Phylogeny and diversity - Part 2 Flashcards
Draw the simplified tree of gnathostomes including the key traits of each group.
(mixini –> true vertebrae –> Petromyzontiformes) –> jaws, paired fins –> Placoderms, Chondricthyes –> Operculum, branchiostegal rays –> Acanthodii –> lepidotrichia, pleural ribs –> Actinopterygii –> true enamel on teeth, lobed fins –> Actinistia –> Choana –> Dipnomorpha –> folded tooth enamel –> Osteolepimorha –> tetrapoda
Also, indicate which are the osteichthyes and which are the sarcopterygii
Describe the acanthodii.
Very speciose group. Now extinct gnathostomes. Two pump system May have outcompeted placoderms Predominant in oceans for a while.
What is a dipnomorpha?
Lungfish
What is an osteolepimorpha?
Transitional, may not be a fish, important fish-tetrapod fossil
Actinistia includes what kind of extant fish?
Coelocanth
Where did jaws come from?
First 2 gill arches of agnathans.
What could have been the selective advantage of half a jaw?
Increase in size of the first gill arch may have aided in respiration.
Can open and close the mouth for better respiration.
A stronger proto-mouth could have aided in filter-feeding.
What was the purpose of the second arch?
Hyoid arch forming part of the jaw suspension.
What was the first arch?
mandibular arch
What were the purposes of the first two arches when becoming jaws?
Arches 1 and 2 got bigger for respiration with more muscles then got to feeding.
1st arch is main jaw and the second arch is for suspension
Tetrapods don’t have gill arches. What did they become?
Middle ear bones.
What was the split early on from Osteichthyes?
When did it happen?
Sarcopterygii and Actinopterygii
Early on in Devonian (around 400 mya)
What are the most likely ancestors to all actinopterygians?
Paleonoiscids
Describe chondrosteii.
Early actinpterygii
Skeleton mostly cartilage
extant species include paddlefish and sturgeon
Describe holosteii
More of a bony skeleton
Most of the actinopterygians are this.
Describe teleosts.
Most diverse group of fishes.
Majority of fish species.
Modern bony fishes.
Specialized.
Draw a basic graph including osteichthyes, sarcopterygii, tetrapods, actinopterygii, holosteii, chondrosteii, teleosteii and palaeoniscids
refer to notes
What are neopterygii?
Actinopterigian fish.
Stands for new fin.
These fish had more flexible fins, more rays, more lepidotrichia, more mobile.
Gave mobility and maneuverability leading to diversification
What is one way to reconstruct fossil phylogeny?
Scales
a lot of the early work on fish phylogeny was driven by discovering fossilized _____ in different strata
scales
What are the 5 kinds of scales?
Placoid, ganoid, cosmoid, cycloid, ctenoid
Describe placoid scales.
Sharks have this. Smooth one way, sandpaper the other way. Do not grow. Can be replaced Related to teeth. Cannot be used for aging
Describe cosmoid scales.
Found in sarcopterygians.
Grow with fish
have some blood flow
sturdy and thick, not flexible.
Describe ganoid scales.
Found in sturgeon Very hard, bony armour Modified cosmoid good protection grow with fish, hard and good for protection bad for flexibility
Describe cycloid and ctenoid.
Teleosts have these
provide less protection
more flexible and provide mobility
What are the 6 characters that make a teleost, a teleost?
1 - Reduced or missing scales. 2 - Two pump respiratory system 3 - Modified swim bladder 4 - Flexible jaws 5 - Homocercal tail 6 - Specialized fins
What is the evolutionary advantage of reduced or missing scales?
Lost ganoid for cycloid/ctenoid.
More mobility alloted.
Can now go into more environments.
Can catch prey faster and better avoid predators.
What is the evolutionary advantage of the two pump respiratory system?
Breathing without moving.
Can now hide of be stationary.
What is the evolutionary advantage of a modified swimbladder?
Better buoyancy control.
What is the evolutionary advantage of flexible jaws?
Flexibility in feeding.
Prey specialization.
Flexibility in jaws and flexibility among teleosts jaws.
What is the evolutionary advantage of a homocercal (symmetrical) tail?
Allows more powerful swimming.
More maneuverability.
Muscles can better attach for swimming.
What is the evolutionary advantage of specialized fins?
Modifications for feeding (angler), reproduction, holding onto substrate (gobies), etc.
What are the major teleost groups?
(OECOE) osteoglossomorpha Elopomorpha Clupeomorpha Euteleostei Ostariophysi
What is a basic character for osteoglossomorpha?
bony tongue
What is an example species from elopomorpha?
Eels
What are examples of clupeomorphs?
Shad and cod
What is the most speciose group of teleosts?
Ostariphysi - catfishes and cyprinids
What are euteleosts? Example species?
True teleosts.
PErch, drum, goby
Briefly describe: ammocoete
Larval form of lamprey
similar to ancestral chordates.
What is the larval form of Elopomorphs?
Leptocephalus.
Briefly describe: Leptocephalus.
Larval form of elopomorphs.
Very fin without gills.
oxygen exchange through skin
almost all muscle to be able to swim large distances from center of ocean to coast.
Elasmobranchii and chondrostei have a ______, an accessory respiratory structure.
Spiracle
Briefly describe: Spiracle
Acessory respiratory structure of Elasmobranchs and condrosteii.
Extra hole to get water over the gills.
Cleupeiformes have what key things?
Auditory bullae, recessus lateralis.
Briefly describe: auditory bullae.
(Clupeiformes)
Small bubble of gas next to the ear for better hearing.
High frequency hearing.
Briefly describe: recessus lateralis
(Clupeiformes)
Part of the lateral line next to the auditory bullae.
Helps fish detect sounds with lateral line
What is the group that consists of catfishes and minnows?
Ostariphysi
Briefly describe: Weberian ossicles.
Modified bounds that function similarly to an eardrum and function in higher frequency hearing
Found in Ostariphysi
Briefly describe: Shreckstoff
Fright substance that is released when a minnow is bit to cause others to run away
Found in Ostariophysi
