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Allosaur comparison by ScottHartman Allosaur comparison by ScottHartman
My "Big Al" skeletal has been up for a while, but the name is deceiving since Big Al is actually fairly little (it's specimen MOR 693). Allosaurus species are still a bit contentious, so I'm not going to commit at this time to which species of Allosaurus Big Al is, but as you can see it wouldn't want to run into a large A. fragilis.

Also, oddly, the arms seem to be proportionately smaller on Big Al, although I'm not sure what to make of it right now.

Update: Reposed, and updated the Big Al specimen's silhouette.
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:iconxiphactinus:
Xiphactinus Featured By Owner Edited Oct 31, 2018  Hobbyist Traditional Artist
Hi, Scott. I recently found this cranial drawing of the UUVPB 6000 from Bakker, 2000. "Brontosaur killers: Late Jurassic allosaurids as sabre-tooth cat analogues" on this blog theropoddatabase.blogspot.com/… and I noticed that the shape is a bit different from yours. Maybe there's some distortion in the Bakker drawing? I'm sorry if this question doesn't make sense.
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:iconrhe416:
rhe416 Featured By Owner May 12, 2018  Hobbyist Traditional Artist
Will you update A. fragilis?
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:iconscotthartman:
ScottHartman Featured By Owner May 13, 2018  Professional Digital Artist
If/when it needs it.
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:iconrhe416:
rhe416 Featured By Owner May 15, 2018  Hobbyist Traditional Artist
Ok
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:iconthedinorocker:
thedinorocker Featured By Owner Dec 25, 2016
Hi Mr Scott and Marry Xmas!
4 years later what Your opinion about Allosaurus species?
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:iconraptorkil:
raptorkil Featured By Owner Aug 12, 2015
top one looks like a juvenile, beautiful :D
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:iconzadwon:
Zadwon Featured By Owner Oct 6, 2015  Hobbyist General Artist
Big Al was a young adult when he died, only six years old.
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:iconblazze92:
bLAZZE92 Featured By Owner Mar 20, 2016
Juvenile is very different from young adult, besides, there hasn't been any histological work on Big Al, we don't know how old it was when it died.
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:iconrhe416:
rhe416 Featured By Owner May 12, 2018  Hobbyist Traditional Artist
Really? Neat.
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:iconblazze92:
bLAZZE92 Featured By Owner May 24, 2018
Yup, in a comment below I compare its size to specimens that have had their age estimated and it suggests it was anything from 12 to 15 years old, though it is possible it was older, since it belongs to an earlier, presumably smaller species. 
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:iconzadwon:
Zadwon Featured By Owner Mar 21, 2016  Hobbyist General Artist
In the BBC Walking with Dinosaurs special the ballad of Big Al they say that Big Al was six years old when he died. Had to do with his size.
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:iconblazze92:
bLAZZE92 Featured By Owner Mar 21, 2016
That'll be a guestimate at best, histological work on Allosaurus wasn't published until 2006 (Bybee et al. 2006) and it didn't include Big Al, however we can still use it to get an idea of the age of Big Al.

According to Foster and Chure (2006) the femur and tibia of Big Al are 75cm and 67cm long respectively, while the humerus is 32cm long (I forgot the source of this one), comparing to the specimens analyzed in Bybee et al. the length of the femur falls between two individuals estimated at 12 and 13 years old, the tibia is larger than an specimen estimated at 15 years old and the humerus falls between those of two specimens estimated at 13 and 15 years old. Some of the specimens analyzed by Bybee et al. are estimated at 6 years old and they are literally half the size of Big Al.

So, anything between 12 and 15 years old seems reasonable for Big Al. How big it would have grown had it lived to old age? comparing its femur length with that of the definitive largest A. fragilis suggest that it's 77% of full size but Big Al belongs to an earlier species than A. fragilis (by several millions of years) so its age at death might have been higher and it might have been closer to full size for all we know.
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:iconzadwon:
Zadwon Featured By Owner Mar 22, 2016  Hobbyist General Artist
Ok.
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:iconraptorkil:
raptorkil Featured By Owner Oct 6, 2015
I see, thx
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:icontkwth:
TKWTH Featured By Owner Aug 8, 2015  Hobbyist Digital Artist
I'm surprised we can take so many liberties with putting specimens into the Allosaurus genus (skull shape, lower half of the pelvis etc.) but we can't accept things like Linheraptor and Tsaagan as species of Velociraptor, or Tarbosaurus as a species of Tyrannosaurus...
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:iconscotthartman:
ScottHartman Featured By Owner Aug 8, 2015  Professional Digital Artist
There are people who do accept those things. The problem with genus-level taxonomy is that there really isn't a non-arbitrary metric to go by. Hence the number of paleontologists that refer to use their "genericometer" to tell the difference.
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:iconeusou123:
Eusou123 Featured By Owner Jun 17, 2014
What about Saurophaganax? See mine please eusou123.deviantart.com/art/Sa…
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:iconpedrosalas:
PedroSalas Featured By Owner May 1, 2014  Professional Traditional Artist
My version of fragilis

pedrosalas.deviantart.com/art/…
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:icondirtypms:
dirtypms Featured By Owner Aug 8, 2013  Student Filmographer
So "Big Al" is the one at the top, and below is an average-sized Allosaurus?
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:icontyrannosaurusprime:
TyrannosaurusPrime Featured By Owner Jun 5, 2013
Just curious, is Big Al and Big Al 2 part of the Brushy Basin fauna or are they from an earlier part of the formation? :?
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:iconscotthartman:
ScottHartman Featured By Owner Jun 7, 2013  Professional Digital Artist
That's an excellent question. I want to say yes, but I'll have to dig up the paper to be sure.
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:iconikechi1:
Ikechi1 Featured By Owner Mar 10, 2013  Hobbyist General Artist
can i use your skeletal frame references with appropriate crediting?
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:iconscotthartman:
ScottHartman Featured By Owner Mar 11, 2013  Professional Digital Artist
What kind of project are you doing?
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:iconikechi1:
Ikechi1 Featured By Owner Mar 11, 2013  Hobbyist General Artist
not so much a project per say, but i would like to improve the accuracy in my works, and sending skeletals to the person im working with would help improve the accuracy
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:iconscotthartman:
ScottHartman Featured By Owner Mar 11, 2013  Professional Digital Artist
Go ahead. I'll look forward to seeing what you come up with.
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:iconikechi1:
Ikechi1 Featured By Owner Mar 22, 2013  Hobbyist General Artist
thank you for the permission :)
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:icon2195razielim:
2195Razielim Featured By Owner Jan 31, 2013  Hobbyist Photographer
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:icondinobirdman:
DinoBirdMan Featured By Owner Jan 4, 2013  Student Artist
Allosaurus is pretty awsome!:)
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:iconrodolph777:
Rodolph777 Featured By Owner Oct 12, 2012
Hello, Do you think that theropods like neovenatorids and allosaurids could straight their necks in a forward motion to run? Because most depictiones show short necked dinosaurs running with the neck curved and I think that they ran with their heads in a lower stance.
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:iconpaleosir:
paleosir Featured By Owner Jul 2, 2016  Hobbyist Traditional Artist
Well, they could straighten their necks, as they were quite flexible in Allosaurus.
But wheter they did it while running? Idk.
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:icondelirio88:
DELIRIO88 Featured By Owner Aug 31, 2012  Hobbyist General Artist
Hello Mr. Hartman!
I made another restoration helped, by your useful skeletal reconstructions!
[link] :)
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:iconroflo-felorez:
RoFlo-Felorez Featured By Owner Aug 25, 2012  Student Digital Artist
i still feel a bit odd seeing the allosaurs with the sorta "boxy triangle" looking head more like the top ones, i like the bottom type of allosaurs better for some reason
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:iconsupergoji18:
supergoji18 Featured By Owner Aug 25, 2012  Student Traditional Artist
there's certainly a size difference! Which would you say is faster?
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:iconscotthartman:
ScottHartman Featured By Owner Aug 25, 2012  Professional Digital Artist
I wouldn't say either is clearly faster - they share fairly similar hind leg proportions and similar areas for muscle attachments, so I'd guess they were both roughly equally slow.
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:iconsupergoji18:
supergoji18 Featured By Owner Aug 25, 2012  Student Traditional Artist
equally slow?
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:iconscotthartman:
ScottHartman Featured By Owner Aug 25, 2012  Professional Digital Artist
Yeah, allosaurs don't show the same adaptations for speed that say tyrannosaurs do.
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:iconsupergoji18:
supergoji18 Featured By Owner Aug 25, 2012  Student Traditional Artist
how fast do you think their top speed was?
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:iconscotthartman:
ScottHartman Featured By Owner Aug 25, 2012  Professional Digital Artist
Absolute speed is much harder than relative speed, but I'd hazard a guess of 20 mph or so.
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:iconsupergoji18:
supergoji18 Featured By Owner Aug 26, 2012  Student Traditional Artist
I thought they would be a wee bit faster
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:iconzadwon:
Zadwon Featured By Owner Oct 6, 2015  Hobbyist General Artist
Allosaurus was faster then the T-rex. Allosaurus was lighter built than Tyrannosaurus. the T-rex was slow.
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:iconscotthartman:
ScottHartman Featured By Owner Aug 26, 2012  Professional Digital Artist
Allosaurs simply aren't meant for speed - and the problem gets worse in the big guys like Acrocanthosaurus and Giganotosaurus. But then their prey tends to be sauropod and (for Allosaurus at least) stegosaur based, so most of their prey isn't running away. Even Camptosaurus was pretty clunky by ornithiscian standards. Small fast prey like Othnielosaurus were hunted by small theropods.

It doesn't seem to be until the Cretaceous (and really the Late Cretaceous) that non-sauropod dinosaurs combined size and (relative) speed into one package that necessitated big predators that could catch them.
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(2 Replies)
:iconpeteridish:
PeteriDish Featured By Owner Aug 25, 2012  Hobbyist General Artist
does the lower one have proportionally larger arms? Also the fenestrae look different.
What can one learn from skelůetals =D You bring dinosaurs to a whole new perspective, I always spot something interesting. =)
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:iconscotthartman:
ScottHartman Featured By Owner Aug 25, 2012  Professional Digital Artist
Yes, A. fragillis seems to have much larger arms relative to its size, although there's the possibility that it could be ontogenetic (i.e. the arms could get larger as they grow)...although I sort of doubt it.
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:icontheropod1:
theropod1 Featured By Owner Jun 2, 2013  Student Traditional Artist
Don't larger theropods typically have smaller arms relative to size? There seem to be huge differences between these two specimens in other regards, like skull shape (especially in the nasals, maxilla and lacrimals) or tail lenght. Do you support MOR 693 belonging to its own species? I'm inclined to believe it when looking at them.
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:iconscotthartman:
ScottHartman Featured By Owner Jun 2, 2013  Professional Digital Artist
Yes, the general consensus is that MOR 693 belongs to a second species of allosaur. The paper has been in preparation for quite a while now.
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:icontheropod1:
theropod1 Featured By Owner Jun 4, 2013  Student Traditional Artist
Who's working on it?
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:iconscotthartman:
ScottHartman Featured By Owner Jun 5, 2013  Professional Digital Artist
Dan Chure has been working on it for a while, and I believe he may be collaborating with people at the UMNH.
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:iconpeteridish:
PeteriDish Featured By Owner Aug 25, 2012  Hobbyist General Artist
Thank you! The ontogenetic development is an interesting hypothesis, but if it was so, shouldn't the hindlegs undergo similar shift in proportion as well? It seems odd that the rest of the body would grow at a slower rate than the limbs.
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:iconscotthartman:
ScottHartman Featured By Owner Aug 26, 2012  Professional Digital Artist
Not all ontogenetic changes are linear - but that said, I really think a better explanation is either due to species-specific differences, or else as a result of injury or malnutrition.
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:iconpeteridish:
PeteriDish Featured By Owner Aug 26, 2012  Hobbyist General Artist
Yeah, that sounds more plausible to me. I'd really bet on species-specific differences =)
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July 30, 2010
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