BIO 370 Vertebrate Zoology
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Vertebrate Diversity
Class Amphibia Amphibians

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Tetrapod Characteristics

  • 4 walking limbs with toes
  • Specialized atlas, 2 occipital condyles
  • Hyoid apparatus for tongue muscles
  • Middle ear with tympanum, stapes
  • Eyelids

Amphibia Characteristics

    The following apply to Lissamphibia (extant amphibians):
    • Glandular skin
    • Cutaneous gas exchange
    • Short ribs
    • Hands with 4 digits
    • Reduced or absent dermal armor
    • Typically with aquatic larval stage
See also Amphibian Anatomy page

Order Caudata Salamanders, newts

    • Generalized, ancestral body plan
    • Elongate body, 4 walking limbs, and long tail
    • Larvae differ from adults: Have tail fins, external gills, and lateral line

Marbled Salamander
Marbled Salamander, Ambystoma opacum (Family Ambystomatidae), adult; SC; a mostly fossorial species
Spring Salamander Adult
Spring Salamander, Gyrinophilus porphyriticus (Family Plethodontidae), adult; KY
Red-spotted Newt
Red-spotted Newt, Notophthalmus viridescens (Family Salamandridae); PA; terrestrial juvenile stage (larvae and breeding adults are aquatic)
Garden Slender Salamander
Garden Slender Salamander, Batrachoseps major (Family Plethodontidae); CA; a fossorial, worm-like species: note reduced legs
Northwestern Salamander
Northwestern Salamander, Ambystoma gracile (Family Ambystomatidae), larva; WA
Spring Salamander Larva
Spring Salamander, Gyrinophilus porphyriticus (Family Plethodontidae), larva; PA
Lesser Siren, Siren intermedia (Family Sirenidae), an aquatic salamander (note external gills) that lacks hind limbs
Giant Salamander
Chinese Giant Salamander, Andrias davidianus (Family Cryptobranchidae), the world's largest extant amphibian; aquatic

Order Anura Frogs & Toads

    • Body plan specialized for leaping or swimming
    • Vertebral column shortened, forms urostyle
    • Hind legs greatly elongated
    • Fusion of tibia-fibula, ulna-radius
    • Loss of tail
    • Larvae ("tadpoles"): have tails, lack legs; have internal gills, have beak or denticles; lateral line present

Maya Mountain Frog
Maya Mountain Frog, Rana juliani (Family Ranidae); Belize;
a semiaquatic jumper
Rain Frog
Peruvian Rain Frog, Pristimantis peruvianus (Family Craugastoridae); Ecuador;
a semiarboreal? jumper
Sonoran Green Toad
Sonoran Green Toad, Anaxyrus retiformis (Family Bufonidae);
a terrestrial hopper
Western Spadefoot
Western Spadefoot, Spea hammondii (Family Pelobatidae); CA;
a burrower
Dyeing Dart-Poison Frog
Dyeing Dart-Poison Frog, Dendrobates tinctorius (Family Dendrobatidae); a terrestrial walker
Banana Frog
Congo Spiny Reed Frog, Afrixalus osorioi (Family Hyperoliidae); Kenya; a climber
Veined Treefrog
Veined Treefrog, Trachycephalus venulosa (Family Hylidae); Belize; a climber
Horned Frog
Ornate Horned Frog, Ceratophrys ornata (Family Leptodactylidae);
a sit-and-wait predator
Clawed Frog
African Clawed Frog, Xenopus sp.; (Family Pipidae)
a fully aquatic swimmer
Tailed Frog Tadpole
Tailed Frog, Ascaphus truei (Family Ascaphidae), tadpole (ventral side); CA
Bullfrog Tadpole
Bullfrog, Rana catesbeiana (Family Ranidae), tadpole; AZ
Pacific Treefroglet
Pacific Treefrog, metamorphosing froglet, Pseudacris regilla (Family Hylidae); CA

Order Gymnophiona Caecilians

    • Greatly elongated, limbless bodies
    • Usually have segmented rings (dermal folds)
    • Eyes reduced or absent
    • Most are burrowing; some aquatic
Caecilian specimen
Rubber Eel, Typhlonectes sp. (Family Typhlonectidae); preserved specimen

Some Extinct Amphibians (Tetrapods)

BasalTetrapod models Temnospondyl models
Early Basal Tetrapods:
The most primitive tetrapods before the major radiations of Temnospondyls and Leptospondyls.
A large clade that was most diverse during the Permian Period; mostly gone by the end of the Triassic except for a few forms that survived into the Cretaceous. Many forms (especially during the Permian) were terrestrial; Triassic forms mostly semiaquatic. Some reached enormous size.

Lepospondyl models Reptiliomorph models Extinct Lissamphibian models
A group of mostly smaller-sized amphibians diverse during the Carboniferous and Permian Periods. There is some uncertainty about the monophyly of this group. Some were secondarily limbless.
Reptiliomorphs (including Anthracosaurs):
A paraphyletic group of amphibians most closely related to the Amniotes
The clade that includes all extant amphibians. Its relationship to other tetrapod groups is uncertain and it may not be monophyletic.

This page last updated 17 February 2018 by Udo M. Savalli ()
Images and text Udo M. Savalli. All rights reserved.