Wednesday, June 20, 2012

New Research Into Long-Necked Dinosaurs Identifies Potential Key to Their Success

Research Suggests Sauropod Eating Habits the Key to Their Success

The largest land animals ever to exist, the long-necked dinosaurs, otherwise know as the Sauropods, owed their success to the ability to grow big very quickly and to do this they needed to process what they ate very efficiently. A new European study into the likely feeding behaviours and growth rates of Sauropoda, the scientific name for the long-necked dinosaurs, concludes that during the Mesozoic, size really did matter.
Growing Big To Put Off Predators
A team of scientists believe that these animals grew huge to discourage predators, simply becoming to big for carnivorous dinosaurs to hunt effectively. The paper, to be published in the academic and highly respected journal "Science" examines the growth rates of Sauropods and postulates that these monstrous leviathans were warm-blooded. They would have needed high metabolic rates to sustain their rapid growth. Gigantism certainly has its advantages, for example African elephants have virtually no natural predators once they reach a certain size. Some of the members of a British led expedition to Kenya in the early part of the 20th Century recalled a story of a female elephant being attacked and killed by lions but this was an extremely rare occurrence and one that occurred in exceptional circumstances. Lions do attack elephants, especially at night where the carnivores eyesight is much more effective than the elephant's, but in virtually all cases, the attacks are on young animals.
The pride concerned in the Kenyan tale, was very big, consisting of approximately 20 lionesses and some other semi-mature animals. There had been a prolonged period of drought which had limited the game available and the elephant attacked and killed was an immature animal believed to be about 15 years old. The attack occurred at night when this young female elephant got separated from the herd after visiting one of the few remaining water holes in the area. Could this type of behaviour seen in predator/prey relationships today, reflect what occurred with the Dinosauria?
Pack Hunting Predators
It is probable that some carnivorous dinosaurs may have hunted in packs and large numbers of Giganotosaurs or Allosaurs would have been formidable adversaries quite capable of tackling an adult Sauropod had they attacked as a group. From the few trackways that have been preserved showing Sauropods moving in a herd, it seems that the smaller more vulnerable animals were to be found in the middle whilst the larger adults walked towards the outside of the group provided some protection for the younger animals.
Certainly, some of these herbivorous Sauropods grew into giants. Although scientists still debate the maximum size and weights of these animals estimates of 80 to 100 tonnes are not uncommon and some of the lighter Diplodocids could reach lengths in excess of 33 metres or more.
Successful Sauropods
The large bodies and long necks effectively gave these long-necked dinosaur a very efficient feeding platform, allowing them to strip the vegetation from surrounding cycads, tree ferns and horsetails with little movement of their large bodies, indeed it is thought that different species of Sauropod fed on different types of plant matter to limit competition between species. Brachiosaurs for example with their necks held high could browse on the tree tops, stripping away branches and leaves with their peg-like teeth literally combing the food into their mouths. In comparison, other Sauropods that shared the same habitat such as Apatosaurus probably fed on the understorey of vegetation.
Feeding Habits of Dinosaurs
Although the Sauropoda had weak, peg-like teeth, the majority of which were in the front of their mouths, they were very efficient feeders. Their huge simple stomachs were able to process huge amounts of vegetation. The stomach contained vast amounts of bacteria and this bacteria helped to break down the tough cellulose of the plants and the sturdy plant fibres. Studies of the cross-sections of Sauropod fossil bones indicate that these animals grew very quickly. A hatchling could grow from weighing less than two kilogrammes to being a hefty three hundred kilogrammes in its first year.

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