page 5 in lab manual
anterior
posterior
Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Hagfish
Scavenge dead, dying fish and invertebrates.
Have funnel-like mouths - tongue rasps off food.
Where are hagfish classified?

Asian aphrodisiac
Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Vertebrates
Metameric skeletal elements flanking the
nerve cord.
Neural arch was first element to evolve
Hagfish
Lamprey
Shark
Hagfish vertebral elements??
June, 2011
“Ostracoderms” – 430-370 million years
ago - early jawless fish
head shields w/mineralized bone
small bottom-dwelling
Calcium phosphate mineralized tissue
makes head shield and is related to teeth
and scales
enamel and dentine
developmental interaction of epidermis
and dermis
Ancestral jawless fish
 Usually no paired fins
 Notochord mostly remains
 Single nostril
Main groups of modern jawless fish:
Hagfish (Myxiniformes)
Lamprey (Petromyzontiformes)
Similarities in these two groups are probably due
to evolutionary convergence (homoplasy)
Lamprey
Lamprey respiration
Water flows in mouth, through respiratory
tube and out gills
Respiratory tube internally connects gill pores
Specialized flap - velum can close off anterior
end of respiratory tube
!!
Respiratory tube internally connects gill pores
Specialized flap - velum can close off anterior
end of respiratory tube
!!
Branchial muscles squeeze water in and
out of respiratory tube and over gills
 “Tidal ventilation”
!!
Ammocetes - larval form of lamprey
up to 7 years
Uses muscular movements to make
feeding current.
Crassus - Roman general
Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
Superclass Agnatha
Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
- Superclass: Gnathostomata
“jaw-mouthed vertebrates”
~430 million years ago
Two new characteristics:
A jaw - Allows consumption of larger,
more diverse prey.
Mandibular
arch
Hyoid
arch
Gill
arches
Two new characteristics:
 Jaw - Allows consumption of larger,
more diverse prey.
 Paired fins - at least two sets of paired
fins: pectoral and pelvic. Gives
stability and lift, prevents roll. roll
pitch
yaw
Big evolutionary radiation after advent of
first jawed fish...
Acanthodians
Placoderms
Chondrichthyes
Sarcopterygii
Actinopterygii
Phylum Chordata
 Subphylum Urochordata (Tunicata)
 Subphylum Cephalochordata
Craniata group
 Subphylum Vertebrata
 Superclass Agnatha
 Superclass Gnathostomata
Class Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Acanthodians Body armor like ostracoderms, fins
w/spines
Skeleton had some bone
(p.63)
Placoderms - “plate-skinned” fish
Bony plates are in smaller pieces
compared to ostracoderms
Mostly fed on bottom, some mid-level
predators
(p.59)
1 fossil shows live birth
placoderm skull
Dunkleosteus
Bite could exert 22,000lbs
of force per sq inch
First vertebrate “giants”
Placoderm - up to 20 ft, 1 ton