Jacques Gauthier
Encyclopedia
Jacques Armand Gauthier is a vertebrate paleontologist
, comparative morphologist
, and systematist, and one of the founders of the use of cladistics
in biology.
He received a B.S. degree in Zoology at San Diego State University
in 1973, a Masters of Science at the same institute in 1980, and a PhD in Paleontology from the University of California
, Berkeley, in 1984. Currently he is a Professor of Geology and Geophysics and Ecology and Evolutionary Biology and
Curator of Vertebrate Paleontology and Vertebrate Zoology
at Yale University
. His master's thesis, the content of which was published in 1982, is a classic work on the paleontology and phylogeny of the lizard clade Anguimorpha
that remains a core reference for morphological research on Xenosauridae
and Anguidae
in particular. His PhD thesis constituted the first major cladistic analysis of Diapsida, as well as arguing for the monophyly
of the dinosaur
s. He followed this with an important paper on the origin of bird
s from theropods. This was the first detailed cladistic analysis of the theropod dinosaurs, and initiated a revolution in dinosaur phylogenetics, in which cladistics replaced the Linnaean system in the classification and phylogenetic understanding of the dinosaurs.
Gauthier's corpus is remarkable in that he contributed the foundational phylogenetic studies of Archosauria and Lepidosauria
, two major amniote clades; and he was the primary author of the foundational and still widely cited phylogenetic study of Amniota as a whole. The phylogenetic character sets from his 1984 and 1986 works, the 1988 amniote paper, and the 1988 lepidosaur and squamate papers still form the core of essentially all gross-anatomy-based phylogenetic analyses of these groups, and as such are among the most highly cited papers in amniote morphology and paleobiology. The 1988 amniote paper is also frequently cited to demonstrate the importance of taxon sampling in phylogenetic analysis, in particular the importance of sampling rare or fossil taxa that can break 'long branches' along which convergence can occur.
More recently, he has argued together with Kevin de Queiroz for replacing Linnaean taxonomy
with the PhyloCode
. In addition to his theoretical work on systematics and taxonomy, Gauthier continues to study the anatomy and relationships of diapsids, particularly lepidosaurs. His lizard work currently focuses on Scincomorpha
, following on a career-long interest in the unusual clade Xantusiidae. He is a principal investigator on the National Science Foundation
-funded effort to reconstruct the phylogeny of lizards and snakes (Squamata
) using gross anatomy and molecular structure, building on his earlier work in collaboration with Richard Estes and Kevin de Queiroz, which established the most widely accepted phylogeny of the group.
Vertebrate paleontology
Vertebrate paleontology is a large subfield to paleontology seeking to discover the behavior, reproduction and appearance of extinct animals with vertebrae or a notochord, through the study of their fossilized remains...
, comparative morphologist
Comparative anatomy
Comparative anatomy is the study of similarities and differences in the anatomy of organisms. It is closely related to evolutionary biology and phylogeny .-Description:...
, and systematist, and one of the founders of the use of cladistics
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
in biology.
He received a B.S. degree in Zoology at San Diego State University
San Diego State University
San Diego State University , founded in 1897 as San Diego Normal School, is the largest and oldest higher education facility in the greater San Diego area , and is part of the California State University system...
in 1973, a Masters of Science at the same institute in 1980, and a PhD in Paleontology from the University of California
University of California
The University of California is a public university system in the U.S. state of California. Under the California Master Plan for Higher Education, the University of California is a part of the state's three-tier public higher education system, which also includes the California State University...
, Berkeley, in 1984. Currently he is a Professor of Geology and Geophysics and Ecology and Evolutionary Biology and
Curator of Vertebrate Paleontology and Vertebrate Zoology
at Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
. His master's thesis, the content of which was published in 1982, is a classic work on the paleontology and phylogeny of the lizard clade Anguimorpha
Anguimorpha
Anguimorphs of the infraorder Anguimorpha include the anguids , monitor lizards, the extinct mosasaurs, and helodermatids . The infraorder was named by Fürbringer in 1900 to include all autarchoglossans closer to Varanus and Anguis than Scincus...
that remains a core reference for morphological research on Xenosauridae
Xenosauridae
The Xenosauridae is a family of lizards native to Central America and China. Also known as knob-scaled lizards, they have rounded, bumpy scales and osteoderms. Most species prefer moist or semi-aquatic habitats, although they are widespread within their native regions, with some even inhabiting...
and Anguidae
Anguidae
The Anguidae is a large and diverse family of lizards native to the northern hemisphere. The group includes the slowworms, glass lizards, and alligator lizards, among others. Anguidae is divided into three subfamilies and contains 94 species in eight genera. Their closest living relatives are the...
in particular. His PhD thesis constituted the first major cladistic analysis of Diapsida, as well as arguing for the monophyly
Monophyly
In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...
of the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s. He followed this with an important paper on the origin of bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s from theropods. This was the first detailed cladistic analysis of the theropod dinosaurs, and initiated a revolution in dinosaur phylogenetics, in which cladistics replaced the Linnaean system in the classification and phylogenetic understanding of the dinosaurs.
Gauthier's corpus is remarkable in that he contributed the foundational phylogenetic studies of Archosauria and Lepidosauria
Lepidosauria
The Lepidosauria are reptiles with overlapping scales. This subclass includes Squamata and Sphenodontidae. It is a monophyletic group and therefore contains all descendents of a common ancestor. The squamata includes snakes, lizards, tuataras, and amphisbaenia. Lepidosauria is the sister taxon...
, two major amniote clades; and he was the primary author of the foundational and still widely cited phylogenetic study of Amniota as a whole. The phylogenetic character sets from his 1984 and 1986 works, the 1988 amniote paper, and the 1988 lepidosaur and squamate papers still form the core of essentially all gross-anatomy-based phylogenetic analyses of these groups, and as such are among the most highly cited papers in amniote morphology and paleobiology. The 1988 amniote paper is also frequently cited to demonstrate the importance of taxon sampling in phylogenetic analysis, in particular the importance of sampling rare or fossil taxa that can break 'long branches' along which convergence can occur.
More recently, he has argued together with Kevin de Queiroz for replacing Linnaean taxonomy
Linnaean taxonomy
Linnaean taxonomy can mean either of two related concepts:# the particular form of biological classification set up by Carl Linnaeus, as set forth in his Systema Naturæ and subsequent works...
with the PhyloCode
PhyloCode
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a developing draft for a formal set of rules governing phylogenetic nomenclature...
. In addition to his theoretical work on systematics and taxonomy, Gauthier continues to study the anatomy and relationships of diapsids, particularly lepidosaurs. His lizard work currently focuses on Scincomorpha
Scincomorpha
Scincomorpha is an infraorder of saurians....
, following on a career-long interest in the unusual clade Xantusiidae. He is a principal investigator on the National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
-funded effort to reconstruct the phylogeny of lizards and snakes (Squamata
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
) using gross anatomy and molecular structure, building on his earlier work in collaboration with Richard Estes and Kevin de Queiroz, which established the most widely accepted phylogeny of the group.