Classification of Life Forms

Until the 19th century, people thought life forms came in only two kinds: plants and animals. Scientific study revealed that concept too simplistic. Now we have five or six main groups (kingdoms) and the scientists are still debating if that is enough or divided correctly. Classification of life forms is an ongoing problem. Take the viruses, they are not technically alive but often act like they are, so some people give them their own kingdom.

Anatomical Directions

for a quadruped

Anterior = down, towards the belly

ventral = the trunk section; used interchangeably with anterior

palmar = in the hand; replaces anterior in the fore limbs

plantar = in the foot; replaces anterior in the hind limbs

Posterior = up, towards the back

dorsal = in the trunk section, hand, and foot; used interchangeably with posterior

Superior = in a relationship, the part that is nearer the head (proximal)

Inferior = in a relationship, the part that is nearer the tail (distal)

Proximal (superior) = in a relationship, nearer to a point - in a limb that point is the body

Distal (inferior) = in a relationship, farther from a point - in a limb that point is the body

Medius = the middle, a position between upper and lower or between anterior and posterior

Median =  a plane which divides the body into a right and left half

Medial = in a relationship, nearer the median plane

Lateral = in a relationship, farther away from the median plane

Sagittal = a plane through any portion of the body parallel to the median plane

Coronal = a plane which is perpendicular to the median plane

Intermediate = a position between lateral and medial

Superficial = near the skin

Deep = not near the skin

Glossary

Anapsid – see "Tetrapod Skull Design"

Articulate – a series of bones that are not scattered by predation or water.

Cladogram – see "Questions About Fossils"

Diapsid – see "Tetrapod Skull Design"

Digitigrade stance – metatarsals are held off the ground (walks on point) (like Sauropods and elephants)

Eukaryotic Cells – all protists, fungi, plants, and animals = all life except bacteria and archaeans

Euryapsid – see "Tetrapod Skull Design"

Fossil – see "Questions About Fossils"

Gubbio section – geologic layers near Gubbio, Italy.  It contains the K/T layer studied by the Alvarez’s.  The thin clay layer contains 30 times the iridium of those around it.

Hot-Spot Theory – see "Geologic Forces"

Iridium – a rare element in the Earth’s crust but rich within micrometeorites, which rain into our atmosphere constantly.  It can be found in small amounts in volcanic gas.

Magnetic Field – see "Geologic Forces"

Ornithischian – means bird hipped - Hadrosaurs, Pachycephalosaurs, Ceratopsians, Ankylosaurs, and Stegasaurians

Parallel (or Convergent) Evolution – see "Questions About Fossils"

Plantigrade stance – entire foot (toes to ankle) lands on the ground (like most reptiles and humans)

Plate Tectonics – see "Geologic Forces"

Saurischian – means lizard hipped - Theropods (including birds), Segnosaurs, and Sauropods

Sauropsid – reptiles - Two fenestra (holes) behind the orbits: includes all reptiles and their decedents; Archosaurs, lizards, snakes, crocodiles, dinosaurs, birds.

Semi-digitigrade stance – only the ankle is held off the ground (like T. rex and dogs)

Shocked quartz – microscopic, parallel defects produced by a strong shockwave.  It has only been found in nuclear explosions, projectile impacts in laboratory tests, and meteorite impacts.

Shocked Zircon – crystals in the layer dating to 400 million years old that have gone through a considerable shock and thermal event

Synapsid – One fenestra (hole) behind the orbit: includes all Pelycosaurs and all their decedents; Therapsids and mammals.  see "Tetrapod Skull Design"

Tektites – made of oceanic basalt particles heated and melted as they fly through the air.  Tektites are produced through impact only.

Trap – means “stair steps” – refers to the stacked layers of lava from successive flood basalt flows.