The most powerful and fearsome predatory reptile of all time

[Godzillasaurus]

Dec 4, 2014 11:49:25 GMT 5 Grey said:

Godzillasaurus, that's a real mandible from a pliosaur of the Kimmeridge Clay.

Cool!

[coherentsheaf]

New (?) giant pliosaur:

www.russia-ic.com/education_science/science_overview/2434/#.VIoFTMm8CSp

[theropod]

That appears to be the same specimen mentioned two months ago, but i seem to have missed that article.

It seems to be the same type of terrible translation tough, keeps referring to it as a dinosaur, and to pliosaurs as a species. The one I posted even called it a pangolin.

[Grey]

I've tried several times to found the email adress of the russian paleontologist working on it. Unsuccessfully.

C. McHenry is preparing a response to my questions, because they are "very interesting but thorny" so I think he's going to give something interesting.

[Godzillasaurus]

The terms used such as "dinosaur" were probably just mistranslations, as theropod pointed out.

Still, cool find!

[Godzillasaurus]

It would be cool if it could contend with Predator X and the Monster of Aramberri

[Grey]

Even if the size was accurrate, the mandible gives a less striking impression of power compared to the mandible of P. kevani. I think it's reasonnable to suggest these differents Pliosaurus species had different feeding sources given these mandibular, cranial differences.


In the pics, Dr. Forrest is actually explaining that the mandible was about 1 meter shorter in life.

Photos; courtesy of Adam S. Smith

[theropod]

Liopleurodon’s proportions:

Let’s recall, Noé et al. 2003 stated this about the Tübingen skeleton:

The overall length of the animal from which
CAMSM J.27424 came can be estimated by compar-
ison to a skeleton of Liopleurodon ferox (GPIT 1754/2).
GPIT 1754/2 has a skull:total body length ratio of
approximately 1:5.19 (skull length 0.94 m, overall body
length including skull 4.88 m). This would indicate a
calculated overall body length for the CAMSM J.27424
animal of approximately 6.39 metres.

Which lead to some confusion due to the number of conflicting figures and ratios.

First of all, this is the whole quote:

Noè et al. 2003 said:

5.b. The size of the animal
The size of the cranium from which CAMSM J.27424
was derived can be estimated by comparison with
NHM R2680. The isolated cranium of NHM R2680
has a snout to occipital condyle length of 1120 mm
(Andrews, 1913, p. 21) and a paroccipital length of
150 mm (Andrews, 1897, p. 178). CAMSM J.27424
has a paroccipital process length of 165 mm. Assuming
a 1:1 growth ratio between the cranium and paroccipital
process beyond the 1.12 m cranial length of NHM
R2680, the length of skull from which CAMSM
J.27424 came can be estimated at approximately
1.23 m. This length estimate is slightly shorter than an
‘old adult’ (sensu Brown, 1981) individual of Liopleur-
odon ferox (NHM R3536), estimated at 1265 mm from
snout tip to occipital condyle (Andrews, 1913, p. 22).
The overall length of the animal from which
CAMSM J.27424 came can be estimated by compar-
ison to a skeleton of Liopleurodon ferox (GPIT 1754/2).
GPIT 1754/2 has a skull:total body length ratio of
approximately 1:5.19 (skull length 0.94 m, overall body
length including skull 4.88 m). This would indicate a
calculated overall body length for the CAMSM J.27424
animal of approximately 6.39 metres.

It seems rather clear that the figure is condylobasal length. In Liopleurodon, this is a much smaller measurement than maximum skull length because the quadrates slope backwards lateral to the occiput. As we can see in Andrews (1913): NHM R3536 has a condylobasal skull length of 126.5cm and a maximum skull length of 154cm, about 22% greater. As I posted earlier:

Skull  :  length from quadrate to tip of snout   154.0
„  „  occipital condyle to tip of snout   126.5
transverse diameter of occipital condyle   8.0
width between outer ends of quadrates   72.0
width of quadrate   15.0
width of snout at constriction   13.7
,,  ,,  widest par of anterior expansion   15.4
Mandible  :  extreme length   154.0
length of symphysis   30.5
width just behind symphysis   17.0
„  of articular surface   16.7
length of postarticular process   10.5

Teeth
Length along middle of curve  ....   19.0 .. 7.8
Height of crown   7.5   7.0   2.5
Greatest diameter of base of crown 3.0 2.7   1.5

So we’d expect that total skull length in GPIT 1754/2 would be well over a 1m. And indeed, this is what Noé’s (2001) thesis has to say about it:

Noè 2001 said:

Description of Material (ICZN 2000,rec 73C1) (including size/size of parts):
Incomplete cranium, of premaxillae and maxillae, palate and braincase (length approximtely 1 100 mm); complete
mandible with a number of preserved symphysial teeth (approximately 1 150 mm). Entire postcranial skeleton (see
Linder, 1913).

This is important to keep in mind, and it can make a significant difference when estimating total length from skull length.

But there’s more to it, the body length is the real variable.
• Noé 2001 states 5.3m, as is cited by Buchy et al. 2003.
• Noé et al. 2003 claims it to be 4.88m.
• Buchy (2007) used 5m (obviously rounding one way or another, but why? Considering the former two perhaps?).
• Precise interpretation of the ratio (head:body=1:6) repeatedly shared with Grey would actually imply at least 5.64m (But I think we can discount estimates of 6.6m or similar that would result from using a measurement other than CBL, it is obvious the specimen is not that large).

Buchy et al. repeatedly (2003) stated the specimen to be subcomplete, and it looks as if there are way too few caudals. By contrast, Noé (2001) lists the "entire postcranial skeleton" as known.
Sadly I have had no luck trying to track down the paper cited in the thesis, Linder (1913).

My working hypothesis for now is that 4.88m is the specimen as mounted, lacking a number of caudal vertebrae, while 5.3m is the estimated total length. However, that is far from certain, and really confusing indeed, especially since either way I cannot seem to make the (albeit unpublished) 1:6 ratio work.

–––REFERENCES:
Andrews, Charles W. (1913): A descriptive Catalogue of the marine Reptiles of the Oxford Clay. Based on the Leeds Collection in the British Museum (Natural History), London. Part II. London
Buchy, Marie-Céline (2007): Mesozoic marine reptiles from north-east Mexico: description, systematics, assemblages and palaeobiogeography. Karlsruhe
Buchy, Marie-Céline; Frey, Eberhard; Stinnesbeck, Wolfgang; López-Olivia, José G. (2003): First occurrence of a gigantic pliosaurid plesiosaur in the late Jurassic (Kimmeridgian) of Mexico. Bulletin de la Société Geologique de France, Vol. 174 (3) pp. 271-278
Noè, Leslie F. (2001): A taxonomic and functional Study of the Callovian (Middle Jurassic) Pliosauroidea (Reptilia, Sauropterygia). Unpublished PhD thesis. Derby
Noè, Leslie F.; Liston, Jeff; Evans, Mark (2003): The first relatively complete exoccipital-opisthotic from the braincase of the Callovian pliosaur, Liopleurodon. Geological Magazine, Vol. 140 (4) pp. 479-486

[blaze]

You have Noé's thesis?

btw paleoglot has a translation of Linder 1913 link

[theropod]

Yup, just found it today: ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.341402
It requires registration, but that’s worth it imo.

Thanks’s for the paper, but the one I was looking for was this: "Linder, H. (1913) Beitrage zur kenntnis der plesiosaurier-gattungen Peloneustes und Pliosaurus. In Geologische und Palaeontologische Abhandlungen, edited by E. Koken. Jena: Gustav Fischer."

[blaze]

Anyone can register to EThOs?

[theropod]

Yup. or at least nothing during the registration process suggested otherwise. I guess if it’s possible to register, then that’s intentional.

[blaze]

Damn it haha

[theropod]

The body bases on the drawing in Huene 1922 (reconstruction of Leptopterygius acutirostris = Temnodontosaurus burgundiae), but I chose to use the skull of T. eurycephalus.
The size shown here bases on scaling up from Huene’s estimate for a smaller, more complete skeleton found nearby (11m in length, with the largest centra 15.5cm tall). The gian specimen is also more substantial than it looks, there is part of the dorsal and caudal vertebral collumn, ribs and part of a hindlimb, and both McGowan and Huene estimated it at 15-16m, so pretty much what I got.

There are giant (if slightly smaller) vertebrae, teeth and girdle elements from the Jurassic coast that may belong to the same giant temnodontosaurid taxon (McGowan 1996).

Admittedly taxonomy is a little confusing within the genus (due to the mmany synonyms). T. platyodon and T. burgundiae both reach ~9m, perhaps 11m for the biggest isolated remains. The presence of lower jurassic ichthyosaur teeth more than twice the size of the largest known in these taxa suggests the presence of a giant macrophagous form, more similar to T. eurycephalus (hence my choice of skull).

–––References:
Huene, Friedrich von (1922): Die Ichthyosaurier des Lias und ihre Zusammenhänge. Berlin
McGowan, Chris (1996): Giant ichthyosaurs of the Early Jurassic. Canadian Journal of Earth Sciences, Vol. 33 pp. 1011-1021
McGowan, Chris (1974): A Revision of the Longipinnate Ichthyosaurs of the Lower Jurassic of England, with Descriptions of Two New Species (Reptilia: Ichthyosauria). Life Sciences Contributions, Royal Ontario Museum, Vol. 97

[Deleted]

That's one huge ichthyosaur.