Bilaterally symmetrical animals
CLASS: Sarcopterygians
Sarcopterygians in their original form have fleshy fins as opposed to fins with a bone structure. It is these fleshy fins that over time have evolved to become to limbs of today's mammals.
Sarcopterygians in their original form also have more than one dorsal fin.
The earliest fossils of sercopterygians date back to 418 million years ago.
Sarcopterygii can be split into two groups which are called the actinistia and the rhipidistia.
The actinistia are a mysterious animal as they were once thought to be extinct, however since the 1930s discoveries of such animals have been made.
Both actinistia and rhipidistia are essentially lobe finned fish. The striking difference between the two groups is that it is understood that land mammals have evolved from rhipidistia.
Humans evolved from rhipidistia.
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Lobe finned fish from which land mammals have evolved. |
ACTINISTIA Lobe finned fish most closely related to rhipidistia. |
