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Glossary P

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(pronounced pack-ih-SEF-ah-low-SAWR-ids) Pachycephalosaurs (meaning: "thick head lizards") were plant-eating, thick-headed, short-armed, bipedal ornithischian dinosaurs from the late Cretaceous Period. Pachycephalosaurus, Homalocephale, and Stegoceras were pachycephalosaurs. They are sometimes called bone-headed dinosaurs.

(pronounced pack-ih-SEF-ah-low-SAWR-us) Pachycephalosaurus (meaning: "thick head lizard") was a plant-eating, dome-headed dinosaur 15 feet (4.6 m) long; it had a skull up to 10 inches thick (25 cm). It was named by Brown and Schlaikjer in 1943. The type species is P. wyomingensis.

(pronounced pack-ee-RINE-oh-SAWR-us) Pachyrhinosaurus (meaning: "thick-nosed lizard") was a plant-eating, short-frilled ceratopsian dinosaur 18 to 23 feet (5.5 to 7 m) long. Pachyrhinosaurus may or may not have a snout horn - it had a large bony bump on its nose (which may have had a horn growing on it). It also had many small horns on the middle of its frill. It lived during the late Cretaceous Period, about 72 to 68 million years ago. Fossils (12 partial skulls and some assorted bones) have been found in Alberta, Canada, and Alaska, USA. The type species is P. canadensis. Pachyrhinosaurus was named by paleontologist Charles M. Sternberg in 1950.

Pachyrukhos was an early mammal that filled a niche similar to the one that modern-day rabbits inhabit. Pachyrukhos was about 1 foot (30 cm) long. It had large ears and eyes, a pointed snout, a short tail, short front limbs, and well-developed hind legs. It probably moved by hopping. This mammal was probably nocturnal (given its large eyes and ears). This herbivore (plant-eater) ate nuts and tough plant material. It lived from the late Oligocene to the middle Miocene. Fossils have been found in South America.

Paedomorphic organisms retain some juvenile (or larval) characteristics during thier adult stage. An example of a paedomophic species is Cope's Giant Salamander; although it apprears to be a juvenile throughout its life, it can successfully reproduce. Monoclonius is a plant-eating dinosaur that may have paedomorphic (juvenile-like) features.

Pakicetus is an early fossil whale with a pointed snout. It was about 6 ft (1.8 m) long. It was found in Pakistan and dates from the early Eocene (about 54 million years ago). Pakicetus had pointed teeth like Mesonychid and a pinched brain case like Ambulocetus. It had a water-adapted inner ear but still had four limbs (probably paddle-shaped) and may have spent part of its life on land. Pakicetus had nostrils located at the front of head, and no blowhole.

(pronounced PAY-lee-OP-ter-iks) Palaeopteryx (meaning: "ancient wing") was a meat-eater from the late Jurassic Period. It was either a theropod dinosaur (a dromaeosaurid) or a bird; its classification is in dispute. Palaeopteryx was redescribed by Jensen and Padian in 1989 as belonging to Deinonychus. Fossils have been found in North America. Palaeopteryx named by Jensen in 1981. This is dubious genus.

(pronounced PAY-lee-oh-SKINK-us) Palaeoscincus (meaning: "ancient skink") was an armored, plant-eating dinosaur from the late Cretaceous Period, 83-73 million years ago. This nodosaurid ankylosaur was about 18 ft (5.5 m) long. It is known from a single tooth found in Montana, USA. It was named by Leidy in 1856. The type species is P. costatus. Palaeoscincus is a doubtful species; it may be the same as Edmontonia or Panoplosaurus.

Paleoanthropology (meaning: "study of ancient man") is the study of the origins and the ancestors of human beingsby examining fossil remains (and other ancient evidence). A paleoanthropologist studies paleoanthropology.

A scientist who studies plant life from the geological past by looking at fossils and their living descendants.

Paleoclimatology (meaning: "study of ancient climates") is the study of the climates during ancient times.

Paleography is the study of the Earth's geographic features during ancient times.

Paleogeology is the study of the Earth;s geologic conditions during ancient times.

Paleogeophysics is the study of ancient geophysical conditions.

The Palaeognathae (meaning: "ancient jaw") are the largest living birds, and are mostly flightless (but not all flightless are Palaeognathae, and not all Palaeognathae are large). They include the ostrich, emu, kiwi, etc. Palaeognathae are generally fast runners and use kicking as a primary defense. Palaeognaths probably evolved from early Cenozoic flying ancestors. They are grouped together taxonomically based on palate (jaw) structure. (Compare to Neognathae.)

Paleomagnetism is the magnetism that remains in volcanic rock from the time it solidified from magma.

Paleoneuroloy is the study of fossils brains (from brain casts, called endocasts).

Paleontology is the branch of biology that studies the forms of life that existed in former geologic periods, chiefly by studying fossils. "Paleo" means old or ancient. "Ontology" is the study of existence ("onto-" means existence, "-logy" is the study of something).

Palaeontologists are scientists that have specialised in the study of ancient life by examining the remains of plants and animals in the form of fossils. Details of the structure, environment, evolution and distribution is revealed by the fossil remains of organisms. Palaeontology makes important contributions to geology by revealing relationships between rock strata and determining the physical appearance and climate of the past geological ages.

Paleozoic Era
This was from 540 to 250 million years ago. It is the group name for the following periods - Cambrian, Ordivician, Silurian, Devonian, Carboniferous, and Permian periods.

Paleozoogy (meaning: "study of ancient life") is the branch of paleontology that studies fossil animals.

The palpebral is a small bone in the eye socket (in ornithischian dinosaurs and some others).

Palynology is the study of pollen and spores, from both living and fossil plants and protists.

The super-continent that existed in the Late Palaeozoic and Early Mesozoic eras. It was made up of the continental regions that now border the Atlantic and Indian oceans, all joined together into a continuous land mass. Pangaea can be divided into a northern region called Laurasia and a southern region called Gondwanaland. These two halves were joined by a relatively narrow neck of land that eventually parted in about the Middle Jurassic period as the whole of Pangaea started to split up.

(pronounced PAN-oh-ploh-SAWR-us) Panoplosaurus (meaning: "totally armored lizard") was an armored, plant-eating dinosaur from the late Cretaceous Period, 76-73 million years ago. This nodosaurid ankylosaur (no tail club) was about 23 ft (7 m) long and weighed about 3.5 tons. Fossils have been found in found in Alberta, Canada and Montana, USA . It was named in 1919 by Canadian paleontologist L. Lambe, from a specimen found in 1917 in the Judith River Formation in Alberta, Canada. The type species is P. mirus.

(pronounced pan-tha-LASS-ah) Panthalassa (meaning: "All seas") was the super-ocean that existed on Earth during the time of the super-continent Pangaea. Panthalassa existed during the Permian through the Jurassic Period, when Pangaea began to break up; the Tethys sea formed between the northern and southern parts of pangaea as they drifted apart.