Bilaterally symmetrical animals
SERIES: Amniotes
Amniotes are essentially those tetrapods which have robust eggs whether laid externally, or carried by the parent until birth. This would therefore include reptiles, birds and mammals.
This reproductive evolution made the larval stage of amphibians virtually obsolete.
Amniotes developed stronger body structures as they began to explore the Earth's newly discovered land environment between 340 and 310 million years ago.
The evolution of the amniotes involves a major evolutionary split in regard to today's living land vertebrates.
The amniotia series split recognises two classes. These classes are called synapsida and sauropsida.
The synapsida which evolved to become the mammals which we know today were initially the dominant land amniotes. Generally they can be recognised by the presence of an opening in the skull further back in the skull than the eye orbit.
The sauropsida evolved to become reptiles and dinosaurs and birds. However, there has been a lot of speculation about the accuracy of the split between synapsida and sauropsida as fossil discoveries have increased and theories of evolution have become of interest.
Humans evolved from the synapsida.
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Amniotes which evolved to become mammals. |
SAUROPSIDA Amniotes that evolved to become reptiles, dinosaurs and birds. |
