Glossary I
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Iberomesornis
Thought to have been one of the earliest of its kind, this small carnivorous
bird lived in the Early Cretaceous period. Although it had feathers and
a breast bone like modern birds it still had the teeth and claws of its
reptilian ancestors
ICAROSAURUS
Icarosaurus siefkeri was an early gliding reptile (a lepidosaur) that
lived during the Triassic period, roughly 175 to 200 million years ago.
It was 7 inches long and had a 10 inch wingspan. [Coelurosauravus is another
gliding reptiles that lived 250 million years ago, long before Icarosaurus.]
A single fossil of Icarosaurus was found in Granton Quarry, North Bergen,
New Jersey, USA 1960 by Alfred Siefker and Michael Bandrowski. Icarosaurus
was described by Edwin Harris Colbert in 1961.
ICE AGE
An ice age is a time lasting thousands of years during which the Earth
is very cold and largely covered by ice and glaciers.
ICHNITES
(pronounced IK-nites) Also known as trace fossils or ichnofossils, these
are fossilized footprints, nests, dung, gastroliths, burrows, stomach
contents, etc., but not actual body parts. Ichnofossils record the movement
and behavior of animals. Ichnology is the study of ichnites.
ICHNOFOSSILS
Also known as trace fossils or ichnites, these are fossilized footprints,
nests, dung, gastroliths, burrows, stomach contents, coprolite, etc.,
but not actual body parts. Ichnofossils record the movement and behavior
of animals. Ichnology is the study of ichnofossils.
ICHNOGENUS
Ichnogenera (meaning: "footprint groups") are groups of dinosaurs
whose characteristics are surmised only from their fossilized footprints.
When dinosaur trackways are found, it is nearly impossible to determine
which dinosaur genus made the prints, so the prints are given a new genus
name, an ichnogenus. Some ichnogenera include
1. Theropods (bipeds with relatively long, narrow toes ending in claws):
Eubrontes (early Jurassic), Grallator and Coelurosaurichnus (late Triassic),
Carmelopodus (middle Jurassic), Anchisauripus (late Triassic to early
Jurassic period), and Megalosauripus (late Jurassic).
2. Prosauropods:Tetrasauropus (late Triassic), Pseudotetrasauropus (late
Triassic), Otozoum.
3. Sauropods (quadrupeds with 5-toed, elephant-like feet; the inner three
or four toes had claws): Brontopodus.
4. Ornithopods (bipeds or quadrupeds with wider tracks and hoof-like claws):
Anomoepus, Amblydactylus (a hadrosaur).
ICHNOLOGY
Ichnology is the study of fossilized footprints and other ichnofossils.
ICHTHYORNIS
(pronounced ik-thee-ORN-is) Ichthyornis (meaning: "fish bird")
was an 8 inch (20 cm) long, tern-like, extinct bird that lived during
the late Cretaceous Period (135-70 million years ago). It had a large
head, toothed jaws, and long beak. This powerful flyer is the oldest-known
bird that had a keeled breastbone (sternum) similar to that of modern
birds. It lived in flocks, nested on shorelines, and hunted for fish over
the seas. Ichthyornis was originally found in 1872 in Kansas, USA, by
a member of paleontologist Othniel C. Marsh's Yale University expedition.
Ichthyornis was named by Marsh in 1872. Fossils have been found in Kansas
and Texas, USA and Alberta, Canada. (Subclass Odontornithes, Order Ichthyornithiformes)
Ichthyosaur
A group of marine fish-shaped carnivorous reptiles. They had flippers
that were derived from a reptilian forelimb, and whale-like flukes on
its tail. Ophthalmosaurus was an ichthyosaur.
ICHTHYOSTEGA
Ichthyostega were terrestrial tetrapods (having four-legs) that lived
during the late Devonian period. These are the first tetrapods known to
have ventrured onto land. These vertebrates were up to about 4 ft (1.5
m) long; they had a wide body, a fish-like skull, four strong, short legs,
a massive ribcage, and a finned tail. Adults had no gills. Fossils have
been found in East Greenland. Ichthyostega were between fish and amphibians.
IGNEOUS ROCK
When molten rock cools, igneous rock is formed.
Iguanodon
This large four legged herbivore lived in the Early Cretaceous period
and formed large migratory herds. Iguanodon was a successful species which
seems to have evolved teeth for chewing, and a vicious thumb spike with
which to catch predators unawares.
IGUANODONTIDS
(pronounced ig-WAHN-oh-DON-tids) Iguanodontids (family Iguanodontidae,
also called Iguanodonts) were large, plant-eating, ornithischian ornithopods
who lived from the late Jurassic to the late Cretaceous periods. These
dinosaurs had a thumb spike, a toothless beak, a long snout, long toes,
and a bulky tail. Altirhinus, Iguanodon, Camptosaurus, Ouranosaurus, Probactrosaurus,
Tenontosaurus (perhaps a hypsilophodontid), and Valdosaurus were iguanodontids.The
Iguanodontids led to the Hadrosaurids (duckbills).
ILIUM
(pronounced ILL-ee-um) The ilium (plural ilia) is a bone that is part
of the hip, or pelvic girdle.
IMPACT CRATER
Impact craters are the remains of collisions between an asteroid, comet,
or meteorite and the Earth. Some large impact craters include the Chicxulub
crater (off the Yucatan peninsula) and the Shiva crater (off the coast
of India), both of which date from the K-T boundary, 65 million years
ago, and were probably implicated in the K-T mass extinction.
INCERTAE SEDIS
An incertae sedis is a taxonomic name that is uncertain.
Incisor teeth
The cutting teeth that lie at the very front of the jaws of mammals and
mammal-like animals.