Glossary ACR-ALB
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ACROCANTHUS
(pronounced AK-roh-CAN-thus) Acrocanthus (meaning "high-spine"
because of the spikes growing out of its spine) is actually Acrocanthosaurus,
a theropod (a bipedal, meat-eating dinosaur) that lived during the early
Cretaceous period, roughly 115 million-105 million years ago. Acrocanthus
was named by paleontologists Czaplewski, Cifelli, and Langston in 1994,
but was attributed to Langston, 1947.
ACTIOSAURUS
(pronounced ACT-ee-oh-SAWR-us) Actiosaurus (meaning "coast lizard")
is a dinosaur of uncertain phylogenetic placement. Actiosaurus was named
by Sauvage in 1882.
ACTINOPTERYGII
Ray-finned fish (class Actinopterygii), meaning ("ray-shaped fin")
are the largest group of fish. These bony fish evolved during the very
end of the Silurian, about 408 million years ago. These fish dominate
the seas today. Sharks are not ray-finned fish.
ADAPTATION
An adaptation is a response of an organism to changes in its environment
(like the selective survival of plants with better water conservation
during extensive dry times).
ADAPTIVE RADIATION
Adaptive radiation is the diversification of a species as it adapts to
different ecological niches. If successful, the species become specialized
for the new environments (the mechanism being natural selection), and
they eventually evolve into different species.
ADASAURUS
(pronounced AID-a-SAWR-us) Adasaurus (meaning "Ada's (an evil spirit
from Mongolian mythology) lizard") was a bird-like meat-eating dinosaur
that was about 6 ft (2 m) long and weighed roughly 33 pounds (15 kg).
This coelurosaurid, an advanced theropod, lived during the late Cretaceous
period. Incomplete fossils of this biped have been found in Mongolia.
The type species is A. mongoliensis. Adasaurus was named by Rinchen Barsbold
in 1983.
AEGYPTOSAURUS
(pronounced ee-JIP-tuh-SAWR-us) Aegyptosaurus was a primitive, 50 foot
(15 m) long Titanosaurid sauropod that weighed roughly 10500 kg. It was
a long-necked, long-tailed, quadrupedal, plant-eater from the Sahara desert
in Egypt during the mid Cretaceous period. Aegyptosaurus, meaning "Egyptian
Lizard," was named by paleontologist Stromer in 1932. It is known
from fragments of fossilized vertebrae and some leg bones that were destroyed
by bombings in WW II.
AEOLOSAURUS
(pronounced EE-oh-loh-SAWR-us) Aeolosaurus (meaning "Aeolus's [god
of the wind] lizard") was a Titanosaurid dinosaur from the late Cretaceous
period. This sauropod was about 50 feet (15 m) long and weighed roughly
10500 kg. It had dermal plates (armor). An incomplete fossil of this long-necked,
long-tailed, quadrupedal plant-eater were found in a windy area of Patagonia,
Argentina. The type species is A. rionegrinus. It was named by Powell
in 1988.
AEPISAURUS
(pronounced EE-pi-SAWR-us) Aepisaurus (meaning "high lizard")
is a dubious genus of Titanosaurid dinosaur from the early Cretaceous
period. This sauropod was about 50-55 feet (15-17 m) long, weighing roughly
10000 kg. It had dermal plates (armor). Only a humerus (upper arm bone)
was found in France. The type species is A. elephantinus. It was named
by Gervais in 1853.
AEPYCAMELUS
Aepycamelus is the new name of Alticamelus, a prehistoric camel that lived
from the middle through late Miocene. This giraffe-like early camel was
about 10 ft (3 m) tall at the head; it had a small back hump and a short
tail. It had very long legs, and small hooves on its two toes and broad
pads. It probably moved in a manner similar to modern-day camels. Fossils
of this mammal have been found in Colorado, USA.
AËTOSAUR
(pronounced a-EAT-uh-SAWR) Aëtosaurs (meaning "eagle lizards")
were well-armored, spiked, herbivore, quadrupedal, long-tailed, land-dwelling
reptiles (not dinosaurs but early thecodonts) that superficially resembled
crocodiles (but had a much shorter, beak-like snout). These armadillo-like
animals had bulky bodies and most had leaf-shaped teeth. Examples include
Stagonolepis and Desmatosuchus. They lived during the late Triassic period
in North and South America and Europe. Aëtosaurs may have built nests
and protected their eggs.
AETONYX
(pronounced ee-TON-iks) Aetonyx (meaning "eagle claw") is an
invalid name for Massospondylus. The type species is A. palustris. It
was named by Broom in 1911.
AFROVENATOR
(pronounced af-roh-VEN-ah-tor) Afrovenator bakensis was a dinosaur about
27-30 feet (8-9 m) long. It was a theropod, a bipedal, meat-eating, three-fingered,
stiff-tailed predator from Niger, Africa during the Cretaceous period,
about 130 million years ago. A nearly complete Afrovenator ( meaning "African
Hunter") skeleton was found (1993) and named by paleontologist Paul
Sereno et al. (1994).
AGATHAUMAS
(pronounced ag-ah-THAW-mas ) Agathaumas (meaning: "great wonder")
was a ceratopsid resembling Triceratops. This horned plant-eater dates
from the late Cretaceous period. Fossils (only a few bones from the hip
area) have been found in western North America. It was named by paleontologist
Cope in 1872. The type species is A. sylvestris. This genus is a nomen
dubium.
AGE
An age is a unit of geological time which is distinguished by some feature
(like an Ice Age). An age is shorter than epoch, usually lasting from
a few millions of years to about a hundred million years.
AGILISAURUS
(pronounced AJ-il-eh-SAWR-us) Agilisaurus (meaning: "agile lizard")
was a lightly-built dinosaur that was about 3.5-4 feet (1.2-1.7 m) long
and weighed roughly 40 kg. This plant-eater lived during the middle Jurassic
period, about 170 million years ago. It was perhaps a hypsilophodontid.
A nearly complete skeleton was found in China. Agilisaurus was named by
Peng in 1990. The type species is A. louderbecki.
AGROSAURUS
(pronounced AG-roh-SAWR-us) Agrosaurus (meaning: "wild country lizard")
was an ornithischian dinosaur, a primitive prosauropod about 6.5-10 feet
(2-3 m) long, weighing perhaps 18-30 pounds (40-70 kg). This small bipedal
plant-eater had a long tail, short arms, and lived during the late Triassic
period, about 225-213 million years ago. It was thought to be the first
fossil found in Australia, but has since been found to a mislabeled fossil
from Britain (Wales). Only a few bones were found. Agrosaurus was named
by Seeley in 1891. The type species is A. macgillvrayi, but Agrosaurus
is a nomen dubium and is probably the same as Thecodontosaurus antiquus.
ALAMOSAURUS
(pronounced Al-uh-moe-SAWR-us) Alamosaurus (meaning: "Ojo Alamo [New
Mexico] lizard" ) was a long-necked, whip-tailed dinosaur about 69
feet (21 m) long and weighed perhaps 33 tons (30000 kg). It was a quadrupedal,
plant-eater from New Mexico, Texas, and Utah, USA during the late Cretaceous
period, about 73 million to 65 million years ago. It was a sauropod and
a Titanosaurid that may have had some body armor. It was named by Gilmore
in 1922. The type species is A. sanjuanensis.
ALBERTOSAURUS
(pronounced al-BUR-toh-SAWR-us) Albertosaurus was a large, meat-eating
dinosaur from the late Cretaceous period. It was a theropod related to
Tyrannosaurus rex. Albertosaurus was about 8.6 m long and weighed about
2500 kg. The type species is A. sarcophagus.