The Allosauroidea thread (allosaurs, carcharodontosaurs and kin)

dlofnep

Was just reading about this extremely large allosaur - It was nearly as big as a T-Rex at 40 feet (obviously weighed a bit less, like all allosaurs).

If this is the case, would this rate as probably one of the greatest predator's that ever lived - Given Allosaurs are reported to have been lighter, faster and had longer arms which indicated it was primarly a predator first.

Thoughts?

dlofnep

http://upload.wikimedia.org/wikipedia/commons/f/f6/Allosaurus_size_comparison.svg - Size chart.

Galvasean

Epanterias is no longer a valid genus. The specimen has been reassigned to Allosaurus amplexus. Another species of Allosaurus approaching 40feet in lenght was A. maximus (formerly Saurophaganax maximus)
It's worth remembering that Allosaurus was fairly light weight for a large theropod. A 40 foot Allosaurus would weigh about half the weight of a 40 foot Tyrannosaurus.

dlofnep

Yeah, which made them ideal for sprinting after some tasty dinos

Galvasean

The tooth is 9.83cm long, about half the size of T.rex's largest teeth. Precious little else is known about this dinosaur.

The palaeontologists have concluded that this is the largest tooth of a carnivorous dinosaur to have been found to date in Spain.

The features and size of the 9.83 cm tooth provide key information needed to identify its former owner. The researchers are in no doubt - it was a large, predatory, carnivorous dinosaur (theropod) belonging to the Allosauroidea clade, a group that contains large carnivorous dinosaurs measuring between six and 15 metres

Full article here.

Galvasean

Since the new spinosaur has gotten everybody in the mood for some giant carnivore discussion, I thought you might enjoy this piece by Dinosaur Tracking Blog which chronicles the family history of another high spined theropod, Acrocanthosaurus atokensis. Surprisingly, it's not closely related to the spinosaurs at all, but their 'rivals' the carcharodontosaurs (who also feature prominently in the aforementioned thread).


Image by L.D. Austin

Rubecula

In that drawing it looks a lot like a T.Rex with a bad back condition. How would it compare size wise?

Galvasean

The bigest one found was 38 feet (about 11 and a half metres) with a skull over four feet in lenght and an overall similar build to the giant carcharodontosaurs, but not quite as massive in build. It was roughly the same size as a T. rex, although the largest Tyrannosaurus specimens were marginally bigger.

Rubecula

But it has a friendly smile:pac:

Adam Khor

Rubecula wrote: »

But it has a friendly smile:pac:

The same friendly smile you see in crocodiles today...

Adam Khor

In Arkansas, US.

http://washingtonexaminer.com/news/2011/10/new-dinosaur-tracks-found-southwestern-arkansas

Adam Khor

Another article on the same find. The journalists are calling Acrocanthosaurus "T-Rex cousin". o-O

http://abcnews.go.com/Technology/dinosaur-tracks-found-arkansas-cover-football-fields-made/story?id=14690741

Galvasean

The bastardization of every theropod as a 'T. rex cousin' continues....

Adam Khor

Galvasean wrote: »

The bastardization of every theropod as a 'T. rex cousin' continues....

T-Rex must be tired of so many sudden relatives...

Galvasean

It's like when you win the lotto... (I'm told)

Adam Khor

Galvasean wrote: »

It's like when you win the lotto... (I'm told)

Indeed...

Adam Khor

It's two separate discoveries; one of them is a juvenile Acrocanthosaurus found in the Cloverly Formation. The study says that Acrocanthosaurus grew at rates similar to Allosaurus and tyrannosaurs, but also that it seemingly reached adulthood in 20 or 30 years (Tyrannosaurus rex at least grew faster then, as it is said that it reached adulthood at around age 18... or that's the last thing I read).

http://www.sciencedirect.com/science/article/pii/S0031018212001435?v=s5

There's also a baby Brachiosaurus measuring only 2 meters long, found in the Morrison formation:

http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01139.x/abstract

Both are extremely interesting as we know very little about baby dinosaurs- we tend to imagine them as miniatures of their parents yet we know at this point that it wasn´t the case. I only wish they publish reconstructions of the creatures at one point...

Adam Khor

New theropod teeth from the latest Cretaceous (Maastritchian) of Brazil have been found and analyzed. Some of them seem to belong to abelisaurs, but the most interesting ones seem to be from carcharodontosaurs, which were supossed to have went extinct long before the late Cretaceous.
Of course, being just teeth, we can´t be sure- they may belong to some other kind of theropod that developed similar diet habits/teeth, or even to crocodilians. When the blade-like, serrated teeth sebecids were found for the first time, scientists believed non-avian theropods had made it to the Eocene in South America, because the teeth were so similar.

EDIT: A later study found that these teeth may belong to abelisaurids after all.

I have to admit it's an exciting idea, tho- to have T. rex and carcharodontosaurs walking the Earth at the same time, albeit in different places.

http://ojs.c3sl.ufpr.br/ojs2/index.php/rbg/article/view/21309

Galvasean

I guess we may soon be throwing out the conventional logic that carcharodontosaurs were outcompeted by smaller, 'more advanced' theropods. Perhaps another cases of 'lack of evidence =/= evidence of absence'.

Adam Khor

Galvasean wrote: »

I guess we may soon be throwing out the conventional logic that carcharodontosaurs were outcompeted by smaller, 'more advanced' theropods. Perhaps another cases of 'lack of evidence =/= evidence of absence'.

I think it makes sense that if carcharodontosaurs were specialized sauropod-hunters, and sauropods made it to the very end, there is no reason to suposse that carcharodontosaurus wouldn´t make it along with them. Perhaps they simply became rarer/less diverse, but then, same happened with tyrannosaurs in North America it seems.

Galvasean

I wouldn't pay too much heed to that idea. That recent study showed that sauropods were at their most diverse during the Maastrichtian (even more so than in the late Jurassic). I honestly think we'll find more and more Maastrichtian diversity. we just need to dig more!

Adam Khor

It seems there's also a maxilla of the late Cretaceous Brazilian carcharodontosaur, not only teeth. It was quite a bit smaller than its earlier relatives; its skull was only 80 cms long.

http://www.sciencedirect.com/science/article/pii/S0195667112001176

Galvasean

So, considering the time ecological difference and smaller size we can assume this is a different genus to Carcharodontosaurus - any sign of a name yet?

Adam Khor

Not yet, to my knowledge.

Adam Khor

Unfortunately, the article calls Allosaurus "T-Rex's Smaller Cousin" despite the fact that T-Rex is more closely related to penguins or hummingbirds than to Allosaurus.
It misguided me into believing it was about Albertosaurus...

http://news.yahoo.com/t-rexs-smaller-cousin-ate-falcon-study-finds-183243842.html

Galvasean

This culture of calling everything a cousin of T. rex is getting a little bit grating...

But hey at least they follow up with:
"Many people think of Allosaurus as a smaller and earlier version of T. rex, but our engineering analyses show that they were very different predators.""

Rubecula

It is bloody annoying this "everything is related to T-rex" attitude. I think we are predators too so we must be related to T-Rex as well. "ROARRRRRRRRRR"

Adam Khor

Rubecula wrote: »

It is bloody annoying this "everything is related to T-rex" attitude. I think we are predators too so we must be related to T-Rex as well. "ROARRRRRRRRRR"

Guess we are if we consider we are all descended from a same common ancestor... but then why not start calling potatoes T-Rex relatives while we're at it?

PS- Regarding the "Many people think of Allosaurus as a smaller and earlier version of T. rex, but our engineering analyses show that they were very different predators.""part, I figured that out at age 3 and I didn´t need engineering analyses... or a phD :pac:

Galvasean

I just counted the fingers. If it has three it was an allosaur. If it had two it was a tyrannosaur. Bear in mind back then the quality of theropod illustrations was at times dubious.

Kess73

Ties in nicely with my theory of how sparrowhawks are great to watch if one wants to form ideas about theropods. Much better example than a falcon as Sparrowhawks will hunt on foot as well as on the wing making them a much more rounded ambush predator

Some on here may remember me rambling on about it a year or so ago.



Sparrowhawk: The T-rex Allosaurus of back gardens. :P

Adam Khor

Nothing beats Harris hawks or the Johnny Rook when it comes to pack hunting dinos, tho

Then the crested caracara and the secretary bird hunt on land much more often than sparrowhawks.

Rubecula

I like falcons

Kess73

Adam Khor wrote: »

Nothing beats Harris hawks or the Johnny Rook when it comes to pack hunting dinos, tho

Then the crested caracara and the secretary bird hunt on land much more often than sparrowhawks.

When you can get me some of those that will live on my land all year round and who also will breed there by choice each year, then maybe I will change my tune. Until then Sprawks rule.


As a semi related aside, come the breeding season each year Sprawks can give a good account of themselves in terms of being able to work as a pair, far better than most people will give them credit for. Have seen some fascinating hunting techniques (and I call them techniques due to the fact I have seen them repeated a number of times) being utilised by my resident female and her current male over the past few years especially on smaller corvids or in dense hedging.

Adam Khor

Apparently they didn´t suffer much from bone abnormalities but they did suffer constant injury due to their lifestyle. Nothing unexpected I suposse:

http://www.ploscollections.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063409;jsessionid=9FC937EF0D16A51EA761B589DBCD56BA

Rubecula

Which of those is Mapusaurus?

Adam Khor

I think they both are

Rubecula

They look different to me Just by the jawline

Adam Khor

That's because the smaller one is a juvenile:

Rubecula

Lower jaw protrudes a bit by the look of it. Injury, bad assembly or deformity I suppose

Adam Khor

I must confess I don´t see anything strange with it

Galvasean

I think that's common enough in carcharodontosaurids.

Adam Khor

Siats meekerorum, a new giant theropod from North America.

It was a neovenatorid. The remains of a 9 meter long individual were found in 2008, but, as usual, its a juvenile, suggesting it was as big as Acrocanthosaurus, and potentially the second or third largest carnivorous dino ever found in North America. This creature would've been the top predator of its day; only after its fall would tyrannosaurids rise as the new superpredators.

http://www.ibtimes.com/new-dinosaur-siats-meekerorum-discovered-kept-early-tyrannosaurs-check-photo-1482478

Galvasean

I'm guessing it's just the perspective of the picture or did it have a MASSIVE head?

Adam Khor

I think its the perspective, but earlier carcharodontosaurs did have huge heads... Im not sure if the skull was found

Adam Khor

http://news.nationalgeographic.com/news/2014/07/140731-dinosaur-hall-smithsonian-renovation-culture-science/

Adam Khor

Evidence of Allosaurus killed by Stegosaurus. You may already have read this one:

http://westerndigs.org/allosaurus-died-from-stegosaur-spike-to-the-crotch-wyoming-fossil-shows/

Rubecula

not seen that before. Thanks Adam

Adam Khor

Juvenile Allosaurus auctioned, fails to sell.

http://www.dailymail.co.uk/sciencetech/article-3333473/Meet-Little-Al-rare-skeleton-baby-Allosaurus-teeth-like-steak-knives-fetch-500-000-auction.html

Linnaeus

Dear Adam,

Our world has really grown prosaic and blasé if no one has purchased this extraordinary treasure! Well, the price requested may be high; but surely there are numerous well-funded museums all over the world that should be delighted to possess such an amazingly well-preserved fossil? If I were rich, I'd buy it with pleasure!:rolleyes:

What would have been the approximate age of Little Al when he died? Any evidence of the cause of death? Teeth marks, fractures, disease?

Adam Khor

Problem with specimens such as this, which are owned by private parties, is that they're usually unavailable for study, meaning most questions are likely to go unanswered until it goes to a museum or some sort of scientific institution.

I had never heard of Little Al before this.

Adam Khor

Looks like an Allosaurus to me (was found at the Morrison formation of Wyomming, and is about 9 meters long). Experts say it may be a new species, tho.
https://uk.reuters.com/article/uk-auction-aguttes-dinosaur/mystery-dinosaur-skeleton-to-be-auctioned-in-paris-idUKKCN1GR2WV