Virtual Museum: Amphibians

Acanthostega gunneri (cast) was one of the very first tetrapods (animals with 4 legs instead of fins). It differed from the lobe-finned fishes it evolved from by having a neck (the head could be moved independent of the thorax or limbs), elbows, wrists, and digits (fingers and toes). These features were probably adaptations for clambering over debris in shallow water rather than actually moving about on land. It still had a tail fin and gills.

Taxonomy: Tetrapoda

Greenland

Late Devonian Period, 360 Ma

Wyoming Dinosaur Center

Life model of Acanthostega gunnari.

Taxonomy: Tetrapoda

Late Devonian, 365 Ma; Greenland

Wyoming Dinosaur Center

Life model of Ichthyostega sp., a basal tetrapod with a more robust skeleton that allowed it to move about on land.

Taxonomy: Tetrapoda

Late Devonian, 374-359 Ma; Greenland

Wyoming Dinosaur Center

Life model of Greererpeton burkemorani, a basal tetrapod, that became secondarily more aquatic.

Taxonomy: Tetrapoda

Early Carboniferous Period, 330 Ma; North America

Wyoming Dinosaur Center

The temnospondyls were the largest, most diverse group of amphibians (early tetrapods). While some, such as this Koskinonodon perfecta, were semi-aquatic, others were more fully terrestrial or even fully aquatic.

Taxonomy: Tetrapoda; Temnospondyli

Southwestern USA

late Triassic Period, 225 Ma

Arizona Museum of Natural History

Eryops megacephalus reconstructed skeleton.

Taxonomy: Tetrapoda; Temnospondyli

North America

late Carboniferous-early Permian Periods, 310-295 Ma

Museum of Ancient Life, Utah

Another Eryops megacephalus reconstructed skeleton.

Taxonomy: Tetrapoda; Temnospondyli; Eryopidae

Texas

early Permian Periods, 295 Ma

Chicago Field Museum

Cacops aspidephorus reconstructed skeleton.

Taxonomy: Tetrapoda; Temnospondyli; Dissorophidae

Oklahoma

early Permian Period

Chicago Field Museum

Acheloma cumminsi reconstructed skeleton.

Taxonomy: Tetrapoda; Temnospondyli; Trematopidae

Texas

Early Permian Periods, 279-273 Ma

Chicago Field Museum

Amphibamus lyelli fossil cast. This is a relatively small temnospondyl, and may be fairly closely related to the lissamphibia (the clade that includes all extant species).

Taxonomy: Tetrapoda; Temnospondyli; Amphibamidae

Mazon Creek, IL

Carboniferous Period

Chicago Field Museum

The lack of preserved carpal and tarsal bones and gaps between other limb bones in this Sclerocephalus haeuseri indicate that the bones had not fully ossified (turned to bone) and were still partly cartilagenous. This is common among semi-aquatic animals that do not need to support their weight out of water. This specimen is preserved upside down.

Taxonomy: Tetrapoda; Temnospondyli

Germany

Early Permian Period, 280 Ma

Wyoming Dinosaur Center

Micromelerpeton sp., including some carbonization outlining the body soft tissue.

Taxonomy: Tetrapoda; Temnospondyli

Germany

Early Permian Period, 295 Ma

Wyoming Dinosaur Center

Branchiosaurus sp. may the larval (juvenile) form of a larger amphibian.

Taxonomy: Tetrapoda; Temnospondyli

Germany

Permian Period

Black Hills Institute Museum, South Dakota

Saurerpeton obtusum cast.

Taxonomy: Tetrapoda; Temnospondyli

Linton Formation, Jefferson Co., OH

Carboniferous Period, Middle Pennsylvanian Epoch, 305 Ma

Denver Museum of Science & Nature

Some temnospondyls, such as this Aphaneramma sp. (cast of skull), became large crocodile-like predators.

Taxonomy: Tetrapoda; Temnospondyli

Moenkopi Formation, Arizona

Triassic Period

Arizona Museum of Natural History

Cosgriffius campi (cast of skull) is closely related to Aphaneramma (above).

Taxonomy: Tetrapoda; Temnospondyli

Moenkopi Formation, Arizona

Triassic Period

Arizona Museum of Natural History

Eocyclotosaurus sp. skull cast.

Taxonomy: Tetrapoda; Temnospondyli

Moenkopi Formation, Arizona

Late Triassic Period

New Mexico Museum of Natural History & Science

Metoposaurus howardensis skull.

Taxonomy: Tetrapoda; Temnospondyli

Texas

late Triassic Period

Los Angeles Museum of Natural History

Hadrokkosaurus bradyi skull cast.

Taxonomy: Tetrapoda; Temnospondyli

Moenkopi Formation, Arizona

Middle Triassic Period

Arizona Museum of Natural History

Paracyclotosaurus davidi skull cast.

Taxonomy: Tetrapoda; Temnospondyli

NSW, Australia

Middle Triassic Period, 235 Ma

Dinosaur Resource Center, Colorado

The lepospondyls are less diverse and less well known than the temnospondyls. They were mostly smaller sized, and some scientists question whether this is a natural group.

The boomerang-headed Diplocaulus sp. (skeleton and life model shown) is one of the largest of the lepospondyls, about 1 m long. The function of its unusual head shape is not clear, but may have acted as a hydrofoil to regulate water flow over its head, protected external gills, or provided some predator protection by making it difficult to be swallowed.

Taxonomy: Tetrapoda; Lepoospondyli

Vale Formation, Baylor Co., TX

Early Permian Period, 275 Ma

Denver Museum of Science & Nature

Life model of Diploceraspis sp., a smaller relative of Diplocaulus. Note also a giant dragonfly, roaches and a spider.

Taxonomy: Tetrapoda; Lepoospondyli

Permian Period, 270 Ma

Museum of the Rockies, Montana

Life model of Ophiderpeton sp., a secondarily limbless, snake-like amphibian.

Taxonomy: Tetrapoda; Lepoospondyli

Carboniferous Period, Pennsylvanian Epoch; Europe, North America

Museum of Ancient Life, Utah

The term Lissamphibia is used to represent the group that includes all surviving amphibians (frogs, salamanders, and caecilians). Unfortunately, there is still considerable debate about where the Lissamphibia fit among the other extinct amphibian groups.

This frog is Eopelobates sp.

Taxonomy: Tetrapoda; Lissamphibia; Anura; Pelodytidae

Green River Formation, Wyoming

Eocene Epoch

Black Hills Institute Museum, South Dakota

This is the holotype fossil (the specimen used to name and define it) of the frog Aerugaomnis paulus.

Taxonomy: Tetrapoda; Lissamphibia; Anura; Pelodytidae

Fossil Lake, Wyoming

Eocene Epoch

Chicago Field Museum

Fossil of the salamander Paleoamphiuma tetradactylum. Like its modern relatives, it is fully aquatic and has greatly reduced limbs, as can be seen here (the front limb is disarticulated, the hind limb is at roughly the midpoint).

Taxonomy: Tetrapoda; Lissamphibia; Caudata; Sirenidae

Fossil Lake, Wyoming

Eocene Epoch

Chicago Field Museum

Reptiliomorphs are those tetrapods that are closest to the amniotes (tetrapods that lay amniotic eggs on land, including reptiles and mammals.

Cast of Seymouria baylorensis.

Taxonomy: Tetrapoda; Reptiliomorpha; Seymouriidae

Texas

Early Permian Period, 280-270 Ma

New Mexico Museum of Natural History & Science

Seymouria sp. mass death assemblage (cast).

Taxonomy: Tetrapoda; Reptiliomorpha; Seymouriidae

Cutler Formation, Arriba Co., NM

Early Permian Period, 275 Ma

Denver Museum of Science & Nature

Seymouria sanjuanensis reconstructed skeleton.

Taxonomy: Tetrapoda; Reptiliomorpha; Seymouriidae

Texas

Early Permian Period

Chicago Field Museum

Diasparactus zenos reconstructed skeleton.

Taxonomy: Tetrapoda; Reptiliomorpha; Diadectidae

New Mexico

Early Permian Period, 296-295 Ma

Chicago Field Museum

Skull of Diadectes sp., in ventral view (without mandibles).

Taxonomy: Tetrapoda; Reptiliomorpha; Diadectidae

Texas

Permian Period

Chicago Field Museum

Discosauriscus austriacus.

Taxonomy: Tetrapoda; Reptiliomorpha

Russia

Late Permian Period

Black Hills Institute Museum, South Dakota