Frog skeleton

Skeletons, part 2

Today's lab includes the following pages on this site:

Look over all these pages and examine the various bone specimens in terms of what you read. Later, in the lab exam, you'll be asked to identify various specimens, name their important features, and discuss their functional significance. Before you leave lab, you should go over the review on each page to see if you're ready for the lab exam.

 Many of the bones of a frog's skeleton clearly correspond to those of mammals, but there are a few that might confuse you.

Frog skeleton with labeled bones.

Frog skeleton

Pectoral girdle and forelimbs:

  • Radioulna: Instead of a separate radius and ulna in the forelimb, the bones are fused into a single radioulna. Similarly, the tibia and fibula of the hind limb are fused into a single tibiofibula.
  • Scapula: There are two bones corresponding to the mammalian scapula: the suprascapula and the scapula (hidden in this photo).
  • Pelvic girdle: The hip region is not as strange as it might seem at first glance. The urostyle is simply a single vertebra, elongated to match the stretched-out ilium (hip bone).

Frog skull

Refer to Skulls: Reptiles vs. mammals as you look at the skull.

  • Jaw: Like the reptiles, amphibians have multiple bones making up the mandible. There is no temporomandibular joint.
  • Neurocranium: The neurocranium is the part of the skull that surrounds the brain. In frogs it is very small.
  • Occipital condyles: The strucctures at the back of the skull that allow the skull to articulate with the first vertebra. The frog has two occipital condyles, the same as a mammal. Lizards and birds have only one.
  • There is no secondary palate.


 Bullfrog skeleton from Udo Savalli at ASU.

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