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| Crurosauria; No Triassic-Jurassic Extinction | |
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| Topic Started: Jul 6 2010, 03:06 PM (3,324 Views) | |
| Vultur-10 | Jul 6 2010, 03:06 PM Post #1 |
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Introduction: In this alternate evolutionary history, the Triassic-Jurassic Extinction never happened. In our history, this cleared out a lot of the other archosaurs and some of the synapsids, giving the dinosaurs dominance. In this universe, those groups carried on, and so the ecological niches of large land animals have a much greater taxonomic diversity - dinosaurs, crurotarsans, and even some therapsids and a few other groups. (The name Crurosauria is a compound of Crurotarsa + Dinosauria, the two dominant groups of large land vertebrates.) Mammals exist, and are slightly more diverse and larger than in the real Mesozoic, but still nowhere near dominant. Pterosaurs are present, and fill more or less the same role they did in our Mesozoic, though the species are different. Pterodactyloid pterosaurs never develop, nor do birds. The time periods are also different; the Triassic carries on till 183 Mya, including most of our Early Jurassic. A significant marine extinction occurs then, but it has little effect on land. The Jurassic runs from 183 Mya to around 110 Mya, when the rapid diversification of calcific ferns transforms the landscape dramatically. The Cretaceous continues until a hammerblow of massive volcanic eruptions circa 80 Ma. |
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| The Dodo | Jul 24 2010, 01:44 AM Post #16 |
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Prime Specimen
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Will it be another longicolloid? What happens to prosauropods in this project? |
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| Rick Raptor | Jul 24 2010, 11:39 AM Post #17 |
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Adolescent
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I really like this project so far. The omnivorous sauropodomorphs sound really cool I think the largest animal of the Triassic wouldn´t be a Longicolloid, but a large marine reptile, like a giant Ichthyosaur or a sea-going Phytosaur. |
| [My DeviantArt account] | |
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| The Dodo | Jul 25 2010, 04:33 AM Post #18 |
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Prime Specimen
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Probably, I think there were some large Ichthyosaurs in the Triassic anyway. |
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| Ook | Jul 25 2010, 04:48 AM Post #19 |
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not a Transhuman
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in HE ichtiosaurs and plesiosaurs survives triassic and later dominate seas..in this project could dominate descendants of Nothosaurs,placodonts or thalattosaurs |
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| dialforthedevil | Jul 25 2010, 04:50 AM Post #20 |
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Frumentarii Administrator
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Yes i would like to see maybe cetacean equivalents of placodonts
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| Cephylus | Jul 25 2010, 10:06 AM Post #21 |
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Torando of Terror
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This is turning out to be a really well-thought out interesting project. Sorry I didn't post a comment earlier. I really liked the species and is looking forward for more I never thought of an omnivorous longicolloid I would also like a thalattosaur |
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| Vultur-10 | Jul 25 2010, 05:28 PM Post #22 |
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Longicolloids are a prosauropod branch. Being more adaptable, they eventually outcompete the other prosauropods (and the nascent true sauropods). |
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| Vultur-10 | Jul 25 2010, 05:43 PM Post #23 |
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There will be, but in the Jurassic. Though a proto-pelagic placodont may turn up in the Triassic. --- Yes, it's an ichthyosaur! (As I said in an earlier post, in the Triassic longicolloids only get into the a-few-tons range. Ones the size of a big sauropod (dozens of tons) will only show up in the Jurassic. ) In our world, the ichthyosaur genus Shonisaurus reached about 21 meters. In Crurosauria, this line just kept getting bigger... Longsnout Leviathan (Megashonisaurus giganteus) Size: 15 to 30+ meters Diet: Carnivorous - primarily cephalopods Habitat: pelagic, worldwide oceans (migratory) Time: late Triassic (190 Mya) This massive ichthyosaur has a rosette of teeth at the end of its long snout. Behind the teeth, it has fleshy lip-like lobes that seal together tightly, becoming a tube to suck up cephalopods that the teeth have caught. At the back of its mouth are heavy bones, pseudo-teeth, to crack open the shells of shelled cephalopods like ammonites. While its adaptations are focused to eat cephalopods, it will eat other prey - fish and marine reptiles - if given the chance. Like all ichthyosaurs, the Leviathan gives live birth; each offspring is born about 3 meters long. An ichthyosaur calf attains sexual maturity at around twelve years, with a length of 12 to 15 meters and a weight of 10 to 20 tons. They grow at a slightly reduced rate until their early twenties, at which point they tend to be in the range of 22 to 25 meters and 60 to 100 tons. (This unusually rapid post-maturity growth is an adaptation to allow them to grow to large sizes without jeopardizing reproduction early in life.) After this age, growth dramatically slows -- but does not entirely cease, and truly colossal (exceeding thirty meters and 160 tons) ancient bulls scarred with centuries of battle do roam the seas of the latest Triassic; one massive individual reached 33 meters in length. The exact lifespan is unknown, but believed to reach 250 years at least, and probably three centuries or more. Edited by Vultur-10, Jul 25 2010, 05:44 PM.
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| Vultur-10 | Jul 25 2010, 07:02 PM Post #24 |
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I don't plan to kill off the ichthyosaurs until the end-Cretaceous (80 Ma) extinction, but plesiosaurs die out in the late Jurassic. Placodonts will be a BIG deal in the late Jurassic. Nothosaurs ... they might well be competing for the same niche as my fully-aquatic tanystrophids, so I don't think they'd do well at sea. They might become freshwater though. |
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| The Dodo | Jul 26 2010, 05:00 AM Post #25 |
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Prime Specimen
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There is a lot of competition in fresh water too though. Does the Leviathan have an eel like shape like Cymbospondylus? |
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| Vultur-10 | Jul 27 2010, 12:04 AM Post #26 |
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No, the leviathan has a similar body shape to Shonisaurus. The main differences are in growth/size* and jaws. (Shonisaurus really did lack teeth in the posterior part of its jaws -- I've just taken this several steps further for the leviathan's unique squid-eating equipment. After all, cephalopods are certainly viable prey for oversized predators, as the largest predator on Earth today -- the sperm whale -- is a squid-eater.) *We only have one specimen of Shonisaurus sikanniensis (the larger species) though, so theoretically there could have been S. sikanniensis that big. |
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| The Dodo | Jul 27 2010, 01:48 AM Post #27 |
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Prime Specimen
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How about having a filter-feeding Ichthyosaur later on. |
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| Vultur-10 | Jul 30 2010, 12:54 AM Post #28 |
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Sounds great, thanks for the idea! I think it will go in Early Jurassic (160 Mya) as by Late Jurassic (130 Mya) the placodonts will have locked-down the filterfeeder niche; but in Early Jurassic they're still coastal, so there's room for a pelagic filter-feeding ichthyosaur. |
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| Vultur-10 | Jul 30 2010, 01:07 AM Post #29 |
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A theropod and an aetosaur this time... Knifemouth (Halticosaurus ingens) Size: 6-7.5 meters, 500-1000 kg (females slightly larger than males) Diet: Carnivorous (favors large prey) Habitat: Fern swamps, fern plains, and open forests Time: Late Triassic This long, dappled carnivore is named for its teeth, oversized even among theropods. It is a specialized hunter of large animals, such as dicynodonts, longicolloids, the few remaining sauropods and the less armored aetosaurs, attacking and ripping out a large bite, then retreating and waiting as its prey weakens from blood loss -- repeating the process if necessary. This method allows the knifemouth to take down even elephant-sized dicynodonts and ferocious lake wyverns. Knifemouths are solitary except for a very brief courtship period in spring. A female lays only four to six eggs, and hatchlings take two years to mature. The mother cares for her young for about a year, at which time they have become about 4 meters long and weigh 100 kilograms or more, teaching them the tactics of hunting. Thus, females generally lay eggs only every other year. Island Aetosaur (Insularis insularis) Size: 2-3 meters, 100-600 kg Diet: Herbivorous (ferns) Habitat: Fern plains of one island 100 miles off Pangea Time: Late Triassic Due to its isolated island habitat lacking large predators, this species has lost its armor. It rather resembles a bloated lizard. Island aetosaurs breed once every two years, and the female lays 6 to 10 eggs. Offspring take around five years to mature. Edited by Vultur-10, Jul 30 2010, 01:12 AM.
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| The Dodo | Jul 30 2010, 09:28 AM Post #30 |
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Prime Specimen
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Are the Knifemouth's related to Herrerasaurus or something else? |
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