Last edited Mon Dec 28, 2015, 06:29 PM - Edit history (1)
Being able to get into the center of a herd
The larger and more muscle you have, the better for you to get to the middle of a herd when a predator is near. Predators go for the animals at the edge of any herd, these tend to be the weakest animals.
This is also true of female with offspring. The offspring has improved chances of surviving by being in the middle of the herd, thus females will fight to be in the middle of the herd WITH their offspring.
There are exceptions to this rule. Elephants are the best known, they tend to be tightly netted family groups that use their mass to knock down trees and other food sources other animals can not get at. Elephants are known to protect their young by putting the young in the middle of the Family, but little fighting to be in the middle, unlike most other herd animals.
Another exception is the Musk-OX of the arctic. Musk-Ox will form a circle and keep the young inside that circle when a predator is near. Again no fighting to be in the middle of the herd.
Keeping oneself at about 100 Degree, for maximum performance, at minimal energy costs.
One advantage of being large is the mere fact you are big, produces HEAT, that can keep an animal warm. This is seen in large whales today. The larger the volume, the more heat the body generates independent of using ENERGY to produce heat (Warm blooded creatures burn ENERGY to provide the heat needed to be warm blooded and thus active, when you get to the size of elephants you do NOT need to produce the heat through burning energy, you get it by merely being that huge).
Being able to reach food other creatures can NOT get at:
As to other reasons to be large, is to reach food smaller creatures can NOT reach, Giraffes are an example of this. Now Giraffes have long necks, but the number of bones in the neck is the same as in the neck of other mammals. We see the same thing is the long necks of the Brontosaurus type Dinosaur. Such Dinosaurs to get longer than modern Giraffes had to build up their neck muscles and their leg muscles so they could reach even higher to get at the tall trees which appear to be its main source of food.
It is believed, today, that Brontosaurus type Dinosaurs would stand up on their rear legs, balance their front legs over the rest of their body, and then stretch their necks to get at eat off the tallest trees of its time period. Huge size would permit reaching even higher trees (through this concept is disputed, more below).
Please note, unlike mammals whose FRONT legs tend to be larger and more powerful then their rear legs (the better to dig a hole), birds and Dinosaurs tend to have WEAKER front legs then rear legs. Please note, Man and the other primates (including the great apes and the monkeys) tend to be an exception to this rule. Birds tend to be an exception to this rule, given their wings replaced their front legs, but NOT in all species (and when birds get so large they can not longer fly, such as the Ostrich, their become mostly rear leg creatures).
Now most sources have said that based on studies, these Sauropods could NOT get on its two feet and the size was to push through vegetation and its large neck was to efficiency graze over a huge area of trees, but trees not taller then the Sauropods rear legs.
http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Apatosaurus.html
http://www.livescience.com/25024-brachiosaurus.html
A Study in 2013 have indicated that the above restrictions did NOT exists but the study did NOT go into how high the neck could reach:
http://www.livescience.com/25093-apatosaurus.html
Other studies have indicated that the Diplodocids type of Sauropods could get on their rear legs but NOT other Sauropods. The main reason for this is the center of Gravity of a Diplodocid was over its hips, but other Sauropods center of gravity was nearer their front legs. With the center of Gravity over the hips, the Diplodocid would have had no problem standing on its rear legs. The other Sauropods with center of gravity further forward, could NOT have been able to get or keep their center over the rear legs, and thus could NOT stand on their rear legs:
https://en.wikipedia.org/wiki/Diplodocid
Heinrich Mallison (in 2009) was the first to study the physical potential for various sauropods to rear into a tripodal stance. Mallison found that some characters previously linked to rearing adaptations were actually unrelated (such as the wide-set hip bones of titanosaurs) or would have hindered rearing. For example, titanosaurs had an unusually flexible backbone, which would have decreased stability in a tripodal posture and would have put more strain on the muscles. Likewise, it is unlikely that brachiosaurids could rear up onto the hind legs, as their center of gravity was much farther forward than other sauropods, which would cause such a stance to be unstable.[44]
Diplodocids, on the other hand, appear to have been well adapted for rearing up into a tripodal stance. Diplodocids had a center of mass directly over the hips, giving them greater balance on two legs. Diplodocids also had the most mobile necks of sauropods, a well-muscled pelvic girdle, and tail vertebrae with a specialised shape that would allow the tail to bear weight at the point it touched the ground. Mallison concluded that diplodocids were better adapted to rearing than elephants, which do so occasionally in the wild. He also argues that stress fractures in the wild do not occur from everyday behaviour,[44] such as feeding-related activities (contra Rothschild and Molnar).
https://en.wikipedia.org/wiki/Sauropoda#Herding_and_parental_careThe last great group of Sauropods were the Titanosaurs, that have been found on ALL continents including Antarctica:
https://en.wikipedia.org/wiki/Titanosaur
Unlike earlier Sauropods, the Titanosaur had larger FRONT legs then REAR LEGS.
Their forelimbs were also stocky, and often longer than their hind limbs. Their vertebrae (back bones) were solid (not hollowed-out), which may be a throwback to more primitive saurischians. Their spinal column was more flexible, so they were probably more agile than their cousins and better at rearing up.
https://en.wikipedia.org/wiki/TitanosaurUnlike the Brontarous itself (which lived in the Jurassic Period), the Titanosaur lived in the late Cretaceous and thus lived with not only flowering plants but maybe grasses:
The ancestors of flowering plants diverged from gymnosperms around 202–245 million years ago, and the first flowering plants known to exist are from 160 million years ago. They diversified enormously during the Lower Cretaceous and became widespread around 120 million years ago, but replaced conifers as the dominant trees only around 60–100 million years ago.
https://en.wikipedia.org/wiki/Flowering_plantThe Jurassic period was 201 to 145 million years ago
https://en.wikipedia.org/wiki/Jurassic
The Cretaceous period was 145 to 66 million years ago.
https://en.wikipedia.org/wiki/Cretaceous
Thus Flowering plants existed before the Cretaceous period, they only became the dominant type of plant on land in the Cretaceous period.
The Dinosaurs also did NOT eat Grasses:
The earliest firm records of grass pollen are from the Paleocene of South America and Africa, between 60 and 55 million years ago (Jacobs et al., 1999). This date is after the major extinction events that ended the age of dinosaurs and the Cretaceous period
http://www.plantphysiol.org/content/125/3/1198.full#sec-2I bring up grasses, for except for Bamboo (which is a type of Grass), most grasses do not grow taller then three feet. In areas of trees, the trees will grow taller then the grass and then shade out the grass EXCEPT in areas when grazing animals take out the young trees and grasses. The Grass can quickly recover from such grazing but trees take several years and by the time the tree get tall enough to shade out the grass, the grazing animals come back and take out those small trees. We see nothing like Buffalo and other low headed animals in the Dinosaurs except for Stegosaurus (But there appears to be evidence it could stand on its rear legs to eat, the short front legs evolved to provide the smallest neck to any predator). Please note given the domination of Suropods during the Jurassic, the Stegosaurus may have evolved to eat that plant the Suropod found to close to the ground to eat,
https://en.wikipedia.org/wiki/Stegosaurus
Please note the Stegosaurus is a Jurassic Period animal, thus extinct before flowering plants came to dominate the planet and long before grasses.
Back to the Sauropods. I bring up grasses, for in the time of the Titanosaur flowering plants had replaced Conifers as the dominate plant on land, these are still tall plants, including deciduous trees.
Sequoia Trees (a conifer) appears to have been the dominant tree during the time of the Sauropods:
Sequoiadendrons were the dominant tree in North America and Europe during the Jurassic Period (180 to 135 million years ago) and the Cretaceous Period (35 to 70 million years ago)..... About 20 million years ago Sequoiadendrons became extinct in Europe but still survived in Western North America. The Sequoiadendron giganteum, the only surviving member of the Sequoiadendron genus, was relegated to the western slope of the Sierra Nevada Mountains in what is now known as California about 2 million years ago
https://www.giant-sequoia.com/about-sequoia-trees/about-sequoia-trees/Pine is another Conifer that first appeared about 150 million years ago:
http://link.springer.com/article/10.1007%2Fs13595-012-0201-8
as to Flowering trees. Maples are first seen in the fossil record 67 million years ago:
http://online.sfsu.edu/bholzman/courses/Fall01%20projects/acermac.htm
Bamboo appears about 30 million years ago, it is a high source of energy, but did not exists at the time of the dinosaurs.
https://en.wikipedia.org/wiki/Bamboo
http://www.inbar.int/2013/05/new-insights-on-bamboo-genetics-and-evolution
Just a comment that there are reasons to be large, but there are disadvantages if the source of food shifts. Till the raise of the grasses, most plants on land were fairly tall and a long neck working a huge area may have been the most efficient way to eat what was needed to support such a large body.
On the other hand, once you get away from ferns and conifers, you started to see plants that could grow fast and reproduce fast, so the larger ferns and Conifers found themselves outclassed. This would lead extinction of such outclassed plants, but also the animals that feed on them. The Titanosaurs may have grazed on Flowering plants but it may have restricted itself to ferns and confers, we do not know,
One more comment, just before the final extinction, dinosaur diversity took a nosedive. This is the best know fact to OPPOSE the theory of a Meteorite causing the final extinction of the Dinosaurs (Through the theory the Meteorite impact was so severe it created the Deccan Traps of India by a shock wave right through the earth can explain this nosedive and then extinction for it took a couple of thousands of years to kill off the dinosaurs as opposed to the dinosaurs dying overnight do to the impact)
https://en.wikipedia.org/wiki/Deccan_Traps
The Deccan Traps were active only 30,000 years, but that may have been enough to kill off the dinosaurs. The traps are the leading competitive theory as to what caused the extinction of the dinosaurs.
= new reply since forum marked as read
Now, I'd pay to see that.
