Flashcards in Phylogeny and diversity - Part 1 Deck (44)
What is the difference between extinct and extant species?
Extinct species are dead.
Extant species are currently living.
Why do we care about extinct species?
Some of the extinct groups existed for longer than we have.
They laid down the foundation for what we see in extant species.
Fish vs. fishes.
Both are plural.
Fish - when talking about multiple individuals of the same species.
Fishes - if talking about lots of different fish species.
What are chordates.
At some point in development had a notochord, dorsal hollow nerve cord, pharynx with slits, postanal tail and myomeres for locomotion.
Is a hagfish a fish?
Why is there debate?
It is not a vertebrate but it is indeed a chordate.
What are the different fish groups?
Ostracoderms, Hagfish, Lampreys, Placoderms, Chondricthyes,
Important for a few reasons:
1 - probably gave rise to the current, bony fishes
2 - first animal to develop true bone as external armour
3 - major evolutionary advance, filter feeders
Fish, extant, no bone just cartilage
Evolutionary option that didnt lead to anything
6 separate hearts
Been here for a while, didnt lead to anything
No bone but has a vertebral column
Which groups are part of the Agnathans classification? What does this mean?
(most likely a monophyletic grouping)
What do the other groups fall under? What does this mean?
Gnathostomes - not a phylogenetic lumping like Agnathans
major predator in their time
true bone of ostracoderms was probably a defense against these guys
fully movable jaws
didnt lead to anything evolutionarily
may be related to sharks
most common fossil
Sharks and rays
Cartilaginous, no bone
Two separate subgroups
- sharks and rays
True class, all related phylogenetically
What does Osteichthyes mean?
true bony fish
True bone in the skeleton
first to evolve bony skeletal support
Gave rise to tetrapods
lobe-finned (muscular and skeletal support in fin)
skeletal support in body (not in fin)
probably led to diversification of multiple species
What are the advantages of ray fins?
More flexible, allow good swim control and maneuverability
Where did the first fish come from?
Conodonts - cone-tooth
Conodont was probably a _____-_____. (how it eats)
Why do we only care about the Devonian Age?
age of fishes
before this, probably had conodonts becoming fish
at the end of the devonian, all the major groups of fish had evolved
at the end of the devonian, started seeing tetrapods
What drove fish diversification?
Evolution of land plants.
Describe how the evolution of land plants could have led to the diversification of fish.
Increased productivity brought about by land plants drove fish to move to coastal water, opening up new habitats and driving diversification.
What are the key characters needed to become a tetrapod?
1 - Evolution of a neck
2 - Dorsal eyes
3 - enhanced rib cage
Describe roughly what the first proto-tetrapod characteristics would have been.
Lived in water, respired by gills, didnt have lungs, still had scales, had fins.
What was new was the neck, dorsal eyes and heavy ribs.
What was most likely the first proto-tetrapod?
What were the key benefits for the neck for Tiktaalik?
No longer had an operculum but a neck, could look left and right and scan the evnironment for food/predators while swimming ahead.
What were the key benefits of dorsal eyes for Tiktaalik?
Since it now lives in shallow water, wants to eat prey, mainly inverts above it, allows it to find them.
What were the key benefits of a heavy rib cage for Tiktaalik.
Needed to support itself using its lobed-fins in shallow water with head outside the water scanning the environment.
Lots of pressure on the chest. Gravity acts on the organs.
Heavier pectoral girdle protected its internal organs during its scavenging activities.