Did allosaurus evolve into something else? Or did their lineage just die out? Or do we not know
We don't know
phylogenies are really good at figuring out relationships but not so good at figuring out when a species directly evolved into another
so it may have died out. or maybe it did evolve into the later Allosauroids we see. Something like it continued on to form those groups, if nothing else
Speciation is a term used by scientists to describe the process by which a population of organisms give rise to a new species. The idea of a species is wholly man-made, and its true definition varies, but for the purpose of this article:
A species is the largest grouping of individuals which can produce fertile offspring from a mating pair. A species can also be defined as having a specific karyotype (a unique arrangement of DNA chromosomes), or in the case where we don't have genetic data, by having enough unique changes to be significantly different from others in their genetic family.
Cladogenesis in Bears, Source
When we discuss speciation, usually it is Cladogenesis that comes to mind. Cladogenesis occurs when a portion of the population splits off and develops adaptations separately. Think for example, Brown Bears and Polar Bears, which we suspect originated from the same ancestor species.
Anagenesis is a different process, where the separation of species is not a difference in space and/or compatibility, but a difference in time. Think for example Homo sapiens and it's ancestors. I could probably trace an uninterrupted line of ancestors back 10s of millions of years ago, but if you dug up that ancestor's bones, palaeontologists wouldn't call it Homo sapiens.
Anagenesis in Hominids, Source
A population separated by nothing but time alone would still be referred to as different species, because they would have different physical traits and genetic make-up.
Both cladogenesis and anagenesis occurs in populations over time. One group may develop without any splintering for millions of years, and then a group splits off later to become a separate species.
Cladogenesis and Anagenesis, Source
Anagenesis in Ceratopsians
So with that explanation out of the way, let's get to the part that's actually interesting: dinosaurs. Like all organisms, speciation in dinosaurs would've occurred by populations splitting up and specialising, or dying out. But recently, the idea of speciation by anagenesis has been proposed in a certain group of dinosaurs.
Ceratopsians are a group mostly identifiable by their large imposing neck frills and face horns. New species are proposed when they differ enough in the shape and length of their eyebrow horns and their nose horns, the height and width of their neck frills, and the arrangements of parietal horns on and around their frill. There's lots of room for variety in ceratopsian face arrangements.
Styracosaurus, Victor Sales (Deviantart)
Styracosaurus is a fairly mainstream dinosaur, but what's probably not as well known are its close relatives. Ceratopsians such as Stellasaurus and Einiosaurus have been found in fossil beds nearby Styracosaurus. And although there may have been some niche partitioning or sexual selection allowing these dinosaurs to coexist in the same place, new research suggests they were the same group separated by time.
Top: Stellasaurus, HodariNundu (deviantart)
Bottom: Einiosaurus, Calisius (deviantart)
Sexual pressures can drive animals to rapidly develop extreme physical traits for no other reason other than to look attractive. Modern dinosaur species (birds) can have a variety of physically exaggerated traits that serve no purpose beyond attracting mates. In Cockatoos, it's erect feather head crests. In Peacocks, it's massive colourful tail plumes. So perhaps in Ceratopsians, it was face and frill ornamentation.
When Stellasaurus was first described as a species separate from Styracosaurus, some Palaeontologists decided that it represented a transitional species. The relatively straight nasal horn of Styracosaurus had developed into a thicker, more curved structure later in the lineage. The neck frill became sturdier and more robust, the frill horns curving in strange directions. The supposed endpoint in the lineage is Pachyrhinosaurus, who's nasal horn is now a solid plate of bone, and the neck frill is decorated with a variety of horns pointing in every which-way. It may be a less pointy dinosaur, but it was very heavily decorated. And sex sells.
Top: Styracosaurus Anagenesis, Christopher DiPiazza
The Centrosaurine Styracosaurus lineage is not the only subject of Ceratopsian Anagenesis. The Chasmosaurine line has also been suspected of transitional forms, with the recent discovery of Navajoceratops. But in that lineage, speciation pushed towards longer brow horns and taller neck frills in the younger species.
New discoveries Navajoceratops and Terminocavus, Ville Sinkkonen
It is important to note at the time of writing, these theories are not accepted by all of the Palaeontological community. And that also my explanation is not as detailed or accurate as someone with all the right background knowledge could give. So if you are intrigued as to how this theory could be better explained, here's some further reading:
Chris DiPiazza (2020) Stellasaurus: Beast of the Week
John Wilson et al (2020) A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ' Styracosaurus-line' dinosaurs
Stephen Belletini (2020) Was "Rubeosaurus" Styracosaurus After All? YDAW Synapisode #6 (Youtube)
Enrico de Lazaro (2020) Two New Species from New Mexico Help Fill Gap in Evolution of Horned Dinosaurs
Cladogenesis will still be continuing merrily down it's AU route as planned. Is it canon for Jasper to be reasonable/not an antagonist? No. Is it canon for Gems to be able to have babies in the first place? Also no. Cladogenesis was never canon compliant in the first place, so no reason to start now. Also I will get back to work on it soon - the RL issues that put it on hold are currently resolving themselves.
The little Jasper runt is less inquisitive than her Peridot siblings, and prefers to spend time napping. She also likes warmth and pressure, (Pearl's guess is that it's because Kindergarten Quartzes need heat and pressure to form faster) so she can often be found napping underneath (the also napping) Amethyst. Mostly because Jasper doesn't spend as much time sitting in one place. Amethyst doesn't mind, it makes babysitting really easy. (and literal!) Then Amethyst teaches the little Jasper how to spin dash. Chaos ensues.
It’s finally done! Time for the gemlings to meet their first Crystal Gem...
Naturally it was the fusion who came to investigate.
Jasper wasn't surprised – she'd been expecting that the Crystal Gems would send the one who'd already beaten her once. She was more surprised by how quickly the fusion had arrived; the planet's sun had barely set when Jasper had heard the footsteps behind her as she sat watching the retreating tide. In a way she was glad – ever since she had surfaced after leaving Peridot and their offspring the warrior Gem had been plagued with doubts and an instinct that told her to go back to the cavern and destroy anyone or anything that tried to get in after her.
Slowly and carefully, Jasper had gotten to her feet and turned around, her hands at her sides. Her gem itched with the need to summon her helm, but the large Gem knew that would be a very bad idea. She'd found herself facing the fusion whose arms were crossed over her chest, the moonlight glittering on the crystalline knuckles of her gauntlets. The next few minutes had been spent in a tense, uncomfortable silence which was heavy with the mutual knowledge that it could explode into sudden violence at any second. Eventually, the fusion spoke first.
"You separated." For a moment, Jasper had the crazy suspicion that the Crystal Gem somehow knew about Peridot and the gemlings and was accusing her of leaving them. Then she remembered that the last time they'd met, she had been Malachite.
"Yes. Lapis left me here." Not for the first time, Jasper wondered if it had been coincidence that the ocean Gem had dumped her so close to Peridot's hiding place, or if Lazuli had somehow known she was here. "I don't know where she is now," she added, guessing that would be the next question. Given that she hadn't been bubbled yet, things were going better than she had expected.
There were another few moments of awkward silence as the fusion studied Jasper from behind her mirrored shades, weighing her options. The larger Gem didn't move – if this was going to end in violence then she didn't want to be the one who initiated it. Besides, maybe she could beat the fusion if she kept her head, which might win her some respect in the rebel's eyes. But the Crystal Gem still made no move, aggressive or otherwise.
"You wanted us to find you. Why?" To Jasper's surprise, the fusion didn't sound suspicious at all; instead there was a note of genuine curiosity in her voice.
"The situation has changed. We can't go back to Homeworld." Since the fusion had gotten straight to the point, Jasper supposed that she might as well follow suit.
"We?" the fusion asked, the barest hint of an eyebrow appearing over her shades.
"Peridot and I," Jasper replied, feeling an uncomfortable sense of betrayal now that she'd made the Crystal Gems aware of the technician's location. "Something happened that… well…" Despite herself, Jasper found she didn't want to mention the gemlings. Not here. Not in the open. Not where someone could hear them. "It'll be easier if I just show you," she finished lamely, kicking herself as she realised that the fusion would probably assume this was a trap – that was exactly what Jasper would have assumed herself in the rebel's position.
More silence, even more awkward this time. Jasper's eyes dropped to the sandy ground, growing increasingly uncomfortable beneath the fusion's hidden gaze. The warrior Gem waited for the rebel to ask her if she thought she was stupid. But what the fusion did say surprised her even more.
"All right, show me." The fusion's arms dropped to her sides as she cocked her head to the side expectantly.
Momentarily wrong-footed – though it was hardly like she'd been right-footed through this entire encounter – Jasper blinked in surprise, then gestured towards the rocky inlet where the entrance to the cave was hidden. "Follow me, it's this way." As she turned to lead the way, Jasper half-expected a fist to smash into her spine, but all the fusion did was to keep pace with her as the warrior Gem walked away. All of Jasper's instincts were screaming at her - some familiar and telling her not to let a potential enemy follow so closely, others new and insisting that she keep her offspring hidden and safe. Gritting her teeth, Jasper ignored them and hoped she was doing the right thing. Last time she'd ignored her instincts, she'd seen Gems that she'd fought with for centuries devolve into monstrosities before her eyes. She'd told herself it was the price of loyalty and obedience then. Now those loyalties had changed.
Reaching the water, Jasper waded out to the diving spot that led to the cave, and gestured towards it. "There's a tunnel underwater, it leads to a cave. I'll go first," she added, hoping that would make the situation look less like the trap it appeared to be. "Peridot might panic if she saw you first." The thought of the technician waiting alone in there with their helpless brood made something sharp twist in Jasper's gut. "You won't hurt her, will you?" It struck Jasper that she should probably have asked that first. "She was only following orders; none of this was her fault. If you want to blame anyone, blame me."
Again, the fusion studied Jasper for a few moments before speaking. "You're trying to protect her." It wasn't an accusation, if anything the Crystal Gem sounded surprised. "I won't hurt her," she continued. "We know Homeworld sent her, she didn't come here of her own accord."
Jasper supposed that she would just have to trust the fusion; it was too late to turn back now that the rebel knew where the cave was. Steeling herself, and praying that she was doing the right thing – for Peridot and their brood, not Yellow Diamond for once – Jasper dove into the water.
Peridot wished that Jasper had stayed, that she'd never let her go outside to wait for the Crystal Gems. The logic had been sound enough – it still was – but now that she was alone with their brood all the technician wanted was for Jasper to be back again. The gemlings were still sleeping in her lap – tiny, vulnerable things that Peridot wanted to hide somewhere so they couldn't be found. Especially now that Jasper had gone. She scanned the cave briefly, looking for any likely crevices or gaps that would be large enough for the gemlings, but still small enough for her to conceal with her body.
The technician was starting to consider whether she should carve a hiding place out of the rock with a laser when the water in the pool rippled unnaturally, the dim evening light that was filtering through vanishing behind a dark shape. Her hand immediately went to the destabiliser that she'd tucked into the back of her suit – not drawing it, just making sure it was within easy reach. Belatedly, it struck her that it would probably have been a good idea to put her limb enhancements back on, but it was too late for that now.
Tensing as a large shape emerged from the water, Peridot relaxed with a sigh as she saw Jasper's shaggy mane. Maybe the warrior Gem had changed her mind after all. But then their eyes met and Peridot saw something there that she'd never seen before – uncertainty. As Jasper moved towards her, Peridot saw another shape in the pool and her gaze darted back to Jasper in mute fear. Surely the other Gem wouldn't have let herself be followed if there was any danger to the gemlings. Surely.
"It'll be okay Peri," Jasper said quietly, her voice reassuring in spite of the doubt in her eyes. "I won't…" Her voice tailed off as the second Gem entered the cave – the fusion! Peridot's body went rigid as the Crystal Gem pulled herself out of the water and got to her feet. Why would the Crystal Gems have sent the war machine if their intentions were anything but aggressive? The gemlings in her lap began to chirp and squeak as they felt Peridot tense, and the fusion's head immediately snapped towards the sound before the technician could make any attempt to hide them.
For several moments the adult Gems were motionless. The Crystal Gem had sucked in a sharp breath as she saw the gemlings, and although the shades hid her eyes, they couldn't hide her expression of utter shock. Then the fusion shuddered violently as if she was about to split apart – Peridot wondered if that was exactly what was happening – but seemed to regain control as she let out a long, shaky sigh.
"Stars," the fusion murmured softly, then took a few careful steps towards Peridot. Her hands were held outspread in front of her in a peaceful gesture, but the effect was ruined by the heavy gauntlets she wore. Peridot's gaze fixed on them fearfully, wondering how easy it would be for the Crystal Gem to crush her brood with those weapons. Noticing this, the fusion made a quick, flicking motion and the heavy gloves evaporated back into her gems. "I'm not going to hurt you," she said with surprising gentleness, turning her hands so that they were palm-up, gems completely exposed.
Peridot knew the gesture was intended to reassure her, that the fusion was deliberately putting herself in a vulnerable position to demonstrate trust, but she still had to fight the urge to grab for the destabiliser as the fusion knelt slowly in front of her. The gemlings were all awake now, still chirping as they looked curiously up at the new Gem with a complete absence of fear. All except for the runt, who seemed to have picked up on her mother's fear and was watching the fusion closely, her small mane bristling.
"These are yours?" the fusion asked, still with the same gentle tone. Peridot could only nod mutely, realising now that there was no way she could grab the destabiliser without the Crystal Gem noticing. She should have given it to Jasper. The technician nearly threw caution to the wind and grabbed it anyway as the fusion's hands moved towards her brood, but then they stopped. "Can I…" the rebel began, but at that moment the runt seemed to decide that this stranger was an enemy and launched herself from Peridot's lap to sink her teeth into the fusion's index finger.
The technician's eyes went wide in horror at the sight of her smallest daughter dangling from the fusion's hand and beside the Crystal Gem Jasper took a step forwards. But then the fusion started to laugh, and the tension dissipated despite the small gemling's growls.
"This one's made to be a fighter," the fusion commented, unconsciously echoing Jasper's words as she raised her hand to get a better look at the gemling. The runt hung from her finger like a fish on a line, then seemed to realise that perhaps she'd been too hasty as neither of her parents were attacking the stranger. Releasing her grip, the gemling dropped into the hand that the fusion had cupped beneath her. Peridot tensed again – if the Crystal Gem had any intent of taking revenge on her daughter for the indignity now would be the perfect time. Instead, the fusion only set the runt down amidst her sisters, still chuckling softly.
Peridot had unconsciously wrapped her arms around her brood, as if she was afraid the fusion might try to snatch them away. But as the Crystal Gem returned the runt to her, the technician slowly began to relax. The fusion was still staring at the gemlings in fascination and making small sounds of wonder as they looked back at her curiously. On some level, Peridot felt a strange sense of gratification that the rebel was obviously admiring her offspring. It felt right.
Standing to one side, Jasper gradually let her guard down now that it was clear that the fusion wasn't going to harm Peridot or their offspring. She hadn't been convinced when the Crystal Gem had exposed her gems – that was certainly a conciliatory gesture, but having fought the fusion Jasper had also suspected it might be a sign of how little the rebel feared them. However, Jasper was adept at reading opponents' body language, and there was no trace of aggression or threat in the Crystal Gem's posture as she knelt before Peridot. The fusion had leaned closer to get a better look at the gemlings, but was still respecting Peridot's personal space and had her hands folded in her lap.
"I've never seen gemlings before." The fusion's voice echoed strangely, as if more than one voice was speaking. "You're sure Homeworld doesn't know anything about this?" The question was directed at both Jasper and Peridot and was concerned rather than suspicious.
Peridot flinched at the name, her arms automatically tightening around the gemlings once more. "No! They can't know!" she said, her voice shrill with anxiety. "If they knew about this - about them - then they'd want to know how it happened. They'd take them away! Us too," she added, with a nervous glance towards Jasper. "You're not going to contact them, are you?" For all Peridot knew, the Crystal Gems might sell them out to Homeworld in return for amnesty for their stupid planet.
"Of course not," the fusion replied reassuringly. "Homeworld would want to take us too, if they didn't just shatter us immediately." Rocking back on her heels, the Crystal Gem looked up at Jasper. "It looks like we're on the same side now," she commented. "We'll help you, if that's what you want."
The warrior Gem couldn't help a grimace – despite their situation, asking for help was still a humiliating experience. And the fusion knew it; Jasper knew that what she was really asking was 'do you surrender?' But Jasper also knew that the Crystal Gems held the upper hand now, and the fusion could very well have forced her to her knees to beg for assistance. Jasper would probably have done that herself had their positions been reversed. "We would be grateful for your help," she said eventually, glancing down at Peridot and their brood. "We have to do what's best for our offspring," she added, the bitter edge vanishing from her voice.
The fusion nodded in acknowledgement, getting back to her feet. "Then we should go back to the temple. It'll be safer for you there. Amethyst!" She shouted the last word, and moments later a sleek shape leapt up from the pool in a graceful arc and landed on four webbed feet. Peridot recognised it as a species of Earth mustelid, but she wasn't sure if those should be bright purple. The otter rose onto its hind legs, then glowed and stretched as it transformed back into the Crystal Gem runt. The undersized quartz glared at both Jasper and Peridot with obvious antagonism, but the fusion turned and raised a hand to forestall her. "It's all right, Amethyst. Peridot and Jasper are coming back to the temple with us and their gemlings."
"Their what?" The purple Gem scowled, but her expression turned to bewilderment as she saw the gemlings in Peridot's arms – all of them looking up at her and chirping curiously. She looked back at the fusion whose expression Jasper couldn't see, but the Amethyst seemed to be somewhat reassured by what she saw there, her stance relaxing a little. "Okay G, if that's what you think." Her voice was doubtful though, and the glare she flashed towards Jasper spoke volumes - there was definitely still a grudge there. Jasper could live with that if it meant her gemlings were safe.
Casting a wary look towards the purple Gem, Peridot looked up at Jasper nervously. The technician obviously didn't want to ask 'are you sure this is a good idea' with both of the Crystal Gems there, but the query was plain to read in her expression. In her arms, the gemlings were starting to try and wriggle loose, obviously curious about the strangers and wanting a better look at them. They certainly weren't afraid.
Almost imperceptibly, Jasper nodded, and held out a hand to help Peridot to her feet. The technician hesitated for a moment but then reached up to take it, carefully balancing the gemlings in the crook of her other arm. One of the twins immediately swarmed up to Jasper's shoulder to where she could get a better look at the Crystal Gems. Before the warrior Gem could grab her, the gemling sprang at the fusion and caught hold of her shades, chirping at her reflection in fascination.
"And this one's inquisitive," the fusion commented, deftly catching the little Peridot as she lost her grip. "You might want to bubble them for the journey," she added, gently handing the gemling back to Peridot.
This video pretty much summarises what Steven’s relationship with the gemlings will be like in Cladogenesis. Where’s the babies? Where’s the baaaaaaaabieeeeeees?
