ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

LABROSAURUS (pronounced LAB-ro-SAWR-us) Labrosaurus (meaning "greedy lizard") is an invalid name for Allosaurus, a huge, meat-eating dinosaur from the late Jurassic period, about 156 to 135 million years ago. It was a theropod that lived in what is now the western United States.

LABYRINTHODONT Labyrinthodonts (meaning "labyrinth tooth" because of the complex infolding of their tooth enamel) were the first amphibians. These carnivores were the first vertebrates to live on land (at least during part of their life-cycle). They probably lived near the water so they could return to it to lay eggs. Labyrinthodonts had conical teeth with maze-like enamel resembling that of the bony fishes. Labyrinthodonts lived from the late Devonian until the end of the Mesozoic (most died during the end-Triassic extinction). Labyrinthodonts include the groups Ichthyostega, Temnospondyls, Anthracosaurs (batrachosaurs), etc.

LAMBEOSAURUS (pronounced LAM-bee-oh-SAWR-us) Lambeosaurus (named to honor paleontologist L. Lambe) was a duck-billed dinosaur with a large crest from the late Cretaceous period. This plant-eater was about 30 feet (9 m) long.

LANGSTON, JR., WANN Wann Langston, Jr., is an American vertebrate paleontologist. Langston has named and described the dinosaurs Acrocanthosaurus (Stovall and Langston, 1950) and Lophorhothon (1960). He received his Ph.D. from the University of California, Berkeley in 1952. Langston was the Director of the Vertebrate Paleontology Laboratory of the Texas Memorial Museum of Science and History at the University of Texas at Austin from 1969 until 1986 (when he retired); before that, he had been the curator at the National Museum of Canada. Dr. Langston was the thesis advisor of Douglas Lawson when Lawson found the giant pterosaur Quetzalcoatlus.

LAOPTERYX Laopteryx (meaning "stone wing") was a pterosaur (not a dinosaur, but a close relative). This flying reptile lived during the late Jurassic period (about 150 to 144 million years ago) in what is now Wyoming, USA. Laopteryx was named by paleontologist Othniel Marsh in 1881. Laopteryx is a dubious genus. Also, it is uncertain where Laopteryx belongs within pterosauria. Laopteryx was thought to be a bird, but was reclassified as a pterosaur by John Ostrom in 1986.

LAOSAURUS (pronounced LAY-oh-SAWR-us) Laosaurus (meaning "stone lizard") is a doubtful genus of dinosaur that is only known from fragmentary fossils. This small, bipedal plant-eater was a hypsilophodontid ornithischian that was found in Wyoming, USA and Alberta, Canada. It lived during the late Jurassic period, roughly 156 to 145 million years ago. Laosaurus was named by C. Marsh in 1878 from a segment of this dinosaur's tail (a few vertebrae, each about 1 inch=25 mm long). The type species is L. celer. The carious specimens of Laosaurus are probably Othnielia and Dryosaurus.

LAURASIA Laurasia was the northern supercontinent formed after Pangaea broke up during the Jurassic period. Laurasia included what are now North America, Europe, Asia, Greenland, and Iceland.

LAVA Lava is molten rock. It usually comes out of erupting volcanoes.

LAW OF SUPERPOSITION The Law of Superposition states that in a sequence of sedimentary rocks, the lowest layers are the oldest and the uppermost layers are the youngest.

LEAELLYNASAURA (pronounced lee-EL-in-a-SAWR-a) Leaellynasaura was named in 1989 after Leaellyn, the daughter of Thomas A. Rich and Patricia Vickers-Rich, the namers of this dinosaur genus; saura is the feminine form of lizard in Greek. It was a small hypsilophodontid, a bipedal plant-eater 6.5 to 10 feet (2-3 m) long. It differed from other hypsilophodontids in its upper hind leg bone structure (at its base it gets wider from back to front). It had a relatively large brain and good eyesight. Leaellynasaura lived in what is now Australia during the middle Cretaceous (106 million years ago). Australia was within the Antarctic Circle during the early Cretaceous and had a long, dark winter. Leaellynasaura's large eyes would have helped it find food in this relatively dark environment.

LEIDY, JOSEPH Joseph Leidy (1823-1891) was a US anatomist who named the first dinosaurs found in the U.S.A. He excavated the first American dinosaur, Hadrosaurus, in 1858. Leidy named Antrodemus (1870, perhaps Allosaurus), Aublysodon (1868), Deinodon (1856), Diplotomodon (1868), Hadrosaurus (the first nearly-complete dinosaur skeleton and first-known duck-billed dinosaur, 1858), Palaeoscincus (1856), Thespesius (1856), Trachodon (1856), and Troodon (1856). Leidy was also the first scientist to identify many extinct species of camels, horses, sloths, tigers, and rhinoceroses.

LEIDYSUCHUS Leidysuchus (meaning "Leidy's crocodile;" Leidy was a paleontologist) was a long-snouted crocodile that lived during the late Cretaceous period. Fossils of this swamp-dwelling reptile have been found in North America.

LEMUR Lemurs are large-eyed primates from Madagascar (an island off the eastern coast of Africa). Lemurs evolved about 50 million years ago.

LEPIDODENDRON Lepidodendron (also known as the "scale tree") was a giant club moss (a tree-like plant) whose long trunk had bark with a diamond-shaped pattern (the scars of old, dead branches that fell off). This ancient lycopod was over 130 ft (40 m) tall; the trunk was over 6 ft (1.8 m) in diameter. Lepidodendron lived in swampy areas during the Carboniferous Period (about 360 to 286 million years ago). It has spirally-arranged leaves that ended in cones. By the time the dinosaurs lived, the giant club mosses had died out and were replaced by smaller club mosses.

LEPIDOSAURS Lepidosaurs are a subgroup of reptiles which includes snakes and lizards.

LEPOSPONDYL Lepospondyls were small, common amphibians with very long, slim bodies (Lepospondyls superficially resembled salamanders or snakes). These extinct insectivores had a long skull with sharp teeth and weak limbs. They lived during the Middle Pennsylvanian (=late Carboniferous) through the late Permian period. Lepospondyls probably lived near the water so they could return to it to lay eggs. Lepospondyls included: the snake-likeAïstopods (e.g., Ophiderpeton and Phlegethontia), the newt-like Nectrideans (e.g., Diplocaulus and Keraterpeton), the varied Microsaurs (e.g., Microbranchis and Pantylus), Adelogyrinids, and Lysorophids.

LEPTOCYCAS Leptocycas gracilis was a cycad (a primitive seed plant) that lived during the late Triassic period. It was a palm-like tree with a long, woody trunk that lived in warm climates. This tree was about 4.8 ft (1.5 m) tall. Separate male and female plants exist (they are dioecious). This gymnosperm had long, divided leaves and produced large seed cones.

LEPTOPTERYGIUS Leptopterygius (also known as Temnodontosaurus) was a late Ichthyosaur, an extinct marine reptile, not a dinosaur. It was about 30 feet (9 m) long and looked a bit like a modern-day dolphin (but it is not at all related to the dolphins). It had a torpedo-shaped body, a long, narrow, toothed snout, 4 long, narrow paddles, a fish-like tail, and a triangular dorsal fin. They were viviparous (they gave birth to live young). These fish-eaters lived in shallow seas over what is now Europe (Germany and England) during the late Jurassic period. (Order Ichthyosauria, Family Leptopterygiidae)

LESOTHOSAURUS (pronounced le-SOH-toh-SAWR-us) Lesothosaurus (meaning "Lesotho (South Africa) lizard") was a very early ornithopod, a small, fast, bipedal, plant eating dinosaur. It lived during the early Jurassic period.

LEWISUCHUS Lewisuchus was a small, fast-moving genus of archosauromorphs (not a dinosaur, but another type of reptile, a thecodont). This quadruped had a four-chambered heart, large, powerful jaws and a long tail. Its legs were not sprawling (like those of most reptiles) but were columnar, like the dinosaurs. Lewisuchus lived during the Triassic period. The type species is L. admixtus. Lewisuchus was named by Romer in 1972.

LILLIPUT EFFECT The Lilliput Effect (named by Adam Urbanek, 1993) notes the appearance of small body size in surviving animals after an extinction event. The name Lilliput is from Jonathan Swift's novel Gulliver's Travels; in the novel, the Lilliputians were very tiny people.

LINNEAN SYSTEM The Linnean System is a method of classifying organisms based on a simple hierarchical structure. Organisms are divided into groups using the following system: Kingdom, Phylum, Class, Order, Family, Genus and Species.

LIOPLEURODON (pronounced LIE-oh-PLOOR-oh-don) Liopleurodon (meaning "smooth-sided tooth") was the biggest plesiosaur, up to 39-49 feet (12-15 m). It had a long body with a large head, a short neck, powerful jaws and teeth, and four long, wide, strong flippers. The skull was 10 feet (3 m) long. Fossils were found in England, France, Germany, and eastern Europe. It lived during the late Jurassic period. Liopleurodon was not a dinosaur, but another type of extinct reptile. Liopleurodon was named by French paleontologist H.E. Sauvage in 1873. L. ferox (Martill, 1991) is the biggest-known species of Liopleurodon

LIVING FOSSILS A living fossil (an oxymoron) is an organism that lived during ancient times and still lives today, relatively unchanged, like the Coelacanth, the horseshoe crab, the gingko tree, cycads, horsetails, club mosses, and many, many other well-adapted organisms.

LIZARD-HIPPED DINOSAURS The "Lizard-Hipped" dinosaurs (Saurischians) had a hip structure similar to that of lizards. Oddly enough, these dinosaurs were the ancestors of the birds. They are divided into the theropods (bipedal carnivores like Allosaurus) and sauropodomorphs (huge, quadrupedal herbivores like Apatosaurus).

LIZARDS Lizards are fast-moving reptilian predators with powerful jaws; the dinosaurs were not lizards. The first lizards evolved during the late Permian period; these small lizards were insect eaters. Lizards had a boom during the Jurassic period, when all the major modern groups of lizards came into existence. Lizards and snakes are closely related, but lizard are an earlier group. Other, more distant living relatives of lizards include the crocodilians, tortoises, and turtles. Classification: Subclass Anapsida, Order Squamata (snakes and lizards), Suborder Laecertilia (lizards).

LOBE-FINNED FISH Lobe-finned fish (Crossopterygii) are bony fish whose fins are supported on fleshy lobes. Lobe-finned fish appeared during the Silurian period (roughly 420 million years ago). The Coelacanth and the extinct Rhipidistians are examples of lobe-finned fish.

LONGISQUAMA Longisquama was a small, early archosaur (not a dinosaur) that lived during the early Triassic period, about 245 million years ago. This unusual reptile was about 6 inches long, had a long tail, a pointed snout, and long feather-like scales coming out of its back (possibly arranged in pairs). These scales may have been used for gliding from trees. Fossils have been found in Kyrgyzstan. Longisquama was named by Alexander Sharov in 1970. The type species is L. insignis.

LONG NECK The long-necked dinosaurs were sauropods like Diplodocus, Apatosaurus, and Brachiosaurus.

LOW SEASONALITY Low seasonality is when there is only a small difference in temperature between the seasons (with mild winters and summers). Compare to stong seasonality, in which the difference in temperatures between the seasons is big (for example, with a hot summer and a cold winter).

LUFENGOSAURUS (pronounced LOO-FUHNG-oh-SAWR-us) Lufengosaurus (meaning "Lufeng (China) lizard") was a plateosaurid prosauropod, a long-necked, small-headed, quadrupedal, herbivorous dinosaur with widely spaced teeth. It was about 20 feet (6 m) long. This large plant-eater lived in what is now China during the early Jurassic period (208-200 million years ago). Lufengosaurus was named by Chung Chien Young in 1941.

ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

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

Enchanted Learning^®
Over 35,000 Web Pages
Sample Pages for Prospective Subscribers, or click below

Click to read our Privacy Policy

E-mail