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| Alternate sea reptiles | |
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| Topic Started: Jan 21 2010, 05:35 PM (1,161 Views) | |
| Carlos | Jan 21 2010, 05:35 PM Post #1 |
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Adveho in me Lucifero
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As you al know, the Mesozoic oceans were ruled by plesiosauroids (both plesiosaurs and pliosaurs), mosasaurs, ichthyosaurs, turtles and sea dweeling crocs. However, during the Triassic several other linages of marine reptiles existed, and I was wondering of how the Jurassic and Cretaceous oceans would look like if things were different. For starters, the nothosaurs, which would produce later the plesiosaurs, would have gone extinct, or at least the pistosaurs (the appearent direct ancestors of plesiosauriods) would have gone dead; most likely the thalattosaurs would have gone into power, first maybe as mosasaur like creaturs before gradually becoming more streamlined like in ichthyosaurs, which would either be gone at the T/J event or gradually decline. In fact, while the post-Triassic Mesozoic had two main groups of sauropsids taking the cetacean niches (plesiosauroids and ichthosaurs, and later plesiosauroids and mosasaurs), most likely thalattosaurs would take most niches by the end of the Cretaceous. The Triassic was also inhabited by sea going temnospondyl "amphibians" and hupehsuchians (ichthtyosaur like reptiles with an armour instead of dorsal fin, an eel like tail and fins that were mostly clawless webbed digits than perhaps true flippers), the first occupying a gharial like niche and the later appearently being bottom filter feeders akin to grey whales; maybe both groups would survive quite some time afterwards, though the marine temnospondyls would probably had been replaced by phytosaurs, proterochampsids or crocodillians (in fact I'd prefer either of the first two than the last). The seal niches most likely would had been occupied by phytosaurs, if they survived, or by choristoderes, which could take the sea by the Cretaceous. Maybe, instead of mosasaurs, there would be sea dweeling sphenodontians, albeit not probably not as marine and probably able to pass through the KT event alongside choristoderes. Marine turtles perhaps would take longer to appear if placodonts had survived; most likely only by the end of the Cretaceous would turtles have been a presence in marine biomes. In our world, pterosaurs never took an aquatic niche, perhaps due to competition due to aquatic sauropsids and because of their wing membranes, though if there's not enough competition I'd assume a "pterosaurian penguin" could evolve. Maybe birds will take that niche first and create hesperornithid like forms though. |
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Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
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| ATEK Azul | Jan 21 2010, 06:07 PM Post #2 |
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Transhuman
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Okay while this sounds interesting your making alot of suggestions with multiple groups each, so my question is could you clarify what real world groups are gone and what new ones take their niches and when do they take them or get replaced? Also if Pterosaurs had penguin equivelents could they have survived the K-T event since it's possible(meaning if they were around back then, I know they're alive) Penguins in our world survived it when they first came about? Also what would a 4 limbed Penguin with Pterosaur derived flippers look like? Other than that good project it just needs clarification. |
| I am dyslexic, please ignore the typo's! | |
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| The Dodo | Jan 21 2010, 07:34 PM Post #3 |
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Prime Specimen
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I don't think pterosaurs with penguin niches would necessarily survive seeing that hesperornithids didn't. Were penguins around in the Cretaceous because I thought they first appeared during the Paleocene. Is this meant to be a part of your Terra Alternative project JohnFaa? |
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| ATEK Azul | Jan 21 2010, 09:39 PM Post #4 |
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Transhuman
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I had heard that there was a possibillity Penguins evolved right before the K-T event. Also While this would be good for Terra Alternativa he normally posts these there if that's what their for. And you have a good point talking about Hesperornis which was simular to Penguins though still extinct. |
| I am dyslexic, please ignore the typo's! | |
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| Cynovolans | Jan 21 2010, 10:22 PM Post #5 |
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Servant to Empress Min
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How would the Pleurosauridae family be affected by this? We only know two species, and they seem to occupy a niche similar to sea snakes. You know I could actually imagine pterosaurs as being penguin-like. Edited by Cynovolans, Jan 21 2010, 10:24 PM.
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I wish I could give the public a true picture of the queen as she appeared at her best, but this would be impossible, even had she permitted a photograph to be taken, for her charming play of expression while in conversation, the character and intellect which were then revealed, were only half seen when the face was in repose. -Lilias Underwood when speaking of Empress Myeongseong "I was born in the dark. I went out into the light, and your Majesty, it is my displeasure to inform you that I have returned to the dark. I envision a Seoul of towering buildings filled with Western establishments that will place herself back above the Japanese barbarians. Great things lie ahead for the Kingdom, great things. We must take action, your Majesty, without hesitation, to further modernize this still ancient kingdom."-Min Young-ik to Empress Myeongseong | |
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| Carlos | Jan 22 2010, 04:23 AM Post #6 |
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Adveho in me Lucifero
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Pleurosauridae could rise to mosasaur level, if you wish. This is more of an idea generator; obviously I might use aspects of this in my project, but it is meant to give ideas, to make this site serve its purpose, that of generating speculative creatures. Penguins weren't around in the Cretaceous; if they were, they are able to fly. Its possible that penguin like pterosaurs wouldn't evolve until the Cenozoic, or maybe Mesozoic and Cenozoic linages could exist |
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Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
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| The Dodo | Jan 22 2010, 06:38 AM Post #7 |
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Prime Specimen
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If a pterosaur took up penguin niches I imagine that they would look more like a seal. The wing membranes might come in handy for moving through the water. |
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| Scrublord | Jan 22 2010, 09:02 AM Post #8 |
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Father Pellegrini
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What if there WERE marine non-avian dinosaurs? What group do you imagine they would have evolved from (I always imagined it being from something like Suchomimus or Baryonyx)? |
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My Projects: The Neozoic Redux Valhalla--Take Three! The Big One Deviantart Account: http://elsqiubbonator.deviantart.com In the end, the best advice I could give you would be to do your project in a way that feels natural to you, rather than trying to imitate some geek with a laptop in Colorado. --Heteromorph | |
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| Carlos | Jan 22 2010, 10:36 AM Post #9 |
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Adveho in me Lucifero
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Spinosaurs, no doubt |
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| T.Neo | Jan 22 2010, 11:17 AM Post #10 |
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Translunar injection: TLI
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A swimming nonavian dinosaur would be interesting. I wonder how it would propel itself through the water. I don't see pterosaurs attaining aquatic roles though. They were quite ungainly on land and reproducing in coastal areas would leave them vulnerable to predation. Wing membranes would just add drag, IMO. |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| Carlos | Jan 22 2010, 11:27 AM Post #11 |
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Adveho in me Lucifero
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I invisioned two evolutionary paths: 1. From ornithocheiroids: while some ornithocheirids like Anhanguera hunted fish from the air, several like pteranodontids feeded on the water surface like most modern seabirds. Maybe a form that chased after fish underwater like a gannet could evolve to become more aquatic, loosing flight. 2. Alternatively, either ctenochasmatoids like Pterodactylus or dsungaripteroids could develop marine forms, seeing as they hunted aquatic prey by wading, not from the air. Because pterosaurs already had flight musculature, switching from the air to the water may not be oo difficult; only the patagium seems to stand in the way, considering its a large surface area prone to loose heat, but pterosaur wing membranes were more complex than bat ones, and besides they could specialise to life in the sea in warm waters. Also, because pterosaurs layed thin shelled eggs, ovovipary is not out of question. |
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| Rick Raptor | Jan 22 2010, 12:06 PM Post #12 |
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Adolescent
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How about a giant baleen-whale-like Pterodaustro descendant? |
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| Carlos | Jan 22 2010, 01:09 PM Post #13 |
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Adveho in me Lucifero
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Maybe as a Cenozoic form. |
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Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
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| Carlos | Jan 26 2010, 02:20 PM Post #14 |
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Adveho in me Lucifero
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Designed a time line for marine sauropsid evolution: Jurassic: For some reason marine ecosystems weren't as affected as in our world, and most of the marine reptile diversity endured. However, ichthyosaurs, much like in HE, were already quite specialised as pelagic hunters, and slowly declined into more specialised niches. Nothosaurs were generally replace by their most derived branch, pistosaurs, which take the place of pinnipedes, while the thalattosaurs further specialised to life in the sea and become mosasaur/early ichthyosaur like; both groups dominate most niches. Because phytosaurs never disappeared they produced a number of specialised marine forms, paralleling the metriorhynchids, while the enigmatic hupehsuchians explode into a radiation of river dolphin and baleen whale analogues. Placodonts rule in turtle niches, while pachypleurosaurs, if surviving this long, fade away to give choristoderes and sphenodontians a domain over their niches. Early Cretaceous: Ichthyosaurs fade from existence as their last niches, those of pelagic cephalopod eaters (akin to modern sperm and beaked whales), are occupied by hupehsuchians. Thallatosaurs are now mosark like and take their place as cetacean analogues, with pistosaurs becoming progressively more pliosaur like. Placodonts face the arrival of true sea turtles, and sphenodontians diversify more in marine niches, but they are still predominant. Late Cretaceous: Just like the ichthyosaurs before them, hupehsuchians become rarer thanks to the Turonian extinctions, now mostly represented as pelagic beaked whale analogues. Thallatosaurs also suffer looses, becoming more specialised, while phytosaurs in the seas are only seen as filter feeders. Pistosaurs have their own little golden age, and so sphenodontians, which go far enough to produce their own mockeries of HE's mosasaurs. Champsosaurs occupy niches in HE taken by marine gharials and dyrosaurs, while instead of hesperornithes spinosaurs appear in the coastoal waters. Sea turtles have won the evolutionary battle against placodonts. Paleogene: Most marine reptiles fade from existence, except for champsosaurs, turtles and some marine sphenodontians (possible hupehsuchian remains from this era). Because birds never evolved it was up to pterosaurs to produce aquatic forms, deriving from either pteranodontians or dsungaripteroids. Squamata joins the oceans Neogene: Sans for some marine champsosaurs, sphenodontians, squamates and of course turtles, the only marine sauropsids are pterosaurs; mammals took over the oceans otherwise. Edited by Carlos, Jan 26 2010, 02:20 PM.
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Lemuria: http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/ Terra Alternativa: http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/ My Patreon: https://www.patreon.com/Carliro ![]() | |
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| Canis Lupis | Jan 26 2010, 02:28 PM Post #15 |
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Dinosaurs eat man, woman inherits the Earth.
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There was an old theory (now disproven) about compsognathus. It was once that that the compies had webbing in their hands so they could hunt small fish. What if that were actually true? That could produce non-avian marine dinosaurs creatures. |
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