ZOO*2090 - Lecture Flashcards
When was the Early Cambrian?
Around 540 million years ago.
When was the Middle Cambrian era?
Around 520 million years ago.
Give 3 ways the origin of vertebrates can be studied.
- The fossil record ( most direct but a fossilization is a rare event).
- Phylogenetic approach (determine common ancestry).
- Evolutionary developmental biology.
About what time did the earliest vertebrates arise?
Around the same time as the first chordates ( early Cambrian).
In what subphylum are Amphioxus?
Subphylum Cephalochordata (branchiostomata).
In what subphylum are Tunicates?
Subphylum Urochordata.
What is the difference between “Craniata” and Vertebrata?
Craniata is an unranked taxon that included vertebrates and hagfish (even though hagfish only have rudimentary vertebrae, not real vertebrae).
What are the 5 major innovations of the vertebrates?
- Vertebral column
- Head: cranium & brain
- Jaws
- Paired Limbs
- Cleidoic egg
*note: not all species have #3-5, and all innovations are derived.
Label the parts of a vertebral column.
Neural spine, Neural arch, Centrum, Hemal arch, Hemal spine, Intervertebral body, Dorsal hollow nerve cord, blood vessel.
Why is it significant to have a vertebral column?
- Support,
- Protection,
- Muscle attachment/ locomotion
How does the neural tube form?
Migrating neural crest cells push dorsal edges of neural plate together to form a tube.
What is the significance of a head?
- Houses brain
- Allows for brain expansion
- Provides protection
What are Agnatha?
Class. Jawless fishes
ex. hagfishes and lampreys
Describe the evolution of jaws in 3 steps.
- Invertebrates –> used suspension feeding (cilia); ineffective because passive
- Agnatha –> muscular pharyngeal pump made suspension feeding more active + evolution of gills
- Gnathastomes –> evolved jaws and muscular mouth to grab & “chew” food.
What is the significance of limbs?
They allow for better movement.
What is the significance of a cleidoic egg?
- Allows eggs to sit outside of water
- Provides protection outside of water
*Note: to produce hard shells, it took the evolution of many different membranes.
What are tetrapods? Give examples.
Tetrapods –> animals out of water, with limbs.
ex. amphibians (frogs, salamanders), reptilians (snakes, lizards), birds, mammals.
What are Chondrichthyes?
Class. Have jaws.
ex. sharks and rays
What is “Osteichthyes”?
Class. Have jaws.
ex. bony fishes
What is Amphibia?
Class. Have jaws. Tetrapods.
ex. frogs and salamanders
What is Reptilia?
Class. Have jaws. Tetrapods.
ex. snakes, lizards, turtles
What is Aves?
Class. have jaws. tetrapods.
ex. birds
What is Mammalia?
Class. Have jaws. Tetrapods.
ex. mammals
How is diversity made? (aka what are the 3 processes of development).
- Cleavage –> from zygote to multicellular hollow blastula
- Gastrulation & neurulation –> cell movement (formation of multilayer structure)
- Differentiation & organogenesis –> from cell layers to organs