cva unit one: the vertebrates

Craniate hypothesis

Craniate hypothesis

Lampreys + Gnathostomes

Cyclostome Hypothesis

Hagfishes + Lampreys

Which theory is more supported? Why? Craniate or Cyclostome

Cyclostome; molecular data

Cyclostomes are a ____ group.

artificial; paraphyletic

Are hagfishes considered a part of monophyly Vertebrata?

Yes

Hagfishes loss of vertebrae is considered a ______.

Autapomorphy

Myxini

Hagfishes

Petromyzontiformes

Lampreys

Cyclostomes “Obvious” Plesiomorphies

agnathous, lack of paired appendages

Cyclostome Hypothetical Plesiomorphies

• soft-bodied

• cartilaginous skeleton/absence of mineralized tissues

• simple “vetebral” elements in lamprey, lost in hagfish

Cyclostome Apomorphies

• anatomy of oral apparatus

• pouched gills

What does Conodonta mean?

“Cone Teeth”

Are Conodonta extinct or extant?

Extinct

What does the term “Ostracoderms” mean?

Shell Skin

Name the 4 Orders of Agnatha

• Myxini(hagfishes)

• Petromyzontiformes(lampreys)

• Conodonta

• Ostracoderms

Agnatha means-

Jawless

This image depicts which hypothesis?

Craniate

This image depicts what hypothesis?

Cyclostome

Which phylogeny is more supported? A or B

B Cyclostome

Name the superclass, and order of the two different organisms.

Superclass: Agnatha

Order: Left-Petromyzontiformes(lampreys) and Right-Conodonta

Ignoring the placement of Conodonts. What is wrong with this phylogeny?

One: Urochordata, the sister group to vertebrata should be switched with cephalochordata. i.e. depicts paedomorphic theory instead of plesiomorphic

Two: Myxinoids and Petromyzonitids should be in a sister group while gnathostomes are basal. i.e. Cyclostome Hypothesis

Identify the missing Orders.

A. Myxini

B. Petromyzontiformes

C. Conodonta

D. Ostracoderms

What makes Order Ostracoderm so important to the Vertebrata Phylogeny? (i.e. What apomorphy?)

• earliest known vertebrates with a mineralized skeleton

• marking the emergence of skeletal bone

What Superclass and Order did this organism belong to? Why is this order relevant to evolution of vertebrates?

Agnatha; Ostracoderms. Emergence of skeletal bone.

What Superclass and Order did this organism belong to? Why is this order relevant to evolution of vertebrates?

Agnatha; Ostracoderms. Emergence of skeletal bone.

What does “Gnathostomata” mean?

jawed vertebrates

What is the synapomorphy associated with Gnathostomata and relative to all vertebrates?

jaws

Is the ancestor to Gnathostomes known?

No

Characteristics of Class Placodermi

• extinct

• paired fins

• bony dermal scales

• notochord

• ossified vertebral elements

Two Sub Classes of Chondrichthyes

Elasmobranchii and Holocephali

Four Orders of Subclass Elasmobranchii

Cladoselacoimorpha(extinct), Xenacanthimorpha(extinct), Selachimorpha, Batoidea

What are the key differences between Elasmobranchii and Holocephali?

• Elasmobranch have a “free” palatoquadrate while Holocephali’s palatoquadrates are fused to the chondrocranium.

• Elasmobranch teeth are rapidly replaced while Holocephali’s tooth plates are replaced slowly.

Teleostomi:

Osteichthyes and Acanthodii

“Spiny Sharks” refers to what class?

Acanthodii

Key Characteristics of Acanthodii

• Dorsal fin and large spine

• Prominent notochord with ossified arches

• Skulls well ossified

DNA sequence revealed Chondrichthyans have lost-

Genes that turn cartilage into bone, i.e. reduced ossification.

The bony fishes

Osteichthyes

Two Subclasses of Osteichthyes

Actinopterygii (ray-finned fishes) and Sarcopterygii (lobe(fleshy)-finned fishes)

Two Superorders of Subclass Actinopterygii

Paleonisciformes and Neopterygii

Three Orders of Superorder Paleonisciformes

• Paleonisdoids

• Polypteriformes

• Acipenseriformes

Which superorder of Osteichthyes has reduction of ossification in some taxa?

Palaeonisciformes

Order Polypteriformes

bichirs

Order Acipenseriformes

paddlefish, sturgeons

Orders of Superorder Neopterygii

• Lepisosteiformes

• Amiiformes

• Subdisvison Teleostei

Chondrostei

• Paleonisoids

• Polypteriformes

• Acipenseriformes

Holosteans

Lepisosteiformes and Amiiformes

Lepisosteiformes

gars

Amiiformes

bowfin

What Subclass of Osteichthyes was once known as Chonanichthyes because they have Chonae (Internal Nares)?

Sarcopterygii

The Superorders of Subclass Sarcopterygii

• Coelacanthiformes

• Dipnomorpha

• Rhipidistia

Orders of Superorder Dipnomorpha

• Porolepiformes

• Dipnoi

Name the notable symplesiomorphies Dipnomorpha and extant Amphibians share.

• Skeletal structure

• Structure of circulatory system

Characteristics of Superorder Rhipidistia

• freshwater

• prominent notochord w/ primitive (tetrapod-like) verterbral elements

What feature is present in Rhipidistians and Tetrapods?

Nasal sac/ Internal Nares (choana)

The Two Extinct Orders of Superorder Rhipidistia

Osteolepiformes, Rhizodontomorpha, Elpistostegalians

Phylogenetic Relationship between Superorder Rhipidistia and Tetrapods

• share numerous synapomorphies w/ earliest(stem) tetrapods

• some consider these as basal forms in a clade Tetrapodmorpha

Tetrapodmorpha

Rhipidistia and Tetrapoda

Osteolepimorphies

Eusthenopteron and Osteolepis

Rhisodontomorphs

Gooloogongja, Megalichthyes, and Rhizodus

Elpistostegalians

Panderichthys and Tikataalik

Chiridium

Muscular limb w/ well defined joints and digits

Within tetrapodmorpha Chiridium is a ___________

Synapomorphy

Within Tetrapoda Chiridium is a __________

symplesiomorphy

Labyrinthodontia is a _____phyletic assemblage

Polyphyletic

Subclass Labrythhodontia excludes subclass-

Lissamphibia

Subclass Labyrinthodontia

stem tetrapods

What Class?

Placodermi

What Class?

Placodermi

What Class and Subclass?

Chondrichthyes; Elasmobranchii

Acanthodii + Osteichthyes

Teleostomi

What Class?

Acanthodii

What kind of fin?

Metapterygial

What kind of fin?

Archipterygial

What kind of fin as at the top? What kind of fin is at the bottom?

Top: Archi

Bottom: Meta

Order Dipnoi

Lungfishes

Name the Class, Subclass, and Superorder.

Osteichthyes, Sarcopterygii, and Rhipidistia

Labyrinthodontia is a ______phyletic assemblage.

poly

What Theory does this phylogeny support?

Paedomorphic Theory

What theory does this phylogeny support?

Plesiomorphic Theory

Name Class and Subclass.

Class: Chondrichthyes

Subclass: Holocephali

Coelacanthiformes aka ____.

Latimeria

Name Class and Subclass.

Class: Amphibia

Subclass: Labyrinthodontia

Name Class and Subclass.

Class: Amphibia

Subclass: Labyrinthodontia

Name Class and Subclass.

Class: Amphibia

Subclass: Labyrinthodontia

Name Class and Subclass.

Class: Amphibia

Subclass: Lepospondyli

Which origin of Lissamphibia Hypothesis is supported by Kardong?

B

anamniota

all previously discussed vertebrates

amniota

Classes: Reptilia, Aves, Synapsida, Mammalia

Name the highlighted structure and its function.

Amnion

-fluid filled (amniotic fluid)

- surrounds embryo

-protection

Name the highlighted structure and its function.

Allantois

- serves for deposition of embryonic wastes

Name the highlighted structure and its function.

Chorion

- encloses all embryonic structures (yolk included)

- passive respiratory surface

- often fuses w/ allantois (chorioallantoic membrane)

Name the highlighted structure.

Shell

sauropsida

reptiles + birds

anapsid

no fenestra

synapsid

ventral fenestra

diapsid

two fenestra

“euryapsid”

one dorsal fenestra

Match organism with amniote skull type.

C1

D2

A3

B4

cotylosauria

stem amniotes/reptiles

is it definitive that cotylosauria are amion?

no! not clear!