Amniota

1 Lizards, rabbits, and humans are in the clade Amniota, which form a small V nested in the upper right-hand corner of the V-shaped Vertebrata clade.

2 Returning to Figure 20.10, note that the amniotic egg is a shared ancestral character for the Amniota clade, while having hair is a shared derived character for some organisms in this group.

3 Integration of morphological data sets for phylogenetic analysis of Amniota: the importance of integumentary characters and increased taxonomic sampling.

4 The Amphibians are followed in the Permian period by the first Amniota, the oldest reptiles; from these develop later, in the Triassic period, the Birds on the one hand, and the Mammals on the other.

5 One of the most obvious examples of this is the allantois in the Amniota.

6 The amniotic egg evolved before hair because the Amniota clade is larger than the clade that encompasses animals with hair.

7 Returning to Figure 1, note that the amniotic egg is a shared ancestral character for the Amniota clade, while having hair is a shared derived character for some organisms in this group.

8 Molecular diversity and evolution of neuron types in the amniote brainBehavioural processes.

9 Three-dimensional skin cast and compression fossils from unknown amniotes.

10 The fossils are a kind of milepost for when amniotes were settling in on land and establishing the foundational traits of later creatures like fuzzy mammals and feathery dinosaurs.

11 Described Thursday in Current Biology, these tatters of fossil skin and various skin impressions come from some of the earliest amniotes.

12 During the Carboniferous Period, the evolutionary adaption of the amniote egg allowed the early tetrapods to lay their eggs on land — allowing the species to transition to a fully on-land lifestyle, according to the University of California Museum of Paleontology.

13 The solution to land's dry nature was to encase eggs in a number of membrane layers, in what is now known as an amniote egg.

14 The tumor that afflicted a poor Pappochelys some 240 million years ago is the oldest evidence of this type of cancer in an amniote, a lineage of four-limbed vertebrates, or tetrapods, that includes reptiles, birds and mammals.

15 The fossilized critter is an amniote—a land-dwelling vertebrate that lays eggs— and has four legs.