The first vertebrates recognizable as tetrapods appeared in the mid-Devonian. It is generally agreed that their ancestors were lobe-finned fish. What is not agreed is how close either of the extant groups of lobe-finned fish, lungfish or coelacanths, is to the actual ancestor of the tetrapods. The soft anatomy of living lungfish shares many similarities with that of living amphibians. Many of these similarities are not present in either coelacanths or any members of the other extant bony fish group, the ray-finned fishes. Many very well preserved lungfish from the Devonian possess specialized features that would appear to exclude them from being ancestral to tetrapods. I am hypothesizing that lungfish in the Devonian may have included metamorphosis in their life cycle and that neoteny in some species may have been an early corollary. These reproductively mature neotenous lungfish would not have had the specialised features of metamorphosed adults. Fossils of these neotenous forms may have more closely resembled the tetrapod ancestral lobe-finned fish, currently believed to be a panderichthiad fish. Living lungfish have a number of larval features, which suggest paedomorphosis. Also of significance is the very large genome of living lungfish, which, in urodele amphibians, is a feature correlated with neoteny. Our current knowledge of the thyroid axis in the lungfish, Neoceratodus forsteri, is consistent with neoteny in amphibians, but the only Devonian fossil considered to be a larval lungfish bears no resemblance to living lungfish or to panderichthiads. The enigmatic phylogenetic relationship of lungfish with the first tetrapods remains, but the hunt for other forms of larval Devonian lungfish is on!

Jean M P Joss

General and comparative endocrinology

一般和比较内分泌学发表的文章涉及在亚分子、分子、细胞和有机体分析水平上脊椎动物和无脊椎动物内分泌系统的许多复杂性。

The journal "General and Comparative Endocrinology" publishes articles that explore the complexities of the endocrine systems of vertebrates and invertebrates at the submolecular, molecular, cellular, and organismal levels.

《General and Comparative Endocrinology》期刊发表的文章涉及脊椎动物和无脊椎动物内分泌系统在亚分子、分子、细胞和有机体分析水平上的复杂性。

General and Comparative Endocrinology

Gen Comp Endocrinol

Lungfish evolution and development.

It is hypothesizing that lungfish in the Devonian may have included metamorphosis in their life cycle and that neoteny in some species may have been an early corollary, and the hunt for other forms of larval Devonian lungfish is on.

Category	Quartile
医学	3
医学, 内分泌学与代谢	4

Lungfish evolution and development.

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