ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

APATODON (pronounced uh-PAT-uh-don) Apatodon is a doubtful genus; it is probably an Allosaurus. It was a huge, meat-eating dinosaur from the late Jurassic period, about 156 million to 135 million years ago. It was a theropod that lived in what is now the western United States.

APATOSAURUS (pronounced uh-PAT-uh-SAWR-us) Apatosaurus was a huge sauropod from the Jurassic period. It was about 70 to 90 ft (21-27 m) long and weighed roughly 42500 kg. This quadrupedal plant-eater used to be known as Brontosaurus

APOMORPHY An apomorphy is a new genetic characteristic to a clade. Feathers are an apomorphy for birds.

AQUATILAVIPES Aquatilavipes is an early bird known only from its footprints, which are modern looking (not reptilian like Archaeopteryx). It lived during the early Cretaceous period, about 130 million years ago; these are the oldest-known bird tracks. Fossil footprints have been found in Canada.

ARAGOSAURUS (pronounced AHR-ah-go-SAWR-us) Aragosaurus (meaning "Aragón (Spain) lizard") was a large, quadrupedal plant-eating dinosaur that lived during the early Cretaceous period, about 130-120 million years ago. This sauropod was about 60 ft (18 m) long and weighed about 28000 kg. It had a long neck, a long powerful tail, a small head, and a bulky body. It was similar to Camarasaurus. A partial fossil was found in Spain. It was named by Sanz, Buscalioni, Casanovi and Santafe in 1987. The type species is A. ischiatus.

ARALOSAURUS (pronounced AR-a-lo-SAWR-us) Aralosaurus (meaning "Aral Sea lizard") was a plant-eating dinosaur that lived during the late Cretaceous period, about 95-80 million years ago. This sauropod was about 30 ft (9 m) long, and weighed roughly 5000 kg. It had a toothless beak, a stiff tail, and a bulky body. A partial fossil was found in Kazakhstan. It was named by Rozhdestvensky in 1968. The type species is A. tuberiferus.

ARARIPEDACTYLUS Araripedactylus was a pterosaur (not a dinosaur). This Pterodactyloid had a skull 1.6 ft (50 cm) long and an estimated wingspan 16 feet (4.8 m). Fossils of this flying reptile were found in northeastern Brazil . This carnivore lived during the early Cretaceous period. Araripedactylus was described in 1971 by L.I. Price.

ARAUCANORAPTOR Araucanoraptor (which means "Argentinian Araucan thief") was a meat-eating dinosaur with sickle-like toe claws. It was about 8 ft (2.5 m) long. Fossils of this coelurosauris theropod were found in Argentina . Araucanoraptor lived during the late Cretaceous period, roughly 90 million years ago. Araucanoraptor was named in 1997 by paleontologist F. Novas. The type species is A. argentinus.

ARCHAEOCERATOPS (pronounced AHR-kee-oh-SER-a-tops) Archaeoceratops (meaning "ancient horned-face") is the oldest-known ceratopsian dinosaur. It lived during the early Cretaceous period, about 95-80 million years ago. A partial skeleton was found in China. It was named by Dong and Azuma in 1996. The type species is A. shimai.

ARCHAEOCETE (pronounced AHR-kee-oh-SEAT) Archaeocetes (meaning "ancient whales") are early whales - whales that lived during the Eocene period (roughly 55-34 million years ago) . Some archaeocetes include Pakicetus, Ambulocetus, Basilosaurus, Remingtonocetus, Dorudon, and other early whales, some of which had hind limbs.

ARCHAEOPTERYX (pronounced ark-ee-OP-ter-icks) Archaeopteryx (meaning "ancient wing") is a very old prehistoric bird dating from the Jurassic period, about 150 million years ago. It had teeth, feathers, three claws on each wing, a flat sternum (breastbone), and a long, bony tail.

ARCHAEORAPTOR Archaeoraptor liaoningensis (meaning "ancient robber from Liaoning [China]") is a newly-discovered dinosaur, which was recently found to be a fradulent fossil created by combining two separate fossils. This turkey-sized theropod was said to have lived about 120-140 million years ago. It supposedly had hollow bones, feathers, a long tail, and its shoulder girdle and breast bone were similar to those of modern birds, indicating that it may have been able to fly. Fossils of this bipedal meat-eater were found in Liaoning Province, China.

ARCHAEORNIS Archaeornis (meaning "ancient bird"), named in 1917 by Petronievics and Woodward, is actually Archaeopteryx (the Berlin specimen).

ARCHAEORNITHOIDES (pronounced AHR-kee-OR-nith-OI-deez) Archaeornithoides (meaning "Archaeornis-like [dinosaur]") was a Coelurosaurid dinosaur about 3 ft (1 m) long, weighing roughly 2 kg. This bird-like, meat-eating dinosaur had unserrated teeth. A partial skull of a juvenile Archaeornithoides was found in Mongolia. It dates from the late Cretaceous period. This advanced theropod was named by Elzanowski and Wellnhofer in 1992. The type species is A. deinosauricus.

ARCHAEORNITHOMIMUS (pronounced AHR-kee-or-NITH-oh-MIME-us) Archaeornithomimus (meaning "ancient bird mimic") was a small Coelurosaurid dinosaur about 3 ft (1 m) long, weighing roughly 20 kg. This bird-like, meat-eating dinosaur had three fingers, which leads to questions about its being an ornithomimid. A partial skull of a juvenile Archaeornithoides was found in China. It dates from the late Cretaceous period. This advanced theropod was named by Russell in 1972. The type species of this doubtful genus is A. asiaticus.

ARCHAEOZAOIC or ARCHEAN The Archaeozoic (also called the Archean) was an eon of geologic time during which the earliest life forms evolved. One celled organisms, including blue-green algae, archaeans, and bacteria appear in the sea. This began to free oxygen into the atmosphere.The Archaeozoic lasted from 3.9 to 2.5 billion years ago. Archaeozoic means "ancient life."

ARCHAEOTHYRIS Archaeothyris is the oldest-known pelycosaur. This long-tailed quadruped lived in warm, humid forests of the early-mid Pennsylvanian period, about 300 million years ago. Archaeothyris looked sperficially like a lizard and was about 20 inches (50 cm) long. This carnivore (meat-eater) had strong jaws and sharp, pointed teeth; it may have eaten small reptiles like Hylonomus. Fossils have been found in Nova Scotia, North America. Clasification: Subclass Synapsida, Order Pelycosauris, Family Ophicodontia.

ARCHELON Archelon was huge marine turtle (a chelonian) that lived during the late Cretaceous period. It was not a dinosaur. Archelon had a wide, flattened shell, paddle-like legs, a long, narrow head, weak jaws, and a pointed tail. It may have eaten jellyfish. Archelon's back probably had a leathery covering or horny plates over a bony framework on its back. This carnivore was about 10-13 feet (3-4 m) long. Fossils have been found in Kansas and South Dakota, USA.

ARCHILLOBATOR Achillobator (Achilles was a Greek hero with a vulnerable heel tendon and bator is Mongolian for hero) was an advanced meat-eating dinosaur that was about 16 ft (5 m) long. This large dromaeosaur (deinonychosaur) has a sickle-shaped claw on each foot. This theropod lived during the late Cretaceous periodA. giganticus.

ARCHIMEDES Archimedes was a corkscrew-shaped colonial genus of bryozoan named for the ancient Greek Archimedes, who invented the water screw (the bryozoan looks like the water screw). The marine bryozoan Archimedes were tubular-shaped zooids with calcified walls. They lived in colonies during the Carboniferous, roughly 360 to 280 million years ago. Classification: Kingdom Animalia, Phylum Bryozoa, Class Stenolaemata, Order Fenestrida, Family Fenestellidae, Genus Archimedes, many species.

ARCHITEUTHIS (pronounced ark-ee-TOO-this) Architeuthis is the giant squid. It is the largest squid and the largest invertebrate (animal without a backbone), but it has never been seen since it lives very deep in the oceans. The largest-known Architeuthis was 57 feet (17.5 m) long. It has eight arms, two longer feeding tentacles, a beak, a large head, and two eyes larger than basketballs! These soft-bodied cephalopods are fast-moving carnivores that catch prey with their tentacles, then poison it with a bite from beak-like jaws. They move by squirting water through a siphon, a type of jet propulsion. Only dead examples of Architeuthis have been found. Its only enemy is the sperm whale who hunts it deep in the ocean.

ARCHOSAUR (pronounced ARK-uh-sawr) Archosaurs (meaning "ruling lizard") were reptiles that dominated the Mesozoic Era. They included the crocodilians, pterosaurs, thecodonts, dinosaurs (and birds).

ARCTOSAURUS (pronounced ARK-toh-SAWR-us) Arctosaurus meaning "arctic lizard" was a meat-eating dinosaur that lived during the late Triassic period. This theropod was about 10 feet (3 m) long. Fossils of Arctosaurus were found in Canada . Arctosaurus was described in 1875 by Adams. The type species is A. osborni, but Arctosaurus is nomen dubium (only neck vertebrae have been found and it may or may not even be a theropod).

ARGENTINOSAURUS (pronounced ahr-gen-TEEN-oh-SAWR-us) Argentinosaurus huinculensis was a 130-140 feet (40-42 m) long titanosaurid sauropod weighing perhaps 73 tonnes. It was an enormous, long-necked, long-tailed, quadrupedal, plant-eater from Argentina, South America during the Cretaceous period. Argentinosaurus, meaning "Argentina Lizard," was named by paleontologists Coria & José Bonaparte in 1993. It is known from fossilized back vertebrae, tibia, ribs and sacrum. It may be the largest dinosaur.

ARGYROSAURUS (pronounced AHR-ji-ro-SAWR-us) Argyrosaurus (meaning "silver lizard") was a large plant-eating dinosaur about 70 ft (21 m) long weighing roughly 20000 kg. This massive quadruped. Some limbs have been found in Argentina and Uruguay. It dates from the late Cretaceous period, about 73-65 million years ago. This sauropod, perhaps an armored titanosaurid, was named by Lydekker in 1893. The type species of this doubtful genus is A. superbus.

ARISTOSAURUS (pronounced uh-RIST-uh-SAWR-us) Aristosaurus is an invalid name for Massospondylus, an herbivorous Saurischian dinosaur from the late Triassic period.

ARISTOSUCHUS (pronounced uh-RIST-uh-SUE-kus) Aristosuchus (meaning "best lizard") is an old (invalid) name for Calamospondylus. It was a bipedal, meat-eating theropod dinosaur with large hand claws. This coelurosaur dates from the early Cretaceous period, about 125 million years old. This predator was perhaps 6.5 ft (2 m) long, weighing about 65 pounds (30 kg).

ARKANSAURUS (pronounced AHR-kan-SAWR-us) Arkansaurus (meaning "Arkansas lizard") was a bird-like, bipedal, meat-eating dinosaur (a theropod) that lived during the late Cretaceous period. (It is a coelurosaur and perhaps an ornothimimid.) This dinosaur is known from foot bones found in Arkansas, USA. Fossilized foot bones and claws were found in 1972 by J. B. Friday while looking for a lost cow on his farm near Lockesburg, Arkansas, USA. Arkansaurus was informally named and described by the geologist James Harrison Quinn in 1973, but this dinosaur has not been formally described (hence it is a nomen nudum). The type species is A. fridayi (the species name honors J.B. Friday, who found the fossil and donated it to the University of Arkansas).

ARRHINOCERATOPS (pronounced aye-RYE-no-SER-uh-tops) Arrhinoceratops (meaning "without nose-horn face") was a ceratopsian dinosaur about 20 feet (6 m) long, weighing roughly 3540 kg. It was a frilled, horned, plant-eater from the late Cretaceous period, about 72 million-68 million years ago. It is known from a skull found in Alberta, Canada. It was named by paleontologist Wm. A. Parks in 1925. The type species is A. brachyops.

ARSINOITHERIUM Arsinoitherium was an early, rhinoceros-like mammal that lived during the early Oligocene (about 38 to 23 million years ago). Although it looked like a rhinoceros, it is more closely related to elephants. This large quadruped had 5-toed legs. It had 2 huge, conical, hollow horns made of bone on its snout. It was about 11.5 feet (3.5 m) long and about 6 ft (1.8 m) tall at the shoulder. This plant eater may have lived in forests near rivers. Fossils of Arsinoitherium have been found in Faiyum, Egypt. Classification: Class Mammalia (mammals), Subclass Theria, Infraclass Eutheria (placental mammals) Order Embrithopoda, Genus Arsinoitherium.

ARSTANOSAURUS (pronounced ahr-stahn-oh-SAWR-us) Arstanosaurus (meaning "Arstan (Kazakhstan) lizard" ) was a lambeosaurine hadrosaur dinosaur (it was originally though to be a ceratopsian) roughly 50 feet (15 m) long. It was a beaked plant-eater from the late Cretaceous period, about 87.5 million-73 million years ago. It is known from a very incomplete skeleton found in Kazakhstan. Arstanosaurus was named by paleontologists Suslov and Shilin in 1982. The type species is A. akkurganensis.

ARTHROPLEURA (pronounced AHR-throw-PLOOR-ah) Arthropleura was a six-foot long myriapod (related to millipedes), an arthropod with spines jutting out all along the sides of its exoskeleton. This jointed animal lived in damp forests during the Carboniferous (roughly 300 million years ago).

ARTHROPODS (pronounced AHR-throw-pods) Arthropods are a group of animals with exoskeletons made of chitin, segmented bodies, and jointed limbs. Insects, arachnids, trilobites, crustaceans, and others are arthropods.

ARTHURDACTYLUS Arthurdactylus conan-doylensis (named for Sir Arthur Conan Doyle, who wrote "The Lost World") was a pterosaur (not a dinosaur). This Pterodactyloid had an estimated wingspan 15 feet (4.6 m); this pterodactyl has wings that were proportionately longer than any other pterosaur. Fossils of this flying reptile were found in northeastern Brazil . This carnivore lived during the early Cretaceous period. Arthurdactylus was described in 1994 by E. Frey and D. Martill.

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