Ornithischian size

[theropod]

Post any kind of evidence regarding the size of members of ornithischia here (estimates, examples, visual comparisons etc.).

This will likely involve giant ornithopods, ankylosaurs, stegosaurs and ceratopsians in particular, but feel free to post information on any kind of of ornithischian.

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These two DML entries are about Ceratopsipes or very large ceratopsia in general:
dml.cmnh.org/1996Aug/msg00129.html
dml.cmnh.org/1996Aug/msg00217.html

One enigmatic taxon that I find very interesting is Dacentrurus. I recall seing pictures→ and reading reports→ of a huge pelvis claimed to be 1.5m wide[!], but sadly nothing conclusive.
The holotype pelvis seems pretty wide itself: www.lib.utexas.edu/books/britfossils/html/txu-oclc-13370987-2-dinosauria-plate72.php

Does anyone have a reliable size estimate for this specimen and/or more data on the giant pelvis?

[Fragillimus335]

I've looked into Dacentrurus quite a bit, and it appears to be quite large. The holotype has a femur nearly as long as the largest Stegosaurus specimen, which measured around 7.5 meters long. The 1.5 meter wide pelvis appears to be about that size. I've seen pictures of an adult women in front of it, and it's almost as wide as she is tall. Scaled to Greg Paul's Stegosaurus skeletal the animal would be ~9-9.5 meters long not counting tail spikes. A corresponding weight would probably be 7+ tons. Another cool feature is that it's spikes are flattened and blade-like rather than conical.

[theropod]

9-9.5m in standing lenght or axial lenght?

[blaze]

The largest Stegosaurus spp. femur belongs to YPM 853 and is 1348mm long, the femur of the holotype of Dacentrurus is 1232mm, however the shaft of both have almost identical mediolateral width at 165.7mm vs 165mm (Benson, 2014. Supplemental).

edit: I have read Darren Naish' post on the DML about Dacentrurus, it seems to be 1.5m wide at the level of the acetabula, so my comment below is inconsequential. He also says that it indicates a 10m individual.

Using the femur you can't make it be 9-9.5m long using Paul's skeletal and using the pelvis, you have to take into account that they are built differently.



The iliac blades are flared laterally in Dacentrurus while they are straight in Stegosaurus. (check figure 1 here) Another source of comparison could be the humerus, the type of Dacentrurus actually has a longer (760mm vs 575mm), thicker (370mm vs 352mm in circumference) humerus than than of YPM 853 (Benson, 2014. Supplemental), however the difference in circumference could maybe fall in the range of variation seen in a single individual because in the holotype of Miragaia, the left humerus has a circumference of 369mm (715mm long) while the right has one of 356mm (654mm long) (Mateus et al., 2009. Supplemental). Miragaia btw is the closest relative of Dacentrurus. Miragaia is a surprise but at least when it comes to the size of the forelimbs it's in the race along the largest Stegosaurus and the type of Dacentrurus. I found Owen's description of Dacentrurus but weirdly enough he never mentions how wide the pelvis is.

Regarding Ceratpsipes, I think we can add another one to Paul's "giant ceratopsids" and "ceratopsid with clown shoes" options, "mud".

[blaze]

I kept looking at Dacentrurus, I found no more information on a 1.5m wide pelvis, however, looking at the plates in Owen's description, along with the other measurements he gives, the 1.5m wide pelvis might be that of the holotype itself (although not actually 1.5m wide but more like 1.4m and change.

I also looked at other supposed giant hadrosaurs, Ornithotarsus, Holtz claims is 12m long but comparisons with Hadrosaurus suggests an smaller size of roughly 10-11m at most (greatest width of distal end of tibia 355mm in Ornithotarsus vs 254cm in Hadrosaurus).

Another one of Holtz giants is Hypsibema missouriensis which he has in his book at "15m?" long, I found its description, Gilmore and Stewart (1945), the caudal vertebrae are about the same length as those of the type of Magnapaulia (the 9m specimen) but they are only half as tall. From where did the myth of this vertebrae being gigantic came from? we might never know.

[creature386]

Sorry for changing the topic from Dacentrurus to Stegosaurus, but can anyone enlighten me there? According to blaze, Paul claimed it to be 7 m long. However, The Dinosauria said that it was the largest Stegosaurus species and up to 9 m long. Also, how reliable is this?

The most common track morphotype from Quarry 5 ichnofacies range are wider medio-laterally than deep anterio-posteriorly, tridactyl with blunt digits ending in squared, hoof-like claws. Combined, these characters point to the pes of a single genus: Stegosaurus. Stegosaurus-morphotype tracks range in size from hatchling (estimated body mass 3kg) to adult animals (estimated body mass 6-8 tons). One talus block demonstrates adult stegosaur pedal track partially crushing a juvenile Stegosaurus-morphotype track, implying social behavior amongst juvenile and adult stegosaurs.

gsa.confex.com/gsa/2010AM/finalprogram/abstract_182427.htm
I once posted this on carnivora (Ausar maybe remembers it) and kinda hoped that blaze would find it and correct it, if necessary.

[blaze]

I think I have an idea, using limb bone circumference equations, the largest Stegosaurus and the type of Dacentrurus turn up at some 7 tonnes.

I'm of the idea that the common "Stegosaurus was 9m" is based on old mounts with too many vertebrae but I have not checked this thoroughly.

[Fragillimus335]

Aug 29, 2014 19:59:32 GMT 5 blaze said:

I think I have an idea, using limb bone circumference equations, the largest Stegosaurus and the type of Dacentrurus turn up at some 7 tonnes.

I'm of the idea that the common "Stegosaurus was 9m" is based on old mounts with too many vertebrae but I have not checked this thoroughly.

Yeah, the average Stegosaurus was probably in the 6-6.5 meter range, with the largest specimens approaching 8 meters.

[creature386]

OK, thanks guys! If Fragilimus (who normally is a bit more liberal when it comes to sizes) also agrees that 9 m may be too much, I guess you guys are right.

[Cross]

There doesn't seem to be many threads dealing with this subject. Most of the threads here regarding record sizes deal with theropods and sauropods, but not ceratopsids, stegosaurians, ankylosaurs, or hadrosaurids. Any ornithischian experts here? 

[theropod]

There actually already is one: theworldofanimals.proboards.com/thread/883/ornithischian-size

[creature386]

Moved and I now have to bump this because people would otherwise not notice it.

[Cross]

Apparently, the Hell Creek Edmontosaurus/Anatosaurus could reach sizes more or less on par with Shantungosaurus. 


saurian.maxmediacorp.com/?p=549 

[Supercommunist]

That hadrosaur looks a lot longer than fifteen meters in that size comparison.

[Cross]

Unless the T. rex is just not a fully grown individual.