Comparative Anatomy I Flashcards
Chordates comprise 3 subphyla that make up the phylum chordata. What are the 3 subphyla?
Cephalochordata (amphioxus)
Urochordata (sea squirts)
Vertebrata
What are the 2 superclasses of subphylum vertebrata?
Pisces
Tetrapods
What does the Pisces superclass of subphylum Vertebrata include?
All fishes, extant and extinct
What does the Tetrapods superclass of subphylum Vertebrata include?
All tetrapods, both extant and extinct
What is characteristic of Agnathans?
They lack jaws and paired appendages
The group of Agnathans includes both extinct ostracoderms and living marine hagfishes and marine and freshwater lampreys. Ostracoderms are the oldest known vertebrates. During what period did they first appear?
Cambrian
What subgroup of Pisces do placoderms belong to? What is unique about these?
Gnathostomes - first vertebrates with jaws. All placoderms are extinct
All vertebrates other than _________ possess jaws
Agnathans
What are the four major anatomical features that an animal must possess in order to be included in the phylum Chordata?
Dorsal hollow nerve cord
Pharyngeal “gill” slits, arches, and pouches
Notochord
Post-anal tail
[the first 3 are considered “the big 3”]
True or false: the “big 3” anatomical features necessary to be considered phylum chordata do NOT have to be present in adult, but they must be present in embryo or larva
True; adult sea squirts have a notochord in the tail in the larval form, but it is lost in the sessile adults
What anatomical feature is only found in vertebrates?
The vertebral column
What 2 individuals contributed to the theory of natural selection?
Charles Darwin
Alfred Russel Wallace
______________ refers to similarity in function in structures in 2+ species. Although the function is similar, neither the anatomy nor the embryological development is similar.
Analogy
__________ refers to structural similarity uniquely evolved (due to inheritance from a common ancestor or developed from a common embryonic anlage). Anatomy and development are similar, but function does not have to be similar.
Homology
A dolphin fin and a carp fin are an example of ____________ structures
Analogous
A dolphin fin and a lizard arm are considered ____________ structures
Homologous
Diapsid dinosaurs are classified into 2 groups based on what?
Pelvic girdle
What are considered the bird-hipped dinosaurs?
Ornithischians
What are considered the lizard-hipped dinosaurs?
Saurischians
The outermost layer of the vertebrate integument is the epidermis, which is derived from what germ layer?
Ectoderm
What type of epithelium is the epidermis?
Stratified squamous
Is the epidermis innervated? Is it vascularized?
It is innervated but not vascularized
The dermis layer of the vertebrate integument is derived from what germ layer?
Mesoderm
What type of tissue is the dermis?
Irregular, dense fibrous connective tissue
What characteristic of the epidermis is unique to vertebrates? [BOLD]
The stratified nature of the epidermis is unique to vertebrates
[other animals have no more than a simple epithelium in their integument]
In fishes, the dermal derivatives (scales) are usually much more developed and complex than the epidermal derivatives. The integument of the first vertebrates was __________, a characteristic which would be detrimental for a terrestrial lifestyle
Armored
What were the specific integumentary terrestrial adaptations from the first vertebrates to amphibians?
Armor tended to disappear
Skin became softer and smoother, which put them at risk for dessication because it was less adapted for water conservation
In amphibians, the epidermis became more complex and culminated in the formation of what epidermal layer?
Keratinized stratum corneum
What is the outermost layer of the integument and in what species did it first appear in? [BOLD]
Stratum corneum
First appeared in amphibians
The stratum corneum first appeared in amphibians, but it became extremely well-developed in __________
Reptiles
What are the benefits to a highly well-developed stratum corneum?
Reduces water loss, and also the necessity for many epidermal glands
What is the major derivative of the stratum corneum in reptiles? [BOLD]
Epidermal scales
What are the major epidermal derivatives/hallmarks of avian integument? [BOLD]
Feathers
[also note that birds have relatively thin skin with a well-developed stratum corneum]
What do the designations of thick skin vs. thin skin refer to?
This designation refers to the complexity of the epidermis and not to the overall thickness of the skin
“Thick skin” (which may be thinner than some skin elsewhere on the body) is ONLY found on palms of hands and soles of feet
Describe the regional variation of the vertebral column in fishes (what 2 types do they have and do these have hemal arches?)
Precaudal - include all the more cranial vertebrae that lack a hemal arch
Caudal - include all the vertebrae caudal to the precaudal vertebrae; these possess hemal arches
What part of the amniote vertebra functionally replaces the notochord?
Centrum
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum that is concave at both ends?
Amphicoelous (some reptiles)
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where only the cranial end is concave?
Procoelous (most reptiles)
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where only the caudal end is concave?
Opisthocoelous
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where both ends are flat?
Acoelous (mammals)
Describe regional variation in amniote vertebrae (what 4 types do we have?)
Cervical
Trunk (thoracic and lumbar)
Sacral
Caudal
How many cervical vertebrae do almost all mammals have?
7
In what species does the atlas/axis complex first appear? [BOLD]
Reptiles
In what 2 ways do sacral vertebrae articulate with the ilium? [BOLD]
Directly or via sacral ribs
What type of amniote vertebrae are variable with hemal arches? [BOLD]
Caudal
The pectoral girdle is composed what 2 components?
Dermal and endochondral