Branchiosaurus (Greek for "gill lizard") is a genus of small, lightly-built early prehistoric amphibians. Pictured here is the dorsal vertebra.

Dorsal Vertebra of Branchiosaurus

Branchiosaurus (Greek for "gill lizard") is a genus of small, lightly-built early prehistoric amphibians.…

A dorsal vertebra, side view.

Side View of a Dorsal Vertebra

A dorsal vertebra, side view.

Hylonomus was an early reptile. It lived 315 Ma (million years ago) during the Carboniferous period. Pictured here is the dorsal vertebra

Dorsal Vertebra of the Hylonomus

Hylonomus was an early reptile. It lived 315 Ma (million years ago) during the Carboniferous period.…

A dorsal vertebra. Labels: 1, the body; 2, face for the head of a rib; 3, superior face of the body; 4, superior half of the intervertebral notch; 5, interior half of the intervertebral notch; 6, spinous process; 7, articular face for the tubercle of a rib; 8, two superior oblique processes; 9, two inferior oblique processes.

Dorsal Vertebra

A dorsal vertebra. Labels: 1, the body; 2, face for the head of a rib; 3, superior face of the body;…