ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

EARTH The Earth is the third planet from the Sun.

ECHINODERMATA Echinoderms (meaning "spiny skin") are a phylum of salt-water animals whose living members have five arms or rays (or multiples of five). They are mostly bottom-dwellers. These invertebrates include: starfish (sea stars), sea urchins, sand dollars, crinoids, sea squirts, sea cucumbers, etc.

ECHINODON (pronounced ee-KINE-oh-don) Echinodon (meaning "spiny tooth") was a small, early, bipedal, plant-eating dinosaur from the late Jurassic period, about 145 million years ago. This poorly-known ornithischian was about 2 ft (60 cm) long. It is known from a very incomplete fossil found in Dorset, England. Echinodon was named by Owen in 1861. The type species is E. becklessi. Its classification is uncertain.

ECTOTHERMIC Ectotherms are animals whose internal temperature changes with the environment (they are cold-blooded). They rely upon the external temperature and their behavior (like sunning themselves) to regulate their body temperature. Amphibians, most fish, and most reptiles are ectothermic.

EDAPHOSAURUS (pronounced ah-DAFF-oh-SAWR-us) Edaphosaurus (meaning "pavement lizard" - Cope's term for its tooth plates) was an herbivorous early synapsid that lived during the late Carboniferous and early Permian period, about 320 to 258 million years ago, long before the dinosaurs existed. This pelycosaur (early synapsids) was related to Dimetrodon and had long spines growing out of its backbone. These spines had distinctive crossbars on them and may have been covered by skin, forming a thermoregulatory sail. This quadruped was about 11 feet (3.2 m) long and weighed about 660 pounds (300 kg), had a small head, large eyes, a barrel-shaped body, and a long tail. It lived in wet areas (in swamps and near lakes) and ate rough plant material that it could crush with its flat teeth. Its fossils have been found in Europe and North America.

EDENTULOUS Edentulous means toothless.

EDMONTONIA (pronounced ed-mon-TONE-ee-ah) Edmontonia (meaning "from Edmonton") was an Ankylosaur, a heavily armored herbivore (plant-eater) that was 20 - 23 ft (6 - 7 m) long. It was covered with bony plates and spikes, and had a wide, flat skull. The teeth were small and the jaws were weak. The legs were thick and the feet were very wide. It was a late Cretaceous (76-68 million years ago) ornithischian dinosaur whose fossils were originally found in 1924 in Alberta, Canada (the fossils were unearthed in the Red Deer River valley about 11 kilometers (7 miles) west of the town of Morrin, near the Edmonton rock formation, hence its name) by George Paterson. Edmontonia fossils have been found in Canada (Alberta) and the USA (Montana, S. Dakota, and Texas). Edmontonia was named by the fossil hunter C. M. Sternberg in 1928. The type species is E. longiceps.

EDMONTOSAURUS (pronounced ed-MON-toh-SAWR-us) Edmontosaurus was a large, Cretaceous, plant-eating, duck-billed dinosaur.

EFRAASIA (pronounced ee-FRAYS-ee-ah) Efraasia (named after its discover, Eberhard Fraas) was a sauropodomorph (a primitive plant-eating dinosaur from the late Triassic period in what is now Germany. It was 8 ft = 2.5 m long). Efraasia is actually a juvenile specimen of the genus Sellosaurus.

EGG Some animals hatch from eggs. Fossilized eggs from some prehistoric animals have been found.

ELASMOSAURUS (pronounced eh-LAZZ-mo-SAWR-us) Elasmosaurus (meaning "plate lizard") was a huge, long-necked, Cretaceous marine reptile - a plesiosaur, not a dinosaur.

ELASMOTHERIUM (pronounced ee-LAS-mo-THEER-ee-um) Elasmotherium (meaning "plate monster") was an ancient plant-eating mammal that lived during the Pleistocene. This heavily-built quadruped walked on four short, stocky hoofed legs. It had a huge horn on its forehead; the horn may have been up to 6.5 ft (2 m) long (fossils of the horn have not been found). Elasmotherium was bigger than an elephant; it was 16-26 ft (5-8 m) long and it weighed roughly 3.5 to 4.5 tons (3-4 tonnes). The teeth were tall-crowned and were covered with cement and wrinkled enamel. Fossils have been found in Europe and Asia; this giant lived and grazed on the Eurasian steppes. Elasmotherium sibricus was named by Johannes Fridericus Brandt in 1878. Classification: Class Mammalia (mammal), Order Perissodactyla (odd-toed ungulates), Suborder Ceratomorpha (tapirs, rhinos), Family Rhinocerotidae (Elasmotherium, Teleoceras, Trigonias, Coelodonta), Genus Elasmotherium.

EMBASAURUS (pronounced EM-bah-SAWR-us) Embasaurus (meaning "Emba lizard," named for the Emba River in Kazakhstan) was a meat-eating dinosaur from the late Cretaceous period. It is known from 2 partial vertebrae found in Kazakhstan. Embasaurus was named by Riabinin in 1931. The type species is E. minax. This is a dubious genus because of the sparse fossils.

EMBRYO An embryo is a very young, unborn organism. Some fossilized dinosaur embryos have been found.

ENDOCRANIAL CAVITY The endocranial cavity is the area within the skull where the brain and other tissue are located.

ENDOTHERMIC Endotherms maintain a relatively constant internal temperature. Endothermic animals generate their own body heat to maintain their body temperature, which is usually higher than that of the surroundings. Heat from the bloodstream circulates through the body in order to maintain the animal's temperature. Birds and mammals are endothermic.

EOALULAVIS Eoalulavis was the earliest bird that had good maneuverability while flying, even at low speeds (this extra flight control is obtained from a tuft of feathers on the thumb called the alula - it also helps in takeoffs and landings). Fossils of this extinct bird have been found in Spain. (Class Aves)

EOBRONTOSAURUS (pronounced EE-oh-BRON-toh-SAWR-us) Eobrontosaurus (meaning "dawn thunder lizard") was a huge plant-eating dinosaur from the late Jurassic period.. This long-necked, whip-tailed, small-headed quadruped was very similar to Apatosaurus (the original Brontosaurus), but slightly more primitive. It was a diplodocid sauropod. A partial fossil was found in Wyoming, USA. The type species is E. yahnahpin (Filla, James & Redman, 1994). Eobrontosaurus was named by American paleontologist Robert Bakker in 1998.

EOCERATOPS (pronounced EE-oh-SER-ah-tops) Eoceratops (meaning "dawn horn face") was an early ceratopsian dinosaur. This ceratopsid had a short frill and three short horns on its face. It had a large skull, four sturdy legs with hoof-like claws, a bulky body and a short, pointed tail. It lived during the late Cretaceous period. This dubious genus may have been an ancestor of Triceratops or it may be a juvenile Chasmosaurus. Fossils have been found in North America. Eoceratops was named by Canadian paleontologist L. Lambe in 1915. The type species is Eoceratops canadensis. For more information, see Chasmosaurus.

EOHIPPUS Eohippus (meaning "dawn horse") is the genus of the earliest-known horse. Another name for this genus is Hyracotherium. It dates from the early Eocene Epoch and lived in the Northern hemisphere (Asia, Europe, and N. America). It was 2 feet (60 cm) long and 12-14 inches high at the shoulder (the size of a small dog!). It had a long skull with 44 long-crowned teeth (it could only eat soft leaves). It had 4 hoofed toes on the front feet and 3 hoofed toes on each hind foot. Family Equidae.

EORAPTOR (pronounced EE-oh-RAP-tor) Eoraptor is the oldest known dinosaur. It was a bipedal plant-eater from 228 million years ago (during the late Triassic period).

EOSUCHIAN Eosuchians (meaning "early crocodile") were reptiles that evolved during the late Triassic period, about 220 million years ago. These lizard-like diapsids probably gave rise to lizards and snakes. They walked on four sprawling legs and had a very long tail - some lived in the water (like Hovasaurus). Fossils of Eosuchians have been found in Southern and south-eastern Africa and Madagascar. The newly-found bipedal Eudibamus was an Eosuchian. Other Eosuchians include Thadeosaurus and Hovasaurus. Classification:Class Reptilia, Subclass Diapsida, Order Eosuchia.

EPANTERIAS (pronounced ee-pan-TEER-ee-as ) Epanterias (meaning "buttressed," referring to the vertebrae) was a huge meat-eating dinosaur from the late Jurassic period. It was rounghly 35 ft (11 m) long and may have weighed 3-5 tonnes. Fragmentary fossils were found in western North America. Epanterias was named by paleontologist Cope in 1878. Epanterias may be the same as Allosaurus amplexus . It was originally thought to be a giant plant-eater, a sauropod.

EPOCCIPITAL The epoccipital is a bone edging the frill of certatopian dinosaurs.

EPOCH An epoch is a division of a geologic period; it is the smallest division of geologic time, lasting several million years.

EQ The EQ (encephalization quotient) is the ratio of the brain weight of the animal to the brain weight of a "typical" animal of the same body weight. This measure was developed by the Harry J. Jerison in the 1970's. This helps determine the relative intelligence of extinct animals. Dromaeosaurid dinosaurs had the highest EQ among the dinosaurs.

EQUISETUM Equisetum (a modern genus of horsetail) is a primitive, spore-bearing plant (a sphenopsid) with rhizomes. Its side branches are arranged in rings along the hollow stem. Other genera of horsetail were common during the Mesozoic Era, like Neocalamites, Calamites etc. Horsetails date from the Devonian period 408-360 million years ago, but are still around today and are invasive weeds.

EQUUS (pronounced EK-wiss) The modern horse (genus Equus, which also includes zebras, asses, etc.) evolved about 4 million years ago in North America. It spread to Asia, Europe and Africa. The North American horses went extinct about 8,000 years ago, probably because of disease.

ERIC "Eric" is a 85 percent complete opalized leptocleidine pliosaur (a marine reptile) from the early Cretaceous in Australia (it was named to honor Eric Idle of Monty Python, the television comedy show). Eric the pliosaur was a marine carnivore (meat-eater) that was about 6.5 ft (2 m) long. Fish back bones (and gastroliths) were found in the stomach area of this fossil, so it likely ate small fish, catching them in its crocodile-like jaws.

ERLIKOSAURUS (pronounced ER-lik-oh-SAWR-us) Erlikosaurus (meaning "Erlik's lizard"; Erlik is the king of the dead in Mongolian myths) was a meat-eating dinosaur. This theropod was about 16-20 ft (5-6 m) long and lived during the late Cretaceous period. Fossils of this . therizinosaur have been found in Mongolia. Only a partial skeleton (including a skull) has been found. Erlikosaurus was named by Barsbold and Perle in 1980. The type species is E. andrewsi.

ERYOPS (pronounced EAR-ee-ops) Eryops (meaning "long eye" or "drawn-out eye" in Greek) was a common, primitive labyrinthodontid amphibian that lived in Permian period swamps. This meat-eater had a stout body with very wide ribs, a strong spine, four short, strong legs, a short tail, and a wide, elongated skull with many sharp teeth. Its teeth had enamel with a folded pattern. Eryops was about 5 feet (1.5 m) long, one of the largest land animals of its time. Eryops was a fierce predator on land and in the water; it may have eaten mostly fish, small reptiles and amphibians. It may have been preyed upon by Dimetrodon, which was a faster moving animal. Eryops may have been slow moving on land. Fossils have been found in Texas, USA. Eryops was named by E. D. Cope in 1887.

ERYTHROSUCHUS (pronounced ee-RITH-row-SOOK-us) Erythrosuchus (meaning "red crocodile") was a large, meat-eating thecodont (a socket-toothed reptile). It was not a dinosaur, but was closely related to them. Erythrosuchus had long, stong jaws and ate plant-eaters, like dicynodonts. It lived during the late Triassic period, about 220 million years ago. Fossils were found in South Africa. Erythrosuchus was named by R. Broom in 1905.

ESOPHAGUS The esophagus is the tube from the mouth to the stomach.

ESTEMMENOSUCHUS (pronounced es-TEM-en-oh-SOOK-us) Estemmenosuchus (meaning "crowned crocodile") was a large, quadrupedal animal about 13 feet (4 m) long and over 6.5 feet (2 m) tall. It was not a dinosaur. This plant-eater had long, sharp, forward-pointing teeth in the front of the mouth and smaller cheek teeth at the sides; these teeth let Estemmenosuchus eat a wide variety of tough plant material (like cycads, horsetails, and conifers). Estemmenosuchus had a massive skull, a short tail, and a bulky body. The thick skull had many bony knobs: two by the nostrils, two in the middle of the snout, and two moose-like "horns" over the eyes. Fossilized skin shows a smooth, scaleless texture. Estemmenosuchus' predators may have included Eotitanosuchids and Brithopodids.This dicynodont therapsid (sometimes called mammal-like reptiles) lived during the late Permian period (roughly 255 million years ago, before the dinosaurs evolved). Fossils have been found in eastern Russia. Estemmenosuchus was named by P.K.Chudinov in 1913.

EUBRONTES (pronounced you-BRONT-tees) Eubrontes giganteus is a dinosaur known only from its fossilized, three-toed footprints, an ichnogenus. Eubrontes means "true thunder." The sandstone tracks range from 10-16 inches (25.5-41 cm) long and they are spaced 3.5-4.5 feet (1-1.4 m) apart. These sizes indicate that the dinosaur who made the prints was about 5 feet (1.5 m) tall at the hip (about the size of Dilophosaurus). The shape and pattern of the prints indicate that it was a theropod, a bipedal meat-eater. The tracks date from about 200 million years ago, during the early Jurassic period. Eubrontes trackways were found in Connecticut, USA. Geologist Edward Hitchcock named them in 1845. No fossilized bones have been found in the vicinity, but over 2,000 tracks have been uncovered in what is now Dinosaur State Park. Eubrontes is the state fossil of Connecticut.

EUCOELPOHYSIS (pronounced you-SEE-loh-FIE-sis) Eucoelophysis (meaning "true hollow form") was a meat-eating dinosaur. It was about 8-10 ft (2.5-3 m) long and weighed about 33-66 pounds (15-30 kg). This coelophysoid theropod lived during the late Triassic period in what is now New Mexico, USA. Only partial skeletons have been found. Eucoelophysis was named by Sullivan and Lucas in 1999. The type species is E. baldwini.

EUDIBAMUS Eudibamus cursoris was a small, fast-moving lizard that lived during the Permian period, roughly 290 million years ago. It is the earliest-known animal that walked on two legs (it was facultatively bipedal; it ran on two legs when it needed to). Eudibamus' hind legs were long, and its front legs were short and weak (the hind legs were 64% longer than the front legs and 34% longer than its trunk). It also had a long tail. This plant-eater used its speed to avoid its predators. It was 10.3 inches (26.1 cm) long. David Berman (of the Carnegie Museum of Natural History) estimated that Eudibamus could run about 15 miles per hour (24 kph). Fossils of this synapsid were found in a quarry near Gotha, Germany, in 1993. Eudibamus was named by Robert Reisz, et al. Eudibamus was not a dinosaur, but another, much earlier type of reptile. Dimetrodon was a contemporary of Eudibamus. Classification: class Reptilia (reptiles), order Eosuchia, suborder Bolosaurida, family Bolosauridae, Genus Eudibamus, species E. cursoris.

EUDIMORPHODON Eudimorphodon (meaning "true two-form tooth") was a pterosaur with a 2.5 feet (0.75 m) long wingspan, with large eyes, a short neck, many sharp teeth in pointed jaws (for eating fish and insects), and a diamond-shaped flap of skin at the end of the long, pointed tail. From what is now Italy during the late Triassic period. It was not a dinosaur, but type of extinct, flying reptile. It was named by Zambelli in 1973

EUOPLOCEPHALUS (pronounced YOU-oh-plo-SEF-ah-lus) Euoplocephalus was a heavily armored, plant-eating dinosaur from the late Cretaceous period, about 76-70 million years ago. It was about 20-23 feet (6-7 m) long and about 5.8 feet (1.7 m) wide. This solitary animal had a bony tail-club and armor covering most of its body. Fossils were found in Alberta, Canada. Euoplocephalus was named by paleontologist Lambe in 1910.

EUPARKERIA Euparkeria was a small, early, land-dwelling archosauriform (a reptile closely related to the archosaurs; Euparkeria was a branch off the evolutionary tree very soon before the emergence of dinosaurs). This fast-running quadruped had a semi-erect posture; it could walk on four legs, the front limbs were much shorter than the hind limbs, indicating that it may have been able to run bipedally for short distances. This carnivore (meat-eater) had a long tail, four-fingered hands, large, flexible jaws and many sharp, serrated teeth in sockets. It was about 1.5 ft (0.5 m) long. Euparkeria dates from the early Triassic period, about 225 million years ago. Fossils have only been found in southern Africa.

EXOSKELETON An exoskeleton is a tough, structural body armor made of chitin (a type of protein). Arthropods (insects, arachnids, trilobites, crustaceans, etc.) have exoskeletons.

EXTENSOR MUSCLE An extensor muscle which straightens out a joint. (Compare with a flexor muscle, its opposite)

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