Topic 7: Unikonts IV (Deuterostomes) Flashcards
What are the shared derived characteristics of the deuterostome clade?
radial, intermediate cleavage
coelom forms from archenteron
blastopore becomes anus
What are the shared derived traits of the phylum chordata?
notochord
dorsal, hollow nerve cord
post-anal tail
pharyngeal slits of clefts
What are the derived traits of vertebrates?
bone or cartilage vertebrae that replace notochord
2+ hox clusters
How did vertebrates get more than 2 hox clusters? What is the advantage of this?
complete genome duplication
increased genetic complexity -> more complex body plan
What is the basal vertebrate and it’s characteristic?
jawless fish
cartilage, not bone
What is the SDTs of gnathostomes?
hinged jaw
bony skeleton
4 hox clusters
What is the basal gnathostome? What characteristics do they have?
chondrichthyes - cartilanginous fish
bone only in teeth and fin scales
What is the SDT of Osteichthyes?
Swim bladder (homologous with lungs)
What is the basal clade of osteichthyes?
actinopterygii - ray finned fish
What is the shared derived trait of lobe-fins?
muscular fins/limbs for locomotion
What are the basal clades of lobe-fins?
actinistia
dipnoi
What are the shared derived trait of tetrapods?
4 limbs with digits
neck
fused with pelvic girdle - efficiently transmits forces through body
What are the basal tetrapods?
amphibia
What are the SDTs of amniotes?
amniotic egg
ribcage ventilation
What is an amnion?
membrane that forms fluid filled sac around embryo
What are the derived traits of animals?
mammary glads
give birth to live young
hair, fat layer under skin -> retain heat
What are the three groups of mammals?
monotremes
marsupials
eutherians
What are the basal mammals?
monotremes
What are the characteristics of monotremes?
lay eggs
have hair
produce milk, but no nipples
What are the characteristics of marsupials?
give birth to live young
have nipples
Define placenta
structure for nutrient exchange from mother to embryo
What is the sister to eutherians?
marsupials
What are the characteristics of eutherians?
complex placenta
longer pregnancy than marsupials
complete their embryonic development in uterus
What are the derived traits of primates?
large brain, short jaws grasping hands/feet forward facing eyes high parental care complex social behavior monkeys, apes - fully opposable thumb
