Glossary Of Paleontology/Geology Terms

aragonite

An unstable form of crystalline calcite (CACO3) used by most cephalopods as material for the shell.

ammonite

Common name for all the Ammonoidea. Only used here to describe the highly evolved Phylloceratina, Lytoceratina, Ancyloceratina, and Ammonitina.

ammonoidea

An major group of cephalopods, extinct since the end of the Cretaceous period. Characterized by a more complex suture line than the nautiloids or coleoids.

artiodactyla

Ungulate whose weight is carried by the 3rd and 4th toes. Includes pigs, deer, antelopes, sheep, goats, hippos, and cattle. These animals have extra "stomachs" in front of the regular stomach to allow fermentation of cellulosic fiber prior to completion of digestion.

body chamber

The living chamber. Connected to the buoyancy chambers by the siphuncle. The final, outermost chamber where the animal lived open to the sea.

coleoidea

Of the three major groups of cephalopods, the one with the most living members. Includes squids, octopus, and cuttlefish. The extinct belemnites were also coleoids.

coprolite

Fossilized animal dung.

dorsal

The dorsal surface of the whorl of a cephalopod shell is the surface towards the center of the spiral.

endogastric

Coiling over the dorsal surface of the shell. Nautilus and ammonites normally coil endogastrically.

exogastric

Coiling under the ventral surface of the shell. Coleoids commonly coil exogastrically.

lacustrine (deposits)

Sediments formed in fresh water areas.

lobe

A part of the ammonoidea suture line. A septum lobe points towards the previous or posterior suture line.

meristics

A series of measurements on a fish, such as scale or fin ray counts, which are used to differentiate species of fish.

monophyletic

A group of related organisms including the most recent common ancestor and all descendants of that ancestor. Also called a "clade."

morphology

The form and structure of an organism.

nautiloidea

The earliest and most primitive of the three major groups of cephalopods. A few species, such as Nautilus pompilius survive.

orogeny

A natural mountain building event.

perissodactyla

The odd toed ungulates. Some having only one toe to bear the weight. Includes horses, tapirs, and rhinoceroses. These animals ferment the cellulosic fiber they eat in the hind-gut or intestines.

phragmocone

The chambered (camerated) part of the cephalopod shell. Preceeds the body chamber.

primate

Generalist mammals with distinguishing characteristics that include: Mobile shoulder joints, 5 digits with opposable thumbs, forward facing eye sockets enclosed in bone, a complex visual system including stereoscopic vision, and an enlarged cerebral cortex.

pterygiophore

Cartilage or bone structure supporting fin rays or spines. Erector and depressor muscles are attached to the pterygiphores.

saddle

A part of the ammonoidea suture line. Points towards the next (anterior) suture line.

septum

Transverse partition dividing shell into camerae, attached to inside of shell wall along suture line.

siphuncle

The thin tubular extension from the back of nautiloids and ammonoids. Passes through each chamber and, by regulating the water and gas levels in the chambers it passes through, allows the animal to regulate bouyancy.

standard length

In fossil fishes, the distance from the most forward part of the head to the end of the vertebral column.

suture line

In ammonites, the pattern made by the lobes and saddles around the edge of a septum. Related ammonites have similar suture patterns. Used as an aide in classifying ammonites.

umbilicus

The recessed center of an ammonite or nautilus shell.

ungulate

Having hooves, such as horses, deer, ETC.

ventral

The ventral surface of the whorl of a cephalopod shell is the surface towards the outside of the spiral.