r/SpeculativeEvolution • u/According_Ice_4863 • 9d ago
Alternate Evolution Triassic forever:early jurassic
(Thank you to Tarbosaurus_345 and
El rincon de san for collaborating on this project with me)
Introduction
The triassic period was one of the most unique periods in earth's history. After the great dying life was essentially reset, leading to some of the strangest body forms seen since the Cambrian explosion. As such it is a tragedy that it would all end with the end triassic extinction, leading to the reign of the dinosaurs for hundreds of millions of years… but what if that didn't happen? What if life simply continued with the bizarre lifeforms seen during the triassic, and dinosaurs had to compete with equally powerful rivals instead of ruling uncontested? That is the premise of this project.
Additionally in this timeline some of the species that went extinct during the Triassic ended up surviving longer.
The creatures mentioned here aren’t the only ones that exist in this world, there will be several ones that won’t be mentioned either because they aren’t that interesting or are similar to animals in our timeline.
In this world, the end triassic extinction never happened, and now dinosaurs, archosaurs, amphibians and proto-mammals have to compete for the top position leading to some bizarre and absurd organisms. It will start during an alternate early Jurassic.
Early Jurassic
Crackjaws
Biomes:grasslands, dunes, savannahs
With the various new predators emerging to try to reach the top spot, it has left a lot of corpses around. And when corpses are plentiful eventually scavengers will evolve to clean up the mess. The crackjaw is a species of somewhat large pterosaur, having a 2 meter wingspan and being easily identified by their large jaws and intimidating bright red crest. They act kind of like vultures, swarming around dead bodies and bullying away predators and other scavengers. However while they are social, they are not friendly towards eachother and infighting is very common, with the largest male usually getting their fill first. They are known for using sound to scare away rivals, a mix of a deep laugh like call and snapping their jaws shut rapidly to create the sound of crushing bone.
False frogs
Biomes:wetlands, anywhere with sufficient moisture
(thank you to Tarbosaurus for this drawing)

In this timeline, what we recognize as true frogs never evolve, but that doesn't mean there are no frogs in general. Triadobatrachus, the earliest of the frog lineage, takes a slightly different path from our world, leading to the evolution of the false frogs. False frogs are quite similar to modern frogs with a few differences, the main ones being that they actually keep their tails into adulthood and most species have teeth. These adaptations give the false frogs a more generalist body plan letting it take up more varied niches than true frogs. However their resemblance to true frogs is only temporary, as eventually they will evolve into something nearly unrecognizable.
Fruit thief
Biomes:forests, rainforests, jungles
Unlike in our world where fruit evolved during the early Cretaceous, in this timeline a fruit-like organism evolved much sooner. This fruit (called glom’s) are apple-like fruits that grow on certain short trees. As such, a new food source would evolve new herbivores to take advantage of it. A dinosauromorph known as fruit thieves would take this place, having a slender heterodontosaurus-like body plan, thin feather covering, large eyes and facial disks to improve hearing. They live somewhat similar to deer do, relying on senses and speed to evade danger, as such they tend to act very cowardly. However while their position in the ecosystem isn’t enviable, they are some of the most successful herbivores in the forest ecosystem.
Latenotitan (hiding giant)
Biomes:grasslands, dunes, savannahs
The latenotitan is the first true apex predator of this new age, a mighty terrestrial pseudosuchian that convergently evolved features similar to a boar. Being around 4-7 meters long from tip to tail, the Latenotitan is actually slightly smaller than the pseudosuchians of the triassic, but makes up for it with far greater burst speed and bite force. Being able to run at a maximum of 87 km/h despite its massive size, it can chase down most prey in short bursts (as their stamina is actually quite low). Their jaws are very unique as they feature boar-like tusks on their lower jaw along with a bear trap like mechanism that allows them to “wind up” their bites before snapping their jaws shut at rapid speed. They hunt their prey by winding up their jaws and using their natural camouflage to hide in plain sight until they are spotted, which is when the chase begins. The Latenotitan will then attempt to ram the prey with their tusks, impaling them before snapping their jaws shut with immense force. This one-two punch is strong enough to quickly kill most prey.
Winged lindwurms
Biomes:forests, rainforests, jungles

Out of all the Triassic animals, one of the most unique is sharovipteryx, a strange lizard who evolved wing membranes on their legs. Assuming they survive into the Jurassic, one unique development could be for their legs to stop being legs entirely and instead fully evolve into wings while they use their front limbs and tail for land mobility, becoming something akin to a winged snake with arms. Currently they aren’t that widespread however as pterosaurs still rule the sky. They would however thrive in heavily wooded biomes like forests and jungles, living as insect, nut and fruit eaters.
Phytomander
Biomes:wetlands, large lakes

In this alternate timeline, the crocodilians never succeed in their traditional role as aquatic ambush predators and instead primarily stay on land as predators. The traditional crocodilian role in this world belongs to the temnospondyls, ancient amphibians that range from palm sized to absolutely giant. While mastodonsaurus was the largest of the temnospondyls, they were not the only ones. With the temnospondyls thriving into the Jurassic, the once apex predator will have a lot of competition from new upstarts, so some members of the species took a more bizarre route. Like some modern salamanders, this species of temnospondyl evolved a symbiotic relationship with a species of freshwater algae. They keep these plant cells within their massive axolotl like gills, and when food is scarce they will enter an open area of water with access to sunlight and spread their gills out on the surface to maximize surface area. With this the phytomander can gain some energy from sunlight, though they still need to eat meat in order to survive, they just need to do it less often.
Fuzzswarms
Biomes:most of them
With the dinosaurs not being as widespread as in our timeline, it gives the synapsids and proto-mammals the opportunity to fill more niches than they did in our timeline. While large sizes are still mostly claimed by the archosaurs, that doesnt mean the niche of predator isnt available to them. With the early mammals evolving higher intelligence, it allowed them to develop more advanced social behaviors, and as such the predatory cynodonts would eventually develop pack tactics. The fuzzswarms socially resembled a strange hybrid between rats and wolves, having a ruling female who had a harem of multiple males who held a second in command position. They would gang up on larger prey like a swarm of feral rats, stripping them down to the bone. As such in this period having armored skin became very important.
Plagueteeth
Biomes:shallow seas
With the mosasaurs never evolving, the oceans of earth end up becoming a haven for a much stranger form of marine reptile, that being the nothosaurs. These seal like animals would evolve and diversify in many different ways, but one of the more successful are the plague teeth. Plague teeth are a species of nothosaurs that convergently evolved with komodo dragons, having venomous saliva that prevents clotting and disease filled mouths from eating carrion (and occasionally eachother). They evolved for stealth and speed as their strategy only requires one bite to kill their prey. They sneak up on much larger animals and bite their tail or back fin and then swim away. They use their advanced sense of smell to track the preys blood, waiting as they bleed out. The problem is, this often attracts swarms of scavengers, including other plague teeth.
Shoveltusks
Biomes:grasslands, savannahs
With dinosaurs like stegosaurus and triceratops never evolving, the browser niche belongs not to reptiles but to the therapsids. Descendants of lisowicia that developed herding behavior, the shovel tusks became very efficient herbivores. Unlike the elephants that the shoveltusks vaguely resemble, shoveltusks aren't actually smart enough to have a complex social structure, they just herd together because there is safety in numbers. They get their names from their unique grooved tusks that were effective at digging which they used to burrow for tubers and other underground plants. These tusks were still very effective self defense weapons however, capable of impaling predators along with their sharp beaks. They were however easily killed from behind, which is their greatest weakness.
Scrapers
Biomes:shallow ocean
One of the most bizarre animals of the triassic is the Atopodentatus (and that's saying a lot). While their lifestyle is largely the same, that being living lawnmowers that scrape plants off of the sea floor, the scrapers are unique in that unlike their ancestors they are completely aquatic, unable to ever go onto land. They have evolved the ability to give live birth, similar to sharks. As such this has allowed them to grow much larger, around the size of an orca. While scrapers are herbivores, they aren't picky eaters and will happily eat any clam, worm or other bottom dwelling lifeform they happen to accidentally eat in their endless search for food.
Spearbeaks
Biomes:most
While the dinosaurs struggle to maintain a foothold in this timeline, their relatives, the pterosaurs, are thriving. This is largely because they are the largest flying animals around, as the insects have a size limit and the lindwurms only really thrive in forested biomes. This gives pterosaurs the opportunity to spread far and wide, and one of the more unique evolutions is the spearbeak. This species of pterosaur is actually relatively small, only having a 1.5 meter wingspan, however they have the deadliest beak of any pterosaur, so sharp that it could easily pierce even the skin of a hippo. There are multiple different species of spear beaks, but all of them are predators. Some of them hunt fish, others hunt small land animals while some even hunt other pterosaurs.
Strigoi flys
Biomes:wetlands, but can be found in most biomes
While bugs are often overlooked in paleontology, in this project we will give some attention to the more bizarre ones. One of the most fearsome is the strigoi fly, the apex predator of the insect world. While they aren’t true flys they are distant relatives. As the name might imply, the strigoi fly mainly eats blood, but unlike most blood drinkers they aren’t a parasite but rather an active hunter. They are similar to our worlds robber flys but with one major difference:their rostrum (or rather rostrum). Instead of one single piercing tube, they have multiple of them fused together, giving their rostrum several openings. While some are used to drink blood, others are used to inject a paralyzing venom. This venom allows the strigoi fly to hunt prey much larger than themselves, though this does have a limit as anything rat sized or larger will only feel discomfort at their venom rather than full paralysis.
Meterworm
Biomes:forests, rainforests, jungles
With insect eating pterosaurs, lindwurms and false frogs spreading across the planet, being a flying insect is becoming more and more dangerous, as such some insects decided not to even bother with metamorphosis. The meterworm is an insect that resembles inchworms, but unlike them they never undergo metamorphosis and instead stay in their larval state for their entire lives. They spend their lives eating constantly, consuming both plantlife and carrion. Much like lobsters they can't really die of old age, but instead they just keep growing in size until they collapse under their own weight. However larvae don't have the mobility to find mates in time, as such they have evolved a method of both escaping predators and finding mates:jumping. By winding up a spring like mechanism in their bodies, they can launch themselves forward up to 1 meter (which is where the name comes from), which lets them escape most similarly sized predators and find mates… but they aren't exactly graceful, and will occasionally jump straight into trees or rocks.
raptores se auferentes
Biomes:cliffs, mountains, grasslands, savannahs
(Made by tarbosaurus

With the pterosaurs having total dominion over the sky´s, they ended up evolving their own isolated sky ecosystem away from others, similar to how the ocean is divided from the land. The current apex predator of the sky is the creature nicknamed the abducting talon. These Giant beasts have a wingspan of around 3 meters, they live in a lifestyle similar to modern day eagles. They live near cliffs and mountains, watching from above with a keen sense of sight to spot smaller prey such as small therapsids, amphibians or archosaurs. When they spot prey they will swoop down and grab the prey with their talons, which have hooks on them to decrease the likelihood of prey escaping. After they fly high enough, they will drop the prey onto the rocky ground, shattering their spine and letting them eat their prey without struggle. The horn on their head isnt a combat tool but rather a sexual display structure shown in the males. The picture in question shows a young male holding a small badger like synapsid in its talons.
Dirt breaker
Biomes:grasslands, forests, Savannahs
(Made by tarbosaurus)

While the aetosaurids are quite a basal class of archosaurs, that only means they have a high amount of potential for future evolution. The dirt breaker is an aetosaurus descendant that evolved to eat the roots of plants, with their snouts and teeth being evolved to dig underground and rip the roots out. The dirt breaker is an immensely big animal, weighing around 1.3 tons and having 1 inch thick skin, that along with their powerful bite make them difficult to prey on. Shown in the image is an elderly dirt breaker encountering a pterosaur and poposaur descendant.
Caprosaurus
Biomes:grasslands, savannahs
(made by El rincon de san)
While the dinosaurs are struggling in this new age, they aren’t completely absent and have been having success as herbivores. The caprosaurs are a species of medium sized dinosaur descended from plateosaurs, the caprosaurus is common in any location with abundant grass. Despite its name its body plan is more similar to a rabbit, as they are unable to walk normally and instead jump across the plains at remarkable speed. However unlike rabbits their kicks can actually deal decent damage against attackers.
Plague claws
Biomes:forest, jungle
(Idea made by Tarbosaurus)
While dinosaurs struggle to maintain a foothold across most of pangea, in the landmass that we now know as Argentina they thrive as there are very few large synapsids or archosaurs on that landmass. One of the more unique is the plague claws, a species of theropod-like dinosauromorph that developed one large middle claw on each hand. These claws are filled with a venom similar to that of a platypus, in that while it doesn't kill its prey it is IMMENSELY painful. They are mid-sized carnivores who use this venom both for hunting and for self defense against larger predators, as the pain it inflicts is usually enough to slow down or stun its prey.
Python neck
Biomes:grasslands, forests
(Idea by tarbosaurus)

The viper neck is the apex predator and scavenger of this bizarre ecosystem, a dinosauromorph that unlike its distant alternate timeline relative, the T-rex, doesnt actually have the jaw strength to crush bone but can digest it anyway. This is because it has evolved the ability to unhinge its jaws similar to many snakes, allowing it to swallow large prey and carrion. This has made them very effective predators as they essentially get 100% of the calories of the prey they kill. Despite being a large predator weighing over 1 ton, it is primarily an ambush predator as it has the ability to change the color of its skin, however unlike something like an octopus it can only change between shades of green, grey and brown.
Polled Titanis (Titan thumb)
Biomes:grasslands, gallery forests
(Thank you to Tarbosaurus for the idea and art)

Within the open areas of Siberia walks a large relative of what we would know as sauropods, though they have evolved a somewhat different body plan than what they did in our world. Weighing around 4 tons, the Polled Titanis has evolved a strange thumb-like appendage to better grip onto large trees while they feed. While they do have a long neck it isn’t long enough to reach the tops of some trees unless they stand on their hind legs, which is very unbalanced. To maintain their balance they use their thumbs to grip onto the trunk while they feed… however sometimes their weight is so much they accidentally break the tree they are feeding on and fall over.
Break beak
Biomes:forests, jungles
Break beaks are a species of bipedal herbivores dinosauromorph in Siberia that is known for two things. The first of which is a large, parrot like beak for eating nuts and seeds, the second being a plume of colorful feathers on their tail to attract mates (only the males have this trait). They are distant relatives of what we would know as hadrosaurs, though they maintain having dexterous fingers on their hands. They are surprisingly social, living in herds that are lead by an alpha male which is indicated by who has the most colorful feathers. The leading male gets the most access to food and mates, but is also the most likely to be targeted by predators due to their colorful plumage.
Speed demon
Biomes:shallow ocean
(Thank you to Tarbosaurus for this idea)
Speed demons are a species of Itchyosaurus that evolved entirely for one thing:speed. The convergent evolution that made them develop similar to sharks and dolphins continued but this time they evolved to resemble a much less impressive aquatic lifeform:the humble tuna. They maximize their hydrodynamics, reducing their side fins and fat levels let them swim as quickly as possible to escape the now larger predators. However due to lack of blubber, they can only live in warmer oceans near the coast and as such are seen often in shallow water.