Largest mosasaur

[coherentsheaf]

Anyway, scott Hartman has a new Tylosaurus skeletal:
scotthartman.deviantart.com/art/Tylosaurus-pembinensis-543156057

[blaze]

^That reminds me of something, Hartman's Tylosaurus pembinensis skeletal has a lower jaw to total length ratio of 1:7, theropod wrote this "The largest mosasaur I’m aware of is still the giant quadrate illustrated by Lingham-Soliar. If legit, with a skull length of 1.95m and similar proportions to those in Blaze’s reconstruction, the owner would be about 14.4m long and 10.5t in weight." To cut to the chase my reconstruction has the head too small, I claimed it had an skull to total length ratio of 1:7.7 like in an almost complete Tylosaurus estimated to be 8.8m, I assumed Pmx-Q but I can't corroborate that such specimen actually has that ratio and said specimen has a lower jaw to total length ratio of 1:7.15 while that of my reconstruction is 1:7.63, making the head about 7% too small, correcting this the axial lenght in one with a 195cm skull would go down from 15.5m to 14.5m and tip to tip length would then go from 14.4m to 13.5m.

[theropod]

I’ll try to collect a list of measurements here:

Hartman’s Tylosaurus pembinensis:
skull (max): 140px [1.00]
postcranial (tip-tip): 819px [5.85], total (+skull): 959px [6.85]
mandible (max): 147px [1.05]
postcranial (axial length): 863px [6.16], total (+skull): 1003px [7.16]
greatest restored body depth: 121px [0.86]

Platecarpus (Lindgren et al. 2010):
skull (max): 244px [1.00]
postcranial (tip-tip): 1745px [7.15], total (+skull): 1989px [8.15]
mandible (max): 246px [1.01]
postcranial (axial length): 1861px [7.63], total (+skull): 2105px [8.63]
greatest restored body depth: 255px [1.05]

Plotosaurus (Russell 1967):
skull (max): 438px [1.00], mandible protrudes to 451px in front of posterior edge of skull
postcranial (tip-tip)-measured: 2907px [6.64], total (+skull&mandible): 3358px [7.67]
postcranial (tip-tip)-estimated based on degree of curvature in Platecarpus: 2754px [6.29], total (+skull&mandible): 3205px [7.32]
mandible (max): 476px [1.09]
postcranial (axial length): 2937px [6.71], total (+skull&mandible): 3388px [7.74]
greatest restored body depth: (skeleton only) 433px [0.99]

Prognathodon saturator (Dortangs et al. 2002):
skull (max): 385px [1.00]
postcranial (tip-tip)-measured: 2347px [6.10], total (+skull): 2732px [7.10]
postcranial (tip-tip)-estimated based on degree of curvature in Platecarpus: 2264px [5.88], total (+skull): 2649px [6.88]
mandible (max): 397px [1.03]
postcranial (axial length): 2414px [6.27], total (+skull): 2799px [7.27]
greatest restored body depth: 348px [0.90]

measurements as indicated:

[Grey]

Can't say too much but the source is solid, a gigantic Tylosaurus skull 6.5-7 feet long, is being unearthed in Texas.

[Deleted]

Jan 17, 2016 22:07:35 GMT 5 Grey said:

Can't say too much but the source is solid, a gigantic Tylosaurus skull 6.5-7 feet long, is being unearthed in Texas.

Taking the upper bound, that would mean an individual ~14.7 meters long or so, assuming proportions similar to Scott Hartman's skeletal.

[Grey]

Jan 18, 2016 3:41:26 GMT 5 @brolyeuphyfusion said:

Jan 17, 2016 22:07:35 GMT 5 Grey said:

Can't say too much but the source is solid, a gigantic Tylosaurus skull 6.5-7 feet long, is being unearthed in Texas.

Taking the upper bound, that would mean an individual ~14.7 meters long or so, assuming proportions similar to Scott Hartman's skeletal.

The relationship skull/body in Tylosaurus is expected to be 7.1-7.7, so if the upper bound is right, we possibly have a 16m Tylosaurus.

However it is unclear if this skull will go in private collection or not.

[theropod]

@brolyeuphyfusion 47.95ft or 14.62m based on the upper end of 7ft/2.13m (which would likely make it the largest known mosasaur skull, at least by length). Sticking with the lower end of 6.5ft/1.98m brings it down to 13.57m.
All assuming the same proportions as in Hartman’s T. pembinensis.

[blaze]

Grey
Looking at the mostly complete specimens in table 2 of Russell (1967), the head* seems to grow relatively larger at larger body sizes, the 1:7.7 ratio comes from a 6.3m long specimen, an 8.8m specimen has a ratio of 1:7.2, the ratio in Hartman's reconstruction presumably from a larger specimen, is 1:6.8

The same appears to be true for the Platecarpus in that table.

*Russell writes head but I'm sure he actually means mandible as in one of his sources for the measurements, what Russell called head the cited publication called it head and jaw.

[Grey]

Jan 18, 2016 20:04:19 GMT 5 theropod said:

@brolyeuphyfusion 47.95ft or 14.62m based on the upper end of 7ft/2.13m (which would likely make it the largest known mosasaur skull, at least by length). Sticking with the lower end of 6.5ft/1.98m brings it down to 13.57m.
All assuming the same proportions as in Hartman’s T. pembinensis.

Actually it seems to be a large proriger.

[theropod]

That’s what I’d have expected, simply based on size. Have they already sufficiently prepared the piece for a species level diagnosis then?

[blaze]

So, it just occurred to me to count how many vertebrae the mounted skeleton of Bruce has, I can't reliably count those of the tail due to the angle of the photo but there's no problem for the precaudals (includes pygals), there's 48 of them, 12 more than what's seen in exceptionally complete specimens of Tylosaurus, if this is not the result of "sequestering caudals as precaudals" then this puts in serious doubts the record length claim of Bruce, yes it might be the longest mounted moasasaur skeleton in the world but is only so because it has way too many vertebrae.

This also applies to Bunker, I also counted how many vertebrae it has, and while it does have 36 precaudals, it has at least 111 caudals, which is around 30 more than what Williston and Osborn estimate as the complete number of caudals in Tylosaurus, Russell (1967) does write that the caudal count is up to 112 but I'm not sure of what's this based on.

[Grey]

MOSASAURS – HOW LARGE DID THEY REALLY GET?

Michael Everhart, John W.M. Jagt, Eric W.A. Mulder & Anne S. Schulp

The recent blockbuster film Jurassic World, featuring a CGI animation of a rather large “mosasaur”, prompted us to reflect on the ultimate size mosasaurs could really attain. The possibly 60 m sea monster as displayed at the “Jurassic [Sea] World” theme park in the film markedly exceeds the size of any known mosasaur specimen. Given the interest the film has generated, we feel that a review of extremely large mosasaur fossils is warranted here, if only to put film-star mosasaurs in perspective. Mosasaurs evolved during the latter part of the Cretaceous from small shore-dwelling reptiles into a wide variety of species to exploit a wide variety of niches – and ranging in size from the diminutive Carinodens to the largest tylosaurines and mosasaurines which exceeded 15 m in length.

The estimated body length of 17,6 m referred to by Lingham-Soliar (1995) is based on extrapolations on the “Hageman” specimen in the NHMM collections (NHMM 009002), a 920-mm-long portion of dentary with 13 tooth positions, which must have belonged to a considerably larger specimen than the holotype. The Natuurhistorisch Museum Maastricht collection also hosts a quadrate that is about 150% the average size of this bone in an “adult” Mosasaurus hoffmanni. This specimen, NHMM 003892, is 215 mm tall, and may represent an mosasaur that was close to 18 m in total length. The Penza Mosasaurus sp. specimen reported by Grigoriev (2014) from Russia is also in the 17 m size range, as well as Tylosaurus (Hainosaurus) bernardi from Belgium.

In the Western Interior Seaway of North America, Tylosaurus proriger had reached lengths of 15,8 m or more by the Early Campanian, based on the Bunker specimen (KUVP 5033) from western Kansas and similarly sized remains from Texas and Manitoba. Fragments of larger individuals have been reported but are not well documented.

Given enough time, and supported by a little help from Archimedes, mammals which adapted to aquatic life eventually reached body sizes well beyond those of the largest mosasaurs, although those marine mammals adapted to a planktonivorous lifestyle. So would a 60-metre mosasaur be a biological possibility at all? Or would the squamate Bauplan hit the biomechanical constraints at a lower length already? The curve of the largest mosasaur body lengths did not show any indication of “plateauing” towards the K/Pg boundary. Had they not gone extinct, would the hypothetical Eocene giant “Killer Mosa” have discouraged any mammal moving into the marine realm?

References
Grigoriev, D. V. (2014) Giant Mosasaurus hoffmanni (Squamata, Mosasauridae) from the Cretaceous (Maastrichtian) of Penza, Russia. Proceedings of the Zoological Institute RAS 318(2): 148–167.
Lingham-Soliar, T. (1995) Anatomy and functional morphology of the largest marine reptile known, Mosasaurus hoffmanni (Mosasauridae, Reptilia) from the Upper Cretaceous, Upper Maastrichtian of the Netherlands. Philosophical Transactions of the Royal Society of London B347: 155-172.

[creature386]

Didn't Everhart once say that the Bunker Tylosaurus was only 12 m long or were there any revisions on that?

[theropod]

In any way those figures strike me as very strange, and are very different from his earlier expressions (although he has never been very consistent about the largest mosasaurs’ sizes on his website). But generally what he once (I think) expressed to Grey privately sounds a lot more reasonable; 15m being a more reasonable length for the biggest specimens.

The biggest Mosasaurus remains indicating a skull ~195cm in length→, and the biggest Tylosaurus, that seems to be in a similar range (see above→), just aren’t consistent with greater total length unless we assume unrealistically small heads.

[jhg]

I always imagined it to be Tylosaurus. Although, I could be biased since it's my favorite.