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#holocephali
alphynix · 1 year
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Maghriboselache mohamezanei was a cartilaginous fish from the late Devonian Period, about 369 million years ago, living in the shallow marine waters that covered what is now the Anti-Atlas mountain range of Morocco in northwest Africa.
Up to around 2.5m long (~8'), it's known from several exceptionally well-preserved and near-complete skeletons.
It had a streamlined body with large pectoral fins, small pelvic fins, and a strongly keeled crescent-shaped tail fin. And although it was superficially shark-like in appearance, it was actually part of a lineage known as cladoselachids, which were much closer related to modern chimaeras than to sharks.
It's unclear if Maghriboselache had two dorsal fins like its close relative Cladoselache, but some specimens preserve evidence of a chunky spine where the front dorsal fin would have been. Others show no sign of a front dorsal fin or spine at all, suggesting there may have been some sexual dimorphism going on in this species, with males having a spine (and possibly also an associated front dorsal fin) and females only having a rear dorsal fin.
But the most unusual feature of Maghriboselache was its nose.
It had a very broad snout with large and unusually widely-spaced nostrils, which would have given it the ability to "smell in stereo" and determine the direction of scents carried through the water much more precisely – making it the earliest known example of that sort of sensory specialization.
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NixIllustration.com | Tumblr | Twitter | Patreon
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quark-nova · 1 year
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Sometimes I see you on my dash doing a science and it makes me happy and do you have any shark facts pls? Sharks are so cool. Especially the weird deep sea sharks that always get ignored when ppl talk about great whites and such (no shame to great whites they are very lovable,)
Of course I have quite a lot!
Okay so we can start with the first shark ancestors, the spiny sharks! They lived in the Silurian, more than 400 million years ago. They looked pretty unique as each fin was actually a spine supporting the whole fin, and had already reacquired the cartilaginous skeleton that modern sharks have!
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Nobu Tamura / CC BY-SA 4.0
They often had a bunch of little pairs of "finlets" (not real fins, but spines serving a similar purpose) between their actual fins! So spiky!
Then we come to the true sharks (and rays). Or, nearly. Turns out, there are two main groups of shark-like cartilaginous fish alive today. On the one hand the sharks and rays, and on the other hand the chimeras, majestic creatures often found in the deep sea!
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Havforskingsinstituttet / CC BY-SA 4.0
Turns out however, the ancestors of chimeras were historically way more shark-like! And ranged between adorable and pretty weird, and more often than not both! Here's one of them: the sawblade shark, Helicoprion!
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Entelognathus / CC BY-SA 4.0
And here's the anvil shark!
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DiBgd / CC BY-SA 4.0
And the wtfshark, Squaloraja!
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Nix Illustrations / I don't know the license but he's on Tumblr
And now we can move on to the actual sharks. And rays. And sawsharks. And sawfish. And sawskates. The design so good they had to invent it thrice.
Here's a sawfish (these ones are closer to rays!), heavily judging whoever took the photograph. Surprisingly, they're the largest of the bunch, reaching up to 7 meters - while sawsharks are barely a meter in length at best, and sawskates aren't alive anymore but could reach a respectable 4 meters! (although they were wider relative to their size, which has to count for something?)
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Simon Fraser University - University Communications / CC BY 2.0
Now that we saw the saws, we can move on to actual sharks... wait what's that? An interruption by the coolest species of six-finned ray?
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Robert Fisher, Virginia Sea Grant / CC BY-ND 2.0
Seems like it. Of course I had to mention my favourite cartilaginous fish in the bunch. Cownose rays (and their manta ray cousins) are the only vertebrates to have developed an entire new pair of fins - on their face, to help them grab stuff! Since fish paired fins are homologous to our limbs, it would be like having an extra pair of arms coming from our face!
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Robert Fisher, Virginia Sea Grant / CC BY-ND 2.0
Back to sharks now (finally)! And speaking of stuff it's rare to have six of, what about sixgill sharks?
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No author information / Public domain
The most divergent group of true sharks alive today, the deep-sea creatures that we call frilled sharks are actually very derived, despite their prehistoric appearance! Ironically, their more ordinary-looking sixgill cousins, the cow sharks, are more representative of how sharks started off back in the days!
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NOAA / Public domain
Still six gills because why not. Or even seven, because really, why not.
Next step on our shark list (and back to the regular five-gill pattern), the angelsharks! Or sand devils, because they really couldn't decide on these ones. Angels or devils, they're absolutely adorable pancakes.
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Nick Long / CC BY-SA 2.0
Now, we would still have five more orders of sharks to go, but these are the pretty well-known ones (great white shark, hammerhead shark, etc.) and this post is getting pretty big, so I'm happy to have presented cool unique ones already! Have a nice day, and don't forget - there are always more shark species to learn about!
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squartsquartson · 8 months
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Squart back with some deep sea fuckos and facts for y'all.
-The humpback angler fish has an interesting mating ritual where the male, who is much smaller than the female, will attach itself to the female and fuse to her, giving her a permanent supply of sperm in exchange for nutrients.
-The big fin squid is a somewhat recent discovery. Not much is known since only a few specimens have been observed in nature, but we think that they use those extremely long tendrils to snag prey when they swim by.
-Chimeras are a type of fish related to sharks. The spine at the beginning of their dorsal fin is venomous.
-The colossal squid is considered to be the largest species of squid by mass.
Want merch? Check our shop! https://squartthesquidartist.myshopify.com/
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ketrinadrawsalot · 1 year
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Year of the Rabbit (Fish)
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unofficial-sean · 2 years
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Here is a taxonomy bracket that I use to help me with shark species categorization and relatedness. The top image is specific to sharks and features images as well as brief descriptions and the criteria for each branch. The bottom image is expanded to include holocephalans (chimaeriformes), as well as skates and rays. Basically, everything under “chondricthyes”
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dragonthunders01 · 7 months
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Spectember D5: Sexual Selection
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Through the different timelines, there is an alternative world that witnessed a deep ice age in the Permian caused by a prominent shift of the continent crust moving Pangea down into the south pole and blocking ocean currents, worsening the life conditions and turning most of the continent in a tundra, in the aftermath when the position of Pangea returned to something like its original position life was changed greatly, as unlike in our timeline earth was not suffocated in fire but got cold so a new variety of animals developed and survived.
In the oceans, Holocephali had a resurgence post Permian mega ice age, as their groups did not suffer horrible, things like Petalodontiforms, Eugeneodontids and other did not perish, but then there were other more varied forms evolving too, some sample are within Chimaeriforms which they in a better spot now that they aren’t relegated to the deep ocean but as diverse surface dwellers, some groups started to exploit their clasper structure in ways that would make them look almost unfitting for survival, this as a response of sexual selection. From there, a new group evolved, the Clasperantlers (Delirocephalia)
They are short body forms, small caudal fins but with large pectoral fins, these have the peculiarity that male claspers now have become these super elaborated ornamental structures that works mostly for exhibition or fight, depending of the species. They derive from ornamental structures around the orbits and the whole dorsal fin spine that developed into an articulated claw-like structure, something resembling the ornamental spines of Symmoriiformes but capable of movement.
The most common species is the Pentanichecephale monstruorum, small in size, about 30 cm in length, females look pretty much average to a chimaera with short tail, with a small dorsal fin, but the male in the other hand possess an ostentatious arrangement of 5 long horn-like structures, being 2 pairs growing around the orbit, with the middle 5th one the derived dorsal fin. They tend to be moderate in size but when mating season approaches, they start to grow in size, being covered in layers of dead tissue and useful against other males, they can break and regenerate, males often have to stand multiple fights before mating with a female which can hold with the 5th horn.
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charichoardfag2 · 10 days
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CDIN - A gender that chondrichthyan in nature
ELIN - A gender that is Elasmobranchii in nature
HOIN - A gender that is Holocephali in nature
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seedworldplanningblog · 2 months
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Great dying extinction event, 100+ million years post Anthropocene.
Cause: High levels of volcanic activity and climatic shifts created conditions comparable to the Late Permian period (but not as extreme).
No terrestrial animals over 35 lbs (16 kg) survived.
Survivors:
• Mammals: Shrews, Moles, Tenrecs, Rodents, Lagomorphs
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• Birds: Passerines, Fowl, Pigeons, Shorebirds, Sea birds
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• Herptiles: Lizards, Snakes, Anurans
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• Fish: Teleosts, Holocephali, Rays, Dogfish sharks, Bamboo sharks, Cat sharks
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• Invertebrates: Sponges, Cnidarians, Worms, Arthropods, Mollusks etc.
🪼🪱🐜🦗🪲🦟🪳🦋🕷️🦂🦀🦐🦪🐌🦑
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dungeons-and-tetrapods · 10 months
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Intro and Sophont List
This is a DnD rehaul inspired by @danbensen's Fellow Tetrapod story.
All races and classes available to DnD 5e will be reinterpreted as a sophont according to his guide for making FT sophonts. (Skill trees will be available for each sophont species).
Sophonts currently in FT will not be added until the current workload is complete. Sophont list below, although it's a heavy WIP.
Humans (Human, Hominid)
Noxissum (Aaracrocka, Pelagornis) -> thrill-seeking sophonts that live on cliffsides
Volutor (Aasimar, Polyneoptera)
Fixers [of Flesh] (Autognome, Canis) -> climbing oophagous sophonts with a focus on hunger
? (Bugbear, Barbourofelidae)
Harvau (Centaur, Mesohippus)
? (Changeling, Coleoidea)
Hemadele (Dhampir, Geospiza) -> blood-drinking sophonts that trade themselves for food
Deager (Dragonborn, Toxicofera) -> artistic sophonts with sprayed venom that dyes
Korrines (Dwarf, Herpestoidea) -> burrowing sophonts with deep familial bonds
Helbosi (Elf, Acariformes)
? (Fairy, Microraptoria)
? (Firbolg/Giant/Goliath, Pecora)
? (Genasi, Spiralia)
Breakers [They that Break the Waves] (Gnome, Otariidae)
? (Goblin, Holocephali)
? (Halfling, Callitrichidae)
? (Kenku, Corvides)
? (Kobold, Isoptera)
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Taxon Tuesday #5: Chondrichthyes
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Chondrichthyes is the class that holds cartilaginous fishes (sharks, rays, skates, etc.)  They’ve been around for well over 400 million years.  Oldies but goodies am I right?  Some of their distinguishing features are: skeletons made mostly of cartilage; skin covered in tooth-like placoid scales or denticles; teeth that are regularly shed and replaced; a piece of anatomy in males called a “pelvic clasper”, used for courtship and mating (I’m not looking that up for you sorry ✌)
These uncalcified friends are found in the clade Gnathostomata (jaw-having vertebrates).  Their cousins are Placoderms (extinct armored fishies) and Euteleostomes (bony boys - includes bony fishies and tetrapods, or land-walking friends).
Chondrichthyes itself is divided into two major subclasses.  The first is Holocephali, which holds the single order Chimaeriformes...the order of the chimaeras.  The second is Elasmobranchii, which holds 3 superorders, each of which hold 4 orders.  Taxonomy is rarely this well-balanced.  There are a lot of names, so I’ve drawn them in the picture below, with subtitles explaining what they contain.  You will have to click on it to view it fully, because it��s extremely crowded :(  Someday I will learn how to make these trees correctly.
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Sources used:
https://en.wikipedia.org/wiki/Chondrichthyes
https://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/chondrichthyes.html
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fishfactsfriday · 1 year
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Fish Facts #10 Deep Sea Chimaera
In Greek mythology the Chimaera was a monstrous fire breathing hybrid of a lion, a goat, and a snake for a tail. However the real Chimaera might seem even more strange to some. Some alternative names you might know them by are ghost sharks, ratfish, or rabbitfish.
The chimaera are primarily deep sea fish who’s body lacks a skeleton but is made up of cartilage, similar to sharks, they have been found in waters around 1,000 feet (305 meters).
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Instead of having pointed teeth it has 3 pairs of crushing plates similar to a ray’s and the general shape of it’s body reminding people of a shark, those animals being its closest living relatives.
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For an adult chimaera its size can vary from 60 cm (2 feet) to 200 cm (6.5 feet), fairly small compared to most other deep sea creatures.
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Those peculiar dots on its face are sensory organs which a large majority of fish have and are scaleless.
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Although their gills are not visible, they do have them! The four gills are hidden by a sort of flesh curtain called a Operculum. The holocephalans are the only group of fish that possess true nostrils. Respiratory water is drawn in through the “nostrils” and passed over the gill arches.
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They also swim primarily with their large side pectoral fins instead of their tail like sharks do, making them akin to ocean birds.
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These fish belong to subclass Holocephali, which is over 420 million years old but despite being that old there are more than 50 species living today. Also here is a wacky tidbit, Holocephali translates to whole head in latin!
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The exposed mouth of a plough-nose chimaera, which ses its snout to probe the sediment in search of food. It's nostrils are also visible in this image.
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They also a carry toxic spine in front of their first dorsal fin to protect from any attacks. Although definitive proof of spine toxicity is lacking in the literature, medical reports suggest fishermen have experienced burning and numbing sensations for weeks after puncture traumas from chimaera spines. (I did find a couple medical journal pertaining to the injuries, please let me know if you would like to read it and I will be glad to share!)
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alphynix · 2 years
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The eugeneodonts were a group of cartilaginous fish that convergently resembled sharks but were actually much closer related to modern chimaeras. They had unique "tooth whorls" in their jaws, and the most famous member of the group is probably Helicoprion, whose bizarre buzzsaw-like tooth arrangement was only properly understood within the last decade.
Ornithoprion hertwigi here was one of the first eugeneodonts found with fossilized skull material, and helped with the early understanding of just how their weird jaw anatomy actually worked.
It lived during the Late Carboniferous, about 315-307 million years ago, in a shallow tropical sea that covered what is now southwestern Indiana, USA.
At only around 50cm long (~1'8") it was one of the smaller eugeneodonts, and along with a small Helicoprion-like tooth whorl it also had a distinctive highly elongated chin. Similar to modern halfbeak fish this structure may have served a sensory function, helping Ornithoprion to detect prey in dark or murky waters.
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Nix Illustration | Tumblr | Twitter | Patreon
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sepialunaris · 4 years
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We are SO sleeping on how weird prehistoric fishes are. Like our legged fish ancestors or armored placoderms like Dunkleosteus are weird in their own way but they have nothing on them
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Pycnodonts: literally any body shape they want that uncanny valley except some genera that look like normal trevallies
(Rostropycnodus, Stenoprotome, Gladiopycnodus, Maraldichthys by Joshua Knüppe)
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Holocephali: cartiliginous fish closely related to chimaeras, which means they are relatives to sharks.
(Traquairius agkistrocephalus, Belantsea, and Squaloraja by Stanton F. Fink, Iniopterygidae by Ray Troll)
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animalids · 4 years
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Chimaera (Chimaeriformes)
Photo by NOAA Ocean Exploration & Research
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fargusno · 5 years
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Several hidden fishes from Iceland datamined from Ace Fishing’s internal files. Some of these were teased in the teaser website for Iceland’s update
All copyrights goes to Com2uS
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unofficial-sean · 2 years
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Miss Renae
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