally better than nonphylogenetic methods and variance partitioning with PVR. FIC methods and PGLS are sensitive to the model of evolution (and, hence, to branch length errors). Our results suggest that regressing raw character contrasts against raw geological age contrasts yields a good combination of power and Type I error rate. New software to facilitate batch analysis is presented.

Contributions to zoology, Apr 13, 2018

Simulation-based and experimental studies are crucial to produce factual arguments to solve theor... more Simulation-based and experimental studies are crucial to produce factual arguments to solve theoretical and methodological debates in phylogenetics. However, despite the large number of works that tested the relative efficiency of phylogenetic methods with various evolutionary models, the capacity of methods to manage various sources of error and homoplasy has almost never been studied. By applying ordered and unordered methods to datasets with iterative addition of errors in the ordering scheme, we show that unordered coding in parsimony is not a more cautious option. A second debate concerns how to handle reversals, especially when they are regarded as possible synapomorphies. By comparing analyses of reversible and irreversible characters, we show empirically that three-taxon analysis (3ta) manages reversals better than parsimony. For Brownian motion data, we highlight that 3ta is also more efficient than parsimony in managing random errors, which might result from taphonomic problems or any homoplasy generating events that do not follow the dichotomy reversal/ convergence, such as lateral gene transfer. We show parsimony to be more efficient with numerous character states (more than four), and 3ta to be more efficient with binary characters, both methods being equally efficient with four states per character. We finally compare methods using two empirical cases of known evolution.

Contributions to zoology, Oct 20, 2010

Absolute (Linnaean) ranks are essential to rank-based nomenclature (RN), which has been used by t... more Absolute (Linnaean) ranks are essential to rank-based nomenclature (RN), which has been used by the vast majority of systematists for the last 150 years. They are widely recognized as being subjective among taxonomists, but not necessarily in other fields. For this reason, phylogenetic nomenclature (PN) and other alternative nomenclatural systems have been developed. However, reluctance to accept alternative nomenclatural systems and continued use of higher taxa of a given Linnaean category in comparative analyses presumably reflect a lack of appreciation of the deleterious effects of the subjective nature of Linnaean categories in other biological fields, such as conservation and evolutionary biology. To make that point clearer, evolutionary models under which such categories would be natural are presented and are shown to be highly unrealistic and to lack empirical support. Under all realistic evolutionary models, ranking of taxa into Linnaean categories is highly subjective. Solutions that could make taxonomic ranks objective are surveyed. A review of the literature illustrates two problems created by the use of Linnaean categories in comparative or evolutionary studies, namely suboptimal taxonomic sampling schemes in studies of character evolution, and unreliable biodiversity assessment drawn on the basis of counting higher taxa (taxon surrogacy).

Geodiversitas, Mar 29, 2013

The origins of the extant amphibians (frogs, salamanders, caecilians) remain controversial after ... more The origins of the extant amphibians (frogs, salamanders, caecilians) remain controversial after over a century of debate. Three groups of hypotheses persist in the current literature: the "temnospondyl hypothesis" (TH) which roots Lissamphibia Haeckel, 1866 (the smallest clade composed of the extant amphibians) within the Paleozoic temnospondyls, the "lepospondyl hypothesis" (LH) which postulates a monophyletic Lissamphibia nested within the Paleozoic lepospondyls, and the "polyphyly hypothesis" (PH), according to which the frogs and the salamanders are temnospondyls while the caecilians are lepospondyls. The discovery of the Middle Jurassic to Pliocene albanerpetontids, which are very similar to the extant amphibians, has complicated rather than resolved this situation. We present a review of recent publications and theses in this field, several of which show more support for the LH than for the TH and considerably more than for the PH. In addition, we show that there is no particular attraction between long-bodied lissamphibians (caecilians) and long-bodied lepospondyls (such as the lysorophians): when they are removed from two published matrices, reanalyses nonetheless find the LH. In one case the LH is found even when all salamanders are removed as well. We furthermore propose that the complex of characters called the salamander mode of autopodium development is (in its less extreme forms) plesiomorphic for limbed vertebrates, so the apparent presence of this mode of development in temnospondyls cannot support the TH or the PH. Still, a consensus will not be reached soon, despite the increasing

Peer Community Journal, Jan 21, 2022

The origin of extant amphibians has been studied using several sources of data and methods, inclu... more The origin of extant amphibians has been studied using several sources of data and methods, including phylogenetic analyses of morphological data, molecular dating, stratigraphic data, and integration of ossification sequence data, but a consensus about their affinities with other Paleozoic tetrapods has failed to emerge. We have compiled five datasets to assess the relative support for six competing hypotheses about the origin of extant amphibians: a monophyletic origin among temnospondyls, a monophyletic origin among lepospondyls, a diphyletic origin among both temnospondyls and lepospondyls, a diphyletic origin among temnospondyls alone, and two variants of a triphyletic origin, in which anurans and urodeles come from different temnospondyl taxa while caecilians come from lepospondyls and are either closer to anurans and urodeles or to amniotes. Our datasets comprise ossification sequences of up to 107 terminal taxa and up to eight cranial bones, and up to 65 terminal taxa and up to seven appendicular bones, respectively. Among extinct taxa, only two or three temnospondyl can be analyzed simultaneously for cranial data, but this is not an insuperable problem because each of the six tested hypotheses implies a different position of temnospondyls and caecilians relative to other sampled taxa. For appendicular data, more extinct taxa can be analyzed, including some lepospondyls and the finned tetrapodomorph Eusthenopteron, in addition to temnospondyls. The data are analyzed through maximum likelihood, and the AICc (corrected Akaike Information Criterion) weights of the six hypotheses allow us to assess their relative support. By an unexpectedly large margin, our analyses of the cranial data support a monophyletic origin among lepospondyls; a monophyletic origin among temnospondyls, the current near-consensus, is a distant second. All other hypotheses are exceedingly unlikely according to our data. Surprisingly, analysis of the appendicular data supports triphyly of extant amphibians within a clade that unites lepospondyls and temnospondyls, contrary to all phylogenies based on molecular data and recent trees based on paleontological data, but this conclusion is not very robust.

Evolutionary Biology-new York, Jul 11, 2009

recently reviewed the controversial topic of extant amphibian origins, on which three (groups of)... more recently reviewed the controversial topic of extant amphibian origins, on which three (groups of) hypotheses exist at the moment. Anderson favors the "polyphyly hypothesis" (PH), which considers the extant amphibians to be polyphyletic with respect to many Paleozoic limbed vertebrates and was most recently supported by the analysis of Anderson et al. (2008). Another is the "temnospondyl hypothesis" (TH -lissamphibians nested within temnospondyls), most recently supported by . We prefer the "lepospondyl hypothesis" (LH -lissamphibians nested within "lepospondyls"; most recently supported by Vallin and Laurin, 2004 and Marjanović and Laurin, 2008a). We would like to clarify important points that were not discussed in Anderson's review, or for which crucial arguments were left out. argues that most molecular dates favor the PH because they suggest a Devonian or Early Carboniferous diversification of Lissamphibia. This is inaccurate, since the confidence intervals of the dates obtained by range from Early Carboniferous to Middle Permian, and our own molecular dating suggests a Permian origin. Indeed, three methods (molecular dating, a paleontological supertree and a confidence interval on the stratigraphic range of Lissamphibia) all hint at a Permian or (less likely) a Late Carboniferous origin of Lissamphibia (Marjanović and Laurin, 2007, 2008b). Citing Milner (2004), Anderson (2008: 234) argues that the LH is mainly supported by loss characters, and that this is problematic "given the relative ease that these losses can arise via paedomorphosis, which appears to evolve repeatedly." This is especially surprising because we count (Supplementary Table ) about fifty loss characters in the matrix by Anderson et al. (2008) -more than one out of five characters -, including several that describe the loss of bones that ossified late in the ontogeny of branchiosaurids and/or the aïstopod Phlegethontia (Anderson, 2002) and are absent in lissamphibians. Abbreviations: LH, lepospondyl hypothesis; PH, polyphyly hypothesis; TH, temnospondyl hypothesis; Salientia: Triadobatrachus and the "frogs" OTU. Contents of the clade Clade contradicts: Bootstrap percentage LH PH TH all "lepospondyls", Lissamphibia no yes yes 67.5 all "lepospondyls" except Adelogyrinus, Lissamphibia no yes yes 43.6 Temnospondyli no yes yes 36.5 all "lepospondyls", Lissamphibia, Limnoscelis no yes yes 35.8 all "lepospondyls", Lissamphibia, Limnoscelis, Seymouria, Proterogyrinus no yes yes 30.3 all "lepospondyls" except Adelogyrinus and Microbrachis, Lissamphibia no yes yes 28.6 all "lepospondyls", Lissamphibia, Limnoscelis, Seymouria no yes yes 27.8 all temnospondyls except Eryops, Ecolsonia, Acheloma and Tambachia no yes yes 25.9 Tersomius, Doleserpeton, Micropholis, Eoscopus, Platyrhinops, Amphibamus, Gerobatrachus (thus same as above except Balanerpeton, Dendrerpeton, Branchiosauridae and Micromelerpetontidae) no rather yes rather yes 25.3 Doleserpeton, Amphibamus, Gerobatrachus no rather no rather no 24.1 all temnospondyls except Balanerpeton, Dendrerpeton and Eryops no yes yes 23.1 Lissamphibia no yes no 22.7 Rhynchonkos, Eocaecilia yes no yes 22.4 Brachydectes, Lissamphibia no yes yes 22.1 Tersomius, Doleserpeton, Eoscopus, Platyrhinops, Amphibamus, Gerobatrachus no rather yes rather yes 20.1 all "nectrideans", Aïstopoda, Brachydectes, Lissamphibia no yes yes 19.3 all "nectrideans", Aïstopoda, Albanerpetontidae, salamanders, Salientia yes yes yes 18.1 Aïstopoda, Brachydectes, Lissamphibia no yes yes 17.3 all "nectrideans", Aïstopoda, Brachydectes, Albanerpetontidae, salamanders, Salientia yes yes yes 17.0 all temnospondyls except Balanerpeton, Dendrerpeton, Eryops, Ecolsonia, Acheloma and Tambachia, all "lepospondyls", Lissamphibia no no 1 rather yes 16.6 Aïstopoda, Albanerpetontidae, salamanders, Salientia yes yes yes 15.9 all "lepospondyls" except Microbrachis, Utaherpeton and Adelogyrinus, Lissamphibia no yes yes 14.4 same as above except Tuditanus, Asaphestera, Hapsidopareion and Saxonerpeton no yes yes 14.1 Gerobatrachus, salamanders, Salientia yes no no 13.9 all temnospondyls except Balanerpeton, Dendrerpeton and Eryops, all "lepospondyls", Lissamphibia no no 1 rather yes 13.9 all "nectrideans" except Scincosaurus, Aïstopoda, Brachydectes, Lissamphibia no yes yes 12.2 all "lepospondyls" except Utaherpeton and no yes yes 12.2 Adelogyrinus, Lissamphibia Doleserpeton, Platyrhinops, Gerobatrachus no rather no rather no 11.9 all "lepospondyls" except Utaherpeton, Lissamphibia no yes yes 11.1 Greererpeton, Temnospondyli no yes yes 10.8 Rhynchonkos, Batropetes, all "nectrideans", Aïstopoda, Brachydectes, Lissamphibia no yes yes 9.6 same as above except Rhynchonkos no yes yes 9.4 Hapsidopareion, Brachydectes no no no 9.4 Gymnarthridae, Rhynchonkos, Eocaecilia yes no yes 9.3 all temnospondyls except Eryops, all "lepospondyls", Lissamphibia no no 1 rather no 9.3 Aïstopoda, Brachydectes, Lissamphibia except Eocaecilia yes yes yes 9.2 all "lepospondyls", Eocaecilia, Albanerpetontidae yes no yes 9.0 all temnospondyls except Eryops, Ecolsonia, Acheloma and Tambachia, all "lepospondyls", Lissamphibia no no 1 rather no 9.0 Platyrhinops, Amphibamus, Gerobatrachus no rather no rather no 9.0 Lissamphibia without Albanerpetontidae no yes no 8.7 Utaherpeton, all "nectrideans", Aïstopoda, Brachydectes, Lissamphibia no yes yes 8.4 Pantylidae, Gymnarthridae, Ostodolepididae, Rhynchonkos, Batropetes, Eocaecilia yes no yes 8.3 all "lepospondyls" except Tuditanus, Asaphestera, Microbrachis and Adelogyrinus, Lissamphibia no yes yes 8.1 Albanerpetontidae, salamanders no no no 7.9 Batropetes, Utaherpeton, all "nectrideans", Aïstopoda, Brachydectes, Lissamphibia no yes yes 7.4 Doleserpeton, Platyrhinops, Amphibamus, Gerobatrachus, salamanders, Salientia yes no yes 7.4 Brachydectes, Eocaecilia yes no yes 7.3 Temnospondyli, salamanders, Salientia yes no yes 7.3 all "lepospondyls" except Adelogyrinus, Eocaecilia, Albanerpetontidae yes no yes 7.1 Doleserpeton, Gerobatrachus, salamanders, Salientia yes no yes 7.0 Batropetes, Eocaecilia yes no yes 6.4 Gerobatrachus, Lissamphibia except Eocaecilia yes no yes 6.3 Brachydectes, Lissamphibia except Eocaecilia yes yes yes 6.1 Rhynchonkos, Batropetes, Eocaecilia yes no yes 6.1 Pantylidae, Gymnarthridae, Rhynchonkos, Batropetes, Eocaecilia yes no yes 5.9 all "lepospondyls" except Utaherpeton and Adelogyrinus, Eocaecilia, Albanerpetontidae yes no yes 5.2 same as above except Albanerpetontidae and all "nectrideans" other than Ptyonius (!) yes no yes 5.1

Systematic Biology, Feb 1, 2004

Biological Journal of The Linnean Society, Oct 16, 2013

The cladistic literature does not always specify the kind of multistate character treatment that ... more The cladistic literature does not always specify the kind of multistate character treatment that is applied for an analysis. Characters can be treated either as unordered transformation series or as rooted [three-item analysis (3ia)] or unrooted state trees (ordered characters). We aimed to measure the impact of these character treatments on phylogenetic inference. Discrete characters can be represented either as rows or columns in matrices (e.g. for parsimony) or as hierarchies for 3ia. In the present study, we use simulated and empirical examples to assess the relative merits of each method considering both the character treatment and representation. We measure two parameters (resolving power and artefactual resolution) using a new tree comparison metric, ITRI (inter-tree retention index). Our results suggest that the hierarchical character representation not only results (with our simulation settings) in the greatest resolving power, but also in the highest artefactual resolution. Our empirical examples provide equivocal results. Parsimony unordered states yield less resolving power and more artefactual resolutions than parsimony ordered states, both with our simulated and empirical data. Relationships between three operational taxonomic units (OTUs), irrespective of their relationships with other OTUs, are called three-item statements (3is). We compare the intersection tree (which reconstructs a single tree from all of the common 3is of source trees) with the traditional strict consensus and show that the intersection tree retains more of the information contained in the source trees.

The description of the small Late Triassic temnospondyl Chinlestegophis ushered in a potentially ... more The description of the small Late Triassic temnospondyl Chinlestegophis ushered in a potentially radically new understanding of the origins of the extant amphibian clades. Together with the fragmentary Rileymillerus, Chinlestegophis was argued to link the extant caecilians to the Permo-Triassic stereospondyl temnospondyls rather than to frogs and salamanders (and through them to amphibamiform temnospondyls or to brachystelechid and lysorophian “lepospondyls”). We review previously published and newly discovered problems with the comparative description of Chinlestegophis and with the accompanying phylogenetic analyses. Most of the features previously interpreted to be shared by caecilians, Chinlestegophis and/or other stereospondyls have different distributions than scored in the analysis. We also find no evidence for an incipient tentacular sulcus in Chinlestegophis, and note that its vertebrae and unreduced ribs, dermal shoulder girdle, and ulna are unlike those of any extant amph...

Journal of Mammalian Evolution, 2018

In the fossil record, it has been shown that various clades of secondarily aquatic tetrapods expe... more In the fossil record, it has been shown that various clades of secondarily aquatic tetrapods experienced an initial densification of their bones in the early stages of their evolution, and developed spongier and lighter bones only later in their evolution, with the acquisition of more efficient swimming modes. Although the inner bone structure of most secondarily aquatic tetrapods has already been studied, no research hitherto focused on true seals, or Phocidae. However, preliminary observations previously made on a Miocene species, Nanophoca vitulinoides, suggested that this taxon showed pronounced specialization of bone structure as compared to other seals. This feature justifies a specific comparative study, which is the purpose of this article. Microanatomical analysis of bones of N. vitulinoides shows compactness values nearing 100%, which is much higher than in other semi-aquatic mammals, pinnipeds included. Osteohistological analyses show virtually complete remodeling of the medullary territory by Haversian substitution. Extreme bone compactness locally resulted from an imbalance, towards reconstruction, of this process. Cortical regions were less intensely remodeled. In a number of specimens, the cortex shows clear growth marks as seasonal lines of arrested growth. The results suggest that, despite the extreme compactness of long bones of N. vitulinoides and the small size of this

Cladistics, Feb 21, 2019

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Comptes Rendus Palevol, Jul 1, 2011

Université Pierre et Marie Curie.

Journal of Vertebrate Paleontology, Jun 30, 2022

Canadian Journal of Earth Sciences, Mar 1, 1989

Redescription of Colobomycter pholeter Vaughn, a small amniote from the Lower Permian of Oklahoma... more Redescription of Colobomycter pholeter Vaughn, a small amniote from the Lower Permian of Oklahoma, provides evidence that it is not a mammal-like reptile. Osteological features used to associate Colobomycter with the family Eothyrididae are also present in protorothyridids. Colobomycter has a large sheet-like jugal in the temporal region, precluding the presence of a pelycosaurian lateral temporal opening. Derived osteological features shared with members of the family Protorothyrididae suggest that Colobomycter might be a member of that family, but this assignment must remain tentative because of the fragmentary nature of the known specimens.

Journal of Vertebrate Paleontology, Dec 31, 1996

ABSTRACT Several specimens of Ariekanerpeton sigalovi are described and illustrated for the first... more ABSTRACT Several specimens of Ariekanerpeton sigalovi are described and illustrated for the first time. This taxon is similar to Discosauriscus austriacus, and only three characters separate them: 1) the absence of an interpterygoid vacuity, 2) the loss of a phalanx in the fourth manual digit, and 3) the absence of dermal scales in post-metamorphic specimens of Ariekanerpeton. Both taxa are represented by larvae and juvenile post-metamorphic specimens, but no fully adult individuals. Ariekanerpeton and Discosauriscus share several derived characters with Seymouria and are considered to be closely related to the latter.