1. Плезиозавры могли двигаться не только вперёд, но и назад.
2. А насколько была подвижна их шея в вертикальной плоскости?

1. Ну они могли плыть и задом-наперёд и моментально разворачиваться на месте.

2. Насчёт горизонтальной плоскости понятно, в этом отношении она была сверхгибкая.
Про муренозавра я знаю, кажется ты до этого и говорил. По-моему так было у всех плезиозавров.
Габуния считает, что они охотилиь с места. Я тоже так думаю - либо с места, либо неторопливо проплывая мимо косяка рыб.

1. Кашалот
2. Мауизавр
3. Мегалодон
4. Спинозавр
5. Базилозавр
6. Тилозавр
7. Мозазавр
8. Хищник Икс
9. Титанобоа
10. Гиганотозавр
11. Кархародонтозавр
12. Эласмозавр
13. Колоссальный кальмар
14. Тираннозавр
15. Дейнозух
http://img812.imageshack.us/img812/9531/top15chart2.jpg

Lusonectes sauvagei, a new plesiosauroid from the Toarcian (Lower Jurassic) of Alhadas, Portugal

THE NATURE OF MAUISAURUS HAASTI HECTOR, 1874 (REPTILIA: PLESIOSAURIA)                                        http://www.bioone.org/doi/abs/10.1671/0 … 2.0.CO%3B2     Сдесь пишут,что мауизавр 8 м длиной!

Спинозавр :

В некоторых источниках(например в вике) указывают длину в 20м, в иных 16 м.Здесь вот 8м, так что до конца не ясно.

Ну реальные кости посолидней википедии  без ссылок на источник

Cisuralius :

Так и пропорции разными могут быть, если скелет неполный.

Данные о 8 м длине из ПДФ ,как у взрослого мауизавра могут быть разные пропорции в пределах вида?

The oldest lower Upper Cretaceous plesiosaurs (Reptilia, Sauropterygia) from southern Patagonia, Argentina

The internal cranial anatomy of the Plesiosauria (Reptilia, Sauropterygia): evidence for a functional secondary palate

Скелет Polycotylus latippinus из верхнего мела Канзаса, содержащий в области живота фрагменты скелета меньшего экземпляра, возможно, нерождённого плода


Вероятно, плезиозавры рождали небольшое количество (в данном случае одного) крупных детёнышей. Сочетание живорождения, большого размера детёнышей и небольшого количества детёнышей в выводке заметно отличается от картины, которая наблюдается у других морских рептилий, но напоминает К-стратегию, свойственную всем современным морским млекопитающим и нескольким видам ящериц (некоторым лигосомным сцинкам).

F.R. O’Keefe, L.M. Chiappe (2011) Viviparity and K-Selected Life History in a Mesozoic Marine Plesiosaur (Reptilia, Sauropterygia)

http://faculty.weber.edu/rmeyers/Fins%2 … 20fins.pdf   

Ну конечно быстрее плизоавр! У него короткая шея, а длинная шея плезиозавра препятсвовала быстрому "полету" в воде. Да и плиозавр должен был догонять жертву, тех же акул, а плезиозавр пользовался шеей - иначе зачем ему такая гибкая шея? Он мог "выстреливать" ею, мое мнение.

Рекорд эласмозавра побили.
Albertonectes:

There is a new incredibly long necked elasmosaur in the latest JVP; Albertonectes vanderveldei.
It has even more vertebrae (76) than Elasmosaurus.

A new elasmosaurid plesiosaur, Albertonectes vanderveldei, gen. et sp.
nov., is described on the basis of an almost complete postcranial
skeleton from the upper Campanian, Bearpaw Formation in Alberta,
Canada. The new taxon is distinguished by a unique set of
characters—76 cervicals, lateral longitudinal ridge on posterior-most
cervicals, relatively wide clavicular arch, tapered ventral projection
at the median symphysis of coracoids, pointed anterolateral projection
of pubis, fused posterior-most caudal vertebrae, and a relatively
slender humerus. Ninety-seven chert gastroliths were also recovered
with the specimen, and their mean diameters range from <1 to 13.5 cm.
Shape analysis indicates that most of the gastroliths were ingested in
the vicinity of a beach environment. Evidence that the carcass was
scavenged by sharks includes a tooth-marked coracoid, two shed
Squalicorax sp. teeth, and small, localized disruptions to the
skeleton. Preliminary phylogenetic analysis confirms the inclusion of
Albertonectes in a clade comprised of ‘middle’ to Late Cretaceous,
long-necked elasmosaurid plesiosaurs. The number of cervical vertebrae
associated with different elasmosaur genera does not show any
correlation with phylogeny. Both neck and total body length of
Albertonectes are the longest among known elasmosaurs, and highlight
the morphological extremes attained by this group of plesiosaurs.

Giraffes, with their beautifully elongated necks, have only seven cervical vertebrae. So do you, and, for that matter, most mammals. (Sloths and manatees are among the few oddballs that differ.) Short or long, mammal necks are typically supported by just seven bones. But other creatures played by different anatomical rules. The fantastic sauropod dinosaurs – such as the familiar Diplodocus and what may have been the largest terrestrial animal ever, Amphicoelias – had a higher number of intricately modified neck vertebrae. One of my favorite dinosaurs, Apatosaurus, had 15 neck vertebrae.

Other prehistoric creatures racked on even more bones. And paleontologists may have just identified the animal with the highest cervical vertebra count of all time. In the latest issue of the Journal of Vertebrate Paleontology, researchers Tai Kubo, Mark Mitchell, and Donald Henderson describe a new elasmosaur from the roughly 70-million-year-old rock of Alberta, Canada’s Bearpaw Formation. They have named the quad-paddled, long-necked marine reptile Albertonectes vanderveldei, and, while the creature’s skull went missing, the rest of the plesiosaur is represented by a nearly complete skeleton that stretched about 37 feet long in life.

The Albertonectes specimen designated TMP 2007.011.0001. The plesiosaur's disjointed neck is to the right. From Kubo et al., 2012.


Most of that length was neck. Even though the Albertonectes specimen – designated TMP 2007.011.0001 – folded up on itself prior to fossilization, it is immediately clear that this animal had a wonderfully long neck. When reconstructed, Albertonectes had 76 cervical vertebrae that stretched about 23 feet from the back of the skull to the neck’s base. This barely edges out the nearest competition for cervical count – the more famous Elasmosaurus had 71 neck vertebrae. And Albertonectes has also just become the longest elasmosaur we know of. While some of the big-headed, short-necked pliosaurs attained larger sizes – such as the still-unnamed Predator X – Albertonectes sets the new limit for the longest of the long-necked plesiosaurs.

Why did Albertonectes have such an extreme neck? Paleontologists have been puzzling over the natural history of long-necked plesiosaurs for over a century, but the lifestyles of these marine reptiles remains frustratingly obscured by the depth of time between us and them. One thing seems certain, though – these animals were not the snake-necked predators I so often saw in paleo books as a kid. Quite the contrary. Albertonectes and closely related forms probably had relatively stiff necks, and the jumbled nature of TMP 2007.011.0001 throws support to this interpretation.

When the decaying body of the Albertonectes hit the sea floor, Kubo and co-authors propose, the front portion of the neck buckled under the weight of the rest of the plesiosaur’s body. Rather than coiling neatly, though, the animal’s stiff neck broke into different segments. This arrangement, coupled with the lack of flexibility seen between each neck vertebra, means that these marine reptiles were not rapidly whipping their necks around after fish and squid. Even though they were among the first magnificent monsters to be uncovered by 19th century paleontologists, plesiosaurs remain some of the most puzzling fossil creatures we have ever encountered.

References:

Kubo, T., Mitchell, M., & Henderson, D. (2012). Albertonectes vanderveldei , a new elasmosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Alberta
Journal of Vertebrate Paleontology, 32 (3), 557-572 DOI: 10.1080/02724634.2012.658124