Glossary P
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PACHYCEPHALOSAURIDS
(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.
Pachycephalosaurus
(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.
PACHYRHINOSAURUS
(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
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
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
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.
PALAEOPTERYX
(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.
PALAEOSCINCUS
(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
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.
Paleobotanist
A scientist who studies plant life from the geological past by looking
at fossils and their living descendants.
PALEOCLIMATOLOGY
Paleoclimatology (meaning: "study of ancient climates") is the
study of the climates during ancient times.
PALEOGEOGRAPHY
Paleography is the study of the Earth's geographic features during ancient
times.
PALEOGEOLOGY
Paleogeology is the study of the Earth;s geologic conditions during ancient
times.
PALEOGEOPHYSICS
Paleogeophysics is the study of ancient geophysical conditions.
PALEOGNATHAE
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
Paleomagnetism is the magnetism that remains in volcanic rock from the
time it solidified from magma.
PALEONEUROLOGY
Paleoneuroloy is the study of fossils brains (from brain casts, called
endocasts).
PALEONTOLOGY
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).
Paleontologist
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.
PALEOZOOLOGY
Paleozoogy (meaning: "study of ancient life") is the branch
of paleontology that studies fossil animals.
PALPEBRAL
The palpebral is a small bone in the eye socket (in ornithischian dinosaurs
and some others).
PALYNOLOGY
Palynology is the study of pollen and spores, from both living and fossil
plants and protists.
Pangaea
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.
PANOPLOSAURUS
(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.
PANTHALASSA
(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.