Matoria: A Dangerous World

[creature386]

In order to have penguin-like feather coating, the ancestors of that penguin-spino have to have bird-like feathers (and not merely some hair) which is very unlikely.

Losing the sail might work if you can come up with a plausible evolutionary reason.

[smedz]

creature386 

I might have something that might work, but also might not. So I'll need you or someone to tell if it will work or not. 


In Matoria, all the fish dwell in deeper water, so sticking to the shallows won't work. So it might be better to get in the water to catch them, and over time, they lost the sail to become better divers. 

[smedz]

Deinocheirus-

In Matoria, maybe it can fill the role therizinosaurs had and the claws could get as long as a person.

[creature386]

If the hypthesis that Spinosaurus used its sail like a sailfish is correct, it might not be much of a hindrance in diving.
However, since we don't know much about spinosaurid sails, you can probably get away with saying they used to be used for cooling and became redundant once they spent more time in the water.

[smedz]

Dec 27, 2019 18:57:25 GMT 5 creature386 said:

If the hypthesis that Spinosaurus used its sail like a sailfish is correct, it might not be much of a hindrance in diving.
However, since we don't know much about spinosaurid sails, you can probably get away with saying they used to be used for cooling and became redundant once they spent more time in the water.

Really? I was always thinking that was outdated. Guess that goes to show how up to date I am with dinosaurs. Anyway the diving thing came from this. 



Spinosaurus Was a Terrible Swimmer
This famous dinosaur wasn't very skilled in the water, after all

By Brian Switek on August 23, 2018
Spinosaurus Was a Terrible Swimmer
Digital models of Spinosaurus, floating. Credit: Henderson 2018
Spinosaurus has always been weird. From the time the first bones of this Cretaceous carnivore were named in 1915, it has stood out as one of the most bizarre dinosaurs of all time. It’s hard to ignore a sail the size of a small billboard jutting from a theropod’s back.

The dinosaur has only gotten stranger in the century since its initial identification. New fossils and an expanded dinosaur family tree altered images of Spinosaurus from an Allosaurus-lookalike with some extra flair into a crocodile-snouted, heavy-clawed semiaquatic superpredator. Then in 2014, a new image - announced in Science and further ballyhooed by National Geographic - made Spinosaurus the first known non-avian dinosaur that may have specialized in a semiaquatic lifestyle, its short legs and strange new proportions suiting it to the water rather than the land. (Of course other dinosaurs - like giant sauropods - had been considered as waterlogged in the past, but the new Spinosaurus seemed to have adaptations to life in the water as opposed to just being placed there on a hunch.) This dinosaur didn’t wade along the shore like a Cretaceous grizzly, this new image proposed, but a skilled swimmer that nabbed giant lungfish and other prey among the depths of lakes and rivers themselves.

But the broader paleontological community was rightly skeptical of the new interpretation from the outset, and a new analysis suggests that Spinosaurus wasn't very skilled in the water, after all.    


Paleontologist Donald Henderson, who has written a spate of papers about the varying abilities of dinosaurs in water, used digital models of Spinosaurus and other theropods to investigate how the great sail-back would have fared in the water. These included models of close relatives - such as Suchomimus - and terrestrial theropods like Tyrannosaurus, as well as an alligator and emperor penguin facsimiles as a check on the methods. What Henderson found runs counter to images of aquatically-adept spinosaurs.

As it turns out, Spinosaurus was a perfectly adequate floater. The dinosaur - like the other non-avian theropods analyzed in the study - would have been able to freely float in water while keeping its head above the surface. “Spinosaurus is certainly able to float and breathe with the head above water,” Henderson writes. But this isn’t really that remarkable, given theropods of varying size were easily capable of doing the same. They also all shared a center of mass oriented in front of the hips, indicating that Spinosaurus - like Tyrannosaurus, Allosaurus, and the rest - was perfectly capable of walking around on land.     


Swimming is another story. For one thing, it seems that Spinosaurus would've had a hard time sinking in order to pursue prey underwater. While the alligator model sank when its lung volume was deflated between 40 and 50 percent, for example, the digital model of Spinosaurus wouldn't sink even when its lungs were deflated 75 percent. Needless to say, this is a major impediment to chasing after fish below the surface. And that’s not all. Spinosaurus was not very stable in the water, Henderson found, no doubt in part to the huge sail jutting from its back. Henderson’s digital model had a tendency to roll on its side without some kind of motion to prevent it. Plunk a Spinosaurus in the water, in other words, and it’d soon flop over without some motion to prevent tipping.

This doesn’t mean that Spinosaurus was a complete landlubber. The overall picture of the dinosaur’s anatomy, as well as clues from related species, make it likely that Spinosaurus was closely tied to waterways and   grabbed much of its food from along the shores. But the image of Spinosaurus as an immense and immaculate swimmer, better suited to paddling through lakes than walking on land, doesn’t hold up. And that only makes Spinosaurus stranger still. Given that paleontologists have yet to uncover anything close to a complete skeleton - popular restorations and reconstructions are based on composites of multiple specimens and spinosaur species - we are really just getting to know Spinosaurus. The dinosaur will continue to metamorphose just as the science studying it does.    


blogs.scientificamerican.com/laelaps/spinosaurus-was-a-terrible-swimmer/        

[creature386]

Henderson's study is controversial. See André de Oliviera's post here for more detail:
www.quora.com/Is-it-now-impossible-for-Spinosaurus-to-be-semiaquatic
I'm not saying it is wrong. My point is just that we know only very little about Spinosaurus, so you can get away with a lot as long as you can plausibly explain it.
Think of it that way. You cannot get away with a more-or-less realistic worldbuiliding project that includes aliens on the moon. We know the moon has no aliens. Including aliens around Alpha Centauri is a whole different matter, however, even though this is still unlikely.

[smedz]

Dec 27, 2019 19:36:37 GMT 5 creature386 said:

Henderson's study is controversial. See André de Oliviera's post here for more detail:
www.quora.com/Is-it-now-impossible-for-Spinosaurus-to-be-semiaquatic
I'm not saying it is wrong. My point is just that we know only very little about Spinosaurus, so you can get away with a lot as long as you can plausibly explain it.
Think of it that way. You cannot get away with a more-or-less realistic worldbuiliding project that includes aliens on the moon. We know the moon has no aliens. Including aliens around Alpha Centauri is a whole different matter, however, even though this is still unlikely.

Thank you so much creature386! Honestly, I now find myself agreeing with that person. 

The new evolutionary reason to lose the sail. 

When a population of Oxalaia ventured into Matoria, they began to spend more time in the water because the fish of Matoria do not spend much time in shallow water, so they had to venture to deeper waters. And since they spent more time in the water, thermal regulation was no longer really needed and so they lost the sail altogether.

[smedz]

Deinocheirus- the claws could get longer so it can fill the role that therizinosaurs had and the males could develop a resonating chamber that blows up when they make their mating call to impress females.

Deinonychus and Utahraptor- Both get smaller to avoid competing with the larger carnivores, with the descendant of Deinonychus now having a troodon-like niche and Utharaptors descendant being as big as a swan. However, unlike its ancestors the sickle claws are bladed on the undersides.

dinosauria101

creature386

What do you guys think?

[dinosauria101]

Sorry that I wasn't really posting in the thread lately. I think that would be a pretty good example of fast evolution to do well as quickly as possible

[creature386]

Fast evolution? They had 65 million years+ to evolve like that, if I'm not mistaken.
If anything, it is rather slow (not a critique, it'd be hard to imagine such large changes realistically).
I like the raptor and Deinocheirus suggestions, by the way.

[smedz]

Daspletosaurus-

Hunts in the jungles to avoid competition with the abelisaurs, the skull becomes larger, more robust for a bigger bite force to help take down big and armored prey.

Speaking of which we should get a list of herbivorous dinosaurs for Matoria.

[smedz]

dinosauria101

Were South America and Africa connected during the mid-Cretaceous? I ask because I just learned Deltadromeus lived in North Africa during the mid cretaceous and the maps I've seen don't show the two continents connected, but for all, I know those maps probably only show the late cretaceous, and since Matoria is located in the Pacific Ocean and if Africa and South America weren't connected then how could Deltadromeus make it to Matoria?

[dinosauria101]

Yep, they were very close to each other AFAIK. Not connected but close

[creature386]

The two continents had completed their breakup just before Deltadromeus first appeared:

The “Equatorial” segment of the South Atlantic margin (Fig. 2) was the youngest region of plate break-up. Magnetic anomalies cannot be interpreted due to equatorial formation of the oceanic crust relative to spreading direction. However, Anomaly 33 and fracture zone segments are well defined. Seafloor spreading is believed to have propagated into this area after Anomaly M0 (120.4 Ma) (Nürnberg and Müller, 1991), ~100 Ma (Torsvik et al., 2009), 105 Ma (Moulin et al., 2010) or 102–96 Ma (Eagles, 2007), corresponding to a subtle bend in the fracture zones in the South Atlantic.

www.researchgate.net/publication/235762480_Global_continental_and_ocean_basin_reconstructions_since_200_Ma
So, no, they were not connected.

That being said, there is a hypothesis that monkeys reached South America from Africa by crossing the South Atlantic Ocean with rafts, Life of Pi-style. Obviously, a Deltadromeus was much larger than a monkey and needed more food than a monkey. The shorter distances might have compensated for that, however.

[Infinity Blade]

I've read that there is no grass on this landmass.

Just curious, are there just no angiosperms on Matoria? Is the flora a pre-early Cretaceous one?