vert exam 2

What groups are included in Rhipidistia?

Dipnoi (lungfish)

Tetrapoda (tetrapods)

Describe 1 synapomorphy of Rhipistia & how this differs structurally and functionally from non-Rhipidistians

1. heart w/ separate pulmonary

2. systemic circulation

Describe 1 characteristic previously believed to be Rhipidistian synapomorphy, but which is now understood not to be. Why did this change?

internal nares (choanae), not considered a synapomorphy because choanae evolved separately in dipnoi and tetrapods, common ancestors didn’t have it

In what clade are lungfishes? How amny extant species are there?

lungfish are Dipnoi

6 extant species

Describe the respiratory structures in lungfishes and how this varies among species.

two vascularized lungs (except Australian spp)

nonfunctional gills in all except Australian spp

Besides lungs, name 4 other relatively unique internal morphological characters of lungfishes.

complete notochord

unique teeth

spiral valve in intestine

largest genome among verts

Describe estivation in lungfishes.

estivate in mud burrows during dry season

surrounded itself with mucous cocoon

convert ammonia waste to urea when estivating

What is meant by “Tetrapodomorpha”?

non-tetrapod tetrapodomorpha fish

sarcopterygian fish characteristics

fishapod characteristics

tetrapod-like characteristics

What non-Tetrapod species is considered the most closely related species to Tetrapods?

Elpistostege watsoni

Stem Tetrapodomorpha are often called fiahapods. Name 3 fish-like, 3 tetrapod-like, and 2 fishapod characters of these species.

fish like:

• gills

• scales

• pelvic fins not attached to vert. column

fishapod like:

• arms w/ thick bones, flexible wrists, rays that resemble digits

• ear region intermediate bt fish and tetrapod

tetrapod like:

• neck

• tetrapod lungs

• tetrapod rib bones

What are the 2 major clades within Tetrapoda and what extant groups are included in each?

Batrachomorpha - Amphibia

Reptiliomorpha - Amniota

Describe the general evolutionary trend in morphological changes as Tetrapods evolved from their Sarcopterygian Tetrapodomorpha ancestors.

1. loss of dermal bones (operculum, fin rays, fish scales)

2. increase in endochondral bone (limb bones larger, carpals/digits added, pectoral/pelvic girdles larger, zygopophyses added to vert)

Describe 4 features of early Tetrapods associated with their limbs that differed significantly from non-Tetrapods and why there may have been natural selection for the evolution of these characters.

1. no opercular bone connection bt pectoral girdle and skull (allows for independent head movement & development of neck)

2. absence of dermal fin rays (replaced by increase endochondral bones)

3. pelvis (support for hindlimb propelled movements along bottom or lunges)

4. limbs w/ carpals, tarsals, and phalanges (easier to navigate along bottom & in plants)

Describe 1 feature of early Tetrapods associated with their vertebral column that differed significantly from non Tetrapods and why there may have been natural selection for the evolution of this character.

1. zygapophyses add stability to axial skeleton (more support for walking on bottom or lifting head)

Name 3 of the earliest known Tetrapods. How did the limbs of slightly more recent Tetrapods differ from these?

1. Acanthostega

2. Ichthyostega

3. Tulerpeton

they had more than 5 digits (6-8)

List 4 hypotheses for why early Tetrapods may have lived in shallow water.

1. escape predation

2. reduce predation of eggs

3. exploit new feeding opportunities

4. better thermoregulation for improved digestion

List 5 hypotheses for why early Tetrapods may have left the water.

1. enable overland movement to escape drying ponds

2. new habitat (plants) w/ fewer competitors for this

3. dispersal of juveniles

4. search for safer moist spots to put eggs

5. basking in sun

List 4 skeletal changes necessary for early Tetrapods to succeed on land.

5 digits

forelimbs

hindlimbs

wrists

Why were terrestrial Tetrapods able to diversify in body form so much from their aquatic ancestors?

gravity had stronger effect since air is less dense than water

modifications needed for support and movement

air is less viscous than water, streamlining unnecessary/diverse body forms

In what ways did respiratory structures and ventilation methods change in terrestrial Tetrapods as compared to their aquatic ancestors?

air density/viscosity making tidal flow designs instead of unidirectional flow

In what ways did the circulatory system of terrestrial Tetrapods change from their aquatic ancestors?

circulatory systems diversified:

higher blood pressure needed to move blood against gravity

counter current not required

In what ways did terrestrial Tetrapods change to prevent water loss as compared to their aquatic ancestors?

• more efficient kidneys for water absorption

• conversion of NH3 into uric acid

• adding lipids, keratin/scales

List the major groups within Batrachomorpha and describe each.

Temnospondyls: largest, long lasting extinct non-amniote tetrapods

Lissamphibia: modern anamniote tetrapods

Leospondyls: extinct small salamander like anamniotes

Lissamphibians are often described as anamniotic. Why is this misleading?

classifying only by what they lack, ignoring diversity on how they reproduce

List 3 different ways in which “amphibian” may be used, the clades included in these different usages, and why it may be defined in these different ways.

1. Batrachomorphs + anamniote Reptiliomorphs

2. Batrachomorpha only

3. Lissamphibia only

What are the 2 crown Tetrapod clades and which includes amphibians?

Batrachomorpha and Reptiliomorpha

List the 3 crown Lissamphibia clades – Scientific and common names

Anura (frogs and toads)

Caudata (salamanders)

Gymnophiona (caecilians)

Lissamphibia synapomorphies

a. List 3 associated with the mouth

1. pedicellate teeth

crowns and pedicel

Lissamphibia synapomorphies

b. List 2 associated with the ears

1. opercular apparatus

2. amphibian papilla

opercular apparatus transfers vibrations from pectoral girdle to oval window —> vibration of amphibian papilla in inner ear

Lissamphibia synapomorphies

c. List 2 associated with the eyes

1. green rods in retina

2. levator bulbi muscle

Lissamphibia synapomorphies

d. List 1 additional not from a-c associated w/ the head

1. two occipital condyles

Lissamphibia synapomorphies

e. List 2 associated with the skin

1. skin w/ mucous and granular glands

2. vascularized

3. folds to increase surface area

4. secretion of lipids

Lissamphibia synapomorphies

f. List 4 associated with respiration

1. cutaneous respiration

2. buccopharyngeal pump

Lissamphibia synapomorphies

g. List 4 associated with the body

1. no/short straight ribs

4. Describe the unique morphology of the teeth of Lissamphibia in detail.

2 segments to teeth: crown and pedicel

both made of dentin

crown covered in enamel

pedicel anchored to inside of jaw

Describe the morphology and function of the Lissamphibian middle and inner ear IN DETAIL.

A. collumella - bone in middle ear, transmits sounds from tympanum of outer ear to oval window of inner ear

frequencies vibrate basilar papilla (base for hair cells) in inner ear

B. opercular apparatus - operculum (cartilage on oval window) and operculum muscle (to pectoral girdle)

transfers vibrations from pectoral girdle to oval window (vibration of amphibian papilla in inner ear)

Describe the unique morphology and functions of Lissamphibian skin. - How does this compare to other vertebrates (fish, mammals, birds)? - Which specific Lissamphibia groups produce substantial toxins?

A. mucous gland - secretions of slimy mucus to keep moist skin for respiration and defense

B. granular (serous gland) - evenly distributed across dorsal surface to produce array of chemicals

Bufonidae and Dendrobatid

What is cutaneous respiration and how does it vary among Lissamphibia groups? - What about non-Lissamphibia groups?

gas exchange where breathing occurs through skin, not lungs/gills

needs vascularized skin, moist

folds to increase surface area

happens in other animals but more important in amphibians

Describe morphological adaptations which allow and improve cutaneous respiration.

vascularized skin

thin skin

folds in skin

Describe the 4 steps associated with the function of the buccopharyngeal pump. - How is this manner of breathing different than in mammals? What about bichirs?

1. nostrils open, glottis closed (floor of buccal cavity lowered to bring in air)

2. nostrils open, glottis open (body wall contracts emptying lungs out nares, ABOVE new air in buccal pharyngeal pocket)

3. nostrils close, glottis open (buccal cavity contracts pushing air into lungs)

4. nostrils open, glottis closed (rapid buccal floor pumping clears cavity, priming)

Where are the levator bulbi muscles and what is their function?

in floor of orbit between eye and roof of mouth

elevates eye causing it to bulge

enlarges buccal cavity to assist in air intake

How are the ribs of Lissamphibia relatively unique compared to other Tetrapods? - How is this difference associated with their mode of respiration?

no/short ribs that don’t encircle body

Describe a unique morphological adaptation found in Lissamphibian eyes. - What might be the function of this adaptation?

green rods in retina, blue-sensitive

function in low light

What is an occipital condyle and how is this different in Lissamphibia vs other vertebrates?

bony skull projections articulated with 1st vertebra

other verts have 1, frogs have 2

Lissamphibian skin is generally thin to allow cutaneous respiration. Why is this a disadvantage? - What are 5 adaptations found in different frogs to compensate for this disadvantage?

thin skin leads to water loss

1. secretion of lipids to reduce evaporation

2. cocoon made from shed skin

3. pelvic path: bumpy and vascularized

4. mucus gland

5. granular gland

How do different types of frogs obtain much or most of their water?

toads have thick dorsal skin

Do any Lissamphibia have scales?

some caecilians have scales

What are hypothesized functions of costal grooves and annuli?

wick water from moist ventral surface onto dorsum

aid movement in water

What are osteoderms? Do they occur in any Lissamphibia? What are their hypothesized functions?

vascular bony deposits in dermal skin layers

in several frog spp

absorb water/calcium reservoir

What is lamina calcarea? Does it occur in any Lissamphibia? What are their hypothesized functions?

mineralized tissue at interface between superficial and deep dermis

in some frog spp

protective layer/calium reservoir

Do amphibians shed? How?

Ecdysis

cyclic - days to weeks

only outer layer

Compare the skeletons of caecilians, frogs, and salamanders.

axial skeleton

caecilian: 100-300 pre-caudal vert, no sacral vert, 1 cervical, w/o tail, ribs don’t wrap

salamander: 10-70 pre-caudal, 1 cervical +trunk, 1 sacral, 20-100 caudal, short ribs

frog: 6-9 pre-caudal, 1 cervical, 1 sacral, 2-3 caudal (urostyle), no ribs

Compare the skeletons of caecilians, frogs, and salamanders.

Appendicular skeleton

caecilian: no appendicular skeleton or muscles

salamander: pectoral girdle unmineralized cart & not fused, pelvic girdle some unmineralized cart, reduced limbs

frog: pectoral girdle variable, pelvic girdle modified for jumping, limbs modified for jumping

What is a urostyle? Describe its morphology.

fusion of 2-3 caudal vertebrae + ossified hypochord

shock absorber for jumping, supports pelvis

Describe frog skeletal modifications for jumping.

elongated bones: proximal tarsals (calcaneum and astragulus)

fused bones: tibiofibula, radioulna, urostyle

Describe IN DETAIL the mechanics of how frogs jump.

tendon preloading critical to distance jumping

muscles preload tendons

1. plantaris longus (calf) muscle on tibiofibula shortens

2. stretched distal tendon which is wrapped around ankle bone to foot

3. muscle relaxation causes tendon recoil and rapid extension of ankle joint

List and briefly describe the 4 typical respiratory structures in amphibians. - What other structures are used for respiration in some species?

1. lungs (pulmonary respiration), buccopharyngeal pumping

2. gills (size depends on O2 of water)

3. skin (cutaneous respiration), vascularized and moist skin

4. buccopharyngeal mucosa (throat and mouth vascularized)

Which amphibians are lungless?

Plethodontidae, lungless salamanders

How does the amphibian circulatory system differ from fish? What about from mammals? - How does the circulatory system of tadpoles differ from adult frogs?

1. erythocytes with nucleus (not mammals)

2. separate systemic and pulmonary circuits allow for different BPs

3. adults w/ double circulation and 3 chambered heart (tadpoles have single circulation w/ 2 chambered heart)

4. tissue is ventricle reduces mixing O2 rich/poor blood (mixing varies by spp)

5. when diving, O2 poor blood diverted from lungs

List and describe the contribution of the different structures involved in sound production in frogs.

1. lungs

2. vocal sacs

3. vocal cords vibrating

lungs and vocal sacs inflated via buccopharyngeal pump, air forced across vocal cords, vocal cords vibrate producing sound waves, sound waves resonate on buccal cavity

What is a frog vocal sac, where does it occur, what are 3 types in different frogs, & what is its function?

outpocket of buccal cavity that connects via vocal slit

resonating chamber altering pitch and volume

1. median subgular

2. paired subgular

3. paired lateral

What morphological factors affect the call sound in different frogs?

pitch determined by rate of vibration of vocal cords

vocal cord vibration rate determined by MASS and TENSION of vocal cords

sound affected by size/shape/location of vocal sacs

Reproductive mode and development for different orders

caecilians: ½ are viviparous and ½ are oviparous

salamanders: most are oviparous

frogs: most are oviparous

list oviposition in frogs

1. into water

2. foam nest

3. dorsum of female

4. vocal sac

5. stomach

define and explain neotany in salamanders

becoming sexually mature while retaining some larval external morphological characters

½ of salamanders are obligate neotenes

½ of salamanders are facultative neotenes

Besides, size, list 10 ways tadpole external and internal morphology differs from adult frogs.

1. gill slit and internal gills

2. no limbs

3. short body, tong tail

4. no eyelids

5. mouth w/ keratin teeth or adhesive discs to cling to rocks

6. long, coiled intestine

7. no stomach

8. gland producing digestive enzymes

What is direct development and describe its occurrence in amphibians.

eggs developing directly into small frogs w/o tadpole stage

occurs in many spp

What are the 2 major Tetrapod clades and which extant clades are included in each?

Batrachomorpha: Lissamphibia

Reptiliomorpha: Amniota

What is the primary Reptiliomorpha synapomorphy we discussed and how does this compare to Batrachomorphs? - How does this compare to later (extant) Reptiliomorphs and to later (extant) Batrachomorphs?

They were amniotic

Batrachomorpha was anamniotic

In what way was reproduction in early (stem), but not later, Reptiliomorphs similar to Batrachomorphs?

early Reptiliomorphs are unclear of anamniote-amniote status

What is the major crown Reptiliomorph clade and what are the 3 clades into which it can be divided? - Which major extant clades occur in each of these 3 clades?

Amniota

1. Synapsida: mammals

2. Parareptiles: anapsid reptiles

3. Eureptilia: diapsids

What is 1 major Amniote synapomorphy associated with reproduction?

amniotic egg

shell + 4 extraembryonic membranes

1. amnion

2. yolk sac

3. allantois

4. chorion

Describe the structure of the amniotic egg. - What is an extraembryonic membrane, i.e. (A) from where does it develop, (B) what is their general function? - Is the entire egg made from extraembryonic membranes?

1. amnion: fluid filled sac surrounding embryo, prevents desiccation, cushions

2. yolk sac: holds yolk

3. allantois: gas exchange, nitrogenous waste storage

4. chorion: surrounds other 3 Em and gas exchange

shell is not a part of EMs

Why are we somewhat unclear about which animal was the 1st Amniote?

few fossil eggs of early Reptiliomorphs, unsure if they are amniotic

What are 2 skeletal synapomorphies of Amniotes and how does this compare to anamniote tetrapods?

1. ankle bones (tibiale, intermedium, proximal centrale fused to form astralagus)

2. pelvis joined to vertebral column by 2 pairs of sacral ribs (1 pair in anamniote tetrapods)

What is a character used to differentiate clades within Reptiliomorpha and what are some reasons its use as a taxonomic indicator is potentially confusing? - What are 2 hypotheses for the origin of this character?

occurrence of post-orbital (temporal) fenestrae

bilaterally symmetrical holes caudal to orbit

1. anapsid (1)

2. synapsid, euryapsid (2)

3. diapsid (3)

lightening skulls, improve alignment for muscle attachment

What are the 3 major Amniote clades and what is the clade into which 2 are included?

Synapsida

Sauropsida: Parareptile, Eureptilia

Is Parareptilia monophyletic? - Why is the use of postorbital fenestra as a taxonomic indicator also confusing in this clade? - What is a major clade Parareptilia?

monophyletic based off of skull synapomorphies

confusing bs diapsids evolved many times

Discuss varying examples of postorbital fenestrae in different Diapsid clades. (Lepidosaurs (lizards, snakes, Sphenodon), Archosaurs (Dinosaurs, birds, crocs, turtles)

1. 2 pairs of postorbital fenestrae

2. suborbital fenestrae

Besides postorbital fenestrae, what are 2 other Diapsida skull synapomorphies?

1. occipital condyle on bassioccipital only

2. solid immobile articulation bt tibia and astragalus

What is the crown clade of the Diapsida? - What is the crown clade of that previous crown clade and its 2 major subclades? - What extant clades occur in these 2 major subclades?

Neodiapsida:

Sauria: Lepidosauromorpha and Archosauromorpha