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Ectotherm
Translation: Outside Heat
An ectotherm (EK-toe-therm) is a cold-blooded animal whose body heat comes
from exposure to the sun or some other source of heat in its environment.
Ectotherms regulate their body temperature by moving in and out of shaded
areas. Today's snakes and alligators, as well as lizards, are ectotherms.
See Endotherm and Homoiotherm.
Ectothermic
The condition of a cold-blooded animal raising or lowering its internal
temperature by exposure to the Sun or another heat source. See Ectotherm.
Eggs
Most, if not all, dinosaurs laid eggs, and many fossilized eggs, egg shells,
and even embryos have been found in dinosaur nests. Some complete eggs
have been found, but most are in bits and pieces. The largest egg found
to date is 10 inches (25 cm long). Eggs were generally laid in sandy nests.
Some nests have been found to contain only one egg, while others contained
more eggs than was possible for a dinosaur to lay, suggesting that perhaps
more than one dinosaur shared the same nest or that the nest was used year
after year. The first dinosaur eggs to be found were of Protoceratops,
but some of the most important eggs found were of Maiasaura, since the
nests in which they were found revealed clues to nurturing behavior in
dinosaurs. It is possible, however, that some dinosaurs gave live birth
to their offspring.
Elmisauridae (Elmisaurids)
Translation: Foot Lizards
Elmisauridae (el-mi-SAW-ri-day) is a rare subfamily of the Maniraptora
theropods. This subfamily had small, lightly-built bodies bearing slim
hands and large feet.
Endotherm
Translation: Inner Heat
An Endotherm (EN-doe-therm) is a warm-blooded animal. Its internal temperature
does not change with the temperature of its environment; it maintains a
constant internal temperature. An endotherm regulates its temperature by
perspiring, panting, and shivering. It is speculated that at least some
dinosaurs may have been endothermic. Some may have been covered with feathers
or even fur, although except in the case of Archaeopteryx, there is no
proof of feathers, much less fur. Why do we believe that dinosaurs were
warm-blooded? Walking upright is one indication. Also being bipedal indicates
speed, high activity and agility. Birds are warm-blooded, and there is
evidence that birds are descended from the dinosaurs. For more information,
see "Warm-Blooded vs. Cold-Blooded" in Theories and Controversies.
See Ectotherm
Endothermic
The condition of being warm-blooded or producing heat internally. See Endotherm.
Eosuchians (Eosuchia)
Translation: Early Crocodiles
Eosuchians (ee-o-SOOK-ee-anz) an order of diapsid reptiles that looked
like crocodiles and could be the ancestors of snakes and lizards. These
carnivores preyed on insects and smaller dinosaurs. They could grow up
to 8 feet (2.4 meters) long.
Euhelopodidae (Euhelopodids)
Translation: Good Marsh Foot
The Euhelopodidae (you-HEL-oh-POE-dih-day) is a newly established family
of sauropods possessing unique features, such as a greater number of vertebrae
in front of the pelvis than any other dinosaur; and a more delicate sauropod
skull. Euhelopodids were similar to the Camarasaurinae, having short skulls
and front legs as long as their hind legs. Members of this group of quadrupedal
herbivores lived during the Late Jurassic Period, and have been found in
China.
Evolve
Evolve means to change slowly. Change is marked in gradual stages and takes
many centuries. Generally, species evolve to meet the conditions of its
environment. When a species ceases to evolve or cannot meet the challenge
of its environment, it becomes extinct.
Extinction
The extinction of dinosaurs 66 million years ago has been the subject of
discussion since their fossils were first discovered. Dinosaurs were the
dominant species for over a hundred million years, yet suddenly (in geologic
terms) they disappeared. For more information, see "Extinction of
the Dinosaurs" under Theories and Controversies.
Eustreptospondylidae (Eustreptospondylids)
Translation: Well-Curved Vertabrae Lizards
The Eustreptospondylidae (you-STREP-tuh-spon-DIH-lee-day) is a carnosaur
family, characterized by long heads and short snouts. Currently, Eustreptospondylus
is the only member of this family, although Piatnitzkysaurus has been proposed
to be a relative. Debate continues on whether Eustreptospondylidae is actually
a genus of Megalosauridae.
Eyesight
Species generally develop the equipment they need to be successful. Good
eyesight is not always necessary, as is demonstrated by the rather limited
vision of the modern rhinoceros, which is near-sighted. Often, good hearing
substitutes for good eyesight. Dinosaurs probably had eyesight as modern
species have eyesight; that is, some species probably had good eyesight,
while others depended on other senses. Herbivores such as the ornithopods
probably had good eyesight. Lacking defenses other than speed, their eyesight
would have allowed them to see trouble approaching early enough to sound
the alarm and escape. As predators, theropods probably had excellent hunting
eyes, quick to detect movement at great distances. Dinosaurs may have had
seen in color. There are several arguments supporting this idea: dinosaurs
appear to have been most active in the daytime, and daytime animals are
generally color-sighted; surviving reptiles that are related to dinosaurs,
such as crocodiles and alligators, are color-sighted; and the only descendents
of dinosaurs, birds, are color-sighted.
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