ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

DIADECTES Diadectes is a genus of land-dwelling, quadrupedal, plant-eaters that lived during the Permian period, about 280-250 million year ago. This stegocephalian had a reptilian body, but an amphibian-like skull (similar to the skull of Seymoria). (Diadectomorphs)

DIANCHUNGOSAURUS (pronounced DYE-en-JUNG-oh-SAWR-us ) Dianchungosaurus (meaning "Dianchung, China lizard") was an early ornithischian dinosaur. It was an herbivore with no teeth in the front of the mouth, widely spaced rounded teeth on the sides of the mouth, and three large canine teeth. This lightly-built plant-eater had large nostils. Dianchungosaurus lived during the early Jurassic period, about 208-188 million years ago. Very incomplete fossils have been found in China. The type species is D. elegans. Dianchungosaurus was named by Young in 1982. Due to sparse fossils remains, this is a dubious species.

DIAPSID Diapsids include all the reptiles (except turtles) and birds. They are distinguished by having two holes in the rear upper part of their skulls and two holes behind the eyes (anorbital fenestra).

DIATRYMA Diatryma were human-sized, heavily-built, flightless extinct birds that date from the Tertiary to the early Eocene (38 million to 2 million years ago). They were about 7 feet (2.1 m) tall, had thick legs with clawed feet, tiny wings, and huge, powerful, hooked beaks on a big head. They were probably carnivores (although there is some controversy about this) and perhaps the top predators in what is now western Europe and North America, in an environment that was a tree-covered plain. They nested on the ground. The small, fast, carnivorous mammal Cladosictis may have driven it to extinction by eating its eggs and chicks. Diatryma gigantea was named by paleontologist E.D. Cope in 1876 from a New Mexico fossil. (Subclass Neornithes, Order Gruiformes)

DICERATOPS (pronounced DYE-SER-ah-tops) Diceratops (meaning "two-horned-face") was a large ceratopsian dinosaur from the late Cretaceous period, about 68-65 million years ago. This plant-eater (an ornithischian) had a toothless beak, cheek teeth in the rear of the mouth a, bony, scalloped, head frill with openings in it and 2 forwards-facing horns above its eyes.. Diceratops was up to 30 feet (9 m) long. Only a single skull (with the lower jaw) was found in Wyoming, USA. It was named by paleontologist R. S. Lull in 1905. The type species is D. hatcheri. Diceratops used to be thought of as a diseased specimen of Triceratops, because of the openings in the frill. Diceratops is now believed to be a separate genus (from work by C. Forster).

DICHOTOMOUS KEY A dichotomous key is a method for determining the identity of sometihing (like a butterfly, a plant, or a rock) by going through a series of choices that lead the user to the correct name of the item. At each step of the process, the user is given two choices; each alternative leads to another questions until the identification is completed. For example, a question in a dichotomous key for trees might be something like, "Does it have flat or needle-like leaves?" Dichotomous means "divided in two parts".

DICRAEOSAURUS (pronounced die-CREE-oh-SAWR-us) Dicraeosaurus (meaning "two-forked lizard") was a quadrupedal plant-eating dinosaur from the late Jurassic period, about 156 to 150 million years ago. It was about 45 feet (13 m) long diplodocid sauropod with a long neck and a whip-like tail. Its vertebrae had long spines which formed a short sail back. It had a small, long, narrow head with nostrils over the eyes and pencil-like teeth. The rear legs were much larger than the front legs. Partial fossils have been found in East Africa. It was named by paleontologist Janensch in 1914. The type species is D. hansemanni.

DICYNODONT Dicynodonts (meaning "two dog teeth") were pig-like, herbivorous therapsids with two large tusks in the upper jaw. They lived during the late Permian and Triassic periods. Dicynodonts included Aulacephaledon, Lystrosaurus, Kannemeyeria, Placerias (pictured above), Dinodontosaurus, Ischigualastia, Robertia, and others. Classification: Order Therapsida, Suborder Dicynodontia.

DIGIT A digit is a toe or a finger.

DIGITIGRADE Dinosaurs walked on their toes; the scientific term for this is digitigrade. Only a small part of the foot touches the ground and the animal can move very quickly. Many predators are digitigrade. Other animals that are digitigrade include dogs, cats, and birds. There is a pad of tissue on the back of the feet on these animals that acts like a shock absorber. People, bears, and crocodiles walk differently; they are plantigrade (flat-footed). (Compare with plantigrade.)

DILOPHOSAURUS (pronounced die-LOF-oh-SAWR-us) Dilophosaurus was a carnivorous dinosaur from the early Jurassic period, about 208-194 million years ago. This theropod had two crests on its head and was about 20 feet (6 m) long and weighed roughly 650 to 1,000 pounds (300kg to 450kg). Its femur (thigh bone) was 55.7 cm long. Fossils of this biped have been found in Arizona, USA. The type species is D. wetherilli.

DIMETRODON (pronounced die-MET-roh-don) Dimetrodon was a prehistoric animal with a large sail; it was not a dinosaur but a pelycosaur, an early synapsid.

DIMORPHISM Dimorphism means having two forms. It usually means that an organism has two different types, for example, males and females of some species look different, and are said to be sexually dimorphic.

DIMORPHODON (pronounced die-MORF-oh-don) Dimorphodon (meaning "two-form tooth") was a pterosaur with a 4 feet (1.2 m) long wingspan, with deep, wide jaws resembling the beak of the modern-day puffin, a short neck, and a diamond-shaped flap of skin at the end of the long, pointed tail. From England during the early Jurassic period. It was not a dinosaur, but type of extinct, flying reptile. It was named by R. Owen in 1859.

DINICHTHYS Dinichthys (meaning "terrible fish"), was a family of ancient, meat-eating fishes. Dunkleosteus was the biggest member of this family. It was a heavily armored primitive fish from the Late Devonian period, about 360 million years ago. This top predator was up to 11.5 ft (3.5 m) long and had large, scissor-like cutting jaws with serrated, razor-sharp bones, but no teeth. Its skull was was over 2 feet (65 cm) long. It had a jointed neck, an eel-like tail, a scale-less body, and hinged body shields. Dinichthys were not sharks but placoderms with a shark-like tail. They may have eaten sharks. Fossils have been found in Morocco, Africa, Poland, Belgium, and the USA.

DINICTIS Dinictis was a small, primitive cat from the Oligocene (about 40 million years ago). This extinct, sabertooth cat had a sleek body, short legs, powerfully-muscular jaws, a small brain (in a 7 inch long skull), large canine teeth, and a long tail. Dinictis was plantigrade, walking in a flat-footed manner (unlike modern cats, which are probably much faster, digitigrade, walking on their toes). Dinictis, like modern cats, had three eyelids, the third one being a nictitating membrane (or haw). Dinictis evolved into pseudailurus, which was more like modern-day cats. Dinictis was very similar to Hoplophoneus (the ancestor of smilodon) except the canine teeth were less exaggerated. Dinictis may have preyed upon Indricotherium. Classification: Family Felidae, Subfamily, Machairodontinae, Genus Dinictis.

DINO Dino (from the Greek word deino) means fearfully great or terrible.

DINOCEPHALIAN Dinocephalians (meaning "terrible head") were therapsids from the late Permian period. Some were carnivores, others were herbivores or omnivores. Titanosuchus was a carniverous dinocephalian. Classification: Subclass Synapsida, Order Therapsida, Suborder Dinocephalia ("terrible heads")

DINODONTOSAURUS Dinodontosaurus (meaning "terrifyling tooth lizard") was a large dicynodont that lived during the Triassic period. It was a pig-like plant-eater that had two large tusks in the upper jaw. Its forelimbs were sprawling but the hind limbs were columnar. Fossils were found in Sanga de Niconar, Brazil. Dinodontosaurus was not a dinosaur. Dinodontosaurus was named by E. H. Colbert in 1959. Classification: order Therapsida, suborder Dicynodontia, family Kannemeyeriidae, genus Dinodontosaurus.

DINOHYUS Dinohyus (meaning "terrible pig") was a large, warthog-like hoofed mammal that lived during the early Miocene, roughly 24 million years ago. This herbivore (it ate plants, including roots) had a long skull (over 1 m = 3 feet long), a small braincase, a pair of knob-like protrusions on the back of the lower jaw (in the cheek area), blunt incisors, and wide, strong canine teeth. Its long legs probably made it a fast runner. The neck was short and stout and there was a hump on the shoulders formed by spines along the backbone. It was about 6 feet (2 m) tall at the shoulders and was the biggest and among the last of the Entelodonts. Fossils have been found in western North America (including Battle Creek, South Dakota, USA). Classification: Class Mammalia (mammals), Order Artiodactyla (even-toed ungulates), Family Entelodontidae (large, pig-like mammals from the Oligocene to early Miocene, including Archaeotherium, Megachoerus, Dinohyus, Entelodon and Eoentelodon), Genus Dinohyus.

DINORNIS Dinornis maximus (meaning "huge, terrible bird") was the tallest bird that ever lived. This 11 1/2 ft (3.5 m) tall bird lived in New Zealand. A flightless moa, it had long, heavily-built legs, a long neck, and a bulky body. This slow-moving bird ate seeds and fruit. Dinornis appeared during the Pleistocene and went extinct in around 1800, due to pressures from humans. Dinornis was named by Richard Owen in 1843; Owen had been sent a box of bones from a missionary in New Zealand. (Order Dinornithiformes)

DINOSAUR Dinosaurs were land-dwelling reptiles that walked with an erect stance during the Mesozoic Era. Their unique hip structure caused their legs to stick out from under their bodies, and not sprawl out from the side (like other reptiles). They are extinct, but they evolved into the birds. The word dinosaur (meaning "fearfully great lizard") was coined by Sir Richard Owen in 1841.

DINOSAUR GAME You can make silly dinosaurs with this dinosaur game.

HA HA! DINOSAUR JOKES If dinosaurs told jokes, they'd tell dinosaur jokes!

DINOSAURUS (pronounced DIEN-oh-SAWR-us ) Dinosaurus (meaning "terrifying lizard") was a large, plant-eating dinosaur (a plateosaurid prosauropod ) that lived during the late Triassic period in what is now Europe. Dinosaurus was named by Ruetimeyer in 1856. Dinosaurus (later Gresslyosaurus) is probably the same as the genus Plateosaurus.

DINOTYRANNUS (pronounced DIEN-oh-ty-RAN-us ) Dinotyrannus (meaning "terrifying tyrant") was a large, meat-eating Tyrannosaurid dinosaur (closely related to T. rex). This Coelurosaurid theropod lived during the late Cretaceous period in what is now North America. Dinotyrannus was named by Olshevsky, Ford, and Yamamoto in 1995.

DIPLOCAULUS (pronounced DIP-low-cawl-us) Diplocaulus (meaning "souble stalk") was not a dinosaur but an early amphibian, long extinct. It had a boomerang-shaped head (formed by two elongated bones at the back of the head), four short legs, and a short tail. It was 3 feet (1 m) long and lived from the late Carboniferous to the late Permian period (about 270 million years ago). Its fossils have been found in Texas, USA, North America.

DIPLODOCIDS The Diplodocids (or Diplodocidae) were a group (family) of huge, quadrupedal, long-necked, whip-tailed, plant-eating dinosaurs (sauropods). Diplodocids had a small head with had peg-like teeth and a squarish snout - the two nostrils opened at the top of the head (with one opening). Some Diplodocids included Apatosaurus, Diplodocus, Seismosaurus, Supersaurus, Barosaurus, and others.

DIPLODOCUS Diplodocus (pronounced di-PLOD-uh-kus, meaning double beamed) was a huge, long-necked, whip-tailed, plant-eating sauropod dinosaur from the late Jurassic period, 155 to 145 million years ago. The type species is D. longus.

DIPLOTOMODON Diplotomodon (meaning "double cutting tooth") was a meat-eating dinosaur that lived during the Late Cretaceous period. This coelurosaur (an advanced theropod dinosaur) is only known from a single fossilized tooth that was found in Glouchester County, New Jersey, USA, in 1865 - the tooth has since been lost. The type species is D. horrificus (named by Leidy in 1865) - it is a nomen dubium (a duboius species because too little information is known about it). It was originally called "Tomodon" (which means ""horrific double cutting tooth").

DIPROTODONTIDAE The Diprotodontidae (named by Gill in 1872, meaning "two early teeth") are a family of Australian wombat-like marsupial mammals that have three or fewer upper incisors. Diprotodonts evolved during the middle Miocene period. Diprotodon was a 10 ft (3 m) long Diprotodont from the Pleistocene (about 2 million years ago until about 10,000 years ago); this big plant-eater weighed about 2000 kg.

DIRACODON (pronounced dye-RAK-oh-don ) Diracodon (meaning "neck-point tooth") was a plated ornithopod, a plant-eating dinosaur that lived during the late Jurassic Period in what is now North America. Diracodon was named by Marsh in 1880. This ornithischian may be a stegosaur.

DISCOSAURISCUS Discosauriscus was an ancient amphibian (a seymouriamorph, NOT a dinosaur). This extinct, well-adapted land-dweller had sharp teeth in wide jaws, it walked on four short, sprawling legs, and had a long tail. It lived during the early Permian period (almost 300 million years ago). Discosauriscus was named by Makowsky in 1876. Hundreds of fossils of this tetrapod have been found in Central and Western Europe. Classification: Class Amphibia, Order Seymouriamorpha, Family Seymouridae, Genus Discosauriscus.

DISPERSAL Dispersal is the process in which an organism spreads out geographically. Many dinosaurs dispersed over a large area.

DISTAL Distal means farthest from the point of attachment to the body (compare with proximal, its opposite).

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