#casineria

[vickysaurus-art]

On a moonlit night in the early Carboniferous, two Pulmonoscorpius do a mating dance in the Lepidodendron swamp. Although the giant scorpions have little interest in prey right now, a Balanerpeton amphibian wisely decides to swim away, while several Casineria sleep through the night in the copious tree litter.

[synblr]

A Prologue to Amniotes

Part IV - The egg came first

Late Mississippian. It has been 40 million years since tetrapods first walked on land. Every generation since then, they have remained bound to the waters for at least one moment in their life cycle.

Despite their adaptations for walking on land, early tetrapod reproduction wasn't much different from that of their fish predecessors. Spawning, or external fertilization of an egg mass, with eggs covered in a gelatinous membrane laid in a body of water, prevending the permeable eggs from dessicating.

But things are now changing. While the mid-Carboniferous rainforests still provide safe, moist environments, reptiliomorphs have already begun adventuring further inland. As swamps left room to humid crevices to lay eggs in, creatures like Casineria also began to develop internal fertilization, refusing to leave their reproduction at the mercy of the elements.

Casineria kiddi, an early amniote relative by ДиБгд (CC-BY-SA 4.0)

Adventuring into even drier environments, ancestors of amniotes still had to solve two crucial problems. While a harder shell could prevent the egg from dessicating, it would doom the embryo to suffocation, by preventing it to get rid of carbon dioxide. Furthermore, the small size of the eggs - also constrained by gas exchange - limited the full development of the embryo before hatching.

To solve both of these issues, the outer layers of the eggs would have to be reshaped. The outer gelatinous layer was replaced by a fibrous membrane for protection, and later by the three layers known as extraembryonic membranes: the amnion, chorion and allantois. The innermost amnion would surround and protect the embryo, while the outer chorion and sac-like allantois take care of gas exchange and waste removal.

In the safety of the amniotic egg, the embryo was able to hatch considerably more developed than before. Skipping the larval stage, amniote youngs would hatch as miniatures of the adults, making them able to face the challenges of the Carboniferous world from the day of their birth.

Structure of the amniotic egg, by Lumen Learning (CC-BY)

As the Pennsylvanian began and climate started to dry out, later developments would perfect the ability of early amniotes to survive in drier, fully terrestrial environments. A thicker, less permeable skin will develop, incorporating keratin and preventing dessication. Cutaneous respiration, requiring the skin to be moist at all times, will give way to costal respiration, harnessing the power of the ribcage to expand and contract the lungs. Cutting their last ties with the water, amniotes had finally conquered the land.

On one fateful day, not long after the amniote body plan was perfected, one of the most decisive splits in vertebrate history would occur. A divergence of the amniotes into two major lineages, alternating domination of land, sea and sky for the next 320 million years. But sauropsids like Hylonomus would at first stay in the shadows. The stage of the Late Pennsylvanian would be left to their rivals and cousins, as forerunners like Archaeothyris paved the way for their own lineage: the synapsids.

Archaeothyris, one of the first known synapsids, by ArthurWeasley (CC BY-SA 3.0)

[formiana]

Chapters: 10/10 Fandom: The Magnus Archives (Podcast) Rating: Mature Warnings: Graphic Depictions Of Violence Relationships: Martin Blackwood/Michael | The Distortion, Martin Blackwood/Jonathan "Jon" Sims | The Archivist Characters: Martin Blackwood, Michael | The Distortion (The Magnus Archives), Michael Shelley, Jonathan "Jon" Sims | The Archivist, Not-Them Sasha James, Tim Stoker (The Magnus Archives), Annabelle Cane Additional Tags: Enemies to Lovers, Time Loop, Canon-Typical The Spiral Content (The Magnus Archives), Canon-Typical The Stranger Content (The Magnus Archives), Canon-Typical The Web Content (The Magnus Archives), Eventual Web!Martin, but also eventual Spiral!Martin, he's very adaptable and this isn't a good thing, Slow Burn, Or as close as you can get to slow burn when only one involved party remembers anything, Canon-Typical Violence, Canonical Character Death, (actually Sasha died before the fic but it's a major theme so I wanted to tag it), Alternate Universe - Canon Divergence, Set during Season 2 around episode 58!, Horror and Romance and Humor and Angst, Fix-It of Sorts, As much as anything can be fixed in Season 2 Summary:

Months after the Prentiss attack, Martin Blackwood is having a bad day.

Relationships among his coworkers have fallen apart, their boss is stalking them, and no one can quite shake the feeling that danger is still close by. Martin's doing his best to hold everyone together, but tea and sympathy aren't working like they used to. The sole bright spot is that it's much easier to have a crush on Jon now that he's decided Martin isn't a murderer. Mostly, though, Martin's just glad to make it through the day...

...until he wakes up and has to live the same bad day all over again.

Martin finds himself caught in a loop, reliving the 19th November over and over again, struggling to understand why this is happening and what he has to do to get out. His dear coworker Sasha is acting very strange, spiders keep crawling over everything, and at the center of it all is a man with long, sharp hands, who might be to blame... or might be the key to escaping all of this.

(Or: Michael, Not-Sasha, and Annabelle have a three-sided tug-of-war over Martin's brain, while Martin hooks up with the guy who got him into this mess and keeps trying to Fifty-First-Dates his boss.)

[gammija]

(on a sidenote, Revolving Doors by Casineria is rlly good and yall should read it if you like martin and michael and time loops and spiders)

is ao3 down again 😭😭😭

[extinctworld-ua]

Hylonomus

Гілоном (лат. Hylonomus, від др.-грец. ὑλονόμος «той, що мешкає в лісах, лісовий») – вимерлий тетрапод кам’яновугільного періоду. Це найраніша справжня рептилія (Westlothiana старша, але в неї спірна систематика, а інший тетрапод, Casineria, відомий за досить фрагментарними залишками). Єдиним видом є типовий вид Hylonomus lyelli.

Повний текст на сайті "Вимерлий світ":

https://extinctworld.in.ua/hylonomus/

[spooksier]

Whats the TMA fic :))?

ooohhh casineria you want to write a fr book some day so bad

[albertonykus]

Do we know of any amniotes that weren't synapsids or sauropsids?

We do not, and the reason we don’t is that it’s by definition impossible! Amniota is now most commonly given a crown-group definition, “the last common ancestor of living mammals and reptiles and all of its descendants”. Given that Synapsida and Sauropsida as defined (”closer to mammals than to living reptiles” and “closer to living reptiles than to mammals” respectively) represent the most basic split in this clade, it is impossible for something to be an amniote without being either a sauropsid or synapsid. (The one exception to this would be the last common ancestor of all amniotes, but most of the time we assume that we won’t be able to identify direct ancestors with any certainty.)

We do know, however, of a few possible stem-amniotes (namely Westlothiana and Casineria) that might be considered true amniotes if our definition of Amniota was just a little more inclusive. The problem is that the main alternative definition to crown-group Amniota is an apomorphy-based one that hinges upon the presence of an amniotic egg, a feature that is impossible to ascertain without the discovery of fossilized eggs.

[rawrdinosaurfriends]

The joke is I don't even know what 'cladistics' are, just that my biology/paleo friends constantly complain about them.

Website | Twitter | Ask

[formiana]

Chapters: 1/8 Fandom: The Magnus Archives (Podcast) Rating: Mature Warnings: Graphic Depictions Of Violence Relationships: Martin Blackwood/Michael | The Distortion, Martin Blackwood/Jonathan "Jon" Sims | The Archivist Characters: Martin Blackwood, Michael | The Distortion (The Magnus Archives), Michael Shelley, Jonathan "Jon" Sims | The Archivist, Not-Them Sasha James, Tim Stoker (The Magnus Archives), Annabelle Cane Additional Tags: Enemies to Lovers, Time Loop, Canon-Typical The Spiral Content (The Magnus Archives), Canon-Typical The Stranger Content (The Magnus Archives), Canon-Typical The Web Content (The Magnus Archives), Eventual Web!Martin, but also eventual Spiral!Martin, he's very adaptable and this isn't a good thing, Slow Burn, Or as close as you can get to slow burn when only one involved party remembers anything, Canon-Typical Violence, Canonical Character Death, (actually Sasha died before the fic but it's a major theme so I wanted to tag it), Alternate Universe - Canon Divergence, Set during Season 2 around episode 58!, Horror and Romance and Humor and Angst, Fix-It of Sorts, As much as anything can be fixed in Season 2 Summary:

Months after the Prentiss attack, Martin Blackwood is having a bad day.

Relationships among his coworkers have fallen apart, their boss is stalking them, and no one can quite shake the feeling that danger is still close by. Martin's doing his best to hold everyone together, but tea and sympathy aren't working like they used to. The sole bright spot is that it's much easier to have a crush on Jon now that he's decided Martin isn't a murderer. Mostly, though, Martin's just glad to make it through the day...

...until he wakes up and has to live the same bad day all over again.

Martin finds himself caught in a loop, reliving the 19th November over and over again, struggling to understand why this is happening and what he has to do to get out. His dear coworker Sasha is acting very strange, spiders keep crawling over everything, and at the center of it all is a man with long, sharp hands, who might be to blame... or might be the key to escaping all of this.

(Or: Michael, Not-Sasha, and Annabelle have a three-sided tug-of-war over Martin's brain, while Martin hooks up with the guy who got him into this mess and keeps trying to Fifty-First-Dates his boss.)