Glossary

Paleontology terms

Quick definitions of the concepts that appear in articles across the site. Use the filter below to browse by category.

Eras and geological time

Cretaceous (Cretáceo): Last period of the Mesozoic, from about 145 to 66 Ma. Ends with the K-Pg mass extinction that wiped out all non-avian dinosaurs.
Geological formation (Formação geológica): A body of rock with distinct characteristics that can be mapped in the field. Examples: Hell Creek (USA, late Cretaceous), Morrison (USA, Late Jurassic), Santana (Brazil, Early Cretaceous).
Geological stage (Estágio geológico): Subdivision of a geological period. For example, the Maastrichtian is the last stage of the Cretaceous, when Tyrannosaurus rex and Triceratops lived.
Jurassic (Jurássico): Middle period of the Mesozoic, from about 201 to 145 Ma. Marked by the diversification of giant sauropods and the first large theropods.
Mesozoic (Mesozoico): Geological era between about 252 and 66 million years ago, divided into three periods: Triassic, Jurassic, and Cretaceous. Known as the "age of dinosaurs."
Mya / Ma: Abbreviations for "million years ago" (Mya) or "million years" as a measure of time (Ma).
Triassic (Triássico): First period of the Mesozoic, from about 252 to 201 Ma. The first dinosaurs appear at the end of this period, in ecosystems dominated by other reptiles.

Anatomy

Femur (Fêmur): Thigh bone, usually the largest and most robust in the skeleton. Femur length is often used to estimate a dinosaur's body mass.
Furcula (Furcúlula): The "wishbone," formed by the fusion of the two clavicles. Present in theropods and all modern birds, providing evidence of the evolutionary relationship between the groups.
Osteoderm (Osteoderma): Bony plate that forms in the skin, found mainly in ankylosaurs, stegosaurs, and some titanosaur sauropods. Functions as armor or for thermoregulation.
Pelvis (Pelve): Bony structure connecting the spine to the hind limbs. Dinosaurs are divided into two major orders based on pelvis architecture: Saurischia and Ornithischia.
Sacrum (Sacro): Set of fused vertebrae that connect to the pelvis. In dinosaurs, the sacrum is a key structure for classification because the number of sacral vertebrae varies between groups.
Skull (Crânio): Bony structure that protects the brain and supports the face. In paleontology, skull morphology is one of the main sources of characters used to identify and classify species.
Vertebra (Vértebra): Each of the individual bones that make up the spine. Dinosaur vertebrae are often diagnostic, meaning they allow species identification even without the rest of the skeleton.

Taxonomic groups

Abelisauridae: Family of carnivorous theropods from the Late Cretaceous, mostly from Gondwana. They had short, robust skulls and extremely reduced forelimbs. Includes Carnotaurus, Majungasaurus, and Abelisaurus.
Allosauridae: Family of carnivorous theropods from the Jurassic, dominant in the Morrison Formation of North America. Allosaurus is the best-known representative.
Ankylosauria: Group of armored herbivorous dinosaurs, with bony plates (osteoderms) covering the body and, in some, a club at the end of the tail. Includes Ankylosaurus and Borealopelta.
Carcharodontosauridae: Family of giant carnivorous theropods from the Cretaceous, with serrated teeth similar to those of sharks (hence the name). Includes Giganotosaurus, Mapusaurus, and Carcharodontosaurus.
Ceratopsia: Group of herbivorous dinosaurs with horns and neck frills, such as Triceratops and Protoceratops. They went extinct alongside the other non-avian dinosaurs.
Dinosauria: Monophyletic group defined by specific pelvis and limb characteristics. Includes all dinosaurs, from modern birds to giant sauropods.
Dromaeosauridae: Family of small to medium-sized theropods with retractable sickle-shaped claws on the hind feet. Includes Velociraptor, Deinonychus, and Dakotaraptor. They were feathered.
Ornithischia: The other major dinosaur order, characterized by a pelvis with the pubis pointing backward (similar to birds, hence the name). Includes ornithopods, ceratopsians, stegosaurs, and ankylosaurs.
Ornithopoda: Group of herbivorous dinosaurs that walked on both two and four legs. Includes Iguanodon and the hadrosaurs (duck-billed dinosaurs).
Saurischia: One of the two major dinosaur orders, characterized by a pelvis with the pubis pointing forward. Includes theropods and sauropods.
Sauropoda: Group of long-necked, quadrupedal herbivorous dinosaurs, including Brachiosaurus, Diplodocus, and Argentinosaurus. They are the largest land animals that have ever existed.
Spinosauridae: Family of carnivorous theropods with long crocodile-like snouts, adapted for fish-eating. Includes Spinosaurus, Baryonyx, Suchomimus, and Irritator.
Stegosauria: Group of herbivorous dinosaurs with plates and spines along the back and tail, such as Stegosaurus and Kentrosaurus. They flourished mainly in the Jurassic.
Theropoda: Group of bipedal dinosaurs, predominantly carnivorous, including Tyrannosaurus, Velociraptor, and Spinosaurus. Modern birds evolved from theropods.
Tyrannosauridae: Family of large carnivorous theropods from the Late Cretaceous, with reduced forelimbs and robust skulls. Includes T-Rex, Albertosaurus, Tarbosaurus, and Gorgosaurus.

Non-dinosaur reptiles

Crocodylomorph (Crocodilomorfo): Group that includes modern crocodilians and their extinct relatives, some of which were fully terrestrial or marine during the Mesozoic.
Ichthyosaur (Ictiossauro): Marine reptile with a body shape similar to a fish or dolphin, fully adapted to life at sea. NOT a dinosaur. Includes Temnodontosaurus, Cymbospondylus, and Ophthalmosaurus.
Mosasaur (Mosassauro): Marine reptile from the Late Cretaceous, a close relative of modern lizards. Top predators of the oceans at the end of the Mesozoic. Includes Mosasaurus and Prognathodon.
Plesiosaur (Plesiossauro): Long-necked marine reptile with four paddle-shaped flippers. NOT a dinosaur. Includes Elasmosaurus.
Pliosaur (Pliossauro): Subgroup of plesiosaurs with short necks and large heads, apex predators of Jurassic and Early Cretaceous oceans. Includes Liopleurodon, Pliosaurus, Kronosaurus, and Rhomaleosaurus.
Pterosaur (Pterossauro): Mesozoic flying reptile, NOT a dinosaur. Had wings formed by a skin membrane stretched over the fourth finger. Includes Anhanguera, Pteranodon, and Quetzalcoatlus.

Paleontology concepts

Apex predator (Predador apex): Animal at the top of an ecosystem's food chain, with no natural predators. T-Rex and Carcharodontosaurus were apex predators in their times and regions.
Bipedalism (Bipedalismo): Locomotion on two legs. Practically all theropods were bipedal; other dinosaur groups were quadrupedal or facultative (capable of both).
Bone histology (Histologia óssea): Microscopic study of bone tissues. Allows estimation of age, growth rate, metabolism, and pathologies in fossils.
Carnivore (Carnívoro): Animal whose diet consists mainly of meat. Most theropods were carnivorous.
Clade (Clado): Group formed by a common ancestor and all of its descendants. Different from a "paraphyletic group," which excludes some descendants.
Cladogram (Cladograma): Tree-shaped diagram representing the relationships among groups. Each branching point (node) indicates a hypothetical common ancestor.
Coprolite (Coprólito): Fossilized feces. Coprolites preserve remains of prey and plants and provide direct information about the diet of extinct animals.
Gondwana: Southern Hemisphere supercontinent that resulted from the breakup of Pangaea. Included the future South America, Africa, Australia, Antarctica, India, and Madagascar.
Herbivore (Herbívoro): Animal whose diet consists mainly of plants. Sauropods, ornithopods, ceratopsians, and stegosaurs were herbivores.
Holotype (Holótipo): Physical specimen designated by the original author as the reference for defining the species. Every valid scientific name has an associated holotype.
Laurasia (Laurásia): Northern Hemisphere supercontinent that resulted from the breakup of Pangaea. Included the future North America, Europe, and Asia.
Lectotype (Lectótipo): Specimen later chosen as the species reference when the original author did not clearly designate a holotype, or when the original was lost.
Omnivore (Onívoro): Animal that feeds on both plants and meat. Some small theropods, such as oviraptorids, were probably omnivorous.
Pangaea (Pangeia): Supercontinent that brought together practically all emergent landmasses at the end of the Permian and beginning of the Triassic. Began breaking up in the Jurassic.
Phylogeny (Filogenia): Evolutionary history and relationships among groups of organisms. Reconstructed through analysis of morphological characters and, in some cases, molecular data.
Piscivore (Piscívoro): Animal whose diet consists mainly of fish. Spinosaurus, Baryonyx, and the pliosaurs were piscivores.
Trace fossil (Icnofóssil): Fossilized trace of an organism's activity, such as footprints, burrows, or bite marks, rather than the animal's body itself.
Wastebasket taxon: Genus historically used as a generic category to classify fragmentary or indeterminate fossils, without real evolutionary coherence. Megalosaurus was a classic example during the 19th century.

Events

Big Five: The five largest mass extinctions in the history of life on Earth: Ordovician-Silurian, Late Devonian, Permian-Triassic, Triassic-Jurassic, and Cretaceous-Paleogene (K-Pg).
K-Pg extinction (Extinção K-Pg): Mass extinction event 66 million years ago that marked the end of the Cretaceous (K) and beginning of the Paleogene (Pg). Caused by the Chicxulub asteroid impact combined with Deccan Traps volcanism. Wiped out about 75% of species, including all non-avian dinosaurs.
LIP: Acronym for "Large Igneous Province." These are massive volcanic events that release large volumes of basalt and gases into the atmosphere, often associated with mass extinctions. Examples: Siberian Traps (252 Ma), CAMP (201 Ma), Deccan Traps (66 Ma).