Pachyderm

Literally \\\"thick-skinned\\\" mammals, such as the rhinoceros, hippopotamus and elephant living today.


Pack hunting

A form of behavior involving the cooperation of a group of individuals of the same species in hunting prey; e.g., modern wolves.


Paedogenesis

1. The production of offspring by an immature form of an organism. 2. See Progenesis


Paedomorphosis/ Paedomorphic

An evolutionary change in which the adults of a descendant species retain some of the characteristics of juvenile forms of the ancestral species. Thus, Paedomorphic. Compare, Peramorphosis.


Palaeomagnetism/ Paleomagnetism

The magnetic bearing left in rocks from the time when they first solidified.


Palaeozoic/Paleozoic

\\\"Ancient life\\\" the period of time (Era) comprising the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian Periods. This was the Era before the dinosaurs who lived during the Mesozoic.


Palatine / Palate

1. Relating to or located in the palate (roof of the mouth) 2. Either of two bones that form the hard palate along with the maxillae.


Palaeo- /Paleo-

A prefix meaning \\\"past\\\" or \\\"acient\\\".


Palaeobiogeography/Paleobiogeography

The study of the geographic distribution of animals and plants in the geologic past.


Paleobiology

1. The study of the living forms and life processes ot the geologic past. 2. Specifically, the study of existing fossil organisms.


Palaeochannel/Paleochannel

A remnant of a stream channel in older rock that has been filled with or buried by the sediment of younger overlying rocks.


Palaeoclimate/Paleoclimate

The climate during a certain interval of geologic time.


Palaeoclimatology/Paleoclimatology

The study of climate in a designated interval of the geologic past.


Palaeoecology/Paleoecology

The study of the relationships between organisms and their environments in the geologic past, with special attention to fossil communities.


Palaeoenvironment/Paleoenvironment

The environmental conditions of the geologic past.


Palaeogeography/Paleogeography

The study of the distrubution and form of the earth\\\'s landmasses in the geologic past.


Palaeoichnology/Paleoichnology

See Ichnology


Palaeomagnetics/Paleomagnetics

The study of the earth\\\'s magnetic field through geologic time.


Palaeoneurology/Paleoneurology

The study of the nervous system of organisms from the geologic past.


Palaeontology/Paleontology

The scientific study of the life forms and activities of the geologic past, especially through the analyses of plant and animal fossils.


Palaeopathology/Paleopathology

The scientific study of the life forms and activities of the geologic past, especially through the analysis of plant and animal fossils.


Palaeosol/Paleosol

An ancient soil that was present or was formed in the geologic past.


Palaeotemperature/Paleotemperature

The prevailing temperature during a certain interval of geologic time.


Palpebral

Small bone found in the rim of the eye socket, especially in ornithischian dinosaurs.


Palynology

The study of fossilized remains of spores and pollen grains.


Palynomorph

A microfossil formed mainly from fossilized pollen and spores, but also typically containing some animal material.


Pangea or Pangaea

A presumed original continent, consisting of all the land area of the earth that later divided into the supercontinents of Laurasia and Gondwana, from which the present continents derived.


Paralectotype

Each specimen of a former syntype series remaining after the designation of a lectotype.


Paraphyletic / Paraphyly

Relating to a taxonomic group that includes a hypothetical common ancestor and some, but not all, the descendants of this ancestor. Thus, Paraphyly.


Paratype

Each specimen of a type series other than the holotype.


Para-sacral spines

Bony spikes projecting from the hip region in stegosaurs.


Pareirasaurids

Large, early plant-eating reptiles of the Permian Period.


Parent species

In the process of species development an existing species that gives rise to one or more recognizably new species (daughter species) and that itself may then continue relatively unchanged or may disappear.


Parental behavior or Parenting

See Altrical behavior


Parietal

1. Relating to the outer wall of an organ or cavity. 2. Either of a pair of bones (sometimes fused into a single bone) forming the sides and top of the skull. 3. Relating to these bones or to the skull in general.


Parietal bone

n., abbrev. par skull bone


Parsimony / Parsimonious

1. The scientific or philosophical principle that an uncertain phenomenon or condition can be described by the simplest, most direct, and most obvious explanation that is available, even though other, more complex explanations could also be possible. 2. Specifically, in describing evolutionary relationships, the principle that a description involving fewer steps or changes should be tested before one involving more. Thus, Parsimonious.


Patella / Patellar

The flat, triangular bone covering the front of the knee, or a structure analogous to the knee; the kneecap. Thus, patellar.


Pathological

Relating to the study of disease


PCR

Polymerase chain reaction, a laboratory technique for the repeated copying of a sequence of DNA material, using specialized heat-stable enzymes of bacteria that exist at extremely high temperatures; the technique results in a large quantity of the DNAsequence and it thus permits the detection and retrieval of a specific sequence that was only a tiny fragment of the orginal DNA material.


Peak ring

A central uplift characterized by a ring of peaks rather than a single peak. Peak rings are typical of larger terrestrial craters above about 50 km in diameter.


Pectoral

Relating to the chest or shoulder.


Pectoral girdle

The bones of the shoulders to which the arms or forelimbs are attached.


Pelage

The fur, hair, or other surface covering of animal.


Pelvic girdle

The bones of the hips.


Pelvis

The hip region of the skeleton


Pelycosaurs

Mammal-like reptiles of the Carboniferous and Permian Periods, some have distinctive \\\"sails\\\" on their backs.


Peramorphosis / Peramorphic

An evolutionary change in which the juveniles of a descendant species display some of the characteristics of adult forms of the ancestral species. Thus, Peramorphic. Compare Paedomorphosis


Percolate

To penetrate gradually with water (and dissolved minerals)


Periosteum / Periosteal

A fibrous connective tissue that covers bones and that has the potential to form new bone material. Thus, periosteal


Permineralization

A process of fossil formation in which additional mineral material is deposited in the pore spaces of originally hard animal parts.


Pes [plural] Pedes

Pedes the hind-foot


Petrification

\\\"Turning to stone\\\" the replacement, by minerals of the original hard tissues of a fossilized organism, so that it becomes stone-like in nature.


Phalanges [singular] Phalanx / Phalangeal

The bones of the fingers or the toes, or of other structures analogous to these. Thus, Phalangeal.


Phanerozoic

\\\"Visible life\\\" the time on Earth between 600 million years ago and today during which recognisable animal and plant remains are known.


Phenotype

The physical appearance and structure of an individual organism, resulting from the interaction of its genetic constitution with the conditions of its environment. Compare, Genotype


Photoclastic studies

The use of light to measure the flexibility of materials.


Photoperiodic

Affected by or involving daily or seasonal changes in the available light.


Photoperiodism / Photoperiodicity

Physiological and behavioral responses of an organism to daily or seasonal changes in the available light. Also, Photoperiodicity.


Phyletic extinction

See Pseudoextinction


Phylogenetic

Relating to the evolutionary relationships whitin and between groups of organisms


Phylogenetic tree

A branching diagram that displays evolutionary relationships among and between organisms by the metaphor of a \\\"tree\\\" in which branches near the top of the tree diverged more recently than those near the base of the tree.


Phylogeny / Phylogenetics / Phylogenesis

Evolutionary relationships and history; the sequence of events that make up the evolutionary past, often depicted by a branching treelike diagram. Also, phylogenetics, phylogenesis.


Phylum

One of the major groupings of the Animal Kingdom


Physiology / Physiological

The sum of the physical processes that occur within a living organism in order to maintain life. Thus, Physiological.


Phytosaurs

Early crocodile-like archosaurs of the Triassic


Pinophyta

See Gymnosperm


Piscivorous

Fish-eating


Placodonts

Shellfish-eating heavily-armoured, turtle-like reptiles of the Triassic Period


Planar features

Microscopic features in grains of quartz or feldspar consisting of very narrow planes of glassy material arranged in parallel sets that have distinct orientations with respect to the grain’s crystal structure.


Plantigrade / Plantar surface

Standing or walking with the plantar surface (the sole of the foot) in contact with the ground; e.g., modern bears, humans. Compare Digitigrade


Plate tectonics

The theory or principle that the earth\\\'s crust is divided into a relatively small number of large, rigid plates that move independently in relation to one another, thus causing significant deformation and other activity along the plate margins.


Plenum

A concept used in religious teaching which is founded on the idea that the Creator formed all Earthly life in its infinite variety on just one occasion, thereby excluding the possibility of extinctions.


Plesiomorph / Plesiomorphic / Plesiomorphy

A charater that is present in an ancestral form also retained an a descendant or descendants. Thus, plesiomorphic, plesiomorphy. Compare Apomorph


Plesiosaurs

Marine reptiles of the Mesozoic Era which swam using large flippers.


Plesiotype

The term \\\"plesiotype\\\" is not even in the Code glossary, but it is essentially a synonym of paratype. Some have used it to denote a specimen \\\"farther removed\\\" from the type specimen than a paratype.


Pleurocoel

A cavity in the sides of vertebrae


Pleurodont

See Acrodont


Pleurodont / Pleurodontia

1. Describing a form of tooth arrangement in which the teeth are attached to the inner wall of the jawbone rather than being set in sockets or fused to the top of the jaw. 2. An animal having such an arrangement of teeth. Thus, Pleurodontia. Compare, thecodont, acrodont.


Pneumatic / Pneumaticity / Pneumatization

1.Relating to or involved in the passage of air. 2. Of a body part conveying air or allowing the passage of air. Thus, Pneumaticity, Pneumatization.


Poikilothermy / Poikilotherm / Poikilothermic

The fact of having a body temperature that will vary significantly according to changes in the temparature of the surrounding environment. Thus, Poikilotherm, Poikilothermic. Compare Homeothermy.


Pollex

The first, or innermost, digit of the manus. This is the \\\"thumb\\\" in humans


Polymerase chain reaction

See PCR


Polymorph

One of the two or more forms (morphs) of a group exhibiting polymorphism. See Polymorphic


Polymorphic / Polymorphous

Occuring in various forms; relating to or displaying polymorphism. Also, polymorphous.


Polymorphism

1. The fact of having significant differences in body form or structure among the individual organisms within a single species or other taxonomic group, occurring when different forms of a gene appear in the same population. 2. The fact of an individual organism\\\'s having significantly different forms at different stages of its life cycle.


Polyphyletic / Polyphyly

Describing an associated group of organisms that do not share a single, exclusive common ancestor. Thus, Polyphyly.


Post-

In anatomy, closer to the rear or tail than some other comparable part.


Postdisplacement

An evolutionary change in which a descendant species has a delayed onset of development or growth in certain structures, in comparison with the ancestral species. Compare, predisplacement.


Posterior

Behind; toward the rear or tail


Postmortem

After death; occurring or present subsequent to the death of an organism.


Postorbital bone

Skull bone


Posture

Normal standing or walking position of an animal.


Pre-

In anatomy, closer to the front or head than some other comparable part.


Precambrian

Referring to the vast Period of time (before the Cambrian Period) that elapsed while the Earth cooled and became a solid planet.


Precocial

Describing a species in which the young are relatiely advanced in development when born. Compare Altrictal.


Precursor

1. In general, something that is present at an earlier time than another thing. 2. An earlier form from which a later form is descended.


Predator

An animal that feeds by hunting, killing, and eating other, typically smaller animals.


Predatory behavior / Predation

The activity of a predator; the fact of feeding on life prey. Also, Predation.


Predentary

1. relating to or located at the front of the lower jaw. 2. A bone at the front of the lower jaw, characteristic of ornithischians.


Predentary bone

Mandible bone, unique to Predentatans among the Dinosauria, just forward of the dentary bone in the lower jaw


Predisplacement

An evolutionary change in which a descendant species has an earlier onset of development or growth in certain structures, in comparison with the ancestral species. Compare postdisplacement.


Prefrontal bone

Skull bone


Premaxillary bone

Skull bone just forward of the maxillary in the upper jaw


Premortem

Before death; occurring or existing prior to death.


Preparator

A person whose work or skill is preparing dinosaur models for reconstructions for display.


Prepubic process

Describes the extention of the pubis forward from the hip socket in later Predentatans


Preservation

The general condition or \\\"state\\\" (of a fossil specimen)


Primary bone

Bone that is formed during the growth of the organism. Compare secondary bone.


Primitive

1. In general, earlier and less developed. 2. Describing a character or feature found in the common ancestor of a species or other taxonomic group.


Process

A projection or outgrowth of bone.


Procoelous

Describes vertebrae in which the front of the centrum is concave and the rear of the centrum is convex -- so that the rear of the vertebra fits into the next vertebra behind like a ball-and-socket joint


Procolophonids

Small primitive, plant-eating reptiles of the Permian Period.


Progenesis

An evolutionary change in which sexual maturity occurs earlier in the descendant species than in the ancestor.


Propodium / Propodial

The front region of the foot, or the bones of the front of the foot. Thus, propodial


Proterosuchians

Hooked-nosed, crocodile-like thecodontians of the late Permian Period


Proto-

A prefix meaning \\\"earliest\\\" or \\\"first\\\"


Proximal

Describes a feature anatomically located near the central part of the body, or near a point of attachment or origin. In anatomy, toward the center or the attached end; inner; closer.


Pseudoextinction

A condition in which all the individuals of a given taxon disappear, but this fact is accompanied by the appearance of one ore more new taxa directly descended from this species. Dinosaurs, if assumed to include modern birds, are an example of pseudoextinction rather than true extinction. Also Phyletic extinction


Pseudofossil

An object that has the appearance of a fossil but actually is not one, either a natural object mistaken for a fossil or a man-made object meant to resemble a fossil.


Pterosaurs

The flying reptiles of the Mesozoic Era. These are distant cousins of the dinosaurs.


Pubic

Relating to or located in the region of the pubis.


Pubic bone

Forward hip bone, reduced to a splint in some Predentatans.


Pubis

The bone forming the front of the pelvic girdle (hip girdle).


Pulmonary

Relating to or involving the lungs.


Pyrite disease

Spontaneous destruction of fossil specimens which contain high concentrations of iron pyrites.