Chapter 1 - Terminology and Chordates
Term | Meaning |
|---|---|
Cranial | Toward the head |
Caudal | Toward the tail |
Rostral | Toward the nose (esp. in 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 |
Plane Description
Sagittal Divides body into left and right
Mid-sagittal Equal left/right halves along midline
Parasagittal Unequal left/right, parallel to midline
Frontal Divides body into dorsal/ventral (front/back)
Transverse 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
Horses have elongated limbs and specialized joints for running
All chordates share these features at some stage:
Notochord: Flexible rod for support
Pharyngeal slits: Openings in the throat region
Endostyle/Thyroid gland: Involved in metabolism
Dorsal hollow nerve cord: Central nervous system structure
Post-anal tail: Tail extending beyond the anus
Concept | Description & Example |
|---|---|
Homology | Shared ancestry (e.g., tortoise foot vs. turtle flipper) |
Analogy | Same function, different ancestry (e.g., bird vs. bat wings) |
Homoplasy | Similar appearance, not necessarily function or ancestry (e.g., ear tufts vs. ears) |
Radial Symmetry | Symmetrical around a central axis |
Bilateral Symmetry | Left/right halves are mirror images |
Taxon | Named group of organisms |
Natural Taxon | Based on evolutionary history |
Artificial Taxon | Grouped by traits, not evolutionary lineage |
Sister Group | Closest relative to a taxon |
Monophyletic | Includes ancestor and all descendants (a clade) |
Paraphyletic | Includes ancestor but not all descendants |
Polyphyletic | Group without a common ancestor |
Extinct | No living members |
Extant | Still existing |