Animal Sizes

[theropod]

This is a place to collect rigorous size estimates or solid size data for various animals. I am of course aware of the numerous topics we have that already deal with this subject for various taxa, and some we even appear to have multiple times (we have at least three or four threads that are arguably mostly discussions about megalodon size, for example), in fact I’ll wager that size-related posts are perhaps the single most abundant type of content here in terms of volume).
So let me explain why I nevertheless thought this thread was appropriate:

> Threads become filled up with debates quickly, and it is difficult to find specific valuable posts
> It is apparent that members, especially with regard to matchups, are often unaware of good information on sizes that has already been posted here, sometimes years ago.
> We lack an inventory of those solid size estimates that are available.
> We lack a place to request information specifically on animal sizes, even though it is often of essential importance to people here.

So I propose we use this thread to share size figures that adhere to a high standard of rigor and verifiability. Essentially, profile-quality material. If you want to request something, simply specify what animal, and if applicable, what kind of size (length/height/mass/average/maximum/minimum/all of them) exactly you want data on. There are a number of older posts by blaze and some other people that I think would lend themselves well to being linked and summarized or reproduced here, so people can find this content when they need it.

In order to ensure scientific quality, legibility, and verifiability I propose some rules:

1) Primary data (e.g. measurements) should be from a reliable source (technical literature, websites or blogs of demonstrably credible individuals). Estimates can be your own (as long as based on solid data), summarizing (or refining, if there are perceived problems with it) an estimate from the literature, or estimates dug up from other threads on here.
2) Use sources, and cite them. That means at least author/year and title of a paper should be given, and/or a direct link (but please a stable one, like a doi or jstor permalink). It should be as easy as possible to verify the information provided.
3) Explain your methods, or the methods of your source. This is to make sure results can be reproduced.
4) Structure your post. I would suggest a formal outline with materials, methods, results, discussion (and summary if you feel the need). That makes them both easier to read and understand, and helps structure the process of making the estimates.
5) Avoid speculations and guesswork as much as humanly possible, rely on quantitative data. That way we can clearly separate what we actually know from what we only believe to know. Also, try to make an assessment of the error margins of your estimates, if possible.
6) Don’t debate on this thread, use one of the many threads we already have, or one of the profile discussions for that, to avoid this thread getting clogged. You can, however, post a different size figure for an animal for which one has already been posted here, provided you follow the aforementioned rules (in fact, that is probably better than just debating, as it forces people to show rigorous methods and verifiable data, instead of unquantifiable, unverifiable statements that often make up a substantial portion of debates). That way, updates can be given or different results pointed out. In that case, please also provide a link to the other size estimate with the post so people can compare them.

If there end up being a sufficiently large number of posts on this thread, we can make an inventory here:

A

Allosaurus (max.)

Anacus (mass)

Apatosaurus (mass)

B
Bison bison (American bison)
Bos gaurus (Gaur)


C
Cervus elaphus (Wapiti/elk)
Caiman yacare

D

Dreadnoughtus (mass)

G

Giraffatitan (mass)

H
Hippopotamus amphibius
Hyaena hyaena (Striped Hyaena)
M
Maip (Mass)

Megatherium

Mammuthus primigenius (wooly mammoth)
Mola mola/alexandrini

N
Neofelis nebulosa (Clouded leopard)

P

Palaeoloxodon (Straight-tusked elephant, mass)

Panthera leo (African lion)
Panthera onca (Mexican Jaguar)
Panthera pardus (Leopard)
Puma concolor (Cougar)

S
Smutsia gigantea (Pangolin, max. mass)
Sus scrofa (Wild Boar)
Syncerus caffer (Cape buffalo)

T

Triceratops (max.)

Tropeognathus (mass)

Tyrannosaurus (average)

U
Ursus arctos (Brown Bear)

[Infinity Blade]

Megatherium

In case anyone still thinks Megatherium was some 8 tonne monster (admittedly this is something I mostly heard in the olden days of my time on AvA forums). These don't seem to be the only body mass estimates for M. americanum over the years, but they're consistent with each other and seem to be the most recent. So I'll discuss them first and maybe edit this post with earlier estimates if anyone wants me to cover them.

Casinos (1996)-> attempted to estimate the body mass of M. americanum using two different methods.

1.) He used two different equations used to estimate dinosaur, bird, and mammal body mass from Anderson et al. (1985), one for quadrupeds and another for bipeds (since he believed that there was evidence for bipedal locomotion in Megatherium). The quadruped equation involved both humerus and femur circumference (in millimeters) at the middle of the shaft, while the biped equation just involved femur circumference. He examined the type specimen of Megatherium.

2.) The second method involved a plaster cast model of M. americanum. It was considered to be a good reconstruction (linear measurements taken on the cast and on the mounted type specimen showed that the cast was made at linear scale 1:10), and so it was used for the water displacement method (the model was submerged in a water reservoir of known volume and the displaced volume was noted).

Equations 1 and 2 resulted in body mass values of 11.213 tonnes and 6.342 tonnes, respectively. The former is a clear overestimate, and Casinos did not believe the type specimen of Megatherium could plausibly be more massive than a large male African elephant of 5.45 tonnes (Alexander, 1989), so he thought the result from the biped equation to be an overestimate as well. The value obtained from the water displacement method, which was 3.8 tonnes, was considered most reasonable (and approximately consistent with an earlier estimation of 3 tonnes).

A much more recent study was conducted by Brassey & Gardiner (2015)->. They made a volumetric estimate to estimate Megatherium's mass. First, they generated a three-dimensional point cloud model of specimen NHMUK 26540 (an articulated composite cast). Then they used an "alpha shapes" (α-shapes) algorithm to estimate body mass volumetrically; α-shapes were determined by the underlying skeletal structure (the skeletal model) and the value of α, for determining the refinement of the three-dimensional shapes fitted around the skeleton. M. americanum was estimated to weigh 3,706 kg. This is actually very consistent with the water displacement method of the plaster cast model by Casinos (1996).

[Infinity Blade]

Can I request information on specific body parts of an animal? I was wondering how massive a sauropod's tail would be relative to its own body (I know relative tail size would vary, so I am wondering about multiple taxa). Or should I ask this in (and move this post to) another thread?

[theropod]

Allosaurus sp. (maximum size, "Epanterias amplexus" specimen)

[Intro] The Epanterias specimen, AMNH 5767, was originally described as a sauropod by Cope in 1878, later redescribed and identified as a theropod by Osborn & Mook (1921) and as indistinguishable from Allosaurus fragilis by Chure (2000). Due to the fragmentary nature of the material, I am tentatively treating it as Allosaurus sp. here. The great size of the material has been noted repeatedly before (e.g. Bakker 1992, Chure 2000), but a rigorous size estimate has not been attempted.

[Mat & Met] The material consists of a coracoid, axis and neural arch of the presumed first dorsal vertebra. There is also a moderate-sized mid-cervical centrum, excluded from further analysis as it does not belong to an exceptionately large individual, and hence likely not the same animal as the rest of the remains.
The originally stated measurements are a preserved height of 290 mm and width of 400 mm and width of the neural spine of 83 mm for the dorsal neural arch (Cope 1878), a height of the axis of 250 mm (Chure 2000) and a coracoid length of ~380 mm (measured digitally from figure in Osborn & Mook 1921, using the known dimensions of the dorsal neural arch in figure to the same scale for reference).

Figure 1: (A-D) AMNH 5767, Holotype of "Epanterias amplexus" Cope 1878. (A) Axis, (B) D1 in anterior and left lateral view. (C) Right coracoid in proximal and lateral view. (D) Middle cervical centrum (C6 or 7) in anterior and left lateral view. (E-G) Allosaurus fragilis. (E) Axis, D1 and Coracoid of ?DINO 2560. (F) Axis of USNM 4734. (G) Axis and D3 of USNM 8367. Scale Bar: 10 cm.

Restored measurements:
D1, restored based on DINO 2560:
   total height            441 mm
   diapophyseal width      452 mm
   parapophyseal width     204 mm
   centrum height          220 mm
   centrum width           186 mm
   centrum length(rim-rim) 123 mm
   centrum length (max.)   191 mm
Axis:
   centrum length
   =|= excl. intercentrum  ~ 100 mm
   =|= incl. intercentrum  156 mm



comparative specimens:

USNM 4734 (Gilmore 1920) Axis centrum+intercentrum length 85 mm D1 (mean of C9 and D2) centrum length e. 106 mm Coracoid: greatest length 170 mm (Based on skeletal reconstruction by Randomdinos¹): TL 7.4 m BM 1300 kg

DINO 2560 (figures and scalebars in Madsen 1976) Axis: centrum + intercentrum 126 mm D1: centrum length 130 mm Coracoid: greatest length 234 mm (based on skeletal reconstruction by ScottHartman², mass estimated from 3D-model): TL 8.6 m BM 1839 kg Figure 2: Volumetric model used for mass estimate of DINO 2560, based on skeletal by Scott Hartman, dorsal view adapted from Bates 2009, specific gravity assumed to be 0.933 (grid=1 m)

USNM 8367 (Gilmore 1920) Axis centrum+intercentrum length 88 mm D3  height 253 mm (based on summed length of the 17 presacral centra preserved in both it and USNM 4734, from Gilmore 1920): TL 7.76 m BM 1501 kg

We can scale up AMNH 5767 based on these three analogues.

[Results]
           method    scale      eTL       eBM
1 usnm_4734_axis_l 1.835294 13.58118  8036.378
2        4734_d1_l 1.801887 13.33396  7605.467
3    4734_coracoid 2.235294 16.54118 14519.357
4 usnm_8367_axis_l 1.772727 13.75636  8361.929
5   8367_dorsals_h 1.743083 13.52632  7949.410
6 DINO_2560_axis_l 1.238095 10.64762  3490.148
7        2560_D1_l 1.469231 12.63538  5832.460
8    2560_coracoid 1.623932 13.96581  7875.624


[Discussion & Conclusions] first of all, we can of course dismiss the 16.5 m, 14.5 t estimate. That this figure diverges so much from the others suggests there is something wrong; perhaps that USNM 4743 is a specimen with an atypically small coracoid, which we should not be assuming here.

This leaves us with the following viable estimates:

          method    scale      eTL       eBM
1 usnm_4734_axis_l 1.835294 13.58118  8036.378
2        4734_d1_l 1.801887 13.33396  7605.467
4 usnm_8367_axis_l 1.772727 13.75636  8361.929
5   8367_dorsals_h 1.743083 13.52632  7949.410
6 DINO_2560_axis_l 1.238095 10.64762  3490.148
7        2560_D1_l 1.469231 12.63538  5832.460
8    2560_coracoid 1.623932 13.96581  7875.624Based on this, we can be fairly confident that AMNH 5767 is among the largest, if not the largest known jurassic theropod specimen, with a length of at least 10.6 m and a mass of at least 3.5 t.

The mean TL of these is 13.1 m. Mean body mass is 7022 kg. The median is 13.5 m and 7875 t.

Estimate 6, based on the DINO 2560 axis is also a little suspicious in terms of how it diverges quite a bit from where the other figures tend to cluster. If we ignore estimate 6 as well, out mean becomes 13.5 m and 7610 kg, the median 13.6 m and 7913 kg. Scaling up Bates’ model of Big Al (7.6 m, ~1.5 t) to 13.5 m gives ~8.4 t, roughly in agreement with this.

As a plausibility test, we can compare the dorsal vertebra to those of other giant theropods, vertebral diameter having been previously taunted as a reliable indicator of body mass:

Figure 3: (A, B) First dorsal vertebrae of giant theropods (A) cf. Allosaurus sp. (AMNH 5767) and (B) Tyrannotitan chubutensis (MPEF-PV 1157, Canale et al. 2015). (C) Fourth dorsal vertebra (anteriormost preserved dorsal) of Tyrannosaurus rex (FMNH PR 2081, Brochu 2003). Scale bar: 10cm

In conclusion, it appears probable that AMNH 5767 is the largest Jurassic theropod specimen, among the largest theropod specimens yet discovered, as suggested by Bakker (1992). Interesting enough, there seems to be an increased ocurrence of very large allosaurids at the very top of the Morrison formation (e.g. Chure 1995, Williamson & Chure 1996).

References:

Bakker, R. T., J. Siegwarth, D. Kralis, and J. Filla. 1992: Edmarka rex, a new, gigantic theropod dinosaur from the middle Morrison Formation, Late Jurassic of the Como Bluff outcrop region. Hunteria 2:1–24.
Bates, K. T. 2009: How big was ‘Big Al’? Quantifying the effect of soft tissue and osteological unknowns on mass predictions for Allosaurus (Dinosauria: Theropoda). Palaeontologia Electronica 12:1–33.
Bates, K. T., R. B. Benson, and P. L. Falkingham. 2012: A computational analysis of locomotor anatomy and body mass evolution in Allosauroidea (Dinosauria: Theropoda). Paleobiology 38:486–507.
Brochu, C. A. 2003: Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Journal of Vertebrate Paleontology 22:1–138.
Canale, J. I., F. E. Novas, and D. Pol. 2015: Osteology and phylogenetic relationships of Tyrannotitan chubutensis Novas, de Valais, Vickers-Rich and Rich, 2005 (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Patagonia, Argentina. Historical Biology 27:1–32.
Chure, D. J. 1995: A reassessment of the gigantic theropod Saurophagus maximus from the Morrison Formation (Upper Jurassic) of Oklahoma, USA. 6th Symposium on Mesozoic terrestrial ecosystems and biotas, short papers. Edited by A.-L. Sun and Y.-Q. Wang. China Ocean Press, Beijing, China:103–106.
Chure, D. J. 2000: A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (UT-CO) and a revision of the theropod family Allosauridae. Ph. D. dissertation, Columbia University.
Cope, D. E. D. 1878: On a new opisthocoelous dinosaur. Annals and Magazine of Natural History 2:194–194.
Gilmore, C. W. 1920: Osteology of the carnivorous Dinosauria in the United States National museum: with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus. US Government printing office.
Madsen, J. H. 1976: Allosaurus fragilis: a revised osteology. Utah Geological and Mining Survey Bulletin 109:1–163.
Osborn, H. F., and C. C. Mook. 1921: Camarasaurus, Amphicoelias, and other sauropods of Cope. Memoirs of the American Museum of Natural History 3:247–387.
Williamson, T. E., and D. J. Chure. 1996: A large allosaurid from the Upper Jurassic Morrison Formation (Brushy Basin Member), west-central New Mexico. Museum of Northern Arizona, Bulletin 60:73–79.

[Infinity Blade]

Sure, why not? That sort of information should be available along with volumetric mass estimates for sauropods.

Okay then. How massive was the tail of:

• Brachiosaurus (or Giraffatitan if that suits people better; representative of our brachiosaurids)?
• Diplodocus (representative of our diplodocids)?
• Argentinosaurus?

I want to know the mass of the tail relative to total body mass as well. I tried to more or less convey the variation in proportional tail size here. If there are any other sauropods with relatively larger (or smaller) tails than any of these, mention them as well.

[theropod]

Oct 22, 2019 16:49:02 GMT 5 Infinity Blade said:

Sure, why not? That sort of information should be available along with volumetric mass estimates for sauropods.

Okay then. How massive was the tail of:

• Brachiosaurus (or Giraffatitan if that suits people better; representative of our brachiosaurids)?
• Diplodocus (representative of our diplodocids)?
• Argentinosaurus?

I want to know the mass of the tail relative to total body mass as well. I tried to more or less convey the variation in proportional tail size here. If there are any other sauropods with relatively larger (or smaller) tails than any of these, mention them as well.

Sauropod body masses
I can look into that further and expand this post when I find the time. Off the top of my head, Argentinosaurus is probably too fragmentary to get a reliable estimate from (certainly one reliably different from related taxa), so it may be better to use a more complete large titanosaur like Futalognkosaurus or Dreadnoughtus.

You can find volumetric figures for Dreadnoughtus, Apatosaurus and Giraffatitan in Bates et al. 2015, [m&m] based on minimum convex hulling and testing various assumptions (such as +21%, and testing the original estimates based on limb-bone regressions).

[Results] minimum models:

Dreadnoughtus schrani (MPM-PV 1156) total volume 26.91 m³ SG 1000 kgm⁻³ mass 25 947.68 kg total (with respiratory structures) SG 821.9 kg/m³ mass 22,117.98 kg hindlimb volume 0.796m³ SG 1000 kgm⁻³ mass 795.80 kg forelimb volume 0.614 m³ SG 1000 kgm⁻³ mass 615.09 kg axial total volume 25.50 m³ SG 1000 kgm⁻³ mass 24,536.80 kg neck volume 3.110 (-0.49 m³) SG 1000kgm⁻³ mass 3109.99 kg (-486.48 kg) trunk volume 20.382 (-4.3 m³) SG 1000 kgm⁻³ mass 20,381.96 kg (-4303.67 kg) tail volume 1.011 SG 1000 kgm⁻³ mass 1011.35 kg

Apatosaurus louisae (CM 3018) total volume 26.63 m³ SG 1000 kgm⁻³ mass 26,699.01 kg total (with respiratory structures) SG 818.8 kg/m³ mass 21 803.21 kg hindlimb volume 1.289 m³ SG 1000 kgm⁻³ mass 1288.92 kg forelimb volume 0.722 m³ SG 1000 kgm⁻³ mass 722.62 kg axial total volume 24.62 m³ SG 1000 kgm⁻³ mass 24 687.47 kg neck volume 2.62 (-0.29 m³) SG 1000kgm⁻³ mass 2615.16 kg (-291.95 kg) trunk volume 20.12 (-4.6 m³) SG 1000 kgm⁻³ mass 20,187.65 kg (-4602.86kg) tail volume 1.86 SG 1000 kgm⁻³ mass 1861.20 kg

Giraffatitan brancai (HM SII) total volume 25.28 m³ SG 1000 kgm⁻³ mass 25,282.88 kg total (with respiratory structures) SG 788.8 kg/m³ mass 19 946.35 kg hindlimb volume 1.046 m³ SG 1000 kgm⁻³ mass 1045.88 kg forelimb volume 0.614 m³ SG 1000 kgm⁻³ mass 615.09 kg axial total volume 25.50 m³ SG 1000 kgm⁻³ mass 24,536.80 kg neck volume 2.46 (-0.33 m³) SG 1000kgm⁻³ mass 2461.00 kg (-332.54 kg) trunk volume 19.85 (-5.00 m³) SG 1000 kgm⁻³ mass 19 850.92 kg (-5000.39 kg) tail volume 0.78 SG 1000 kgm⁻³ mass 774.76 kg

[Discussion] The paper seems to suggest that the +21% models are likely more accurately reflecting real-life body masses, so perhaps the total body masses should be increased by that factor, but that doesn’t really affect the proportions.

This means the tail in Dreadnoughtus is about 4.6% of total body mass, in Apatosaurus it is about 8.5%, in Giraffatitan about 3.9%. The tail of Brachiosaurus altithorax would probably be somewhat larger (and so would total body mass) based on Taylor 2009’s redescription.

Reference:

Bates, K.T., Falkingham, P.L., Macaulay, S., Brassey, C. and Maidment, S.C. 2015. Downsizing a giant: re-evaluating Dreadnoughtus body mass. Biology letters 11 (6): 20150215.

Taylor, M.P. 2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). Journal of vertebrate Paleontology 29 (3): 787–806.

[Infinity Blade]

Palaeoloxodon namadicus

In 2015, paleontologist Asier Larramendi published a paper-> where he documents his own size estimates for various extinct proboscidean taxa. P. namadicus is commonly known as that elephant that weighed 22 tonnes. This size was attributed to one particular specimen (Sagauni II), represented only by a distal femur portion. This portion has been reported to be nearly one-quarter larger than that of a supposedly not yet fully grown P. namadicus individual that has been estimated to weigh 13 tonnes (Sagauni I). Assuming this portion was 20% larger, the elephant's whole femur would have been 1,900 mm in length, giving us an elephant 5.2 meters tall at the withers and 22 tonnes in body mass.[1]

There are, however, several issues with this estimate. The only source of measurement for the femur fragment's size is Prinsep (1834).[2] The fact that this specimen has presumably not been seen, let alone measured, in more than 180 years is sufficient grounds for us to view the size estimate with heavy skepticism. Asier Larramendi himself notes that the specimen must be restudied, essentially admitting that he did not get the chance to study the specimen himself. The specimen is said to "likely" be stored in the Indian Museum of Kolkata, implying that it is not certain that they are there. Until this specimen is recovered, the size estimate will not be anything more than speculative.[1]

Sagauni I is stated by Asier Larramendi to likely be a young individual that could have grown considerably larger, on the grounds that the femoral head was detached.[1] However, looking at the original source describing this material, we find that there is another very large specimen that was found with detached femoral condyles.[2] Presumably, this is Sagauni II, given that this specimen is a single distal portion of a femur, which would have condyles. It seems very suspect to conclude that Sagauni II would have had more room to grow solely on the basis that its femoral condyles were detached, especially if it were supposedly already 22 tonnes. Even Asier Larramendi himself notes that complete long bone epiphysis fusion can occur as late as age 50 in these giant extinct elephants (regardless of sex), a point at which they have long since achieved or surpassed the expected adult body mass of their species. Therefore, it is not a given that Sagauni I was necessarily a young individual simply due to its detached femoral head, if what are certainly fully grown individuals also have incompletely fused long bone epiphyses.[1][2]

Lastly, and most strikingly, Sagauni II's size is based on an estimate of Sagauni I's size. Sagauni I's left femur (which, mind you, was found fragmented), for instance, was estimated to have been "63 inches" long by Prinsep.[2] The problem is that in 1834, the inch was not a standardized unit of measure. Different countries had their own standards for how long an "inch" was (here-> is a mid-19th century tool used to convert different inch standards). It wasn't until 1930 when the British Standards Institution finally standardized the inch into its modern measurement (exactly 25.4 mm), and a few years later when several other countries followed suit. An inch to us does not necessarily equate to an inch for a 19th century Englishman like James Prinsep. Larramendi clearly takes the stated size of 63 inches at face value, stating it to be 1600 mm (63 inches).[2] This further exacerbates the already tenuous credibility of the 22 tonne size estimate, and further outlines the pressing need to reexamine the specimens in question.

In conclusion, in Asier Larramendi's own words in Appendix I of his own paper, "The estimated body size for...Palaeoloxodon namadicus (Sagauni II), should be taken with a grain of salt."[1]

References:

[1] Larramendi, A. 2016. Shoulder height, body mass, and shape of proboscideans. Acta Palaeontologica Polonica 61 (3): 537–574.
[2] Prinsep, J. 1834. Note on the fossil bones on the Nerbudda valley discovered by Dr. G.G. Spilsbury near Narsinhpur. Journal of the Asiatic Society of Bengal 3: 396–403.

[dinosauria101]

Here's something I found in the Largest Sauropods thread in regards to Apatosaurus

"A giant, skeletally immature individual of Apatosaurus from the Morrison Formation of Oklahoma
Matt Wedel
Western University of Health Sciences, Pomona,
USA.
A collection of Apatosaurus fossils from the Morrison Formation of the Oklahoma
panhandle represents several individuals, including at least one of exceptional size.
Elements from the largest individual include cervical, dorsal, and caudal vertebrae, ribs, a
partial scapulocoracoid, distal femur, fibula, and pedal elements.
These elements are all 11-30% larger (linearly) than the equivalent bones from CM 3018, the mounted
Apatosaurus at the Carnegie Museum.
Surprisingly, the giant Oklahoma
Apatosaurus was not skeletally mature when it died.
A dorsal vertebra, OMNH 1329, has a visible
neurocentral fusion line these are all remodelled away in CM 3018.
More compellingly, a very large cervical rib, OMNH 1368, is unfused.
This is consistent with fusion patterns in other neosauropod
s, in which neurocentral fusion precedes fusion of
the cervical ribs.
In Diplodocus and Giraffatitan, the largest individuals with unfused
cervical ribs are less than 80% the linear size (and therefore only half the mass) of the
largest known individuals.
Despite its immense size, the Oklahoma giant probably was
not done growing, and does not represent the upper size limit for
Apatosaurus.
Linear measurements of the Oklahoma
Apatosaurus imply a body mass roughly twice that of
CM 3018.
The latter specimen has been estimated to mass 18-40 tons.
The Oklahoma giant may have massed 36-80 tons, potentially exceeding
Supersaurus and Brachiosaurus and rivalling the largest titanosaurs."

svpca.org/years/2013_edinburgh/abstracts.pdf

A few links:
svpow.com/2012/04/25/the-giant-oklahoma-apatosaurus-omnh-1670/
svpow.com/2012/04/30/the-giant-oklahoma-apatosaurus-omnh-1670-redux/
skeletaldrawing.blogspot.co.at/2012/04/yup-ok-apatosaurus-is-freakin-huge.html
svpow.com/2013/03/24/omnh-1331-is-my-new-hero/

Read more: theworldofanimals.proboards.com/thread/114?page=19#ixzz63Bf7F2UA

[dinosauria101]

Now here's something regarding Mamenchisaurus sinocanadorum, the dwarfer of P. namadicus. The 75 ton figure actually holds water, as per this GDI
www.deviantart.com/spinoinwonderland/journal/Some-more-GDI-s-for-a-few-folks-659947404

[spartan]

What was the mass, height and length of the average and largest Triceratops?

[theropod]

Triceratops/Eotriceratops (maximum size)
[m&m] Seebacher (2001) estimated an 8 m Triceratops horridus at roughly 5 t, which appears unreasonably low, but is at least based on some sort of volumetric methodology. Greg Paul (2010, 2016) estimates an 8 m Triceratops horridus at 9 t in the Princeton Field Guide, which is also presumably based on volumetric models.

The largest specimen Greg Paul lists on his website (USNM 4276) has a ~1.3 m femur. Based on his skeletal (2016), that would correspond to a total length (axial length from the tip of the tail to the tip of the rostral) of about 8.6 m and a shoulder height and skull length of about 2.7 m. So this is consistent with the skull length and overall size suggested by the largest fragmentary material (UCMP 12861 skull length is estimated at ~2.7 m), as well as the skull length of Eotriceratops¹.

Based on Hartman’s skeletal, the largest estimated skull length would result in an animal 9.2 m long, and with a considerably longer femur and larger body size than based on the proportions depicted by Paul, demonstrated individual variation between Triceratops specimens and/or differences between the reconstructions of the two authors.

I’ve tried roughly replicating this in Blender based on Paul’s and Hartman’s skeletals scaled to the appropriate skeletal dimensions, here are the results:

Specimen/dimensions	USNM 4276, 1.3 m femur (Paul 2010), ~2.7 m skull, ~8.6 m TL, ~2.8 m height (at top of back). Based on Paul’s skeleton.	UCMP 12861, est. 2.7 m long skull¹, ~9.2 m TL, 3.3 m tall. Based on Hartman’s skeletal (dorsal view adapted from Paul 2016, see picture to the left)
Axial Postcranium	7.1566 m³	8.3114 m³
Head	1.5637 m³	1.5637 m³
Forelimb [×2]	0.1564 m³ [0.3128m³]	0.2690 m³ [0.5379m³]
Hindlimb [×2]	0.2508 m³ [0.5018m³]	0.3477 m³ [0.6955m³]
Total [mass]	9.5349 m³ [9535kg]	10.7607 m³ [10761kg]

So assuming a specific gravity of 1.0, we get a total length of 8.6 m and body mass of about 9.5 t for the largest specimen based on Paul’s skeletal, and around 9.2 m and 10.8 t based on Hartman’s.

[Discussion] This is a relatively rough estimate, especially around the head, which is tricky to model, but it should be good enough to get a general idea. The results also closely match Paul’s own estimate for the specimen in question, 9.3 t², which he probably based on a scale model, lending further credibility to both figures.

We should also not be too confident about the estimated skull length of 2.7 m, as the specimen is extremely fragmentary (a partial premaxilla and small frill fragment). So consequently we should take figures based on it (i.e. the upper estimate) with a grain of salt. However, Eotriceratops skull is considerably more complete, and it really is this size, so at least this taxon would have a more realistic shot at the upper estimate.

The largest in over 30 Triceratops skulls examined by Scanella & Horner report is BYU 12183 at 2.5 m long, which would make this individual about 8.5 m long and 8.6 t based on Hartman’s skeletal, smaller than the size Paul’s skeletal suggests for the largest femur. Being the largest in 30, that is roughly comparable to Sue or Scotty for T. rex.

I unfortunately have no solid data on average size, however considering Scanella & Horner call AMNH 5116, a 200 cm Triceratops skull "large", I would expect the average to be much smaller than these estimates for the largest individuals, although data from more individuals, and an assessment of their maturity, is needed to establish a reliable average. Scaling from the above figures, a 2 m skull might belong to a 6.3-6.8 m long, 2-2.4 m tall individual that would have massed somewhere between 3.9 and 4.4 t.

Note however that this is an individual the authors considered to be a "young adult", and seems to be rather modest-sized compared to the majority of adults based on the limited data available (Scanella & Horner, tab. 1). Further complicating this is that while the majority of specimens are young adults, only three of them have a reported (parietal length) measurement, so including only specimens with a reported measurement creates a sample heavily skewed towards old adults (of which 6 have a reported measurement or estimate of parietal length) , but we cannot properly include the young adults because they have no measurements.

However just to get an idea, we can assume the 5 young adult specimens without measurements all had parietals about the same length as AMNH 5116, 83 cm, which would then give us an average skull length of 227 cm, average total length of 7.7 m and average body mass of 6.4 t based on this sample (n=14).

References:

Paul, G.S. 2010. The Princeton field guide to dinosaurs. Princeton University Press, Princeton.

Paul, G.S. 2016. The Princeton field guide to dinosaurs. 2nd Ed.. Princeton University Press, Princeton.

Scannella, J.B. and Horner, J.R. 2010. Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30 (4): 1157–1168.

Seebacher, F. 2001. A new method to calculate allometric length-mass relationships of dinosaurs. Journal of Vertebrate Paleontology 21 (1): 51–60.
¹https://www.deviantart.com/eofauna/art/Eotriceratops-vs-Triceratops-341153326

²http://gspauldino.com/data.html

[Life]

Outstanding work, my friend. Keep it up.

[dinosauria101]

Anyone know exactly how much Dreadnoughtus would have continued to grow (based on the maturity of other titanosaurs) had it not died? I might be able to calculate a possible adult size that way.

[Infinity Blade]

This is more of a request than an insightful post. According to this PDF, adult blue whales can weigh from 73 to 136 tonnes, with 173 tonnes being a maximum. The origin of the figure for the 173 female blue whale was Tomilin (1957). The full citation is Tomilin, A. G. 1957. Cetacea. Mammals of the U.S.S.R. and adjacent countries. Volume 9.
Akademii Nauk SSSR, Moskow (translated by the Israel Program for Scientific Translations, Jerusalem, 1967, 717 pp.).

Apparently this female was reported by Tomilin after being taken off South Georgia in 1947. Does anyone know about any further details about how comprehensive this size estimation was?

And finally, *sigh (I just had to ask this question)...how does this compare with the largest sauropods (whether known from reasonable remains or not)?

[dinosauria101]

What was the size of Rajasaurus?
GSP gives 11 meters, Larramendi gives 10.5, Grillo and Delcourt gives 6.6 meters, and 9 meters is a fairly common figure elsewhere. Which is most accurate?