Say farewell to Oxalaia and Sigilmassasaurus.

[Sim]

I had seen those two skeletals before but then completely forgot about them!  They are interesting, thanks for sharing them @stargatedalek!  The robust neural spines remind me of how among Spinosaurus snouts there is a robust and a gracile morph.  As for the slender neural spines, I could see a spinosaurid naturally evolving them, maybe to have a lighter sail.

[Funk]

This is a debate with two distinct camps that keep contradicting each other, so in this case, the newest paper isn't "the truth", just the latest one camp came up with. There simply isn't enough material yet to confirm any one scenario.

[GojiraGuy1954]

As for tooth taxa, I think there are situations where it's safe to name them, such as teeth that are very distinctly identifiable and don't match any contemporaries from nearby areas at the same time.

I disagree. Many genera are incredibly widespread, over many continents, such as Panthera.

[stargatedalek]

As for tooth taxa, I think there are situations where it's safe to name them, such as teeth that are very distinctly identifiable and don't match any contemporaries from nearby areas at the same time.

I disagree. Many genera are incredibly widespread, over many continents, such as Panthera.

Yah, a genus, not a (terrestrial) species.

And these animals were not terrestrial. Isotope sampling shows they ate primarily marine fish, and they are found in coastal environments.

[GojiraGuy1954]

As for tooth taxa, I think there are situations where it's safe to name them, such as teeth that are very distinctly identifiable and don't match any contemporaries from nearby areas at the same time.

I disagree. Many genera are incredibly widespread, over many continents, such as Panthera.

Yah, a genus, not a (terrestrial) species.

And these animals were not terrestrial. Isotope sampling shows they ate primarily marine fish, and they are found in coastal environments.

...Which would make far distribution of these animals even more likely considering large rivers, lakes, and even small oceans such as the young atlantic are less of an obstacle

[stargatedalek]

"Don't match nearby areas" meaning "a terrestrial animal on another continent". Derived spinosaurs are not terrestrial but marine.

[GojiraGuy1954]

So this would mean that Giganotosaurus and Spinosaurus both lived in South America around the same time, right? That's pretty crazy to think about. Would they have met?

No, as S. quilombensis lived in the Alcântara Formation and Giga lived in the Candeleros Formation. Alcântara is in Brazil and Candeleros is in Argentina.

[Sim]

I haven't seen anyone professional arguing that Oxalaia is an additional species of Spinosaurus, only that it's the same as Spinosaurus aegyptiacus.  I also don't see a reason why Spinosaurus and Giganotosaurus couldn't have met.

[GojiraGuy1954]

I haven't seen anyone professional arguing that Oxalaia is an additional species of Spinosaurus, only that it's the same as Spinosaurus aegyptiacus.  I also don't see a reason why Spinosaurus and Giganotosaurus couldn't have met.

1. Just for clarity since Spino is associated with Africa
2. Again, Brazil and Argentina. They are not close together. And separated by land, not water.

[Sim]

1. If you make up a name it just ends up being misleading since it suggests the name has validity.
2. These animals lived for a very long time.  Humans have spread further.  Considering these things I don't see why Giganotosaurus and Spinosaurus couldn't have met.  There are carcharodontosaurid teeth present in the Alcântara Formation, perhaps they belong to Giganotosaurus.

[GojiraGuy1954]

1. If you make up a name it just ends up being misleading since it suggests the name has validity.
2. These animals lived for a very long time.  Humans have spread further.  Considering these things I don't see why Giganotosaurus and Spinosaurus couldn't have met.  There are carcharodontosaurid teeth present in the Alcântara Formation, perhaps they belong to Giganotosaurus.

Giant theropods are in no way comparable to humans. Even T. rex, one of the most successful, only ever reached 2 billion individuals over about 2 million years

[Sim]

You're right that the populations of giant theropods is lower than that of humans, but with enough individuals and enough time I think animals from one formation could reach the other.

[GojiraGuy1954]

You're right that the populations of giant theropods is lower than that of humans, but with enough individuals and enough time I think animals from one formation could reach the other.

Theres no evidence for non avian theropods being migratory

[stargatedalek]

Humans are terrestrial, have tools and can transport resources, bad comparison in so many ways.

Spinosaurus was aquatic and most likely actively marine at that. If it encountered Giganotosaurus or any other large terrestrial theropod, it was the other animal that travelled to a coastline, or a one in millions fluke like when whales end up in the Amazon.

[Stegotyranno420]

You're right that the populations of giant theropods is lower than that of humans, but with enough individuals and enough time I think animals from one formation could reach the other.

Jokes aside,  I think it's very possible for an interaction between a large Spinosaurid and a South Carcharodontosaurid, but it's a bit less likely if it's exactly Giganotosaurus carolini and Spinosaurus Aegpyticus(or quimbolensis?). I think @stargatedalek and @Sim both make great points

[Sim]

Theres no evidence for non avian theropods being migratory

Since sauropods are thought to migrate and they were probably the main food of carcharodontosaurids I don't see why the theropod species wouldn't migrate as well.  Additionally Tyrannosaurus is found in more than formation, some of which are quite far apart.

Humans are terrestrial, have tools and can transport resources, bad comparison in so many ways.

Spinosaurus was aquatic and most likely actively marine at that. If it encountered Giganotosaurus or any other large terrestrial theropod, it was the other animal that travelled to a coastline, or a one in millions fluke like when whales end up in the Amazon.

To be clear, I was referring to prehistoric humans.  I don't think they are a bad comparison to terrestrial theropods in this context.  They still depend on the environment around them.  I don't disagree with what you've said about how Spinosaurus and Giganotosaurus could meet.

[GojiraGuy1954]

Additionally Tyrannosaurus is found in more than formation, some of which are quite far apart.

Tyrannosaurus just had a stupid huge range. It wasn't migratory

[Sim]

How do we know Giganotosaurus didn't have "a stupid huge range" too?  Also dinosaurs including non-avian theropods had to migrate for different species to occur in different formations.

[GojiraGuy1954]

How do we know Giganotosaurus didn't have "a stupid huge range" too?  Also dinosaurs including non-avian theropods had to migrate for different species to occur in different formations.

because there are like no giga fossils and the ones we have are very poorly described

also that second point is completely wrong

[stargatedalek]

How do we know Giganotosaurus didn't have "a stupid huge range" too?  Also dinosaurs including non-avian theropods had to migrate for different species to occur in different formations.

A creatures range expanding isn't migration. Migration is seasonal movements between regions.