Phylogeny and diversity - Part 1 Flashcards
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?
Yes.
It is not a vertebrate but it is indeed a chordate.
What are the different fish groups?
Ostracoderms, Hagfish, Lampreys, Placoderms, Chondricthyes, Osteichtyes - Sarcopterygii - Actinopterygii HOLP COsa
Describe ostracoderms.
Extinct
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
Describe hagfish.
Fish, extant, no bone just cartilage Evolutionary option that didnt lead to anything 6 separate hearts Osmoconformer Scavengers
Describe lampreys.
Extant
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?
Jawless fish HOL Hagfish Ostracoderms Lampreys (most likely a monophyletic grouping)
What do the other groups fall under? What does this mean?
Gnathostomes - not a phylogenetic lumping like Agnathans Jawed fish P COsa Placoderms Chondricthyes Osteicthyes - (sarcopterygii) - (actinopterygii)
Describe placoderms.
Extinct major predator in their time true bone of ostracoderms was probably a defense against these guys fully movable jaws very diverse/speciose didnt lead to anything evolutionarily may be related to sharks most common fossil
Describe condricthyes.
Sharks and rays Cartilaginous, no bone Two separate subgroups - sharks and rays - chimera True class, all related phylogenetically
What does Osteichthyes mean?
true bony fish
Describe Osteichthyes
True bone in the skeleton first to evolve bony skeletal support True class two subclasses - Sarcopterygii - Actinopterygii
Describe sarcopterygii.
Gave rise to tetrapods
lobe-finned (muscular and skeletal support in fin)
bony fish
extant
Describe actinopterygii.
Most fish
ray finned
skeletal support in body (not in fin)
probably led to diversification of multiple species