ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

PSEUDOFOSSIL A pseudofossil is false or fake fossil. Sometimes minerals (like manganese oxide) can discolor rocks naturally and the result is a fossil-like impression. Some pseudofossils are fake fossils manufactured by people.

PSEUDOTETRASAUROPUS Pseudotetrasauropus was a lightly-built bipedal prosauropod dinosaur that is is known only from its five-toed fossilized tracks. This primitive plant-eating ichnogenus lived from the late Triassic period to the Early Jurassic Period and had a broad range in what is now North America.

PSITTACOSAURUS (pronounced SIT-ah-co-SAWR-us) Psittacosaurus (meaning "parrot lizard") was a small, very primitive ceratopsian. This fast-moving plant-eater had a narrow, horny beak with no teeth, and cheek teeth towards the rear of the mouth. It had a boxy skull with short, horn-like projections on the cheeks. It had four long fingers on each hand; the arms were much shorter than the legs. Psittacosaurus could walk on two or four legs. Psittacosaurus was about 5.6 feet (2 m) long and weighed about 50 pounds (25 kg). It lived from 119-97.5 million years ago during the early Cretaceous period. Fossils have been found in Mongolia, China, and Thailand. It was named by paleontologist Henry F. Osborn in 1923. The type species is Psittacosaurus mongoliensis.

PTERANODON (pronounced ter-AN-oh-don) Pteranodons were large, Cretaceous period pterosaurs, flying prehistoric reptiles. They were not dinosaurs. They were toothless hunters who scooped up fish from the seas. They were named by paleontologist O. Marsh in 1876.

PTERIDOPHYTES Pteridophytes are a group of primitive vascular plants that include Lycopods (club mosses), Sphenopsids (horsetails, shown left), and ferns (shown, right). These plants reproduce with spores that germinate only in moist areas; they also reproduce using rhizomes (underground stems). Pteridophytes evolved during the Devonian and were mostly low-growing during the Mesozoic Era. These fast-growing, resilient plants were a source of food for plant-eating dinosaurs that lived in moist areas.

PTERIDOSPERMS Pteridosperms (Seed ferns) were primitive seed plants (not ferns at all) that lived in swampy areas from the Mississipian Epoch through the Mesozoic Era. They had woody stems studded with dried out leaf bases. The tops had fern-like fronds which bore seeds. Some seed ferns include Glossopteris (pictured above), Dicroidium, Caytonia, Denkania, and Lidgettonia.

PTERODACTYLS (pronounced ter-oh-DAK-tils) Pterodactyls or pterodactyloids (meaning "winged finger") were flying, prehistoric reptiles. They were a subgroup of pterosaurs and were not dinosaurs.

PTERODACTYLUS (pronounced ter-oh-DAK-til-us) Pterodactylus (meaning "wing finger") was a pterosaur with a 2.5 foot (0.75 m) wide wingspan. Its head contained long, narrow jaws and sharp teeth, but it had no head crest on top. It is known to have lived in what is now Tanzania, England, France, and Germany during the late Jurassic period. It was not a dinosaur, but type of extinct, flying reptile that lived during the late Jurassic period. It reproduced by laying eggs. Pterodactylus was named by Rafinesque in 1815.

PTERODAUSTRO Pterodaustro (meaning "southern wing") was a pterosaur with a 4 foot (1.2 m) wide wingspan. Its jaws were very long, thick, and blunt, with long teeth in the lower jaw and tiny teeth in the upper jaw. It may have gathered food by skimming it from the ocean surface. It was from what is now Argentina during the late Jurassic period. It was not a dinosaur, but a related, extinct, flying reptile that lived during the eaerly Cretaceous period. It was named by paleontologist J. Bonaparte 1969.

PTEROSAUR (pronounced TER-o-SAWR) Pterosaurs (meaning "winged lizard") were flying, prehistoric reptiles. They were not dinosaurs, but were closely related to them. Pterosaurs were named by Kaup in 1834.

PTERYGOTUS Pterygotus was an Eurypterid, an extinct "sea scorpion." This ancient marine arthropod (a segmented invertebrate with a chitinous exoskeleton and jointed legs) was over 6.5 ft (2 m) long. One specimen in NY, USA was 9 ft (2.75 m) long. These hunters had a scorpion-like stinger which may have contained poison, 3 pairs of jointed legs, 2 clawed arms, 2 paddles, and strong jaws. They may have swum on their backs. This fierce hunter lived in the seas during the Silurian period, over 400 million years ago.

PUBIS The pubis is a bone that is part of the hip, or pelvic girdle. It points downwards and slightly towards the front in saurischians (theropods and sauropods) and downwards and towards the tail in ornithischians.

PUNCTUATED EQUILIBRIA Punctuated equilibria is a theory that addresses the rate of evolutionary change over time. In this theory, long periods of relatively little evolutionary changes are followed by bursts of rapid evolutionary changes in which new species appear. Punctuated equilibria was described by Niles Eldredge and Stephen Jay Gould (1972). (Also see phyletic gradualism.)

PYRORAPTOR Pyroraptor (meaning "fire thief"; given this name because it was found after a forest fire) was a meat-eating dinosaur that lived during the late Cretaceous period. A very incomplete skeleton of this deinonychosaur (an advanced theropod) was found in France. Pyroraptor may be the same as Variraptor. Pyroraptor was named by Allain and Taquet in 2000. The type species is P. olympius.

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