|
|
Post by theropod on Aug 27, 2015 22:00:23 GMT 5
Oh, how much I’ve now come to be annoyed by madeup size figures based on supposedly immature specimens… elosha11 Regarding your previous inquiry as to what led to the assumption that the pliosaurs were dorsally wider:   These are not the respective animals in the scale, just relatives (a plesiosauroid and an ophthalmosaur), but I think they still bring the point across because there’s no reason to assume big differences in the proportions of the ribcage. As you can see, the ichthyosaur’s ribcage is laterally flattened (the entire torso is ~⅓ deeper than wide), while in plesiosaurs rather the opposite seems true(the torso on this one is roughly as wide as it is deep, but see below). In rhomaleosaurs:  So it seems save to assume plesiosaurs were dorsoventrally more flattened than is typical for ichthyosaurs or other axial swimmers. Unfortunately I haven’t been able to make good on the promise of taking some pictures of the Tübingen Liopleuron so far, maybe some other time. |
|
|
|
Post by Grey on Aug 28, 2015 8:49:09 GMT 5
I'm still unsure if they meant 18 m or if it's typo and they meant 15 m. I had discussed with Buchy in 2011 and she said 18 m purely from the media.
Also, I've showed to Sven Sachs, plesiosaur researcher, the giant tooth from the London Museum. He said it's a rosral tooth and the diameter at the base of the crown about 4-5 cm is not unusual. By comparison, I've seen an abstract about the Svalbard pliosaurs where its says their crown base diameter is 6 cm. The lost rostrum of the MoA showed teeth estimated at 5.5 cm in diameter.
Sven said me the crown diameter gives an idea of the alveoli and the size of the head. Sounds like it's a "better" data than tooth length.
Then there are the infamous bite marks in the MoA...
|
|
|
|
Post by Grey on Aug 29, 2015 11:31:15 GMT 5
|
|
|
|
Post by creature386 on Aug 29, 2015 15:30:24 GMT 5
A "wingspan" (from fin to fin) of 8 m, a skull length of 3.2 m, a tooth length of ~15 cm. He also believes that it was a juvenile.
|
|
|
|
Post by Grey on Sept 3, 2015 23:38:31 GMT 5
About the very large tooth from the BNHM, Adam Smith said maybe it's not the largest in the dentition, he's perha0s going to examine it directly.
He said crown height and tooth position is more adequate to use.
|
|
|
|
Post by Grey on Sept 4, 2015 15:30:09 GMT 5
Update, Smith indicates that a large tooth with a large root is among the largest teeth in the dentition.
|
|
|
|
Post by Grey on Sept 21, 2015 17:02:16 GMT 5
Mosasaurus beaugei piece of dentary measuring 89 cm long.  Incomplete Liopleurodon tooth measuring 18 cm in length and 7 cm in diameter. 
|
|
blaze
Paleo-artist 
Posts: 766
|
Post by blaze on Oct 3, 2015 4:12:56 GMT 5
I know this doesn't really belong here but I started reading a bit on Elasmosaurus, the supposedly largest long necked plesiosaur. There is indeed an estimate of 13.7m from Cope (1869) but this was later reduced to 12.7m by Williston (1906) and Welles (1943) because Cope gave it too long a tail but the problem is that using the measurements from Sachs (2005) redescription I can't replicate any of the latter two estimates, much less Cope's, I can only get it to 11m long.
Edit:
To clarify, there isn't that much wiggle room, its only missing 2 cervicals and one is incomplete but their length is easy to estimate, it is also missing many dorsals (13 according to recent publications, 10 according to Cope) but elamosaurid dorsals are fairly uniform in length (Everhart 2005) so multiplying the average of the preserved 6 should be enough, the tail is harder to estimate, I assumed 30 caudals (4 more than Welles) and used a polynomial equation based on the preserved 18.
At the end, with 5mm of cartilage between each vertebrae I got a 6.5m long neck, 2.4m long body and 1.6m long tail, compare to 7m neck, 2.7m body and 2.4m tail in Williston (1906) and ~7.4m neck, ~2.5m body and ~3.3m tail in Cope (1869).
Weirder still is that Cope writes that the preserved vertebral column adds up to ~9.5m and Everhart (2005) writes that he measured them at 9.1m while adding up the measurements in Sachs (2005,2013) only results in 8.1m.
I have to find Welles (1952), I read that it includes individual measurements of the vertebrae just like Sachs rather than the length of each segment as presented by Cope and Williston.
|
|
|
|
Post by Grey on Oct 23, 2015 4:13:33 GMT 5
What is the actual belief for you guys about the bite mark in the pterygoid of the Aramberri pliosaur ?
Frey and Stinnesbeck reports in the 2014 book that it suggests indeed a 300 mm crown. The fact this figure is published makes me wonder if it can be really dismissed.
Is a bite mark definitely a bad evidence for the existence of a über-pliosaur in the Late Jurassic of Mexico ?
|
|
|
|
Post by theropod on Nov 5, 2015 0:45:27 GMT 5
|
|
|
|
Post by Grey on Dec 23, 2015 23:25:41 GMT 5
|
|
|
|
Post by Infinity Blade on Dec 24, 2015 6:53:47 GMT 5
On the bottom of page 9 and top of 10, the authors note that the function of widely-spaced teeth was never elaborated on. Can anyone think of what, if anything, would result from that?
|
|
|
|
Post by Infinity Blade on Dec 24, 2015 7:14:37 GMT 5
 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 How the f*ck did I miss this?! Is this still legit? Does anyone have any idea as to how heavy such a creature would have been? |
|
|
|
Post by theropod on Dec 25, 2015 5:49:13 GMT 5
^Yes, it is, but is is still just as speculative given that we don't know for sure whether the large teeth (suggesting a large macropredaceous ichthyosaur) and the giant Banz specimen belong to the same type of ichthyosaur.
In any case the latter seems to pertain to an ichthyosaur somewhat over 15m long, and a very rough model I made some time ago based on that silhouette suggested something around 25t, but obviously I'm not that sure about the body width, especially the width of the tail.
If this temnodontosaur was indeed a macrophagous taxon, then the title probably goes to it.
|
|
|
|
Post by Grey on Jan 9, 2016 14:54:13 GMT 5
I would still consider the pliosaurs the heaviest carnivorous reptiles known, keeping in mind the fragmentary material suggesting a hypothetical 15m, >30 tonnes (the reportedly huge NHM symphysis by McHenry that I await a photo from).
|
|
