Jacques Gauthier

Jacques Gauthier
Yale University | YU · Department of Geology and Geophysics

About

101
Publications
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9,822
Citations
Citations since 2016
40 Research Items
2954 Citations
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20162017201820192020202120220100200300400
20162017201820192020202120220100200300400
20162017201820192020202120220100200300400

Publications

Publications (101)
Article
Full-text available
Squamata is the most diverse clade of terrestrial vertebrates. Although the origin of pan-squamates lies in the Triassic, the oldest undisputed members of extant clades known from nearly complete, uncrushed material come from the Cretaceous. Here, we describe three-dimensionally preserved partial skulls of two new crown lizards from the Late Jurass...
Article
Full-text available
Birds and mammals independently evolved the highest metabolic rates among living animals¹. Their metabolism generates heat that enables active thermoregulation¹, shaping the ecological niches they can occupy and their adaptability to environmental change². The metabolic performance of birds, which exceeds that of mammals, is thought to have evolved...
Article
Full-text available
Accurate, comprehensive data on life expectancy, growth rates, age structure, and sexual maturation are necessary to inform decision-making for conservation action, but they are often difficult to obtain from wild animals. Osteohistology has proven a reliable method for accessing chronological data in extant and extinct vertebrates. Traditional mar...
Article
Full-text available
Squamate reptiles are a major component of vertebrate biodiversity whose crown-clade traces its origin to a narrow window of time in the Mesozoic during which the main subclades diverged in rapid succession. Deciphering phylogenetic relationships among these lineages has proven challenging given the conflicting signals provided by genomic and pheno...
Data
Majority rule consensus tree of the Bayesian inference analysis for the combined dataset. Values along branches represent posterior probabilities. (TIF)
Data
Probabilities of incorrect (QIHP), polytomous (QIPP) and correct (QIRP) resolution of the four internodes connecting the main lizard clades across all genes. QIPP are relatively low overall, a consequence of the high rates of molecular evolution. Across all four branches and 46 genes, QIHP values surpass QIRP, evidencing higher probabilities of inc...
Data
Morphological dataset. (NEX)
Data
Maximum likelihood gene trees. (NEX)
Data
Accuracy of tree-independent methods (OV and TIGER) to estimate rate of evolution. All variable characters in the molecular dataset (after eliminating poorly-aligned positions with trimAl) were ordered according to increasing rates of evolution, as estimated using maximum likelihood in the time-calibrated topology. The frequency with which characte...
Data
Timescale of the squamate radiation, as estimated by multiple time-calibration studies. Total time is the time spanned between the age of crown Squamata and that of the most recent common ancestor of Anguimorpha with either Iguania or Serpentes, depending on the resolution of Toxicofera obtained by each study. Average internode is the total time di...
Data
Optimal tree for the morphological dataset under maximum parsimony. Values along branches represent jackknife support. (TIF)
Data
Gene tree topological incongruence as a function of node age. Gene support frequency (GSF) corresponds to the fraction of gene trees showing a node present in the concatenated, time-calibrated tree of Zheng & Wiens [32] out of the set of genes sampling all terminals in the corresponding clade. The red curve is a loess regression, and shows a strong...
Data
Properties of the positions eliminated by trimAl. Targeted characters were either highly noisy, as measured using Shannon entropy, or had very high proportion of gaps. Density of eliminated characters increases from blue to red. The elimination of these characters had no impact on topology or support values. (TIF)
Data
Number of genes trees (GS = gene support) showing the same resolution as found in the concatenated molecular and combined topologies, for nodes in which these two differ. Low values are a consequence of both A) missing data, and more frequently B) other topologies being also commonly recovered. (DOCX)
Data
Majority rule consensus tree of the Bayesian inference analysis for the morphological dataset. Values along branches represent posterior probabilities. (TIF)
Data
Optimal tree for the molecular dataset under maximum parsimony. Values along branches represent jackknife support. (TIF)
Data
Majority rule consensus tree of the Bayesian inference analysis for the molecular dataset. Values along branches represent posterior probabilities. (TIF)
Data
Optimal tree for the combined dataset under maximum parsimony. Values along branches represent jackknife support. (TIF)
Data
Phylogenetic informativeness profiles of individual genes. Profiles are arbitrarily subdivided into those peaking before (left, 61%) and after 150 Ma (right, 39%). Note however that the majority of the genes on the right still have informativeness peaks before the estimated time-frame in which the main lizard clades diverged. Only 3 profiles peak d...
Data
Morphological synapomorphies relevant to crown squamate backbone. (DOCX)
Article
Full-text available
We introduce a new non-destructive source of skeletochronological data with applications to species identification, associating disarticulated remains, assessing minimum number of individuals (MNI), and collection management of fossil snakes, but with potential implications for all bony vertebrates, extinct or extant. Study of a diverse sample of R...
Data
Measurements of centrum length and zygantral growth rings in Bogertophis subocularis and Boavus occidentalis (formerly YPM 2770 and 3752) Calculation of standard deviation (s) and 2s is included for Bogertophis subocularis. The so derived values for 2s (in %) are used to estimate whether vertebrae of Boavus occidentalis that are potentially from th...
Article
The fossil record and recent molecular phylogenies support an extraordinary early-Cenozoic radiation of crown birds (Neornithes) after the Cretaceous-Paleogene (K-Pg) mass extinction [1-3]. However, questions remain regarding the mechanisms underlying the survival of the deepest lineages within crown birds across the K-Pg boundary, particularly sin...
Article
Full-text available
Following the Permo-Triassic Extinction, large-bodied diapsid reptiles-with a body length >1 m-rapidly expanded their ecological roles. This diversification is reflected in enormous disparity in the development of the rostrum and adductor chamber. However, it is unclear how marked the diversity of the feeding apparatus was in contemporary small-bod...
Conference Paper
The fossil record of early-diverging pan-archosaurs and pan-lepidosaurs in the Triassic is biased towards large-bodied animals (1+ meters). The Triassic Newark Supergroup of eastern North America has produced tantalizing specimens of small reptiles, hinting at high diversity on the continent. Among these is a remarkable diapsid skull (~2.5 cm lengt...
Article
The interaction between an organism and its environment influences its growth and differentiation during ontogeny. For extinct species in particular, the record of this interaction can be accessed through osteohistology. Such studies have, however, historically focused largely on dinosaurs and mammals, leaving the rest of Amniota understudied. Alth...
Article
Full-text available
Background The highly derived morphology and astounding diversity of snakes has long inspired debate regarding the ecological and evolutionary origin of both the snake total-group (Pan-Serpentes) and crown snakes (Serpentes). Although speculation abounds on the ecology, behavior, and provenance of the earliest snakes, a rigorous, clade-wide analysi...
Article
Full-text available
Worm lizards (Amphisbaenia) are burrowing squamates that live as subterranean predators. Their underground existence should limit dispersal, yet they are widespread throughout the Americas, Europe and Africa. This pattern was traditionally explained by continental drift, but molecular clocks suggest a Cenozoic diversification, long after the break-...
Article
Full-text available
Understanding the phylogenetic position of crown turtles (Testudines) among amniotes has been a source of particular contention. Recent morphological analyses suggest that turtles are sister to all other reptiles, whereas the vast majority of gene sequence analyses support turtles as being inside Diapsida, and usually as sister to crown Archosauria...
Article
Full-text available
Lizards (nonophidian squamates) from a vertical series of localities in the early Eocene Wasatch Formation (Washakie Basin, Wyoming, USA) deposited during an interval of global warming are described on the basis of isolated cranial and some postcranial bones. At least 24 species are present. New material supports a close relationship of the iguanid...
Article
Full-text available
The turtle shell represents a unique modification of the ancestral tetrapod body plan. The homologies of its approximately 50 bones have been the subject of debate for more than 200 years. Although most of those homologies are now firmly established, the evolutionary origin of the dorsal median nuchal bone of the carapace remains unresolved. We pro...
Article
Full-text available
The origin of the turtle shell has perplexed biologists for more than two centuries [1]. It was not until Odontochelys semitestacea [2] was discovered, however, that the fossil and developmental data [3-8] could be synthesized into a model [9] of shell assembly that makes predictions for the as-yet unestablished history of the turtle stem group. We...
Article
Full-text available
The Cretaceous-Paleogene (K-Pg) boundary is marked by a major mass extinction, yet this event is thought to have had little effect on the diversity of lizards and snakes (Squamata). A revision of fossil squamates from the Maastrichtian and Paleocene of North America shows that lizards and snakes suffered a devastating mass extinction coinciding wit...
Article
Full-text available
Snakes are the most diverse group of lizards, but their origins and early evolution remain poorly understood owing to a lack of transitional forms. Several major issues remain outstanding, such as whether snakes originated in a marine or terrestrial environment and how their unique feeding mechanism evolved. The Cretaceous Coniophis precedens was a...
Article
Full-text available
We assembled a dataset of 192 carefully selected species-51 extinct and 141 extant-and 976 apomorphies distributed among 610 phenotypic characters to investigate the phylogeny of Squamata ("lizards," including snakes and amphisbaenians). These data enabled us to infer a tree much like those derived from previous morphological analyses, but with bet...
Article
Full-text available
Joint expeditions by the American Museum of Natural History and Mongolian Academy of Sciences have recovered significant new remains of the basal monstersaur Gobiderma pulchrum. We describe these new specimens in detail and also revisit the originally described material in order to more fully understand this pivotal anguimorph taxon. The newly disc...
Article
Full-text available
Despite much interest in amniote systematics, the origin of turtles remains elusive. Traditional morphological phylogenetic analyses place turtles outside Diapsida-amniotes whose ancestor had two fenestrae in the temporal region of the skull (among the living forms the tuatara, lizards, birds and crocodilians)-and allied with some unfenestrate-skul...
Article
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We introduce a spectacular new specimen of a Late Triassic stem crocodilian identified as Poposaurus gracilis. It is part of a poorly known group, Poposauroidea, that, because of its striking similarities with contemporaneous stem avians (“dinosaurs”), has long puzzled archosaur paleontologists. Observed vertebrate locomotor behaviors, together wit...
Article
The origin of the tridactyl hand of crown birds from the pentadactyl hand of those early theropod dinosaurs lying along the avian stem has become a classic, but at times seemingly intractable, historical problem. The point in question is whether the fingers of crown birds represent digits 1-3 as predicted by generalized trends in the fossil record;...
Article
Full-text available
We introduce a spectacular new specimen of a Late Triassic stem crocodilian identified as Poposaurus gracilis. It is part of a poorly known group, Poposauroidea, that, because of its striking similarities with contemporaneous stem avians (“dinosaurs”), has long puzzled archosaur paleontologists. Observed vertebrate locomotor behaviors, together wit...
Article
Full-text available
The origin of turtles is one of the most contentious issues in systematics with three currently viable hypotheses: turtles as the extant sister to (i) the crocodile-bird clade, (ii) the lizard-tuatara clade, or (iii) Diapsida (a clade composed of (i) and (ii)). We reanalysed a recent dataset that allied turtles with the lizard-tuatara clade and fou...
Article
Full-text available
_Limusaurus_ is a remarkable herbivorous ceratosaur unique among theropods in having digits II, III and IV, with only a small metacarpal vestige of digit I. This raises interesting questions regarding the controversial identity of avian wing digits. The early tetanuran ancestors of birds had tridactyl hands with digital morphologies corresponding t...
Article
The North American Pleistocene Herpetofaunal Stability Hypothesis was established in the 1980s based on summary reviews of primary descriptive paleoherpetological literature. The hypothesis posits that North American herpetofaunas essentially were taxonomically and geographically stable throughout the Quaternary. Modern biogeographic distribution o...
Article
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is rarely collected, probably because itis nocturnal, fossorial, and semiaquatic (Harrisson,1962; Manthey and Grossman, 1997). Few specimensexist in collections worldwide, and skeletons are ex-tremely rare. As a result of limited access to speci-mens, many phylogenetic analyses that include thisspecies relied upon the same specimen (REE 1445, col-l...
Article
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We conducted a comparative study of the cephalic scales in xantusiid lizards. We describe the observed scutellation patterns, compare these to patterns observed in other squamates, and present a revised nomenclature for scincomorph cephalic scales that corrects some previous inconsistencies. Based on anatomical details and topographic relations in...
Article
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The endemic plated lizards (Gerrhosauridae) of Madagascar are one of the most diverse groups of lizards on the island (19 species) and are found in all ecoregions. On an island that presents so many interesting biological questions, plated lizards are an ideal group for examining patterns of diversification due to their high (but tractable) diversi...
Article
The differentiation of the dermal palate and of the septomaxilla in extant squamate reptiles is reviewed in terms of Lakjer's distinctions of a palaeochoanate, incomplete neochoanate, and neochoanate condition. The differentiation of the bones surrounding the mushroom body, Jacobson's organ, and the internal naris (choana) supports a number of clad...
Article
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Compsognathus longipes sits at an important point in theropod evolution at the base of Coelurosauria. Despite its relative completeness and oft-cited morphology, however, the manual morphology has been unclear. This work provides the first detailed study of the morphology of the manus of Compsognathus longipes. It shows that Compsognathus longipes...
Article
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THE CHINLE Formation has historically been studied exten-sively in Arizona and New Mexico, but less so in Utah. This could in part reflect the fact that exposures of this formation are limited in this state to seemingly endless narrow bands of outcrop that are often difficult to access. Because vertebrate fossils from elsewhere in the Chinle Format...
Article
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Article
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Competing hypotheses of early turtle evolution contrast sharply in implying very different ecological settings-aquatic versus terrestrial-for the origin of turtles. We investigate the palaeoecology of extinct turtles by first demonstrating that the forelimbs of extant turtles faithfully reflect habitat preferences, with short-handed turtles being t...
Article
Contentious issues in Night Lizard (Xantusiidae) evolution are revisited using Maximum Likelihood-based Bayesian methods and compared with results from Neighbor-Joining and Maximum Parsimony analyses. Fragments of three mitochondrial genes, the 12S and 16S ribosomal genes, and the cytochrome b gene, are sampled across an ingroup composed of seven x...
Article
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The taxon name "Aves" is currently used for several different clades, a situation that violates the fundamental nomenclatural principle that, to minimize ambiguity, each taxon name should refer to a single taxon. To clarify this situation, we explore some general issues concerning the properties of the three classes of phylogenetic definitions, inc...
Article
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Persistent contradictions in well supported empirical findings usually point to important scientific problems and may even lead to exciting new insights. One of the most enduring problems in evolutionary biology is the apparent conflict between paleontological and embryological evidence regarding the homology of the digits in the avian hand (1, 2)....
Article
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Pneumatization of the postcranial skeleton by the lungs is thought to be a hallmark of the avian skeleton, and to be an adaptation for flight by reducing weight. Pneumatic features have, however, remained elusive in the primitive avialan Archaeopteryx lithographica. The hollow long bones of Archaeopteryx were first interpreted to be pneumatized, bu...
Article
Despite the widely held belief that modem biological taxonomy is evolutionary, some of the most fundamental concepts and principles in the current system of biological nomenclature are based on a nonevolutionary convention that pre-dates widespread acceptance of an evolutionary world view by more than a century. The development of a phylogenetic sy...
Article
Publication of the English-language version of Hennig's (1966) Phylogenetic Systematics marked a turning point in the history of inquiry into the genealogy of life. Hennig catalyzed a long overdue reevaluation of systematic theory and method that should have followed immediately upon publication of Darwin's revolutionary ideas (de Queiroz, 1988). H...
Article
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The laterosphenoid is an ossification of the pila antotica neurocranial cartilage in the anterior sidewall of the braincase of crocodylians and birds. Contrary to published reports, the bone is present in the basal archosauriforms Proterosuchus fergusi, Euparkeria capensis, and Erythrosuchidae, taxa that diverged prior to the origin of the archosau...
Article
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Defining the names of taxa in terms of common ancestry, that is, using phylogenetic definitions of taxon names, departs from a tradition of character-based definitions by granting the concept of evolution a central role in taxonomy. Phylogenetic definitions bear on other taxonomic principles and practices, including the following: (1) Names cannot...
Article
Full-text available
Archaeopteryx is almost universally considered a primitive bird. Debate persists, however, about the taxonomic assignment of the six skeletal fossils. Allometric scaling of osteological data shows that all specimens are consistent with a single growth series. The absence of certain bone fusions suggests that no specimen is full-grown. Allometric pa...