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The world's smallest known vertebrate, Paedophryne amauensis, sitting on a U.S. dime.The dime is 17.9 mm in diameter, for scale. The word amphibian is derived from the Ancient Greek term ἀμφίβιος (amphíbios), which means 'both kinds of life', ἀμφί meaning 'of both kinds' and βίος meaning 'life'.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
The first fully terrestrial vertebrates were reptilian amniotes — their eggs had internal membranes that allowed the developing embryo to breathe but kept water in. This allowed amniotes to lay eggs on dry land, while amphibians generally need to lay their eggs in water (a few amphibians, such as the common Suriname toad, have evolved other ways of getting around this limitation).
The ancestors of true amniotes, such as Casineria kiddi, which lived about 340 million years ago, evolved from amphibian reptiliomorphs and resembled small lizards. At the late Devonian mass extinction (360 million years ago), all known tetrapods were essentially aquatic and fish-like.
The lineages of modern dogs and wolves may have split thousands of years earlier than previously thought. According to new research, the divergence happened around 27,000 to 40,000 years ago, far ...
Evolutionary theory predicted that since amphibians evolved from fish, an intermediate form should be found in rock dated between 365 and 385 million years ago. Such an intermediate form should have many fish-like characteristics, conserved from 385 million years ago or more, but also have many amphibian characteristics as well.
The key innovation in amniotes over amphibians is the amnion, which enables the eggs to retain their aqueous contents on land, rather than needing to stay in water. (Some amniotes later evolved internal fertilization, although many aquatic species outside the tetrapod tree had evolved such before the tetrapods appeared, e.g. Materpiscis.)
Dogs: Their Fossil Relatives and Evolutionary History is a book by Xiaoming Wang and Richard H. Tedford.It was published in 2008 by Columbia University Press.The book offers a "holistic picture of canid evolution" and an overview of existing and extinct taxa, also detailing the evidence for the domestication and evolution of domestic dogs from their wolf ancestors. [1]