Ciro Santilli @cirosantilli 37

Name origin: amnion, a pellicle that covers embryos of both eggs and also during pregnancy.

Includes:

Does not include amphibians. If you include them, you have the tetrapods.

As of 2020, account for about 20% of the known mammal species!!! www.sciencefocus.com/nature/why-are-there-so-many-species-of-bat/ mentions some reasons:

The first found and most important known epigenetic marker.

Happens only on adenine and cytosine. Adenine methylation is much less common in mammal than cytosine methylation, when people say "methylation" they often mean just cytosine methylation.

It often happens on promoters, where it inhibits transcription.

It is quite mind blowing that this is polyphyletic on mammals and birds, what can't parallel evolution achieve??

The second protein to have its structure determined, after myoglobin, by X-ray crystallography, in 1965.

Breaks up peptidoglycan present in the bacterial cell wall, which is thicker in Gram-positive bacteria, which is what this enzyme seems to target.

Part of the inate immune system.

It is present on basically everything that mammals and birds excrete, and it kills bacteria, both of which are reasons why it was discovered relatively early on.

They split up from the rest of the mammals after the monotremes.

Every other mammal has a placenta.

This baby in pouch thing just feels like a pre-placenta stage.

The weirdest mammal clade: they lay fucking eggs. Only 5 known species alive as of 2020.

Eggs are basal: they simply didn't evolve out of what other reptiles do. From which we conclude that milk came before eggs stopped.

So this is the most basal subclade of mammals.

Etymology: means "single hole" in Greek, because like other reptiles it has a single hole for shit, pee and fucking: the cloaca.

Basically mean that parallel evolution happened. Some cool ones:

Mammals and a bunch of extinct animals that look more like mammals than reptiles.

TODO name: Wikipedia says "being with a fused arch" but what does that mean???

Includes:

The exact relationships between those clades is not very clear as there's a bunch of extinct species in the middle we are not sure exactly where they go exactly, some hypothesis are listed at: en.wikipedia.org/w/index.php?title=Tetrapod&oldid=1053601110#Temnospondyl_hypothesis_(TH)

But at least it seems rock solid that those three are actually clades.

epigenetics mechanism.