My favourite subject.

Rubecula

Wot? No Liopleuridon!!!

Rubecula

Adam Khor

Ugh, so much wrong with the second video. It was obviously made hastily by someone who has never opened a book on prehistoric life, and only skimmed through the Internet for the basics while still managing to get almost everything wrong. 

He keeps calling plesiosaurs, ichthyosaurs and other sea animals "dinosaurs" (even Basilosaurus... before he calls it a whale moments later!) s, includes freshwater animals as if they were marine (Hyneria, Titanoboa, Sarcosuchus), includes Pliosaurus twice (Predator X is not "related to Pliosaurus", it IS Pliosaurus!), includes Henodus, a vegetarian, and calls it a deadly predator, and most egregiously, leaves C. megalodon completely out! Where is C. megalodon?? 

Also, he implies that Livyatan's main difference from modern sperm whales was its size (they're actually within the same size range), and same for the "Giant Stingray" (in which he can´t seem to decide whether he's talking about stingrays or manta rays). Most of the sizes he gives are off (Plesiosaurus was small, 3.5 meters or so, not a 25 meter long giant, and Hyneria was actually much larger than 2 meters), and at least one entry (the supposed Colossal Squid ancestor) is completely unknown from the fossil record (there ARE known fossils of giant cephalopods, but they're not closely related to the Colossal Squid). I'm also not sure about "Pelagicetus" being a real animal. And even if it did exist it couldn´t have eaten dolphins as claimed, because basilosaurs went extinct long before the first dolphins appeared. 

When talking about Cetotherium, he missed the opportunity to mention that the pygmy right whale Caperea marginata, a very rarely seen cetacean, was finally examined properly in 2012 thanks to a beached specimen and found to be the last surviving member of the Cetotheriidae family, believed to have been extinct for millions of years. 

Cetotheres were also NOT the first filter feeding whales. 


Finally, many of the pictures he uses are completely unrelated to the animal he's talking about. He uses Pachyrhachis for Madtsoia, for example, and Madtsoia wasn´t even marine. There WERE true sea serpents, but he failed to mention any of them.

Rubecula

Adam Khor wrote: »

Ugh, so much wrong with the second video. It was obviously made hastily by someone who has never opened a book on prehistoric life, and only skimmed through the Internet for the basics while still managing to get almost everything wrong. 

He keeps calling plesiosaurs, ichthyosaurs and other sea animals "dinosaurs" (even Basilosaurus... before he calls it a whale moments later!) s, includes freshwater animals as if they were marine (Hyneria, Titanoboa, Sarcosuchus), includes Pliosaurus twice (Predator X is not "related to Pliosaurus", it IS Pliosaurus!), includes Henodus, a vegetarian, and calls it a deadly predator, and most egregiously, leaves C. megalodon completely out! Where is C. megalodon?? 

Also, he implies that Livyatan's main difference from modern sperm whales was its size (they're actually within the same size range), and same for the "Giant Stingray" (in which he can´t seem to decide whether he's talking about stingrays or manta rays). Most of the sizes he gives are off (Plesiosaurus was small, 3.5 meters or so, not a 25 meter long giant, and Hyneria was actually much larger than 2 meters), and at least one entry (the supposed Colossal Squid ancestor) is completely unknown from the fossil record (there ARE known fossils of giant cephalopods, but they're not closely related to the Colossal Squid). I'm also not sure about "Pelagicetus" being a real animal. And even if it did exist it couldn´t have eaten dolphins as claimed, because basilosaurs went extinct long before the first dolphins appeared. 

When talking about Cetotherium, he missed the opportunity to mention that the pygmy right whale Caperea marginata, a very rarely seen cetacean, was finally examined properly in 2012 thanks to a beached specimen and found to be the last surviving member of the Cetotheriidae family, believed to have been extinct for millions of years. 

Cetotheres were also NOT the first filter feeding whales. 


Finally, many of the pictures he uses are completely unrelated to the animal he's talking about. He uses Pachyrhachis for Madtsoia, for example, and Madtsoia wasn´t even marine. There WERE true sea serpents, but he failed to mention any of them.

Yes yes yes I am not alone then after I posted it it was in my head to take it down again but then I thought to myself let it ride, either I am wrong :eek: or Adam will tear it apart. lol at least we are thinking along similar lines and I am sorry for offending your sensibilities. :D:D

Adam Khor

Am I really that predictable? :B 

Re: Liopleurodon, I'm guessing it didn´t get included because of the recent downsizing? Most sources suggest Liopleurodon would've been within the size range of today's orca (6-7, maybe 9-10 meters tops). The 25 meter long figure made popular by Walking with Dinosaurs was apparently based on a measly skull fragment found in England which was originally interpreted as coming from a pliosaur considerably larger than any previously found. Apparently, a length of 30 meters was considered at one point making it the largest sea reptile known. However the remains are very fragmentary and we can´t tell for sure whether it belonged to Liopleurodon or how big it truly was. 

From what I've read, the biggest pliosaurs known by decent remains would be Pliosaurus and Kronosaurus. Both Pliosaurus kevani and Pliosaurus funkei ("Predator X") are known from incomplete remains but it does seem like their skulls were over 2 meters long. Pliosaurus rossicus (formerly Liopleurodon rossicus) is around 9.6 meters long (and was found along with a colossal ichthyosaur probably 11 meters long, but nobody talks about ichthyosaurs . 

Kronosaurus queenslandicus was originally said to have a skull up to 3.7 meters long, but more recently it was downsized to maybe 2.8 meters (still much bigger than any giant theropod skull known). It also seems that the famous mounted specimen was reconstructed with too many vertebrae so it wouldn´t have been up to 17 meters long as was once claimed, but maybe closer to 9-10 meters. The South American species Kronosaurus boyacensis  has been estimated at 9 meters with a 2.4 meter skull (they had bigger skulls proportionally than Pliosaurus or Liopleurodon, it seems). 





So all things considered, it seems the biggest pliosaurs known thus far from decent remains would've been about as big as a male orca, which is nothing to scoff at (they'd still have little trouble eating a human, which I think we all agree is the important thing). 



It's not impossible that some pliosaurs grew bigger than this, as there are some specimens such as Pliosaurus carpenteri and the near-mythical Monster of Aramberri that are very large in size (11 meter estimate for the latter it seems), yet their vertebrae suggest they were not fully grown. Either the vertebrae on these animals never fully fused, or they still had growing to do in which case we simply haven´t found the really huge ones. Keep in mind that the Monster of Aramberri was reported to have bite marks from what may have been an even larger pliosaur.

Rubecula

Adam Khor

I seriously doubt any of the mentioned animals sans a large Livyatan could be considered a rival to C. megalodon. 

As with the last video, most of the images he used for some of the animals (like Rhamphosuchus) actually depict other creatures.

Rubecula

Adam Khor wrote: »

I seriously doubt any of the mentioned animals sans a large Livyatan could be considered a rival to C. megalodon. 

As with the last video, most of the images he used for some of the animals (like Rhamphosuchus) actually depict other creatures.

to be fair I only posted that video to show the bravery of the cameraman :D

Adam Khor

That reminds me of something I've always wondered. Modern day cetaceans are unusually tolerant of humans compared to other wild animals. They have the power to do lots of harm if they want to, and some of them- like orcas- feed on mammals (like seals and sea lions often larger and better armed than humans), yet attacks by any cetacean species on humans are exceedingly rare (at least in the wild). 
My question is, do you think prehistoric cetaceans would extend us the same courtesy? What would happen, for example, if you went swimming with one of the scary whales and pseudo-dolphins that had zero experience with humans as we hadn´t evolved yet? 

Rubecula

possibly they would react in the same way an ichthyosaur would. oh yummy a land thingy that has dropped in for lunch

Adam Khor

But then why, and at one point did cetaceans decide that they weren´t interested in attacking people? Why aren´t more people eaten by transient orcas for example?

Rubecula

intelligence? only toothed wales have the ability to prey on us and they are the most intelligent. I am only guessing mind you. baleen whales are big but will try to get away. they are more prey than predators/ however the ancestral wales had teeth, had not seen men and possibly low intelligence

Adam Khor

Wonder if cetacean attacks were more common before the age of whaling...

Rubecula

very deep thinking there Adam maybe not, as before waling we seldom met anyone on the roads we were so scarce ourselves, mind you the bible tells us about Jonah

Capt'n Midnight

Great whites don't attack humans as much as some would suppose, unless the human is dressed like a seal.

Mammals would probably be as picky.


Echo sounding would show that we weren't like fishes or seals or other prey.

Rubecula

that would depend on whether the echo sounding had evolved by the time or not.

Adam Khor

From what I've read, cetacean echolocation has been around for about 27 million years if not more. Recent studies have shown that even basilosaurs (although they didn´t have a melon and probably did not echolocate, or only had a more primitive version of echolocation) have adaptations associated with high frequency hearing in modern whales. 
(Also I remember reading something about humpback whales possibly being able to echolocate as well)

Rubecula

not sure on humpback although I do know sounds can disorientate them

Adam Khor

In 2007 there was a study about humpback whales producing "megapclicks" (so named after the whale itself, Megaptera) during night time foraging. The study didn´t reach any conclusions but did suggest that it could be a form of sonar (alternatively, it could be just meant to disorientate or stun fish). 
It is interesting that different kinds of large sea predators, even when they superficially look alike, have gone on completely different directions when it comes to their primary senses. Whales are eminently sound-oriented, whereas ichthyosaurs (and apparently some mosasaurs) were visually oriented (ichthyosaurs being apparently deaf but having the largest eyes of any known vertebrate), and pliosaurs seemingly relied most on their sense of smell.

Rubecula

do you think that ichthyosaurs might have also had such adaptations? Personally I think it is likely that they developed eyes instead.

Adam Khor

Seeing as ichthyosaurs existed for so long there may have been exceptions, but they're supposed to have been deaf- something about their ear bones being too thick and too deep in the skull. This I think stems from a study conducted on a Platypterygius. The same study suggests that there may have been either electroreceptors or mechanoreceptors on the ichthyosaur's lower jaw. But it seems pretty obvious that the ichthyosaur's main sense was eyesight.

If ichthyosaurs were indeed deaf, then there's virtually no chance of them having a high frequency sonar like whales, although it is not impossible that they'd be sensitive to low frequency vibrations, as are snakes (another mostly deaf reptile). Which in turn suggests sounds were probably not very important when it came to ichthyosaur communication, or if they were, it would've been infrasounds, so they would've seem mostly silent to us. All speculation, tho.
Mosasaurs are interesting; some sources suggest they had poor senses of sight and hearing, and even, that their olfactory bulb was poorly developed. However, they do seem to have had a vomeronasal organ, meaning they probably also had a forked tongue like their close relatives- monitor lizards and snakes-, allowing them to taste their way to prey. 

That being said, the skull of Phosphorosaurus makes it abundantly clear that this particular mosasaur at least was well adapted to hunting by sight, probably at night or at great depths. 

Rubecula

great summation Adam thank you for that. I suspect that rather than being deaf ichthyosaurs heard in frequencies far beyond our own senses, but that is purely my own thoughts on the matter.

Capt'n Midnight

Considering how well sound travels in water I'd be surprised if they were deaf.

Unless you live in a waterfall sound provides a very useful warning system.

Capt'n Midnight

Adam Khor wrote: »

That being said, the skull of Phosphorosaurus makes it abundantly clear that this particular mosasaur at least was well adapted to hunting by sight, probably at night or at great depths.

One amazing thing is that though the body plan was similar fish, reptiles and mammals used different senses.

Smell/taste, electro receptors, sight , sound - ecolocation or lateral line.


Then again mantis shrimp take colour vision to the limit.

Rubecula

funny but true

Adam Khor

Relevant to this thread; recent microtomography reveals senses and adaptations of Nothosaurus:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0188509

The study suggests Nothosaurus had good eyesight (probably binocular vision even), but the eyes were pretty much fixed in their orbits, and the vomeronasal organ was atrophied meaning no forked tongue for these guys. Also, salt glands. 

Nothosaurus was apparently a succesful predator, widely spread and could grow up to 7 meters long (at least the species N. zhangi from China did).

Adam Khor

Also relevant to this thread- a new pliosaur has been found in Colombia, very similar to the aforementioned "Kronosaurus" boyacensis; both may actually be the same genus.

"Sachicasaurus" was 10 meters long, meaning it was the same size generally speaking as K. queenslandicus and K. boyacensis. It does seem like this was normal size for these sea reptiles.

https://www.researchgate.net/figure/Sachicasaurus-vitae-gen-et-sp-nov-holotype-MP111209-1-A-B-right-propodials-A_fig6_331043547

https://revistas.unal.edu.co/index.php/esrj/article/view/69916

"Sachicasaurus" lived in the early Cretaceous and was a member of the brachauchenine group- which apparently included the last surviving pliosaurs before they were replaced by mosasaurs. They tended to have bigger heads and smaller teeth, proportionally, than earlier pliosaurs such as Pliosaurus or Liopleurodon.