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1/22/2018

Becky Hardman

University of Tennessee College of Veterinary Medicine [email protected]

416 360 300 250 200 146 65 Objectives

 Define /

 Origin of

 Split of

 Modern Amphibians

 Extant Families

 Simplification

Tetrapod Characteristics

 Four Limbs  Tetra= Four; Pod=Foot  Some lost or vestigial

 “One bonetwo boneslittle blobsfingers/”- Neil Shubin  Some lost or vestigial  Includes all non-

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Amphibian Characteristics “Tetrapod vertebrates that pass through a larval state and undergo into terrestrial adults.” • need moist environment

• Larval; metamorphosis

• Permeable • Cutaneous

• Two Gland Types • Mucous •

• Pedicellate Teeth

• Amphibian papillae/Opercular bone • Can Hear Vibrations

• Fat Bodies

• Green Rods- fxn unknown

• Singular Sacrum • Lost in

Amphibian Characteristics

As a

 Articular surface of axis convex

 Exoccipital Bone articulates with dermal roofing

() 4 digits

 Foot () 5 digits

 Some Secondarily Lost

 Important to determine for fossil realtionships

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Phylogenetic Trees

Phylogenetic Trees

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Darwin’s Tree

Geologic Time Scale

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Devonian: Age of

 Lobed-Finned Fishes  ;  Tetrapodomorpha  Panderichthyids  , Acanthostega  Tetrapods

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416 360 300 250 200 146 65 : Fish to Tetrapod

 Panderichthyids 380 mya  Predators in shallow on top of head  and  Dorsoventrally Flattened*  Pectoral more developed for support/crawling

416 360 300 250 200 146 65 Devonian: Fish to Tetrapod

 Ichthyostega/Acanthostega 365 mya  First tetrapods  Still aquatic  Ichthyostega maybe seal-like on land

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Missing Link or “Fishpod”: 375 mya

416 360 300 250 200 146 65 Tetrapod

Lungs  Earliest Limbs*  Movement and support  Pectorals first Free movement of head*  Functional  Feeding and catching prey

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Tetrapod Advantages

 (1) Unexploited resources  (2) Low in warm shallow swamps  (3) Periodic drought- move between pools

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 First Amphibians  Diverse  Many large fully terrestrial predators  Dermal Armor  Little  Aquatic Lifestyle and  Scary!

 Early Split of Amphibians from All other Tetrapods  Reptilomorphs  Anthracosaurs and all other tetrapods  Batrachomorphs  – ancestors of modern amphibians 

Carboniferous period ~370 MYA. All other tetrapods split from amphibians because of appearance of eggs

Amphibian Split from all other tetrapods ~ 360 mya

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MAJOR AMPHIBIAN GROUP: TEMNOSPONDYLI

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• Group fossil amphibians from early • Diverse and cool http://ayay.co.uk • Many similar to modern • Did not succeed- why? • Hypothesis: wrong time for these adaptations? • Hypothesis: Ancestors for living caecilians- not well supported Microsaurs Nectrideans

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• Ancestors of all living amphibians • Large diverse group spanning all major amphibian periods • Diverse forms • Some with armor • Some padeomorphism • Terrestrial and aquatic • Diverse land tetrapods of - Permian (many now extinct groups) • Aquatic species radiation in - specifically: Stereospondyls • Gave rise to (extant amphibians)

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Zatrachys (https://dibgd.deviantart.com)

Dendrerpton (www.Wikipedia.org)

416 360 300 250 200 146 65 Triassic- Aquatic Shift 245mya

 Temnopsondyli: *  All mostly aquatic  Terrestrial dominated  Miniaturization through progenesis  Scales and dermal armor  Still much diversity  One group marine  Extinct group  (or maybe not??)

]AMPHIBIA

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416 360 300 250 200 146 65 Lissamphibia: Modern Amphibians*

: Amphibia  Monophyletic (most likely)  Caecilians 

 First Appearance  () 245mya

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Lissamphibia: contentious relationships

 Class: Amphibia  Monophyletic (most likely)  Temnospondyls

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416 360 300 250 200 146 65 Triadobatrachus: First Lissamphibian, 245mya

Triadobatrachus  Frog Characteristics  Frog-like pelvic  U shaped

 Ancestral Characteristics  Caudal Vertebrae (Tail)  No Urostyle  14 Presacral vertebrae

Modern

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Karaurus: First Known 150 mya

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Chinlestegophis () 215 mya Eucaecilia: First Known Caecilian 200 mya

Legs

Pardo, J., Small, B., Huttenlocker, A. 2017. Stem caecilian from the Triassic of Colorado sheds light on the origins of lissamphibia. PNAS. doi: 10.1073/pnas.1706752114

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1. Third caecilian fossil discovered in Colorado 2. Dates to Carboniferous 3. Shows strong evidence of a common ancestor of both caecilians and sterospondyls

What does this mean??

Caecilians date back farther than thought Stereospondyls group within and are part of the Lissamphibia group

MAJOR AMPHIBIAN GROUP: TEMNOSPONDYLI

MAJOR AMPHIBIAN GROUP: TEMNOSPONDYLI

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MAJOR AMPHIBIAN GROUPS

Recap

 What period is considered “age of the fishes”

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Recap

 Which specimen linked the fish-like limb with a weight-bearing limb?

Recap

 Which of the following is the first known Lissamphibian?

 A. Triadobatrachus

 B. Eucaecila

 C.

Which of the following groups include modern amphibians?

 Lepospondylii

 Ceolacanths

 Temnospondylii

 Nectrideans

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 Which vertebrates are not considered tetrapods?

 Which are?

 True or False: Weight- bearing was a result of selective for to live on land during drought.

416 360 300 250 200 146 65 Extant (Living) Amphibians

Anura (frogs and ) Gymnophiona (caecilians) (salamanders) # families: 55 # families: 10 # families: 10 # genera: 447 # genera: 33 # genera: 68 # species: 6881 # species: 207 # species: 710

The total number of amphibian species is currently 7,087 (Jan 16, 2013) The total number of amphibian species is currently 7,231 (Jan 21, 2014) The total number of amphibian species is currently 7,384 (Jan 12, 2015) The total number of amphibian species is currently 7,798 (Jan 22, 2018) Source: Amphibiaweb.org

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Amphibian Characteristics- Italics only applies to living amphibians “Tetrapod vertebrates that pass through a larval state and undergo metamorphosis into terrestrial adults.” • Anamniotes • Eggs need moist environment

• Larval; metamorphosis

• Permeable Skin • Cutaneous respiration

• Two Gland Types • Mucous • Poison

• Pedicellate Teeth

• Amphibian papillae/Opercular bone • Can hear low frequencies

• Fat Bodies

• Green Rods- fxn unknown

• Singular Sacrum • Lost in caecilians

416 360 300 250 200 146 65 Evolved Simplifications

 Pronounced in Salamanders

 Paedomorphosis

 Reduction Body Size

 Large Genomes and Cells

 Low Metabolic Rates  Affect history strategies

 Simplified Systems

Anura

•Global Distribution •Shortened Presacral (usually 8) Saltatorial • are reduced or absent (2nd or 4th) •Presacral Vertebrae Firmly Articulated •Large Hind Limbs, No tail (except 1 ) •External Fertilization (usually) •Flat heads and Large Mouths (usually) •Vocal Sacs in Males (usually)

Centrolene prosoblepon sylvatica Hypsiboas rosenbergi holbrooki

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Anuran phylogeny Primitive Derived

36 Families Recognized

Ascaphidae (2 sp) Tailed frogs for Pac NW only Ascaphus

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Microhylidae (687 sp) Diverse strategies New and Old World (Americas) () Dyscophus ()

Bufonidae (607) New and Old world True Toads Cosmopolitan except Australia/New Zealand / marina - Harlequin Frogs Often toxic secretions, and thick glandular skin

www.wikipedia.org

Centrolenidae (153) New World Only Glass Frogs 1 points inward T-shaped terminal phalanges Transparent venter Tropical stream breeding Dense in = red appearance Arboreal

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Hylidae (900+ sp) new world Hypsiboas Osteocephalus Pseudacris old world Many Others Arboreal Toepads with columnar epithelial cells= good adhesion

Ranidae ( 300+) Cosmopolitan Distribution goliath: 300 SVL; world’s largest frog Rhacophorines flying frogs etc Intercalary Cartilage (like hylids) May be own family- NOW ARE Mantellas (now ) Madagascar “poison dart frogs” and

www.dendrogrove.com

Strabomantidae (687 sp) New world only : 515 species!!- most speciose vertebrate ! All direct development “rain frogs” Triangular terminal phalanges

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Scaphiopodidae (New and Old) + Pelobatidae (Old World Only) Spadefoots Europe and NA Scaphiopus Pelobates

Scaphiopus holbrookii

Caecus = Gymnophiona blind Characteristics: •Tropical Distribution • like (7 cm – 1.5 m) •Limbless (pectoral & pelvic girdles absent) •Degenerate Eyes (most are fossorial) • (phallodeum) •20% Viviparous; 80% Oviparous • 10 Families

Dermophis mexicanus bicolor

Ichthyophis kohtaoensis

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•Smokies Diversity Caudata (Urodela) (31)

Characteristics: •Mostly Temperate Distribution •Tailed Amphibians • like (30 mm – 1.5 m) •Well-developed limbs (except aquatic) •Internal Fertilization (most) •Larval Development External (most) •10 Families •Lack Tympanum & (opercular)

Andrias japonicus

Ambystoma talpoideum

Amphiuma tridactylum ruber

?

?

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Salamander Phylogeny

Plethodontidae Derived

Amphiumidae Rhyacotritonidae

Ambystomatidae Dicamptodontidae

Salamandridae

Proteidae

Sirenidae

Hynobiidae

Cryptobranchidae Primitive

Salamander vs Lizard

Moist Skin Epidermal Scales tips Ear holes Rounder head More dorsoventrally Usually body held up over compressed ground

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