Allosaurus the Apex Scavenger

[suspsy]

https://www.sciencedirect.com/science/article/abs/pii/S0304380021002611?fbclid=IwAR0l0a2XW6uWg2VIHVoiYI9RNohckyRr5JVSklhiaWVXBpBd7s9C2ZN2tmE

https://www.pdx.edu/news/giant-jurassic-dinosaur-allosaurus-was-scavenger-not-predator?fbclid=IwAR3aAhXCDTFoQQujXXJNxGoTMXLyoO1cPR6E4yLTFvd3r-zv266rB9xAz10

This study proposes that Allosaurus was primarily if not entirely a scavenger that lived on carrion from the abundant sauropod population in its habitat.

[Leyster]

I remember few articles that were massacred by paleontologists as bad as this one.

Our results may explain why carnosaurs like Allosaurus did not evolve powerful bite forces, binocular vision, or advanced cursorial adaptations. Given the enormous supply of sauropod carrion, they were under no resource-based selective pressure to overpower prey and may have evolved as terrestrial vulture analogues

Yeah, as Bakker (1998) and Anton et al. (2003) exemplified...

Also Cau in this article explained well why Allosauroids are among Theropods the most adapted to hunt sauropods.

[stargatedalek]

Aah, the age old non-problem of Allosaurus being built to hunt sauropods and adult sauropods being categorically impossible for it to hunt. If only sauropods produced offspring by the thousands flooding the environment with more juvenile and subadults than full adults, taking years to grow up ensuring that would be the case at all times...

[Dynomikegojira]

My god that's a new one and I thought I heard everything. I'm all for publishing new theories but the idea of predominantly large scavenger theropods has been criticized and considered unlikely for years.

[Faelrin]

Reminds me of the certain drama revolving a certain large theropod that a certain paleontologist put forth. Sad to see this may go down with my beloved Allosaurus as well (if not its relatives too who have long been proposed to be sauropod hunters).

And the paper also appears to be paywalled so most of us are going to have access to the abstract and that's it.

I take two issues with the abstract however. Was there not an extinction event that opened up the niche carcharodontosaurs once had for tyrannosaurids north of the equator, and abelisaurids south of the equator? Two how do they address the increase in body size for large carcharodontosaurs such as Carcharodontosaurus and Giganotosaurus? My impression has long been that they got larger as their prey did.

I also wonder if and how they compare Allosaurus to other large Morrison formation theropods such as Ceratosaurus and Torvosaurus and the selection pressures of thyreophorans in the area, etc.


I also agree with @stargatedalek. While I don't doubt it would have had ample opportunities to scavenge, there would have been numerous young for it to prey on as well. We can observe this with extant predators as well.

[Bread]

I also wonder if and how they compare Allosaurus to other large Morrison formation theropods such as Ceratosaurus and Torvosaurus and the selection pressures of thyreophorans in the area, etc.

My immediate thought, and simply sprung up once I saw the title, was what about Ceratosaurus? You would think this idea of scavenging would be pointed towards Ceratosaurus over Allosaurus, but here we are I guess...

[Sim]

This study doesn't suggest that only Allosaurus would have been a scavenger, it suggests that all carnosaurs were obligate scavengers.  There are things I've read that contradict this study though.  First, I've read that terrestrial scavenging simply isn't sustainable - I think this was in the debate regarding T. rex being an obligate scavenger.  Next, there's more than one allosaur fossil which have wounds in the shape of a stegosaur tail spike, and a stegosaur plate with a wound that matches an allosaur's bite.  I can't imagine these occuring for any reason other than a predatory allosaur attack.  So I have to conclude this study is nonsense.


Some links describing one of the aforementioned wounds:

https://www.popularmechanics.com/science/animals/a11467/savage-stegosaurus-tail-whip-revealed-by-fossil-17359441/

https://gsa.confex.com/gsa/2014AM/webprogram/Paper247355.html

[suspsy]

Please note that I am not advocating for this study; I merely wanted to share it here for all to see.

[Faelrin]

@Sim Interesting. I knew about the Allosaurus that had been killed with a stegosaur's thagomizer to the pelvic region, but was not aware there were multiple cases of this, or clear evidence of a stegosaur being attacked by an Allosaurus either. I'll have to check out those links you shared. Evidence of this nature can not be ignored when making a paper with such a large claim as this one does, and this also goes back to my earlier comment on if they addressed thryeophoran selection pressures in the areas these particular theropods lived in (or at least until the tyrannosaurs they co-existed with became the dominant predators).

[Sim]

@Faelrin, I read about the other wounds on the Allosaurus and Stegosaurus on the Allosaurus Wikipedia page, at the start of the "Feeding" section: https://en.wikipedia.org/wiki/Allosaurus#Feeding

[andrewsaurus rex]

sounds like an old theory being recycled to me.  The T-Rex scavenger theory was debated for a long time before, for the most part being put to rest.

The idea that all carnosaurs were obligate scavengers seems absurd to me.  For one thing, that would mean there were zero large predators in the ecosystem.   An extremely unlikely situation given there would be an abundant resource to exploit, especially among juvenile sauropod populations, which would be EXPLODING in numbers if there were no predators to pick them off, given the large numbers of eggs sauopods laid.

It has also been demonstrated repeatedly, that terrestrial scavengers can't survive because they are not able to locate food fast enough given their relatively limited search radius as compared to flying creatures.  However, the nature of the ecosystem back then could have been very different from today, perhaps, with oodles of dead sauropods lying around.  Very unlikely but not impossible, I suppose.  But what would be cause all these  sauropods to die, if there were no predators?

Also, it has been demonstrated how important fear is in any ecosystem.  The fear that predators cause.  Without it certain animal populations will grow out of control, pushing others to extinction and eventually overwhelming food resources for all, in time resulting in the collapse of the whole ecosystem.  But there is no evidence that this happened.

I suppose it's not fair to shoot down the theory without reading the entire paper, but on the surface, the idea seems far fetched, to me.

[GojiraGuy1954]

I also wonder if and how they compare Allosaurus to other large Morrison formation theropods such as Ceratosaurus and Torvosaurus and the selection pressures of thyreophorans in the area, etc.

My immediate thought, and simply sprung up once I saw the title, was what about Ceratosaurus? You would think this idea of scavenging would be pointed towards Ceratosaurus over Allosaurus, but here we are I guess...

No terrestrial animal is a full scavenger. Even vultures are capable of killing their own prey sometimes iirc

[stargatedalek]

I also wonder if and how they compare Allosaurus to other large Morrison formation theropods such as Ceratosaurus and Torvosaurus and the selection pressures of thyreophorans in the area, etc.

My immediate thought, and simply sprung up once I saw the title, was what about Ceratosaurus? You would think this idea of scavenging would be pointed towards Ceratosaurus over Allosaurus, but here we are I guess...

No terrestrial animal is a full scavenger. Even vultures are capable of killing their own prey sometimes iirc

Capable doesn't mean they do. Vultures generally do hunt small prey like rodents besides scavenging, but some other scavenging birds like lammergeiers and condors feed essentially only on carrion, seemingly almost if not never hunting to eat (some still chase small animals they encounter by chance, perhaps from boredom).