Genasauria
Encyclopedia
Genasauria is an extinct clade
of beaked, herbivorous
dinosaur
s. The group was first named by paleontologist
Paul Sereno
in 1986, and is typically split into Thyreophora
, a group of armored dinosaurs; and Neornithischia, which included the horned
and duck-billed dinosaurs. Genasauria, as defined by Sereno, consists of Ankylosaurus
magniventris, Pachycephalosaurus
wyomingensis, Parasaurolophus
walkeri, Stegosaurus
stenops, Triceratops
horridus, their most recent common ancestor
, and all descendants. The name Genasauria was used almost exclusively by Sereno for several years, but has gained greater usage in recent years.
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
of beaked, herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
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. The group was first named by paleontologist
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
in 1986, and is typically split into Thyreophora
Thyreophora
The Thyreophora were a subgroup of the ornithischian dinosaurs...
, a group of armored dinosaurs; and Neornithischia, which included the horned
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
and duck-billed dinosaurs. Genasauria, as defined by Sereno, consists of Ankylosaurus
Ankylosaurus
Ankylosaurus is a genus of ankylosaurid dinosaur, containing one species, A. magniventris...
magniventris, Pachycephalosaurus
Pachycephalosaurus
Pachycephalosaurus is a genus of pachycephalosaurid dinosaur. It lived during the Late Cretaceous Period of what is now North America. Remains have been excavated in Montana, South Dakota, and Wyoming. It was an herbivorous or omnivorous creature which is only known from a single skull and a few...
wyomingensis, Parasaurolophus
Parasaurolophus
Parasaurolophus is a genus of ornithopod dinosaur that lived in what is now North America during the Late Cretaceous Period, about 76.5–73 million years ago. It was an herbivore that walked both as a biped and a quadruped. Three species are recognized: P. walkeri , P. tubicen, and the...
walkeri, Stegosaurus
Stegosaurus
Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well...
stenops, Triceratops
Triceratops
Triceratops is a genus of herbivorous ceratopsid dinosaur which lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 65 million years ago in what is now North America. It was one of the last dinosaur genera to appear before the great Cretaceous–Paleogene...
horridus, their most recent common ancestor
Common descent
In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong quantitative support for the theory that all living organisms on Earth are descended from a common ancestor....
, and all descendants. The name Genasauria was used almost exclusively by Sereno for several years, but has gained greater usage in recent years.