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Crurosauria; No Triassic-Jurassic Extinction
Topic Started: Jul 6 2010, 03:06 PM (3,323 Views)
Vultur-10


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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Rick Raptor
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I think it´s no coincidence they have the same name as the Coelophysid Halticosaurus...

The large teeth are probably inspired by those of juvenile Ceratosaurs (their teeth are deeper than their lower jaws!).
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Vultur-10


RickRaptor is right, they're relatives of the real Halticosaurus species. The huge teeth weren't specifically inspired by anything though.
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Cephylus
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Vultur-10
Aug 4 2010, 10:24 PM
RickRaptor is right, they're relatives of the real Halticosaurus species. The huge teeth weren't specifically inspired by anything though.
Great :D :D
I'll look forward for some more carnivores
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Cephylus
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Any updates or new species?
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Vultur-10


Per cephlaken's request, a thalattosaur:


Daggermouth (Halithalattosaurus sp.)
Size: 60-95 cm long, 1-5 kilograms (males larger than females)
Diet: fish, smaller reptiles, cephalopods
Habitat: marine, temperate waters
Time: Late Triassic

These swift thalattosaurs hunt almost anything small enough to eat and capturing it with long, almost needlelike teeth. Their major form of propulsion is a deep, finned tail, and their feet are webbed almost to the point of being flippers.

There are two species, one in the Northern Hemisphere temperate seas, one in the Southern. They hunt continental-shelf waters, coming onshore only to lay eggs.

Daggermouths bury their eggs in beach sand, often on small islands with few predators. Young daggermouths take about three years to mature.

Muddragon (Microthalattosaurus vermivorus)
Size: 20-35 cm long, 100-450 grams (males larger than females)
Diet: benthic invertebrates
Habitat: warm brackish waters -- estuaries, brackish bays, bayous, coastal marshes
Time: Late Triassic

These small thalattosaurs have broad, almost ducklike jaws to scoop through the mud, and long teeth to catch their often slippery prey. They inhabit the brackish waters of Pangaea's eastern coast, north of the equator.

Muddragons lay their clutch of 12-15 eggs on land, covering them with soil and vegetation so that they are not obvious to predators. Young muddragons take a year to mature.
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The Dodo
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Are any of the thalattosaurs going to evolve ovoviviparity?
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Toad of Spades
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It might be difficult for an archosaur though, given that they have specialized in hard calcified shells like bird eggs. Its the same reason why there are no known birds, dinosaurs or pterosaurs that gave live birth and that all their eggs discovered so far have the same overall shell structure.

Its easier for squamates and other non-archosaurs because their eggs have softer leathery shells.
Edited by Toad of Spades, Aug 19 2010, 12:47 PM.
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Carlos
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Thallatosaurs are basal diapsids. And they most likely were already ovoviparous in the Triassic
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

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https://www.patreon.com/Carliro

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Toad of Spades
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Ok, for some reason I was thinking of Thalattosuchians. Thalattosaurs are fine, they shouldn't have any problems.
Edited by Toad of Spades, Aug 19 2010, 07:15 PM.
Sorry Link, I don't give credit. Come back when you're a little...MMMMMM...Richer.

Bread is an animal and humans are %90 aluminum.
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Cephylus
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I love the thattalosaurs!! glad to see new species :lol:
curosauria is a realistic project
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Vultur-10


Some of the very pelagic thalattosaurs might be ovoviviparous. It might be interesting to make some of them evolve large sizes, too

EDIT: Where did this avatar come from? I certainly didn't pick it!

RE EDIT: And now it's gone. Weird.
Edited by Vultur-10, Aug 24 2010, 03:31 PM.
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Vultur-10


PILOCROCODILIA

This group developed from synapsids more basal than mammals. They enjoyed a brief flourishing in the continental central lakes of Pangaea.

Ottercaiman
(Pilosuchus sp.)
Size: varies by species: 0.8 to 2 meters long, 5-50 kg
Diet: predatory
Habitat: continental lakes
Time: Latest Triassic (c. 190 mya)

The ottercaimans are the most diverse genus of pilocrocodilia, and fairly typical in body plan and size (ranging from housecat-size to wolf-size). They rather resemble streamlined weasels with webbed feet and crocodile heads. Their bodies are covered in short, otter-like fur, but their heads are hairless and scaly.

The larger species prey on fish and smaller reptiles, the smaller ones eat crustaceans and small fish. Ottercaiman females lay 6 to 15 eggs, and take one to three years to mature depending on species.

Edited by Vultur-10, Sep 11 2010, 08:07 PM.
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The Dodo
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Nice concept. Would they have any hair?
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Cephylus
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This is nice^^ i'm glad to see this up again.
Are there any rhyncosaurs or pterosaurs in this project/
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Vultur-10


The Dodo
Sep 10 2010, 03:42 AM
Nice concept. Would they have any hair?
Yeah, they have short fur, not too long since they're water living. Head is hairless though.


("Pilocrocodilia" is meant to mean "hairy crocodiles", in fact.)
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