Fossils & Geologic Time, PAL-SIM
Geologic time is the extensive interval of time occupied by the geologic history of Earth. Formal geologic time begins at the start of the Archean Eon (4.0 billion to 2.5 billion years ago) and continues to the present day.
Fossils & Geologic Time Encyclopedia Articles By Title
Paleogene Period, oldest of the three stratigraphic divisions of the Cenozoic Era spanning the interval between......
paleontology, scientific study of life of the geologic past that involves the analysis of plant and animal fossils,......
Paleozoic Era, major interval of geologic time that began 538.8 million years ago with the Cambrian explosion,......
palynology, scientific discipline concerned with the study of plant pollen, spores, and certain microscopic planktonic......
Paradoxides, genus of trilobites (an extinct group of arthropods) found as fossils in Middle Cambrian rocks of......
Parafusulina, genus of extinct fusulinid foraminiferans (single-celled animals with a hard, complexly constructed......
Paraschwagerina, genus of extinct fusulinid foraminiferans (protozoans with a relatively large shell readily preservable......
Charles William Peach was an English naturalist and geologist who made valuable contributions to the knowledge......
Peninj mandible, an almost perfectly preserved fossil jaw of the hominin (of human lineage) species Paranthropus......
Pennsylvanian Subperiod, second major interval of the Carboniferous Period, lasting from 323.2 million to 298.9......
Pentaceratops, (genus Pentaceratops), five-horned herbivorous dinosaur found as fossils in North America and possibly......
Pentremites, extinct genus of stemmed, immobile echinoderms (forms related to the starfish) abundant as marine......
Permian Period, in geologic time, the last period of the Paleozoic Era. The Permian Period began 298.9 million......
Petralona skull, an ancient human cranium discovered in 1960 in a cave near Thessaloníki, northeastern Greece.......
Petrified Forest National Park, desert area containing plant and animal fossils and archaeological sites in eastern......
petrified wood, fossil formed by the invasion of minerals into cavities between and within cells of natural wood,......
Phacops, genus of trilobites (an extinct group of aquatic arthropods) found as fossils in Silurian and Devonian......
Phanerozoic Eon, the span of geologic time extending about 541 million years from the end of the Proterozoic Eon......
Phenacodus, extinct genus of mammals known from fossils of the late Paleocene and early Eocene epochs of North......
Phillipsia, genus of trilobites (an extinct group of aquatic arthropods) uncommonly found as fossils in Carboniferous......
Phoberomys, extinct rodent genus, the largest rodent ever to have lived, that belongs to the infraorder Caviomorpha,......
Phyllograptus, genus of graptolites, an extinct group of small colonial marine animals related to the primitive......
phytosaur, heavily armoured semiaquatic reptiles found as fossils from the Late Triassic Period (about 229 million......
Piltdown man, (Eoanthropus dawsoni), proposed species of extinct hominin (member of the human lineage) whose fossil......
placoderm, any member of an extinct group (Placodermi) of primitive jawed fishes known only from fossil remains.......
Plateosaurus, (genus Plateosaurus), dinosaurs known from extensive fossil material found in Europe dating to the......
Platyceras, genus of extinct gastropods (snails) that occurs as fossils in rocks of Silurian to Permian age (about......
Platycrinites, genus of extinct crinoids, or sea lilies, especially characteristic as fossils of Early Carboniferous......
Platystrophia, genus of extinct brachiopods (lamp shells) occurring as fossils in marine rocks of the Middle Ordovician......
Plectoceras, extinct genus of small marine nautiloid cephalopods, forms related to the modern pearly nautilus,......
Pleistocene Epoch, earlier and major of the two epochs that constitute the Quaternary Period of Earth’s history,......
plesiosaur, (clade Plesiosauria), any of a group of long-necked marine reptiles found as fossils from the late......
Pleuromeia, genus of extinct lycopsid plants from the Triassic Period (about 251 million to 200 million years ago)......
Pliocene Epoch, second of two major worldwide divisions of the Neogene Period, spanning the interval from about......
Pliohippus, extinct genus of horses that inhabited North America during the Pliocene Epoch (5.3–2.6 million years......
pliosaur, a group of large carnivorous marine reptiles characterized by massive heads, short necks, and streamlined......
Podokesaurus, (Podokesaurus holyokensis), small carnivorous North American dinosaur found as a single specimen......
polychaete hypothesis, theory that conodonts (minute toothlike structures found as fossils in marine rocks) are......
polygnathiform, conodont, or small toothlike fossil of uncertain relationship found widely in ancient marine rocks,......
potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive......
Pound Quartzite, formation of Precambrian rocks (dating from 3.96 billion to 540 million years ago) in the region......
Prasopora, extinct genus of bryozoans, small colonial animals that formed mosslike or encrusting growths, especially......
Precambrian, period of time extending from about 4.6 billion years ago (the point at which Earth began to form)......
prefern, any of a group of extinct plants considered transitional between the first land plants, the psilophytes,......
Pridoli Series, uppermost of four main divisions of the Silurian System, representing those rocks deposited worldwide......
proconodontid, a small toothlike structure found in marine rocks formed over a long span of geologic time, that......
protactinium-231–thorium-230 dating, method of age determination that makes use of the quantities of certain protactinium......
Proterozoic Eon, the younger of the two divisions of Precambrian time, the older being the Archean Eon. The Proterozoic......
Protoceratops, (genus Protoceratops), ceratopsian dinosaur found as fossils in the Gobi Desert from 80-million-year-old......
Pseudoschwagerina, extinct genus of fusulinid foraminiferans (single-celled animals with hard shells preservable......
Psittacosaurus, (genus Psittacosaurus), primitive member of the horned dinosaurs (Ceratopsia) found as fossils......
Pteranodon, (genus Pteranodon), flying reptile (pterosaur) found as fossils in North American deposits dating from......
Pteraspis, genus of extinct jawless fishlike vertebrates found as fossils in Early Devonian rocks (those 398 million......
pterodactyl, informal term for a subgroup of flying reptiles (Pterosauria) known from the Late Jurassic through......
pterosaur, any of the flying reptiles that flourished during all periods (Triassic, Jurassic, and Cretaceous) of......
Ptilodus, extinct genus of mammals found as fossils in deposits dated to the Paleocene Epoch (65.5–55.8 million......
Pycnodontiformes, order of extinct fishes of the class Actinopterygii, containing the genus Pycnodus, common in......
Svante Pääbo Swedish evolutionary geneticist who specialized in the study of DNA from ancient specimens and who......
Qafzeh, paleoanthropological site south of Nazareth, Israel, where some of the oldest remains of modern humans......
Quaternary, in the geologic history of Earth, a unit of time within the Cenozoic Era, beginning 2,588,000 years......
Friedrich August Quenstedt was a German mineralogist and paleontologist. Quenstedt studied at the University of......
Quetzalcoatlus, genus made up of two species of giant pterosaurs classified in the family Azhdarchidae, which contains......
radiation-damage dating, method of age determination that makes use of the damage to crystals and the radiation......
Ramapithecus, fossil primate dating from the Middle and Late Miocene epochs (about 16.6 million to 5.3 million......
Rensselaeria, genus of extinct brachiopods (lamp shells) found as fossils in Lower Devonian marine rocks (387 to......
Resserella, extinct genus of brachiopods (lamp shells) that occurs as fossils in marine rocks of Middle Ordovician......
Rhamphorhynchus, (genus Rhamphorhynchus), flying reptile (pterosaurs) found as fossils from the Late Jurassic Period......
rhenium–osmium dating, method of determining the age of the important ore mineral molybdenite; the method is based......
Rhipidistia, extinct group of lobe-finned bony fishes of the order Crossopterygii that included the ancestors of......
Rhynchotrema, extinct genus of brachiopods, or lamp shells, found as fossils in Middle and Late Ordovician rocks......
Rhynchotreta, extinct genus of brachiopods (lamp shells) commonly found as fossils in Silurian marine rocks (between......
Rhynie plant, rootless, leafless, spore-bearing plant preserved in the Rhynie Chert, a mineral deposit that has......
Riversleigh fossils, any of numerous assemblages of fossils found at Riversleigh Station, in northwestern Queensland,......
Roadian Stage, first of the three stages of the Middle Permian (Guadalupian) Series, made up of all rocks deposited......
Alfred Sherwood Romer was a U.S. paleontologist widely known for his concepts of evolutionary history of vertebrate......
rubidium-strontium dating, method of estimating the age of rocks, minerals, and meteorites from measurements of......
sabre-toothed cat, any of the extinct catlike carnivores belonging to either the extinct family Nimravidae or the......
Saccopastore skulls, two Neanderthal fossils found in 1929 and 1935 in a river deposit on the bank of a small tributary......
Saint-Césaire, paleoanthropological site in southwestern France where in 1979 the remains of a young adult male......
Sakmarian Stage, second of the four stages of the Early Permian (Cisuralian) Epoch, encompassing all rocks deposited......
Sanmiguelia, genus of fossil plants based upon impressions of palmlike leaves from the Triassic Period (251 to......
saurischian, any member of one of the two major lineages of dinosaurs, including birds and all dinosaurs more closely......
sauropod, any member of the dinosaur subgroup Sauropoda, marked by large size, a long neck and tail, a four-legged......
sauropterygian, any of the aquatic reptiles found as fossils from the Mesozoic Era (251 million to 66 million years......
Scaphites, extinct genus of cephalopods (animals related to the modern octopus, squid, and nautilus) found as fossils......
Otto Heinrich Schindewolf was a German paleontologist, known for his research on corals and cephalopods. Schindewolf......
Schizodus, extinct genus of small mollusks found as fossils in rocks from the Devonian to the Permian Period (416......
Charles Schuchert was an American paleontologist who was a leader in the development of paleogeography, the study......
Schwagerina, extinct genus of fusulinid foraminiferans, small, single-celled protozoans related to the modern amoeba......
Dunkinfield Henry Scott was an English paleobotanist and leading authority of his time on the structure of fossil......
Scutellosaurus, genus of small ornithischian dinosaurs from the Early Jurassic Period (roughly 200 million to 176......
seed fern, loose confederation of seed plants from the Carboniferous and Permian periods (about 360 to 250 million......
Paul Sereno is an American paleontologist who discovered several notable dinosaur species while on field expeditions......
Serpukhovian Stage, third of three internationally defined stages of the Mississippian Subsystem of the Carboniferous......
Seymouria, extinct genus of terrestrial tetrapod found as fossils in Permian rocks (251 million to 299 million......
Shanidar, site of paleoanthropological excavations in the Zagros Mountains of Iraqi Kurdistan. Two clusters of......
Sigillaria, extinct genus of tree-sized lycopsids from the Carboniferous Period (about 360 to 300 million years......
Silurian Period, in geologic time, the third period of the Paleozoic Era. It began 443.8 million years ago and......
- Introduction
- Gondwana, Fossils, Climate
- Marine Life, Fossils, Reefs
- Fishes, Reefs, Extinctions
- Geology, Fossils, Climate
- Llandovery, Wenlock, & Ludlow
- Fossils, Shallow Seas, Climate
- Platform Margins, Marine Life, Climate
- Correlation, Stratigraphy, Fossils
- Fossils, Stratigraphy, Geology
- Marine Life, Climate Change, Extinctions
Simocetus, dolphinlike toothed whale (or odontocete) from the late Oligocene (28 million to 23 million years ago)......
George Gaylord Simpson was an American paleontologist known for his contributions to evolutionary theory and to......