Glossary DIC - DIN
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DAC - DEI - DIC - DIN - DOR - DRY
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, herbivore
therapsids with two large tusks in the upper jaw. They lived during the
late Permian and Triassic periods.
Didelphodon
This small, four legged omnivore lived in the Late Cretaceous period.
It inhabited forests and river valleys, hunted at night and lived in a
burrow. It was an early marsupial, or pouched mammal, and looked like
a modern opossum.
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 400 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.
Dinilysia
An Early Cretaceous snake. Snakes only evolved towards the end of the
age of the dinosaurs but they survived the extinction in the Late Cretaceous
and are still with us today.
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.