Kronosaurus queenslandicus vs. Dunkleosteus terrelli

[dinosauria101]

Kronosaurus queenslandicus
Kronosaurus (meaning "lizard of Kronos") is an extinct genus of short-necked pliosaur. With an estimated length of 9 to 10.5 metres (30 to 34 ft), it was among the largest pliosaurs, and is named after the leader of the Greek Titans, Cronus. It lived in the Early Cretaceous period (Aptian to Late Albian). Fossil material has been recovered from the Toolebuc Formation (middle to late Albian) and Wallumbilla Formations (Aptian) of Queensland and New South Wales in Australia, and from the upper Paja Formation (late Aptian) in Boyacá, Colombia, and assigned to two species. Current estimates put Kronosaurus at around 9 to 10.5 metres (30 to 34 ft) in length. In 2009, K. queenslandicus was estimated to weigh up to 11,000 kilograms (11 t). The strength of the limb girdles, combined with evidence of large, powerful swimming muscles, indicates that Kronosaurus was likely a fast, active swimmer. Kronosaurus teeth exceed 7 centimetres (2.8 in) in length (the largest up to 30 centimetres (12 in) long with 12 centimetres (4.7 in) crowns). However, they lack carinae (cutting edges) and the distinct trihedral (three facets) of Pliosaurus and Liopleurodon teeth.


Dunkleosteus terrelli
Dunkleosteus is a genus of prehistoric fish, one of the largest arthrodire placoderms ever to have lived, existing during the Late Devonian period, about 380-360 million years ago. This hunter, measuring up to 9 metres (29 ft) and weighing 3.6 tonnes (4.0 short tons), was a hypercarnivorous apex predator. Few other placoderms, save, perhaps, its contemporary, Titanichthys, rivaled Dunkleosteus in size. Due to its heavily armoured nature, Dunkleosteus was likely a relatively slow, but powerful, swimmer. It is thought to have dwelled in diverse zones of inshore waters. Fossilization tends to have preserved only the especially armoured frontal sections of specimens, and thus it is uncertain what exactly the hind sections of this ancient fish were like. nstead of teeth, Dunkleosteus possessed two pairs of sharp bony plates which formed a beak-like structure. After studying a biomechanical model of the fish's jaws, scientists at the Field Museum of Natural History and the University of Chicago concluded that Dunkleosteus had the second most powerful bite of any fish (the giant Megalodon being the strongest). Dunkleosteus could concentrate a pressure of up to 8,000 pounds per square inch (55 MPa) at the tip of its mouth, placing Dunkleosteus in the same league as Tyrannosaurus rex and modern crocodiles as having the most powerful known bite. Dunkleosteus could open its mouth in one-fiftieth of a second, which would have caused a powerful suction that pulled the prey into its mouth, a food-capture technique used by many fish today.

Credit to Wikipedia

[all]

 If you put strong animal that weighs 11 metric tons vs strong animal that weighs close to 4 metric tones with  11 ton animal being more than 2.5 times heavier than 4 ton animal. I think you know what the outcome will be. 

What I don't understand is how can 9-10.5 meter KQ weigh 11 metric tons and 6-10 meter (So at the largest length they are almost equal in length)  DT weigh only 4 metric tons or even slightly less. Yes small difference in length can make significant difference in weight. But that extra  0.5 to 1.5 meters in KQ is mostly tail which is relatively lean. 

[theropod]

What I don't understand is how can 9-10.5 meter KQ weigh 11 metric tons and 6-10 meter (So at the largest length they are almost equal in length) DT weigh only 4 metric tons or even slightly less.

The answer is simple! The figures are wrong.


by blaze, see his post here: theworldofanimals.proboards.com/post/8913

Dunkleosteus simply doesn’t seem to have reached 10 m, at least not unless it had an eel-like body shape. Even 4 t sounds like a significant overestimate, no matter who made up that figure.

[Infinity Blade]

Maybe we should update the OP picture of Dunkleosteus. It's a rather small change, but more recent literature proposes its caudal fin looked different from how it's usually portrayed (given its ecology as a big cruiser with good swimming ability).

peerj.com/articles/4081/

This same paper agrees that 10 meters is an overestimate, but suggests that 8.79 meters is a tenable figure for the largest specimen. It's also got a bulky reconstruction. What do other posters think of this?

[dinosauria101]

Thank god this isn't a mismatch!
I'd expect Dunkleosteus to weigh about 7-8 tons at that size, approaching Kronosaurus' weight. Should make for a closer match than what blaze posted.

Overall, I'd favor Kronosaurus due to size advantage and much larger jaws/bite. But Dunkleosteus has a good chance too; it's got a mean bite of its own, it has armor, it doesn't need to surface to breathe, and it can severely hinder the pliosaur's movement by attacking the flippers.

[Infinity Blade]

Then again, this was their methodology.

"Total body length of D. terrelli was estimated in a regression analysis between the total body length (TBL) and the upper jaw perimeter (UJP) of 245 extant sharks".

I think this is kind of problematic in that, well...Dunkleosteus wasn't a shark.

[dinosauria101]

That may be a bit problematic. You have a point.

Maybe we could scale from close cousins. Apparently, these are the closest:
Eastmanosteus
Golshanichthys
Heterosteus
Yinosteus
Herasmius
Kiangyousteus
Xiangshuiosteus

[theropod]

This is the first I hear of a larger specimen, good find! They suggest that CMNH 5768 has an UJP of 120.0 cm and CMNH 5936 has a UJP of 155.7 cm, so the latter is almost 30% larger, which would mean over twice the weight. Following blaze’s estimate, that would be 7.8 m.

I don’t have a lot of confidence in that extremely bulky built in their life reconstruction though. Their estimate for the same specimen is a bit longer than blaze’s even, and that’s the proportion their 8.8 m estimate bases on as well. The skull would still be the same size (or 30% bigger for the larger specimen, but staying in proportion), so that in the drawing looks way too massive.

And using shark regressions to estimate the size of an arthrodire is obviously a huge problem. Those regressions were for predicting TL from tooth row length. Arthrodires don’t even have teeth!
Of course Coccosteus is tiny by comparison, and not a good analogue. But at least we should look at the actual size of the remains, and whether they fit in the size and morphology that is estimated.

[dinosauria101]

Sept 25, 2019 3:45:04 GMT 5 theropod said:

And using shark regressions to estimate the size of an arthrodire is obviously a huge problem. Those regressions were for predicting TL from tooth row length. Arthrodires don’t even have teeth!

I think a good analogy for a tooth row in placoderms would be the length of the jaw which the horny plates cover

[Grey]

The idea of Dunk having a thunniform plan and a caudal is interesting. Their points are potentially valid regarding the size, there is one very large but the other specimens are well in the more classic 5-7 m IIRC.

By the way, Matt Bille is a science writer kind of cryptid passionnate. He tends to be especially scientifically rigorous when he reviews the science inaccuracies of Steve Alten or Max Hawthorne novels. He is about to be released, Apex Predator, about modern surviving Dunkleosteus in Alaskan waters, with a really scientific approach when possible.

Kind of Brian Switek writing a Meg novel.

I think Dunkleosteus can be a good additional extinct taxa to be added to a wider specter of our culture.

(Mike Everhat is also preparing a novel about surviving mosasaurs, probably having as motivation among others to be frustrated by the JW inaccuracies.)

[theropod]

dinosauria101 This is not about that, it’s about them being so different the measurement for which the regressions are meant literally doesn’t exist in the taxon they are used on. That’s like making a regression based on femur shaft length measured up to the fourth trochanter and then using it on a mammal.

There’s also something weird going on with the regressions. They claim they are for upper jaw perimeter, which they include the entire jawline in, not just the part bearing plates analogous to teeth".

But Lowry et al.’s data for sharks are for dentition length only, not the whole upper jaw perimeter. Now as I just mentioned, dentition length isn’t even a thing in Dunkleosteus.

But still, conflating the two is a problem, because it uses the entire jaw, where only part of it should be included, and thereby inflates the measurement.

The data clearly seem to be the same as the ones used by that study for the express purpose of bite circumference, not upper jaw perimeter. I’m getting the same regression parameters they reported (rounded) for the great white dataset, upper bite circumference=10^-0.79956*TL^1.00662 (vs 10^-0.800*TL^1.007 in the study).
The minimum TL and bite circumference, and the maximum bite circumference are also the same, clearly these seem to be the same measurements. The only thing that’s strange is that there is one specimen with a higher total length than the maximum reported in the original study. But without it the regression doesn’t fit the one from the study, so it cannot have been added in later.

I’m also a little bit in the dark as to where they even got the data from, since they weren’t actually published along with the paper (believe me, I searched), but that at least is quite useful.

[dinosauria101]

Then I guess this depends on what estimate we use. But I don't think I'll take anything too seriously until better conformation

[all]

as far as far as size estimates for Dunkloesteus terrelli i'm not even going to try to guess. some info on the net says 6 meters most say 9 or 10 meters. But i think the one that describes the 6 meter DT is more like an actual scientific paper. and one suggesting 10 meters is more like popular science. so i'm going to go with 6 meters. but under those circumstances it is a mismatch of size. 

As far as the bite however bite force of Dunkleosteus terrelli was indeed 11000 lbs and 80000 lbs on blade tip as I said. as far as  Kronosaurus i don't know how they would 
compare but KQ bite force would have to be very powerful to be stronger than the one Of DT especially the one on the blade-tip. 

As far as weight of DT it seems to me that it would be more than a metric ton. i know average shark is around 2268 kg that is an average shark. Which means average female shark would be bigger. now I know DT is not a shark. but it seems to me that is anything he would be bulkier than the shark. and we are talking about largest example here so 3 metric tons or more seems right to me.

Nonetheless this is not 11 metric tons of KQ or close to it. So obviously Kronosaurus would win this fight. Pound per pound however that might be a different story. 

[Verdugo]

Hartman actually has a Dunkleosteus though. When i try to scale it to 72 cm Skull length to represent the specimen CM 5768 (according to the pic from Blaze), i got a TL of 5.7 m. Now that i don't know how the Skull length is supposed to be measured so there are probably some errors here. But anyway, it seems like the original estimate from Blaze is probably more appropriate. And as Theropod has pointed out, Ferron 2017 conflated UJP with Dentition length so their estimates are probably slightly inflated.

[dinosauria101]

Well as I said, I believe this matchup is closer if we use the 2017 estimate.
But assuming what Blaze got is true (and it could be considering sharks were used), than the placoderm has no chance here.