Chapter 1 - Terminology and Chordates

Cranial

Toward the head.

Caudal

Toward the tail.

Rostral

Toward the nose (especially in the head).

Dorsal

Toward the back.

Ventral

Toward the belly/front.

Medial

Toward the midline.

Lateral

Away from the midline.

Proximal

Closer to the body core (limbs).

Distal

Farther from the body core.

Anterior

Toward the front.

Posterior

Toward the rear.

Superior

Toward the head.

Inferior

Toward the feet.

Sagittal Plane

Divides the body into left and right.

Mid-sagittal Plane

Equal left/right halves along the midline.

Parasagittal Plane

Unequal left/right, parallel to midline.

Frontal Plane

Divides body into dorsal/ventral (front/back).

Transverse Plane

Divides body into cranial/caudal (top/bottom).

Carpus

Equivalent to the human wrist.

Stifle

Equivalent to the human knee.

Hock

Equivalent to the human ankle.

Elbow

Similar location/function as in humans.

Notochord

Flexible rod used for support in chordates.

Pharyngeal slits

Openings in the throat region of chordates.

Endostyle/Thyroid gland

Involved in metabolism in chordates.

Dorsal hollow nerve cord

Central nervous system structure in chordates.

Post-anal tail

Tail extending beyond the anus in chordates.

Homology

Shared ancestry, illustrated by tortoise foot vs. turtle flipper.

Analogy

Same function, different ancestry, as seen with bird vs. bat wings.

Homoplasy

Similar appearance not necessarily indicating function or ancestry.

Radial Symmetry

Symmetrical around a central axis.

Bilateral Symmetry

Left/right halves are mirror images.

Taxon

A named group of organisms.

Natural Taxon

Based on evolutionary history.

Artificial Taxon

Grouped by traits, not evolutionary lineage.

Sister Group

The closest relative to a taxon.

Monophyletic

Includes an ancestor and all its descendants.

Paraphyletic

Includes an ancestor but not all its descendants.

Polyphyletic

Group lacking a common ancestor.

Extinct

No living members.

Extant

Still existing.