A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Appendix

Pachycephalosaurus
Taxon: Pachycephalosauria Pachycephalosauridae
Name means: “thick-headed lizard”
Pronounced: PACK-I-SEF-uh-luh-SAW-rus
Length: about 15 ft (4.5 m)
Time: Late Cretaceous, 68 – 65 mya
Place: Alberta, Montana, Wyoming, South Dakota, Alaska

One of the largest of the pachycephalosaurs, this two-legged plant-eater carried a ten-inch-thick layer of bone atop its skull, forming a massively reinforced dome studded with bumps and spikes. It has been suggested that this structure may have been used as a ram for defense against predators or in competition with other members of the species. Much like bighorn sheep today, pachycephalosaurs might have sparred over mates or territory with bone-jarring head-on impacts. A scattering of bony spikes on the tip of the snout has led some scientists to suggest that Pachycephalosaurus might have used its nose for digging up vegetation. Mistaken for a giant armadillo-like reptile when it was first discovered in Montana, Pachycephalosaurus is actually a cousin to the horned ceratopsian dinosaurs. The genus was given its scientific name in 1943.

Pachyrhinosaurus
Taxon: Centrosaurinae
Name means: “thick-nosed lizard”
Pronounced: PACK-I-RYE-nuh-SAW-rus
Length: 23 feet (7 m )
Time: Late Cretaceous, 72 – 68 mya
Place: Alberta, Alaska
Date: 1950

Although all ceratopsians tend to be sturdy plant-eaters, Pachyrhinosaurus was an especially bulky member of the group. From the short-knob like bump on its otherwise hornless snout to its rectangular skull to its short, thick teeth, the powerful Pachyrhinosaurus was strong and stout. A bone bed in Alberta’s Pipestone Creek yielded more than a dozen skulls and hundreds of other Pachyrhinosaurus fossils. According to scientists, one to three straight horns projected from the midline of the dinosaur’s bony frill. Pachyrhinosaurus finds in Alaska suggest that the species may have migrated in herds. Some experts speculate that the unusual pad of bone on the dinosaur’s snout may have actually supported a large keratinous horn in life, but no direct fossil evidence yet supports this theory. Pachyrhinosaurus was named in 1950.

Pachysaurus
Name means: “thick lizard”
Pronounced: PACK-ee-SAW-rus

This dinosaur is now known as PLATEOSAURUS.

Pachyspondylus Doubtful name,
Name means: “thick vertebra”
Pronounced: PACK-ee-SPON-dil-us

This is now known to be MASSOSPONDYLUS.

Palaeopteryx
Taxon: Theropoda
Name means: “ancient wing”
pronunciation: PAY-lee-OP-ter-iks
Length: Small
time: Late Jurassic
place: North America

This disputed species of theropod was first named, in 1981, for a limb bone supposedly belonging to a bird. Jensen and Padian reidentified the species in 1989 and tried to declare the name invalid for this apparent maniraptorian theropod.

Palaeoscincus.
Taxon: Ankylosauria
Name means: “ancient skink”
Pronunced: PAY-lee-uh-SKING-kus
Length: Unknown
Time: Late Cretaceous
place: Montana

One of the first-known North American ankylosaurs, this species was named based on the discovery of a single tooth. Early paleontologists imagined that the tooth came from an enormous skink, a giant among herbivorous lizards. Palaeoscincus was later reidentified as an armored ankylosaur. Today, most scientists believe that the tooth actually belonged to a specimen of Panoplosaurus or Edmontonia. Palaeoscincus was named in 1856.

Panoplosaurus
Taxon: Ankylosauria Nodosauridae
Name means: “completely armored lizard”
Pronounced: PAN-oh-pluh-SAW-rus
Length: 18 ft (5.5 m)
Time: Late Cretaceous, 76 – 73 mya
Place: Alberta, Montana

This well-known armored dinosaur belonged to the nodosaurid family of club-less ankylosaurids. Panoplosaurus was well-protected by a layer of bony plates all the way from its pear-shaped head to its tail. Defensive spikes protruded from its sides. Panoplosaurus was named in 1919.

Paraiguanodon
Name means: “near Iguanodon” or “near iguana tooth”
Pronounced: PAR-uh-ig-WAN-oh-don

This dinosaur is now known as BACTROSAURUS.

Paranthodon
Taxon: Stegosauria Stegosaurida
Name means: “near flower tooth”
Pronounced: puh-RAN-thuh-don
Length: about 17 ft (5 m)
Time: Early Cretaceous, 145 – 138 mya
Place: South Africa
Date: 1929

When he named Paranthodon in 1929, Owens somewhat imaginatively described this dinosaur’s teeth as being shaped like flowers. The original fossil material came from both Upper Permian and Late Cretaceous deposits. Some of the bones which were once considered Paranthodon material are now thought to have belonged to Anthodon, and others have been reassigned to Palaeoscincus. The rest still belong to this four-legged, plant-eating stegosaur which closely resembled Kentrosaurus.

Pararhabdodon
Taxon: Ornithopoda, probably Iguanodontia
Name means: “near Rhabdodon”
Pronounced: PAR-a-RAB-do-don
Length: 16.5 ft (5 m)
Time: Late Cretaceous, 71 – 65 mya
Place: Spain

Although described as a spike-thumbed iguanodontid when it was named in 1993, this poorly-known four-legged plant-eater may instead have been a crested lambeosaurine duckbill.

Parasaurolophus
Taxon: Hadrosauridae Lambeosaurinae
Name means: “near Saurolophus”
Pronounced: PAR-uh-SAW-ruh-LOH-fus
Length: 30 ft (9 m)
Time: Late Cretaceous, c. 76 - 65 mya
Place: Alberta, Utah, New Mexico

This rarely-found but very distinctive lambeosaurine duckbilled dinosaur is perhaps best known for the long, curving, hollow crest which ran along the top of its skull and projected back over the neck. Given its almost trumpet-like shape, this crest may have been used to produce low-frequency sounds like those used by elephants or whales to communicate over long distances. Alternately, it may have contributed to a keen sense of smell, or simply served to allow a Parasaurolophus to attract a potential mate or to recognize another member of its species. The true answer may be any or all of these – or even something as of yet unguessed-at. Two crest shapes – one longer and more gracefully curving, the other shorter and more sharply downcurved – may have differentiated males from females, juveniles from adults, or represented differences between closely-related species. Parasaurolophus was named in 1922.

Parksosaurus
Taxon: Ornithopoda Hypsilophodontidae
Name means: “Parks’ lizard”
Pronounced: PAHRK-suh-SAW-rus
Length: 7 feet (2 m)
Time: Late Cretaceous, 68 – 65 mya
Place: Alberta, Montana
Date: 1937

Named for noted Canadian paleontologist William Arthur Parks, this small, short-faced, large-eyed dinosaur likely ran on two spry legs. The fingers of its forelimbs may have been used for grasping the plants on which it fed. Parksosaurus may have been one of the last North American hypsilophodonts. The genus was named in 1937.

Paronychodon
Taxon: Theropoda
name means: “near claw tooth”
pronunced: PAR-uh-NYE-kuh-don
Length: Small
time: Late Cretaceous
place: Montana

Known only from its distinctive teeth, the poorly-known Paronychodon was a small meat-eating dinosaur. Unfortunately, it now appears that many of the teeth once assumed to belong to this species were actually just abnormal teeth from Saurornitholestes, Dromaeosaurus and Troodon. True Paronychodon teeth were claw-shaped and almost mammal-like, lacked serrations and were flat on one side. Paronychodon was named by Cope in 1876.

Parvicursor
Taxon: Theropoda
Name means: “small runner”
Pronounced: PAR-vi-KUHR-sor
Length: 3.3 ft (1 m)
Time: Late Cretaceous, 84 – 71 mya
Place: Mongolia, China

Similar to the controversial Mononykus, this small maniraptoran meat-eater was lithe and had many bird-like characteristics in its skeleton. Parvicursor was named in 1996, but few details have been released about the swift little dinosaur.

Patagonykus
Taxon: Theropoda
Name means: “Patagonian claw”
Pronounced: pat-a-GON-i-kus
Length: 6.5 ft (2 m)
Time: Late Cretaceous, 94 – 90 mya
Place: Argentina

Like Mononykus, Patagonykus was a small, bird-like dinosaur which ran swiftly on two long legs. Some paleontologists believe that Patagonykus was actually a primitive bird, while others consider it a theropod dinosaur. Only further study will solve the mystery. Patagonykus was named in 1996.

Patagosaurus
Taxon: Sauropoda Cetiosauridae
Name means: “Patagonian lizard”
Pronounced: PAT-uh-guh-SAW-rus
Length: 59 - 65 ft (18 – 20 m)
Time: Middle Jurassic, 169 – 163 mya
Place: Argentina

This long-necked, browsing sauropod was named for the region of southwestern Argentina where it was discovered. It was about the size of the European sauropod Cetiosaurus. Patagosaurus provided the first proof that large dinosaurs from the Jurassic roamed South America, perhaps crossing between continents over an ancient land bridge. Patagosaurus was named in 1979.

Patricosaurus
Taxon: possibly Theropoda
name means: “ancestral lizard”
pronunciation: PAT-ri-ko-SAW-rus
Length: Small
time: Late Cretaceous
place: Europe

Although first believed to have been a lizard, the poorly-known Patricosaurus has been tentatively identified as a small meat-eating theropod. Its true identity remains uncertain, and further description will have to await the discovery of more and better fossil remains. Patricosaurus was named in 1887.

Pawpawsaurus
Taxon: Ankylosauria Nodosauridae
Name means: “Paw Paw lizard” (for the Paw Paw formation)
Pronounced: paw-paw-SAW-rus
Length: Moderate
Time: Early Cretaceous, c. 112 – 99 mya,
Place: Texas, possibly Utah
Date: 1996

This stocky armored plant-eater’s skull was so well-preserved during and after fossilization that it was able to show paleontologists a then-unknown feature of the club-less nodosaurid ankylosaurs – even the eyelids of this tank-like quadruped were protected by small plates of bony armor. The anatomy of the Pawpawsaurus septum and palate, or roof of the mouth, was primitive compared to the skulls of other nodosaurs like Sauropelta, which was discovered in the same Rocky Mountain regions of Texas. Named in 1996, Pawpawsaurus awaits further study to produce more definite scientific detail.

Peishansaurus
Taxon: possibly Ankylosauridae
name means: “North Moutain lizard”
pronunced: PYE-shan-SAW-rus)
Length: Moderate
time: Late Cretaceous
place: China

Perhaps a member of the armored Ankylosauridae family, this Asian dinosaur was named in 1953 based on the discovery of a weathered jawbone. Because the specimen is so small and apparently undeveloped, it may have belonged to a very young individual. Peishansaurus was named for the North Mountain region of the Xinjiang Ulygur in China.

Pelecanimimus
Taxon: Theropoda Ornithomimosauria
Name means: “pelican mimic”
Pronounced: pel-eh-KAN-I-MIME-us
Length: 6.5 ft (2 m)
Time: Early Cretaceous, 132 – 121 mya
Place: Spain
Date: 1994

This odd fossil specimen was named for its elongated face and fossil impressions just below the skull that resemble the deep throat-pouch of a modern pelican. More than 200 teeth lined the front of the upper and lower jaws, representing the highest tooth count of any theropod dinosaur, according to some experts. Traces of Pelecanimimus skin impressions suggest the possibility that this two-legged meat-eater was covered in a feather-like, downy coat. At one time, this genus was considered to represent an evolutionary intermediate between troodontids and ornithomimids, but this theory is no longer widely accepted. Pelicanimumus was named in 1994.

Pellegrinisaurus
Taxon: Sauropoda Titanosauridae
Name means: “Lake Pellegrini lizard”
Pronounced: pel-e-GREEN-eh-SAW-rus
Length: 66 – 82 ft (20 – 25 m)
Time: Late Cretaceous, 84 – 71 mya
Place: Argentina

Named in 1996 for a region in northern Patagonia, this large plant-eating dinosaur was first thought to belong to the same species as another long-necked sauropod from that area named Epachthosaurus. Based on careful study of the dorsal vertebrae, twice as wide and tall as those of Epachthosaurus, as well as the shape of the neural spines, experts have determined that Pellegrinisaurus represents a new kind of Argentinian sauropod.

Pelorosaurus
Taxon: Sauropoda
name means: “colossal lizard”
pronunciation: PEL-or-uh-SAW-rus
Length: 80 ft (24.5 m)
time: Early Cretaceous
place: England, Portugal, France

Named by Mantell in 1850, this gigantic sauropod was one of the first and largest four-legged browsing dinosaurs ever found in Great Britain. Pelorosaurus is so similar to the more famous Brachiosaurus that some experts have suggested that they may represent different ages of the same species of dinosaur. Rare skin impressions were found alongside one Pelorosaurus specimen, revealing a series of hexagonal plates.

Pentaceratops
Taxon: Ceratopsia
Name means: “five-horned face”
Pronounced: PEN-tuh-SER-uh-tops
Length: 23 – 28 feet (7 – 8 m)
Time: Late Cretaceous, c. 75 – 65 mya
Place: New Mexico
Date: 1923

Osborn named this remarkable ceratopsian in 1923, describing the five horn-like spikes on its face. One horn sat atop the nose, two more projected from above the eyes, and the cheeks bore a pair of prominent, spiked cheek-bones which were not actually horns. The elaborate neck frill of this dinosaur may have been for display purposes, used in attracting a mate or competing with other members of the species. It might also have served as an attachment point for powerful jaw muscles. Like all of the larger ceratopsians, Pentaceratops was a four-legged plant-eater with a beak and scissor-like teeth for shearing through tough vegetation like cottonwoods, palms and pines.

Phaedrolosaurus
Taxon: Theropoda
name means: “nimble dragon”
pronounced: fay-DROH-luh-SAW-rus
Length: Small
time: Early Cretaceous
place: China

This small meat-eating theropod is known only from short, thick teeth with dense serrations for slicing flesh. These were similar to but smaller than the teeth of Deinonychus. Named in 1973, Phaedrolosaurus was probably a lightly-built and agile predator.

Phuwiangosaurus
Taxon: Sauropoda
Name means: “Phu Wiang lizard,” after a region of Thailand
Pronounced: POO-WYANG-o-SAW-rus
Length: 82 – 98 ft (25 – 30 m)
Time: Early Cretaceous, c. 144 – 127 mya
Place: Thailand
Date: 1994

This massive dinosaur, described in 1994, was named for the province of Phu Wiang Teema in northeastern Thailand. Like the other giant sauropods, Phuwiangosaurus had a long neck and tail, walked on four sturdy legs, and browsed on leafy plants.

Phyllodon
Taxon: probably Hypsilophodontidae
Name means: leaf tooth
Pronounced: FYE-luh-don
Length: Small
time: Late Jurassic
place: Portugal

Named for a single bumpy, leaf-shaped tooth in 1973, this small dinosaur appears to have been a plant-eating hypsilophodontid.

Piatnitzkysaurus
Taxon: Theropoda Allosauridae
Name means: “Piatnitzky's lizard”
Pronounced: Pee-yaht-NYIT-skee-SAW-rus
Length: 13 – 20 ft (4 – 6 m)
Time: Middle Jurassic, 169 – 163 mya
Place: Argentina

Named in 1979 for Russian-born Argentine geologist Alejandro Piatnitzky, this meat-eating theropod was found in the Chubut Province of Argentina in 1936. The site was not well excavated until 1977. Piatnitzkysaurus was probably related to Allosaurus and may have been a similar agile predator with teeth and claws well-adapted for slashing and slicing.

Pinacosaurus
Taxon: Ankylosauria Ankylosauridae
Name means: “plank lizard”
Pronounced: pi-NACK-uh-SAW-rus
Length: about 11.5 – 18 ft (3.5 - 5.5 m)
Time: Late Cretaceous, c. 85 – 81 mya
Place: Mongolia, China

This small club-tailed, armored dinosaur was the first of its kind to be discovered in the Gobi Desert. Although a number of Pinacosaurus specimens have since been unearthed in Mongolia, one astounding dig site revealed the skeletons of more than a dozen young dinosaurs of this species huddled together. Experts speculate that the Pinacosaurus group may have been smothered by a sudden sandstorm. This dinosaur’s club-tipped tail could move both side-to-side and up-and-down, probably providing a capable defense against hungry predators. Pinacosaurus was named in 1933.

Pisanosaurus
Taxon: Ornithischia
Name means: “Pisano’s lizard”
Pronounced: pye-SAN-uh-SAW-rus
Length: 3.3 ft (1 m)
Time: Late Triassic, 231 – 225 mya
Place: Argentina

This fast-moving, bipedal plant-eater is one of the oldest known ornithischians. Precise classification of Pisanosaurus has proven difficult due to a dearth of fossil evidence and the animal’s strange anatomical characteristics. Pisanosaurus seems to have been a dinosaur in a world dominated by non-dinosaurian reptiles, the evolutionary explosion of Dinosauria still to come. Pisanosaurus is especially significant because its discovery showed paleontologist that the earliest ornithischian dinosaurs appeared around the same time as the first saurischians. This fascinating dinosaur was named in 1967 for Juan A. Pisano, an Argentine paleontologist.

Piveteausaurus
Taxon: Theropoda
Name means: “Piveteau's lizard”
Pronounced: PEEV-toh-SAW-rus
Length: about 36 ft (11 m)
Time: Middle Jurassic. 166 – 163 mya
Place: France

Based only on a fossilized braincase, this meat-eating theropod was named in 1977 for French paleontologist Jean Piveteau. Piveteausaurus may have been related to Eustreptospondylus; if so, it likely had a very large head, a short neck and forelimbs, and sharply-clawed hindlimbs.

Plateosauravus
Name means: “Plateosaurus ancestor”
Pronounced: PLAT-ee-oh-SAWR-ave-us

This dinosaur is now considered to be EUSKELOSAURUS.

Plateosaurus
Taxon: Prosauropoda Plateosauridae
Name means: “broad lizard” or “flat lizard”
Pronounced: PLAY-tee-uh-SAW-rus
Length: 27.5 feet (8 m)
Time: Late Triassic, 222 – 219 mya
Place: Germany, France, Switzerland

One of the earliest large dinosaurs, this stout, heavily-built plant-eater with a long neck and small head was the namesake of the plateosaurid prosauropod family. It likely walked slowly on four legs, but might have reared up onto two to feed or run. One of the largest and best-known of the prosauropod dinosaurs, Plateosaurus was named in 1837.

Pleurocoelus
Taxon: Sauropoda Brachiosauridae
Name means: “hollow side”
Pronounced: PLOOR-o-SEE-lus
Length: 30 feet (8.8 m)
Time: Early Cretaceous, 131 – 119 mya
Place: Maryland, Texas, England, Portugal
Date: 1888

Marsh named this small sauropod in 1888 for the deep cavities on either side of its backbones. The long-necked, plant-eating Pleurocoelus had a narrow skull. Its teeth were similar to those of Camarasaurus, but thinner. Its toes were unusually slender for a sauropod, and the fourth toe of the back foot may have had a small claw beside the normal sauropod complement of three. Pleurocoelus may have been responsible for the famous “Brontopodus” (“thunder-foot”) footprints preserved in the rock of the Paluxy River of Glen Rose, Texas.

Podokesaurus
Taxon: Theropoda
Name means: “swift foot lizard”
Pronounced: POH-doh-kuh-SAW-rus
Length: about 3.5 ft (1 m)
Time: Early Jurassic, 200 – 188 mya
Place: Massachusetts

This poorly-known carnivore had a lightly-built body with slender, hollow bones. It had a long neck, short and streamlined forelimbs, four-fingered hands, and birdlike feet with three walking toes. Because its proportions and anatomy were similar to Coelophysis, some scientists speculate that Podokesaurus may have been a juvenile of that species. Unfortunately, the single, incomplete specimen of this little dinosaur was destroyed in a fire at Mount Holyoke College in Massachusetts. Podokesaurus was named in 1911.

Poekilopleuron
Taxon: Theropoda
Name means: “varied ribs”
Pronounced: POY-ki-loh-PLOOR-on
Length: 30 ft (9 m)
Time: Middle Jurassic, 175 – 172 mya
Place: France, Russia

The 1838 description of this large meat-eating dinosaur was based on the discovery of three distinct types of fossilized ribs. Unfortunately, the bones were destroyed during World War II. Poekilopleuron seems to have been similar to Torvosaurus and probably had a large head, long and powerful jaws lined with sharp teeth, short forelimbs with three-fingered hands, and strong hindlimbs capable of quick bursts of speed.

Polacanthus
Name means: “many spines”
Pronounced: POL-a-KAN-thus

This dinosaur is now considered to be HYLAEOSAURUS.

Prenocephale
Taxon: Pachycephalosauria Pachycephalosauridae
Name means: “sloping head”
Pronounced: PREE-noh-SEF-uh-lee
Length: 7 feet (2 m)
Time: Late Cretaceous, c. 77 - 69 mya
Place: Mongolia

This plant-eating pachycephalosaurid had a highly domed skull about eight inches long. Like other pachycephalosaurs, it may have employed this solid mass of bone in jarring head-butting charges against predators or rivals. Large eye sockets suggest that this unusual dinosaur may have had exceptional vision. Prenocephale was named in 1974.

Priconodon
Taxon: probably Ankylosauria
name means: “saw-cone tooth”
pronounced: pry-KOH-nuh-don
Length: Unknown
time: Early Cretaceous
place: Maryland

Named by Marsh for a single tooth in 1888, Priconodon was likely an armored plant-eating nodosaur. The sharply-angled tooth was serrated at the edges. Given the poor nature of available fossil material, this genus is not widely considered to be scientifically valid.

Priodontognathus
Taxon: probably Ankylosauria
name means: “saw tooth jaw”
pronounced: PRYE-uh-DON-toh-guh-NAY-thus
Length: Moderate

First mistaken for an iguanodontid, then later re-described as a stegosaur, Priodontognathus has again been revised and is now considered by paleontologists to be a four-legged, plant-eating, armor-plated ankylosaurid. The genus is based on an upper jaw bone, complete with serrated, scelidosaur-like teeth. Named in 1875, Priodontognathus may have been a tail-club-less nodosaurid.

Probactrosaurus
Taxon: Ornithopoda Iguanodontidae
Name means: “before Bactrosaurus”
Pronounced: Proh-BACK-truh-SAW-rus
Length: about 17 – 20 feet (5 – 6 m)
Time: Late Cretaceous, c. 97.5 - 91 mya
Place: China

This plant-eating dinosaur may well have been an evolutionary bridge between the iguanodontids and the “duckbilled” hadrosaurids. Like the more primitive iguanodontids, its narrow snout contained double-layered banks of two tooth rows, in which the functional tooth would eventually be pushed out of place by the new one growing in underneath. Other characteristics of the skull and skeleton were distinctly similar to the more advanced hadrosaurids. Probactrosaurus was named in 1966.

Proceratops
Taxon: Saurischia
Name means: “before horned face”
Pronounced: pro-SER-a-tops
Length: Small
time: Middle Jurassic
place: England

See Ceratops.

Proceratosaurus
Taxon: Theropoda
Name means: “before Ceratosaurus”
Pronounced: proh-se-RAT-o-SAWR-us
Length: about 10 ft (3 m)
Time: Middle Jurassic, 175 – 169 mya
Place: England

This small carnivorous dinosaur carried a horn on its snout and was originally thought to have been an ancestor of Ceratosaurus. Proceratosaurus is known only from a partial skull, which was light and only about ten inches long. Its teeth were cone-shaped, large-rooted and were not well-serrated. Considered by some paleontologists to be the earliest known coelurosaur, Proceratosaurus may have been related to Ornitholestes, Proceratosaurus was named in 1926.

Procompsognathus
Taxon: Theropoda, probably Ceratosauria
name means: “before Compsognathus”
pronounced: proh-KOMP-soh0guh-NAY-thus
Length: Small
time: Late Triassic
place: Germany

Named in 1913, this animal known only from fragmentary fossils was long believed to have been a birdlike dinosaur similar to Compognathus. Recently, scientists discovered that the “Procompsognathus” skull actually belonged to a primitive, non-dinosaurian sphenosuchian or crocodile. The rest of the skeleton appears to represent a small ceratosaurian theropod, much like Coelophysis and Segisaurus.

Prosaurolophus
Taxon: Hadrosauridae Hadrosaurinae
Name means: “before Saurolophus”
Pronounced: PROH-saw-ROL-o-fus
Length: 26 ft (8 m)
Time: Late Cretaceous, 77 – 73 mya
Place: Alberta

Named by Barnum Brown in 1916, this plant-eating duckbilled dinosaur has been proposed as an ancestor to Saurolophus. Prosaurolophus was one of the earliest of the hadrosaurine group. It had a flattened head, a short bill, and a very small crest. Like other hadrosaurids, this dinosaur walked on all four legs but could probably rear onto two to run or to grasp plants with its hoof-like forefeet.

Protarchaeopteryx
Taxon: Theropoda Coelurosauria Maniraptora
Name means: “first Archaeopteryx” or “First ancient-wing”
Pronounced: PROH-tahr-kee-OP-ter-icks
Length: 3 feet (1 m)
Time: Early Cretaceous, c. 127 – 121 mya
Place: China

This turkey-sized, possibly feathered animal was anatomically similar to Archaeopteryx, but more skeletally primitive and unable to fly. Chinese scientists who have studied the fossils believe that Protarchaeopteryx was not simply a flightless bird, but a maniraptoran theropod with a feathery covering totally unrelated to flight, but perhaps used for insulation or display. A large feather or feather-like plume stood at the end of this dinosaur’s tail. Protarchaeopteryx has a short skull like Caudipteryx, but the two have very different teeth. With its long, robust hind legs, this was probably a swift hunter of small insects, mammals or reptiles. A recent discovery, Protarchaeopteryx was named in 1997.

Protoavis
Taxon: Theropoda
Name means: “first bird”
Pronounced: PROH-to-AY-vis
Length: Small
Time: Late Triassic, c. 220 mya
Place: Texas

This hotly-disputed specimen has been called a Triassic bird by Chatterjee. John Ostrom and many other paleontologists disagree, stating that the fragmentary, unarticulated fossils make it impossible to accurately reconstruct this species. The bones may even have come from several different small animals. For now, the study of and debate over Protoavis continue. Further analysis and future discoveries may shed more light on this unusual subject. Protoavis, whatever it may truly be, was named in 1986.

Protoceratops
Taxon: Ceratopsia Protoceratopidae
Name means: “first horned face”
Pronounced: PROH-tuh-SER-uh-tops
Length: 8 ft (2.4 m)
Time: Late Cretaceous, 85 – 77 mya
Place: Mongolia, China

Protoceratops was discovered in the Gobi Desert by a team of scientists working under famed American Museum of Natural History bone hunter Roy Chapman Andrews. This small plant-eater was a primitive ceratopsian dinosaur with a short, bony neck-frill and a parrot-beaked snout. Fossil remains from throughout the Protoceratops life cycle have been studied, giving paleontologists a good idea of how the dinosaur’s proportions changed as it grew from a tiny hatchling to an adult. Two distinct types of adult skulls are known, one with a higher frill and a small horn-like bump on the nose. These may demonstrate physical differences between males and females of the same species. Eggs which were once believed to have belonged to Protoceratops are now known to have come from the bizarre theropod Oviraptor instead. The unique “Fighting Dinosaurs” fossil assemblage from Mongolia contains a snapshot of time – two articulated skeletons, Velociraptor and Protoceratops, which appear to have died while struggling with one another. Giving as good as it got, the small ceratopsian had clamped its beak around the meat-eater’s arm as it died, breaking the bone. Protoceratops was named in 1923.

Protognathosaurus
Taxon: Sauropoda
Name means: “first jaw lizard”
Pronounced: PROH-toh-guh-NAY-thuh-SAW-rus
Length: Large
Time: Early Jurassic, 188 – 163 mya,
Place: China

This large plant-eating browser was possibly a member of the Cetiosauridae family of sauropods. After studying a thick, heavy jaw fragment containing about 20 teeth, scientists decided that Protognathosaurus was more primitive and smaller than most other sauropods. Protognathosaurus was named in 1991.

Protohadros
Taxon: Ornithopoda Hadrosauridae
Name means: “first hadrosaur”
Pronounced: PRO-toh-HAD-rohs
Length: juvenile, about 24 – 27 ft (7 – 8 m)
Time: Middle to Late Cretaceous, 99 – 93.5 mya
Place: Texas

The most primitive hadrosaur discovered to date, Protohadros was found in Denton County, Texas. Its skull bore a long muzzle, with a massive lower jaw. Rows of elaborate teeth indicate that Protohadros had less sophisticated plant-grinding capabilities than most hadrosaurs. The skull’s hinged cheekbones suggest that it was only capable of flexing to a limited degree. The type specimen of Protohadros appears to have been a young adult, so mature individuals may have been slightly larger. Protohadros was found in a river-delta setting, leading some experts to speculate that the bill may have doubled as a scoop for gathering aquatic food. Protohadros was named in 1998.

Psittacosaurus
Taxon: Ceratopsia Psittacosauridae
Name means: “parrot lizard” or “parrot-beaked lizard”
Pronounced: si-TACK-uh-SAW-rus
Length: 6.6 ft (2 m)
Time: Early Cretaceous, 119 – 97.5 mya
Place: Mongolia, China, Thailand

Osborn named this two-legged plant-eater in 1923 for the parrot-like beak at the tip of its short snout. The spry, large-eyed Psittacosaurus appears to represent an evolutionary bridge between small, bipedal herbivorous dinosaurs and large horned ceratopsians like Triceratops and its many relatives. Since the teeth of older specimens show significant wear, Psittacosaurus appears to have fed on particularly tough vegetation, using its nimble hands and strong beak for grasping, tearing and crushing plants.