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38 Cards in this Set

  • Front
  • Back
structural complexes that, in some (or all) descendants, have undergone subsequent adaptation to a variety of conditions

ex: an insectivore hand is generalized compared to a bat wing or seal flipper
structure has necessary form & function before "new" biological role arises
Homologous Traits (Between taxa)
# two or more taxa share a feature that is derived from a common ancestry; structures may not look alike & may not function in same way
criteria: similar position, ontogeny, fossil intermediates, genetics?
endostyle of Protochordates & thyroid gland of vertebrates
# share same position
# share same development or ontogeny
# share a similar "special" reaction to iodine
Structural homologs
Analogous Traits (between taxa)
# features on > 2 or more taxa have a common function
# features do NOT have to look alike to perform same function
# features may or may not have a shared ancestry
Serial Homology (within taxon)Sexual Homology (within taxon, between sexes)
* segmented (metameric) structures share common development, design & function
* e.g. vertebrae, branchiomeric muscles in gills# ome reproductive organs share a common embryonic tissue origin& development during indifferent (undifferentiated stage)
# e.g. gonads (testes & ovaries)
Shared, Derived trait
* Define - absent in ancestor but shared by some of the related descendants, but not other descendants
* Use - forms subsets within descendants; key role in tracing phylogeny
# Taxa - all Animalia
# Shared, Derived Traits

* multicellular
* heterotrophic - can't use sunlight to get energy
* lack cellulose cell walls outside of cellular membrane
* early embryo forms a hollow ball called a blastula
* sperm have flagella
# Taxa - Nematoda, Platyhelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata +
# Shared, Derived Traits

* Triploblastic
o 3 germ (embryonic tissue) layers of ectoderm, mesoderm, endoderm
* Bilateral Symmetry
o body shows cephalization, a head end
o body has 3 principal body axes; longitudinal (anterior-posterior), dorsal-ventral, & lateral (left-right)
# Taxa - e.g. Annelida, Arthropoda, Mollusca & others + Echinodermata, Hemichordata, Chordata
# Shared, Derived Traits

* Complete Gut
o digestive system continuous from a mouth to anus
* Coelom present
o cavity lined by mesodermal membranes that produce fluid to reduce friction during organ movement
o body forms a tube (gut) within a tube to isolate trunk & gut movement
o examples - pleural, pericardial, peritoneal membranes
# Taxa - Echinodermata, Hemichordata, Chordata
# Shared, Derived Traits

* Indeterminate Cleavage
o first few cell divisions of fertilized egg are not yet "programmed" to develop into specific tissues
o early on, each cell can produce a complete individual
* Radial Cleavage
o cell divisions occur in same planes through animal to vegetal pole
o divisions extend out from a central axis & line up on top of each other
* Deuterostome
o embryonic blastopore (first opening) becomes anus
o i.e. true mouth forms later at opposite end of embryo
* Enterocoelous coelom
o coelomic mesoderm folds inward as pockets off of endoderm; varies in some descendants
* Mesodermal internal skeleton
Phylum Chordata
Living Taxa?
Urochordata, Cephalochordata, "Vertebrata"
Chordate Shared, Derived Traits
# Notochord [noto = back]

* long rod forms above dorsal wall of gut; 1st skeletal support system
* flexible, "gel-filled" cells covered with fibrous & elastic tissue layers

# Dorsal hollow nerve cord

* forms from ectoderm - described in embryology chapter

# Pharyngeal gill arches

* expanded anterior portion of gut
* shares dual functions - digestive & respiratory
* earliest taxa - small filter feeders
o trapped small particles of food in mucus
o used cilia to move water over gill arches
o some gas exchange occurs across gill arches, but most gas exchange in skin

# Endostyle

* ciliated groove in floor of pharynx used to track food particles into the gut
* attracts iodine & is in same location & shares iodine function with thyroid of vertebrates
* homologs to endostyle = subpharyngeal gland of lamprey larva = thyroid gland of adult craniates

# Post-anal tail

* locomotory device "behind" body, more efficient position
* has v-shaped muscle segments (myomeres) to provide force
Influence of Paedomorphosis in Craniata/Vertebrae
* Urochordate Life Cycle
o juveniles are free-swimming larvae with long tails & obvious notochord
o adults are sessile/attached to substrate & have lost notochord & tail
* Hypothesized "Vertebrate" Origins
o alternation of developmental stages or life history of ancestor like Urochordata
o "vertebrates" retained some larval Urochordate characteristics into adult stage
o paedomorphosis - refers to special type of alteration in life cycle - next lecture
Clade Craniata
Shared, Derived Traits?
axa - Myxini, Cephalaspidomorphi, all gnathostomes

Cranium, INcreased Brain size, Muscular Pharynx for feeding/gas exchange, debated:True Bone
Clade Vertebrata
Shared, Derived Traits?
Taxa - Cephalaspidomorphi, & all gnathostomata

Vertebrae, 2 pair of semi circular ear canals, Large Eyes
Clade Gnathostomata
Shared, Derived Traits?
Taxa - Placodermi, Acanthodii, Chondrichthyes, Actinopterygii, Sarcopterygii & all Tetrapoda


* cartilage or bony support for mouth - more food intake

Paired appendages

* presence of both pectoral & pelvic paired fins
* improved control over locomotion & aided prey capture

3 pairs of semi-circular ear canals

* added 1 pair of horizontal semi-circular canals
* 3 canals allow detection of acceleration in all 3 body planes
OSTEICHTHYES [oste = bone, ichthy = fish = bony fishes]
# Taxa - Actinopterygii (ray-finned fishes), Sarcopterygii (lobe-finned fishes) & all Tetrapoda
# Trait - presence of lung or swim bladder (in most; may be lost in some Actinopterygii)
SARCOPTERYGII [sarco = flesh, pteryg = fin]
* Taxa - Sarcopterygii (lobe-finned fishes) & all Tetrapoda
* Trait - serial arrangement of bones/cartilages extending far into fin or limbs
TETRAPODA [tetra - four, podo- foot]
# Taxa - Batrachomorpha, Lissamphibians (living amphibians - frogs, salamanders..), & all Amniota
# Traits

* 4 limbs (on most)
* digits or true separate toes/fingers on limbs, if limbs are present
AMNIOTA [amni = fetal lamb; embryonic membrane]
# Taxa - all Sauropsida (Testudines & all Diapsida) & all Synapsida
# Traits

* unique, new extra-embryonic membranes present - the amnion, chorion & allantois
* epidermal scales or hardened stratum corneum covers entire body; skin is dry
* true claws (or claw derivatives) present on digits
Myxini [myx = mucous]
# Taxa - hagfish
# Traits

* eyes primitive, simple & very small
* lacks true vertebral elements
Cephalaspidomorphi [cephal = head, aspid = shield]
# Taxa - lamprey & some fossil taxa
# Traits

* simple vertebral elements - cartilaginous
* larger eyes, more complex ear
Placodermi* [placo = a plate, derm = skin]

* "armored" fishes, many have large dermal plates over head
* unique "teeth" - dermal bones form long cutting edges or "blades" & sharp points
Chondrichthyes [chondr = cartilage, ichthy = fish]
taxa, traits, kind of scales?
# Taxa: shark, skates, rays, ratfish
# Traits

* completely cartilaginous skeleton (may have calcium deposits to harden cartilage)
* placoid scales or tiny "denticles" with projecting tips that feel like sandpaper
* teeth are enlarged placoid scales that are attached to skin & not jaws
* 5-7 pairs of long gill slits usually visible in most (ratfish have a fleshy operculum covering the gills)
* broad, thick, flat paired fins
Actinopterygii [actino = ray, pteryg = fin; ray-finned fishes]
# Taxa - "bony fishes; a misnomer because some of these have partly cartilaginous skeletons

* e.g. salmon, sturgeon, gar, bowfin (Amia), perch, flounder, etc.

# Traits

* bony operculum covers gills
* flexible fin rays made of tiny overlapping bony scales
* a few small bones support base of fin
Sarcopterygii [ sarco - fleshy or lobe finned fishes]
# Taxa - lung fishes & coelacanth; most species are extinct
# Traits

* bony operculum covers gills
* fins contain series of long, "jointed" bones that extend vertically into fin
* muscle associated with these fin bones extends into distal areas
Stegocephali or "Labyrinthodontia" [labyrinth = maze, folded, dontia = teeth]

* some had specialized highly grooved teeth (labyrinthine)
* high otic notch ("ear" opening) in skull angles downward toward brain
Lissamphibia [liss = smooth, amphi - double - refers to dual water & terrestrial adaptations]
# Taxa - frogs, salamanders, caecilians = apodans or legless amphibian
# Traits - most lack dermal or epidermal scales, skin is smooth & moist

* [an = without, apsi = juncture]
Trait - no openings in temporal regions of skull; ear canal in typical "low" postion
NOTE: paraphyletic group!!!
Testudines or Testudomorpha
# grouping uncertain, not closely related to stem amniotes; perhaps related to either lepidosaurs or archosaurs??
# Taxa - turtles, tortoises
# Trait - bony armor around trunk forming a solid dorsal & ventral shell
Lepidosauria or Squamates [lepido = scale, sauri = lizard]
# Taxa - lizards & snakes, tuatara
# Traits -

* modified diapsid skull with 1 or 2 of the arches of bone lost to make skull kinetic
* specialized epidermal scales (see skin lab)
* transverse cloacal slit & hemipenis in males
Archosauria [archo = ruler, chief, sauri = lizard]
# Taxa - alligator, crocodile, caiman & gavial
# Traits

* diapsid skull that retains 2 distinct temporal arches of bone
* anteorbital fenestra is shaped like an inverted triangle
Aves [avi = bird]
* Taxa - birds
* Traits
o feathers?? possibly in some fossil dinosaurs??
o arms modified into wings
o modified diapsid skull - retained lower arch of bone, lost upper arch & opened fossa to the eye socket
Synapsida* [syn = together, apsi = juncture]
* Trait - synapsid skull (1 temporal opening)
includes synapsida and mammalia
Prototheria [proto = first]
* Taxa - monotremes & spiny anteaters
* Trait - egg-laying mammal; epipubic bones

Metatheria [meta = boundary]
* Taxa - opossum & all other marsupials
* Traits - mammal with very short gestation placenta; epipubic bones
Eutheria [eu = good, true ]
# Taxa - "placental mammals"
# Traits - longer gestation placenta than marsupials; single vagina