300 million-year-old tail print shows that scales evolved earlier than expected.
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Scales helped reptiles conquer the land—when did they first evolve?
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One key thing here is that reptile scales are not homologous to fish scales, so reptiles didn’t just get scales from fish ancestors. Reptile scales form from the epidermis. Fish scales form from the dermis, and are more closely related to teeth and mammal hair than to they are to reptile scales.
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Wonderful, deep time is an endless rabbit hole and I find this window and a little earlier (geologically speaking) especially amazing. For context on this 300Mya fossil
en.wikipedia.org
en.wikipedia.org
What's especially cool for me is I'm from Devon and live near Wenlock.
And I'm a Silurian.
Silurian-Devonian Terrestrial Revolution - Wikipedia
Pneumodesmus - Wikipedia
What's especially cool for me is I'm from Devon and live near Wenlock.
And I'm a Silurian.
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Lochkovian caught my eye; Lochkov is a stone's throw from where I live and I used to go fossil hunting for trilobites, graptolites and orthoceras quite often.Wonderful, deep time is an endless rabbit hole and I find this window and a little earlier (geologically speaking) especially amazing. For context on this 300Mya fossil
Silurian-Devonian Terrestrial Revolution - Wikipedia
Pneumodesmus - Wikipedia
What's especially cool for me is I'm from Devon and live near Wenlock.
And I'm a Silurian.
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TL;DR, but it's worth going through the rest of the article, as you'd expect from Ars.
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I have doubts about how this is being reported here:
"Strikingly, these tail prints come complete with scale impressions—at 300 million years old, they’re among the earliest scale impressions we have. This may seem small, but it shows us that some of the hardened skin structures necessary for our ancestors to survive on land had evolved much earlier than previously suspected." ... what?
This is in Permian already, amniotic eggs are already common etc, this isn't that particularly early, certainly not for "surviving on land" to be anything at all novel for vertebrates at the time. And why would scales be anything odd after the Carboniferous rainforest collapse, climate has dried up and presumably that's why the, loosely speaking, reptile-like amniotes have become dominant over their other, again loosely speaking amphibian-like, tetrapod cousins, some millions of years prior to this? Far from much earlier than suspected, isn't this in fact exactly when you'd expect scales to appear?
The abstract seems to be saying something completely different from this article's perspective:
"... still unresolved question of whether the ability to form corneous skin appendages is an apomorphy of a common ancestor of amphibians and amniotes or evolved independently in both groups. ... The traces can be unambiguously attributed to diadectids and are interpreted as the globally first evidence of horned scales in tetrapods close to the origin of amniotes.Taking hitherto little-noticed scaly skin impressions of lepospondyl stem amniotes from the early Permian of Germany into account, the possibility has to be considered that the evolutionary origin of epidermal scales deeply roots among anamniotes."
Soo, the key thing is that these are scales on a lepospondyl, not an amniote! Its not just the age of the trace, but who left it that suggest the origin of these reptilian scales might be even older than amniotic eggs, which IS kinda surprising! But it still makes sense as we're seeing it in a group that is pretty close to amniotes.
"Strikingly, these tail prints come complete with scale impressions—at 300 million years old, they’re among the earliest scale impressions we have. This may seem small, but it shows us that some of the hardened skin structures necessary for our ancestors to survive on land had evolved much earlier than previously suspected." ... what?
This is in Permian already, amniotic eggs are already common etc, this isn't that particularly early, certainly not for "surviving on land" to be anything at all novel for vertebrates at the time. And why would scales be anything odd after the Carboniferous rainforest collapse, climate has dried up and presumably that's why the, loosely speaking, reptile-like amniotes have become dominant over their other, again loosely speaking amphibian-like, tetrapod cousins, some millions of years prior to this? Far from much earlier than suspected, isn't this in fact exactly when you'd expect scales to appear?
The abstract seems to be saying something completely different from this article's perspective:
"... still unresolved question of whether the ability to form corneous skin appendages is an apomorphy of a common ancestor of amphibians and amniotes or evolved independently in both groups. ... The traces can be unambiguously attributed to diadectids and are interpreted as the globally first evidence of horned scales in tetrapods close to the origin of amniotes.Taking hitherto little-noticed scaly skin impressions of lepospondyl stem amniotes from the early Permian of Germany into account, the possibility has to be considered that the evolutionary origin of epidermal scales deeply roots among anamniotes."
Soo, the key thing is that these are scales on a lepospondyl, not an amniote! Its not just the age of the trace, but who left it that suggest the origin of these reptilian scales might be even older than amniotic eggs, which IS kinda surprising! But it still makes sense as we're seeing it in a group that is pretty close to amniotes.
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