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A Speculative Dinosaur Project; What if dinos never died out?
Topic Started: Nov 8 2009, 11:28 AM (3,388 Views)
T.rex09
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What if all non-avian dinosaurs didn't die out? After Dougal Dixon's famous book The New Dinosaurs: An Alternate Evolution many different people have asked that question. I will try to answer it.

Anybody who wants to is welcome to join. I'm a pretty crappy artist so I will probably need the assistance of 1 or 2 artists.
Timelines will be available if you guys request.
"Church if I die you can have my orange juice."-Red vs Blue
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Holben
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Alright, here's what i found. And i've been spelling cretaceous wrong, sorry.
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It seems very likely that pterosaur decline and bird diversification effected each other. These events were happening at the same time. For example, n the German fauna of Solnhofen, Upper Jurassic, a few birds turn up among much more numerous pterosaurs. In later ages pterosaur numbers sink and birdies take to the skies (and waters).

There is a slight problem that needs to be kept in mind. The fossil record is heavily biased towards conditions that happened to be good for fossilisation. The number of coastal sites is heavily over-represented, and some sorts of environment are only pooly represented or totally absent.


For mid cretaceous turbulences,

Quote:
 
Using a classical physiological model based on nutrient uptake kinetics, we explored the effect of turbulence on resource competition and succession between 2 phytoplankton functional groups on ecological and geological time scales. The 2 groups we considered are silica-precipitating diatoms and carbonate-precipitating coccolithophorids. Using published experimental laboratory data for parameterization, our model results suggest that diatoms dominate under highly turbulent regimes, while coccolithophorids tend to dominate under stable, nutrient-depleted conditions. We attribute the success of diatoms in highly dynamic systems to luxury uptake of nutrients afforded by the evolution of storage vacuoles. In contrast, coccolithophorids are more successful in resource-depleted waters, due to their lower minimum limiting-nutrient requirement (R*). We examine how these differences in nutrient acquisition strategy potentially explain the long-term trends in the fortunes of these 2 taxa on geological time scales. The fossil record indicates that coccolithophorids rose to ecological prominence in the mid-Jurassic and reached an apex in the mid-Cretaceous, but have declined throughout the Cenozoic. In contrast, diatoms have risen rapidly in the late Cenozoic, especially from early-Miocene time to the present. Based on paleoclimate reconstructions, from Mesozoic times, we hypothesize that the relative success of the 2 functional groups reflects, in part, long-term changes in upper ocean turbulence and its influence on the temporal distribution of nutrients.


Sorry if that's a bit long, it's just the last few sentences neede. He's saying there were long term changes in the nutrients of the mid-cretaceous seas.

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Volcanism in the middle Cretaceous produced large quantities of basalt on the seafloor and released large amounts of CO2. The middle Cretaceous was much warmer than present, resulting in much higher sea level.


But we all knew about volcanism in the cretaceous anyway. It has been proposed as a contributing factor to the extinction.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Carlos
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Quote:
 
It seems very likely that pterosaur decline and bird diversification effected each other. These events were happening at the same time. For example, n the German fauna of Solnhofen, Upper Jurassic, a few birds turn up among much more numerous pterosaurs. In later ages pterosaur numbers sink and birdies take to the skies (and waters).

There is a slight problem that needs to be kept in mind. The fossil record is heavily biased towards conditions that happened to be good for fossilisation. The number of coastal sites is heavily over-represented, and some sorts of environment are only pooly represented or totally absent.


Where did you got this exactly? Because some of the information is either outdated or misinterpreted; in Solnhofen there were only 1 bird and several pterosaur species (neither group was very numerous, but pterosaurs outnumber birds a lot). Second, there are actually more pterosaurs occupying seabird niches than birds themselves, most associated with diving, something pterosaurs were incapable off. Thus, we have Itchyornis+Gansus+some other random bird vs many genera of Ornithocheirids, Pteranodontians and some Ctenochasmatoids, thus outside of diving niches birds did not control niches now occupied by seabirds back then.
Edited by Carlos, Nov 11 2009, 03:23 PM.
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

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

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Holben
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They found a compsognathus at solnhofen, but the place was underwater, wasn't it?

Well, i got it from a sciencey website, but i wouldn't be surprised it they had misinterpreted something.
Edited by Holben, Nov 11 2009, 03:24 PM.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Carlos
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Compsognathus isn't a bird
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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Holben
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I know, it's a small theropod dinosaur.

I was wondering how it got there. Maybe it was washed out by a flood.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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Carlos
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Back then, Solnhofen was an archipelago in a shallow lagoon. Said lagoon was so shallow that it had a lot of evaporation taking place, and since little to no rain was there end up up have very salty waters, in which animals could easily die in and being very well fossialised, since no animal was that stupid to try to eat a poisonous fish corpse. Sadly, Compsognathus was, and thats why we know they existed, because they went to eat fish poisoned by the salt and died as well.

The kind of environment that Solnhofen was probably benefited pterosaurs as lot more than dinosaurs. For one side, we have pelagic rhamphorhynchids that probably layed there eggs there like modern sea turtles and petrels do on isolated islands. Then we have various species of coastoal pterodactyloids like Pterodactylus, Cynorhamphus and Germanodactylus feeding on invertebrates and small vertebrates that the islands were rich on, with filter feeding Ctenochasma feeding on brine shrimp and Anurognathus flying in search of insects. By contrast, the only dinosaurs were a small coelurosaur and a midget bird
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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Holben
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If you can call it a bird.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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ATEK Azul
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Well I am glad the people here don't hate Bats and I do understand alternate groups being fun, the point I was trying to make was that those new groups always turn into Bats when they should be unique.

And the only thing I will say about the Pterosaur discussion is that it sound like Pterosaurs could have recovered with out the K-T event.
I am dyslexic, please ignore the typo's!
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Holben
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Bats are good.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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ATEK Azul
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Yes Bats are good and have some neat abillities.
I am dyslexic, please ignore the typo's!
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Holben
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Well, maybe no neat abilities. i can do all that.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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T.rex09
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Like or not John, pterosaurs were in decline at the end of the Cretaceous. Only a hand full of species are known from that time. And as for anuragnathids surviving to late Cretaceous, who's idea was that, I mean what proof is there to support that?
"Church if I die you can have my orange juice."-Red vs Blue
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Carlos
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T.rex09
Nov 12 2009, 01:18 PM
Like or not John, pterosaurs were in decline at the end of the Cretaceous. Only a hand full of species are known from that time. And as for anuragnathids surviving to late Cretaceous, who's idea was that, I mean what proof is there to support that?
Look, I've been explaining millions of times why pterosaurs haven't been in decline since the late Cretaceous. There's even papers about that. And the Maastrichian has a very poor fossil record in general.

So, please do some research on this forum. I'm fucking tired of pointing out the same things over and over again, so don't be stupid and look at older posts and everything
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
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Oh, and by the way, I did this post a long time ago:

http://s1.zetaboards.com/Conceptual_Evolution/topic/1399565/

It was to end with this pterosaur decline nonsense. Appearently it didn't work. I honestly don't know if it is because of the media, because of the development of the brain of the people here who are claiming pterosaur decline or because everyone is loves dinosaurs so much to the point of bestiality that they ignore any news on other prehistoric sauropsids
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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Holben
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Alright, we're past that now.

How would these bats manage to evolve? Birds and pterosaurs would compete with them... but maybe less for nocturnal slots, freeing them up time. Well, most mesozoic mammals were probably nocturnal.
Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea.

"It is the old wound my king. It has never healed."
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