questions well answered
Be able to explain the saying "ontogeny recapitulates phylogeny (modern version) and give an
example. - correct answer ✔✔ proposed by Haeckel in 1866 and stated that all vertebrates pass
through early stages of development in which they resemble each evolutionary ancestor.
Ex: embryo heart resembles fish heart (sinus venosus, atria, ventricle, truncus arteriosus),
pharyngeal slits
indicate the possible evolutionary relationships between the tunicates, Amphioxus
(cephalochordata), and echinoderms - correct answer ✔✔ Chordates evolved from ancient
echinoderm. evolved into tunicates after the loss of tentacles and formation of pharynx with gill
slits and tailed larva. The larva of tunicate gained ability to reproduce without adult stage and
created amphioxus.
list the 3 distinguishing characteristics of chordate animals and the additional characteristics of
vertebrates - correct answer ✔✔ notochord, dorsal nerve cord, and pharyngeal slits.
Vertebrates have all three as adults in fish, but notochord and pharyngeal slits are only found in
embryos of reptiles, birds, and mammals. other characteristics of most vertebrates are paired
appendages (except lamprey) and a heart and liver that develop ventral to the digestive tract
distinguish between the term chordate and vertebrate and give examples of chordate animals
that are not vertebrates - correct answer ✔✔ Both chordates and vertebrates contain a nerve
cord, pharyngeal slits, and a post anal tail at some point in their life. The main difference is that
some chordates do not have a vertebral column whereas all vertebrates have a vertebral
column. tunicates and amphioxus are chordates but not vertebrates
give reasons (based on anatomy and/or embryology) why the tunicates and amphioxus are
believed to resemble the ancestors of vertebrate animals - correct answer ✔✔ many of these
, ancestors evolved from larval stages that developed sex organs without metamorphosis. There
are many larval stages of vertebrates today that resemble past ancestors
distinguish between the following terms:
Agnathastome vs gnathostome
fish vs tetrapod
anamniote vs amniote - correct answer ✔✔ agnathastome: no gaws
gnathostome: jaws
fish: water
Land: tetrapod
Anamniote: water
amniote: land
describe the general evolutionary relationships between various fish groups, amphibians,
reptiles, birds, and mammals; which group appeared the most recently - correct answer ✔✔
first fish were agnathans (& ostracoderms). then they gained jaws (gnathostomes). the largest
line of jawed fish are osteichthyes which includes lobe and ray finned fish. lobe finned lung fish
evolves into amphibian. then amniotic eggs formed and allowed verts to move away from water.
amphibian line evolved into synapsid (towards mammals), anapsid (towards turtles) or diapsid
(which led to dinos and birds). birds have appeared the most recently
indicate the important characteristics of ostracoderms, placoderms, chondrichtyhes and
osteichthyes fish - correct answer ✔✔ ostracoderms: flattened, external armor, filter feeders,
no paired appendages
placoderms: paired appendages, jaws, naked body
chondrichtyhes: internal skeleton composed entirely of cartilage
osteichthyes: internal skeleton of bone