Outline-1, BIO 3220, Introduction to Comparative Anatomy, Vertebrate Anatomy, and Taxonomy Review


A.  Definition

1. Anatomy– Description and observation of structures

2. Morphology– Relating & interpreting structures

B. Phylogeny– Evolutionary history of a group or structure; Studied via:

1. Paleontology

2. Functional Adaptation/Comparative Morphology

3. Embryology

C. Homology –Shared common ancestry

D. Analogy –Shared common function

E. Homoplasy/Homoplastic Organs– Shared anatomy, but usually not homologous

F. Form vs. Function

1. Darwin’s Natural Selection

2. Adaptation

3. Preadaptation

G. Evolution –Change in gene frequency in a population

1. Divergent –Related

2. Convergent –Not closely related

3. Parallel –Related & isolated

4. Organic –Present species are descendants of previous species

H. Vestigial vs. Rudimentary Structures

I. Ontogeny –Individual’s life history from fertilization to death

J. Heterochrony –Changes in relative RATES of development

1. Paedogenesis –Gonads develop fast

2. Paedomorphosis –Immature features of ancestor become characteristics of future species

3. Neoteny –Type of paedomorphosis in which larval features are retained in the individual


A. Taxonomical Classification

1. Kingdom Animalia

2. Phylum Chordata

3. Subphylum Vertebrata

B. Chordata Characteristics (600 million years ago)

1. Dorsal hollow nerve cord

2. Notochord –“Back – cord” – First skeletal feature in vertebrates which serves as base & support.

3. Pharyngeal gill slits/arches

4. +/- postanal tail

C. The Vertebrates– Largest chordate subphylum, about 50,000 known species.

1. Origins

a. 500 million years ago – Ordovician Period –Origin of the vertebrates.

Refer to Geologic Period Chart.

b. Prochordates [sea squirts, amphioxus=Branchiostoma]

c. Ammocoetes larva

2. Characteristics

a. Vertebral column

b. Bilateral symmetry

c. Ventral chambered heart

d. Closed circulatory system

e. Complete digestive tract

f. Cephalization

1-head holding sense organs and brain


g. Metamerism –Serial repetition

h. Derived from 3 germ layers

i. Multilayered skin

j. Trunk with coelom lined with body wall

k. True brain

l. Cranium

m. Complex muscular system

n. Some have paired pectoral/pelvic appendages

o. Size

p. Thyroid tissue

D. Review of the Classes – Review Zoology notes; Refer to Classification Page

E. Gnathostomes vs. Agnathostomes (Jawed vs. No-Jaw)

Amniotes vs. Anamniotes (Possess Amnion vs. No Amnion)

Homeotherm/Endotherm vs. Poikilotherm/Ectotherm (Steady temp./Generates heat vs. Temp. varies/heat from environment)

Fish vs. Tetrapod