FNR24150 Exam 1 Notes

# Phylogeny of Amphibians

## Oldest to most recent


1. Lissamphibia
2. Temnospondyli
3. %%Gymnophiona, Anura, Caudata (extant amphibians)%%

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## Why land?

* unexploted %%food%% resources
* aquatic habitat niches already occupied
* %%lack%% of large %%terrestrial predators%%
* largely primitive plants & invertebrates
* %%low O2 in warm H2O%% (land O2 unlimited)

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## Early Tetrapods

* Upper Devonian lobe-finned fish
* %%pelvic and pectoral%% fins slowly transition to %%paired paddles%%
* %%median fins%% still present
* %%small ribcage%%
* Carboniferous labyrinthodont amphibian
* %%paired paddles%% slowly turn into %%limbs%%
* %%larger ribcage%% to account for %%organs%%

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## More Phylogeny (indivudual spp. discussed further below)

* Era: Paleozoic, Period: Devonian
* Ichthyostega, Tiktaalik
* Era: end of Paleozoic-beginning of Mesozoic, Period: end of Permian-beginning of Triassic
* Triadobatrachus
* Era: end of Mesozoic-beginning of Cenozoic, Period: end of Cretaceous-beginning of Tertiary
* Extant salamanders & frogs
* major evolutionary transitions in last %%350 years%%
* %%Amphibians%% were the %%dominant%% land animals for %%~75 million years%%

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## Leposondyli

* very %%small%% yet very %%diverse%% early amphibians
* similar to newts, eels, snakes, lizards, etc.

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## Permian era

* %%droughty%% conditions
* %%reptile & early reptile spp.%% emerged and evolved

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## Tiktaalik


* %%late Devonian%% ==(375 MYA)==
* discovered in %%Canada%% in %%2004%%
* predated %%Ichthyostega%% by %%5 million years%%
* thought to be the oldest up til this point
* %%1-2m%% long
* most notable feature: %%front pair fins with wrist-like structure%%
* other features
* ^^spiracles (primitive nostrils)^^
* ^^lungs & gills^^
* %%1st%% tetrapod with %%proper neck%%
* %%greater flexibility%% during short bouts on land

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## Ichthyostega (“roof fish”)


* %%late Devonian%% ==(370 MYA)==
* discovered in %%Greenland%%
* 5 ft, 50 lbs
* fish & amphibian features
* %%webbed feet%%
* could %%breathe air%% for %%short%% periods of time

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## Eryops


* %%Permian (270 MYA)%%
* %%crocodile-like%% early amphibian
* %%aquatic%% & %%terrestrial%%
* had some structural %%features%% that would %%appear%% in %%later%% reptiles

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## Diplocaulus (“double stalk”)


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* %%middle-late Permian (240-230 MYA)%%
* 3ft, 5-10 lbs
* %%wide V-shaped boomerang head%%
* possibly used to %%navigate strong currents%%
* facilitated rapid opening for %%suction-gape feeding%%

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## Frog Evolution Trends

* several modifications for jumping
* vertebral column %%short%% & %%inflexible%%
* reduction in ^^presacral vertebrae^^
* found within pelvis (cervical, thoracic, lumbar)
* increase ^^rigidity^^, ^^absorption^^ of landing
* transfer ^^energy^^ directly to ^^hind limbs^^
* ^^enlarged^^ pelvic girdle, ^^strengthened^^ & ^^anchored^^ to vertebral column
* ^^no ribs^^
* ^^no tail as adult^^
* overall body ^^truncated^^
* hind limbs ^^elongated^^ for jumping
* ^^muscles^^ modified for jumping

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## Amphibamus (“equal legs”)


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* %%late Carboniferous (300 MYA)%%
* swamps in %%Europe%% & %%NA%%
* 6 inches, few ounces
* more %%salamander-like%% than frog-like
* %%33 presacral vertebrae%%
* common characteristic of early amphibs (%%large amount%% of presacral vertebrae)

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## Gerobatrachus (“frogmander”)


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* %%early Permian (290 MYA)%%
* found in %%Texas%% in %%2008%%
* why is it called “%%frogmander%%?”
* ^^2 fused ankle bones^^
* ^^backbone intermediate in length^^
* decrease from 33 vertebrae in Amphibamus
* ^^large tympanum (large, external ear on frogs)^^
* ^^wide, frog-like skull^^
* likely %%transitional%%
* ==240-275 MYA splitting frogs & salamanders==

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## Triadobatrachus (“proto frog”)


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* %%early Triassic (250 MYA)%%
* found in %%Madagascar%%
* ==first fossil frog==
* characteristics
* ^^short, stubby tails^^
* ^^10 cm^^
* ^^13-14 presacral vertebrae^^
* ^^9 in modern frogs^^

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## Viraella

* %%early Jurassic (~200 MYA)%%
* found in %%Argentina%%
* ==earliest “true” frog==
* may belong to %%Leiopelmatidae%% (modern family)
* %%classic%% frog-like head & large eyes
* legs modified for %%jumping%% (explored in next point)

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## Triadobatrachus vs. Viraella


* Vieraella more truncated overall
* %%reduction%% %%in presacral vertebrae%%
* %%enlarged & fused%% pelvic bones in %%Viraella%%
* fused %%tibiofibula%% in %%Viraella%%

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## Paleobatrachus (“ancient frog”)



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* %%Cretaceous--Tertiary (130-135 MYA)%%
* found in %%Europe%%
* %%completely aquatic%%
* inhabited %%swamp basins%%
* %%volcanic gases%% preserved soft %%tissue%%
* resembles present day %%Xenopus%%

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## Amphibians vs. Reptiles

* amphibians
* clawless
* scaleless
* moist skin (respiration)
* unshelled eggs
* reptiles
* limbs & muscles
* increased brain size (cerebrum & cerebellum)
* more effective jaw
* skeletal structure improved
* skin toughened with scales
* reduced cutaneous respiration
* well-developed lungs
* consequence of scales
* amniote egg
* no longer relied on water for breeding
* arose from anthracosaurs (later tetrapods)

## Order Caudata (Salamanders)

* characteristics
* %%smooth%% skin
* %%long tails%%
* long %%cylindrical%% bodies
* most have %%2 pairs%% of very %%well developed limbs%%
* some have %%nasolabial groove%%
* little groove that runs from nose to lips
* %%costal grooves%%
* body folds found on their sides
* %%carniverous & cannibalistic%%
* secretive & nocturnal
* %%greater diversity%% in ^^development, respiration, and reproduction^^ than any other vertebrate group
* %%nearly all%% salamander larvae have external gills
* reabsorbed later
* Sirenidae keeps external gills (paedomorphic)
* habitat & distribution
* common throughout U.S.
* 70% of \~400 spp. of salamander found worldwide are located in Central & NA
* mostly found in %%moist woodland%% habitats
* ^^hardwood & coniferous forests, grasslands, lowland floodplains^^
* highly dependent on ^^precipitation, temperature, & vegetation type^^
* %%Four-toed Salamander%% requires %%sphagnum bogs%%
* %%22 spp. & 2 hybrid forms%% of the %%unisexual complex group%% are found in IN
* some spp (Wester Lesser Siren) spend summers in %%estivation%% by encapsulating themselves in a %%mucous-lined cocoon%%
* some %%permanently aquatic%% ^^(ponds, lakes, & streams)^^
* some %%terrestrial%% ^^(under logs, leaf litter, rocks)^^
* reproduction
* %%ephemeral wetlands%%
* breeding season: %%late winter--early spring%%
* few breed in fall
* courtship practices
* ^^nudging^^
* ^^tail & chin tapping^^
* ^^tail fanning^^
* majority of salamanders have %%internal fertilization%%
* male salamanders deposit sperm packets (%%spermatophore%%) which the females pick up with their %%cloaca%%
* %%eggs%% are fertilized as they %%travel through the oviduct%% and encounter %%spermatophore%%
* majority of salamander spp. are %%oviparous%% (lay unshelled eggs)
* ==all IN salamanders are oviparous==
* some give birth to %%gilled larvae%% (%%larviparous%%)
* others give birth to %%fully transformed young%% (%%pueriparity%%)
* eggs prone to %%desiccation/drying out%%
* must lay eggs either in %%moist soil%% or in %%water%%
* most %%do not provide parental care%%
* many %%do guard eggs%%
* diet
* %%carnivorous%%; mostly ^^insects, spiders, & earthworms^^
* occasional %%cannablism%%

## Salamander Family Phylogeny

* %%10%% recognized families
* %%60%% genera
* %%400%% spp.
* %%Sirenidae%%