I think historically an 17-18 foot great white would have been large, but not particularly unusual. Even today, I could probably point out 20 or more sharks approaching that size or larger. See Henry Mollet's web page for a number of examples. Still, that size is uncommon today, but I think that's more a factor of the great depression in great white population due to human pressures. Great whites are not thriving today, but orcas are doing very well comparatively. The older records and certainly fossil records indicate great whites used to have a greater sized population.
There was a 5.5m one, 18ft translates to 5.48m. The vast majority of those specimens were probably immatures, wheren't they? According to "Preliminary Studies on the Age and Growth of the White Shark, Carcharodon carcharias, Using Vertebral Bands", they typically mature at 4.2m, we should not include juvenile specimens since we are also talking about adult orcas.
Among adult sharks, I don't think that size is a very rare occurrence.
The main problem when we discuss average size is that people confuse average size in all specimens (you're more likely to encounter a shark that size) and average size in adults specimens.
Then the problem is the difference of mature size in each gender, some females or males mature sooner or later than others females or males. The differences between females and males, of course and the regional differences (South African white sharks appear smaller than in other parts of the worls, whereas Mediterranean white sharks are large, a good part of the world records are Mediterranean).
Inclusion of Juveniles leads to particularly great problems if we are talking about animals with different reproductive strategies, thus it's best to limit it to socially mature ones. Anyway, here thatÂ’s not a problem.
In a number of sharks (including juveniles), no, such a specimen is not common. In a number of mature sharks, its not unusual tough.
Last Edit: Jan 22, 2014 19:46:33 GMT 5 by theropod
Personnally, I judge these discussions about average size quickly limited.
I understand one can say "average size is more representative of the species". But I prefer focuse on the maximum range Nature and evolution allow to one species to reach. Both are important to keep in mind, but I'm more interested in the potential of one species rather the average of one species, which is more complicated to determinate.
A speciesÂ’ maximum can only be approximated*, and it is only representative for particularly large ones' potential, most donÂ’t reach that size. There are several types of "average size" you can compare, "whole-species-average", sexually mature specimens, specimens of a certain age class, osteologically mature...
The latter two are problematic if only a small sample is known (eg. T. rex has only one osteologically mature specimen and the majority of dinosaurs have none), as with almost all extinct species, the first is affected very strongly by the number and relative size of offspring and will thus be too variable for species with a similar adult size. Sexually mature specimens are imo the best solution in most extinct cases, because they are usually available and all represent ecologically mature individuals. Either way, whatÂ’s most important is to chose an objective basis for comparison in accordance with a speciesÂ’ life history, eg. not compare a population of monitor lizards to one of lions while including juvenile stages.
Maximum sizes do not allow for objective comparisons of taxa when there is a notable sample bias towards one (eg. the orca), and as creature pointed out they tend to be much harder to verify even in well-known specimens.
All this means that in Kronosaurus queenslandicus we have no good idea of the maximum size, but much more so with the average size, which means it doesn't make sense to compare it to the reported maximum size of another species.
*The degree of the approximation depends on the size of the sample. Obviously you get much closer, ie. maximum size is far more representative of the species actual maximum, in an orca than in Kronosaurus.
Last Edit: Jan 22, 2014 19:55:52 GMT 5 by theropod
dinokid202: Kronosaurus is a pliosaurid plesiosaur, a sauropterygian. Mosasaurs are a distinct group of aquatic squamates (lizards), closely related to snakes and varanids. If you look at their body plans, you will find countless differences; pliosaurs are much bulkier, have larger heads, four large flippers and a short tail, while mosasaurs are serpentine, with long, flat tails and rather slender bodies.
Post by Infinity Blade on Jan 23, 2014 5:47:31 GMT 5
So what was Kronosaurus' average? I once heard 7 tonnes on Carnivora. Either way, going by the skull comparison on page 1, I think Kronosaurus takes this pretty comfortably.
@runic: ! For a second there, I thought the guy actually joined the forum.
I think Kronosaurus should be favored, even at parity. At least in this case, it would be more maneuverable with its four-flippered method of locomotion, meaning the killer whale would be hard pressed to outflank it. I think this is because with its four flippers, the pliosaur doesn't need to generate as much torque to turn, so unless the orca can generate enough torque to make up for this, it will be less maneuverable than its sauropsid foe. On top of this, this method of locomotion may afford the pliosaur greater acceleration, further granting it greater maneuverability.
Then you have weapons. Not only is the jaw apparatus of the pliosaur far more potent of a weapon than the orca's (the pliosaur almost certainly has a much more powerful bite; bigger teeth; a longer toothrow; and almost certainly generate far more clearance between its jaws, which would serve to create larger wounds and allow it to bite off much larger chunks of flesh), but it can also be brought to bear much better. You can tell from some images online that an orca's skull is relatively small for its size, and therefore doesn't have as much reach/range as the relatively and absolutely enormous skull of Kronosaurus. I invite anyone reading this post who wants to see my point to check out the skull size comparison between Kronosaurus, C. porosus, and O. orca in McHenry (2009) (full PDF right here). The orca's skull is approximately as big as the saltie's, despite the fact that the cetacean is an order of magnitude larger!! Additionally, the orca's cervical vertebrae are extremely short and certainly don't look like they have extensive mobility in any direction. The pliosaur's neck is longer and most likely more mobile, further increasing its attacking reach and range in comparison to the cetacean. Oh, and then you got the pliosaur's probable superior acceleration/maneuverability.
And yes, I am aware of the second weapon of killer whales: ramming, so weaponry isn't as simple as a single jaws comparison. But Kronosaurus' jaws could probably still be brought to bear more easily. An orca still needs to swim towards (literally into) another animal to ram it, thus it has to move its entire body. If it wants to ram Kronosaurus' postcranial regions, it needs to swim an arc around it and then ram its body. Kronosaurus just needs to turn in place to keep facing the cetacean, which it could definitely do with its superior maneuverability. And when close enough, it can use those giant jaws to catch and ravage the whale. Ramming may not even be exclusive to the orca; I've seen two papers that suggest that pliosaurs could ram prey (although, no one has ever rigorously tested this idea).