▷ Large Dinosaurs

Size is one of the issues that has made these prehistoric animals more popular. Now we know that there were large dinosaurs that just imagining them can inspire terror.

It is known that a sauropod egg was barely 25 centimeters in diameter. So how is it possible that they reached gigantic dimensions? Regarding this in particular, one can name the Argentinosaurus which measured more than 30 meters long, 6 meters long and could weigh between 80 and 100 tons.

In the range of the largest carnivorous dinosaurs, the best-known example was the most valid. Tyrannosaurus rex could measure up to 11 meters and the largest example was the fossil found in Madagascar at 13 meters high.

Below we will develop various factors and theories that could have contributed to their enormous body volumes.

Herbivorous dinosaurs were the largest

Growth is usually accompanied by correct nutrition. Something important to note is that during the Mesozoic Era plants were abundant and that provided the herbivorous dinosaurs with a large amount of food.

They had plants in abundance, and could feed themselves without much effort. These vegetables were a source of quality nutrients. Furthermore, by eating large amounts of food, herbivorous dinosaurs accumulated energy.

The gigantism of herbivorous dinosaurs was the factor that allowed them to reach the highest leaves, this is the explanation why the dinosaurs were so big. This was a huge dinosaur that could eat even more food. Furthermore, the digestion of plants was easier than the digestion of meat.

The assimilation of vegetables occurred through microorganisms, whose process causes the stomach to produce heat. The larger the stomach, the more heat it generated. And this high metabolism also promoted the growth of the animal itself.

The sauropods were undoubtedly the largest. They went from measuring 40 centimeters to measuring 30 meters long. The most famous were the Argentinosaurus and the Brachiosaurus. The first was the most massive with a volume that could be around 90 tons. The second could reach 12 meters in height.

This type of development tended to be more successful in warm-blooded animals and quality nutrition also contributed strongly to this type of growth.

One of the advantages of being a herbivore is that this diet saved energy. Carnivores had to hunt to eat. The predator expended more energy compared to herbivorous dinosaurs. Unlike plants, prey were not mobile, so they had to catch them.

This is why carnivores could be very large, but herbivores were enormously large dinosaurs.

The neck of sauropods

It is known that the largest herbivores had long necks and small heads. And that is not at all coincidental since it played a crucial role in preserving the energy of these giant saurians.

Sauropods evolved by eliminating chewing habits, so they ate food in bites. In their diet, the long neck and their intestines were responsible for fermenting the food, which favors digestion without chewing.

The neck had another additional function. In the same way as its long tail, the neck also served the function of evacuating body heat. The high metabolism caused an increase in heat. To counteract this, the dinosaur had to evacuate excess temperature.

The length of large dinosaurs like the Seismosaurus and the Supersaurus were estimated to be about 40 meters each.

The absence of chewing organs allowed sauropods to have a small head. This small size also reduced the demand for blood to the brain, something that became difficult with a long neck. In compensation, the large dinosaurs had enormous hearts to pump their blood.

Reasons for oviparity in large dinosaurs

Dinosaurs were oviparous, something that logically avoided the energy expenditure involved in pregnancy. By avoiding this the animal could continue the process of rapid growth.

Furthermore, the maintenance of the population is essential for the survival of the species. The number of litters is always greater in oviparous than in viviparous ones.

It is said that sauropods laid 3 litters of 10 eggs each year. Laying eggs allows the female to continue feeding, with the peace of mind of knowing that the eggs will keep the nest warm.

Size an intimidating factor for predators

We must not forget that gigantism is an important factor in deterring predators. The most prominent large dinosaurs were herbivores because they required the opportunity to become imposing and defend themselves from animals that could hunt them.

Rapid growth is a vital factor in achieving this goal. It’s like when a lone lion tries to attack an elephant. It is really very difficult for this to be successful.

To deal with this, carnivorous dinosaurs also adopted gigantism, just as happened with Tyrannosaurus. The biggest was the Masiakasorus which was originally from Madagascar that measured 12 meters long and whose body volume was 9 tons.

However, the growth of carnivorous dinosaurs was slower than that of herbivores. This was an evolution that allowed larger animals to survive their predators.

However, this size also had its cons. The demand for energy remained high and required the constant intake of food and in large quantities. To maintain this volume, herbivores consumed hard and fibrous foods.

These included pine cones, pine trees, cycads, fruits, leaves and roots. To aid in digestion, they ingested stones called gastroliths, which favored the assimilation of nutrients. When their main food sources began to disappear, the large dinosaurs disappeared.

Other theories about the size of large dinosaurs

There is no single cause that could have driven the accelerated growth of the dinosaurs. And when it comes to hypotheses, these always offer some aspect of what could have favored this development. The following are some theories that could also explain it.

Hot blood and cold blood

Energy expenditure depended largely on how well an organism controlled its body temperature. Mammals and birds that are warm-blooded had to expend energy to maintain a constant internal body temperature. That’s why they had a high metabolic rate.

However, cold-blooded creatures like reptiles depend on their environment for body heat. Its internal temperature fluctuates depending on the surrounding conditions. Warm-blooded animals must eat much more than cold-blooded animals to produce their own body heat.

Food resources

Whether dinosaurs were cold-blooded or warm-blooded has been the subject of heated debate among paleontologists. Researcher Brian McNab, a paleontologist at the University of Florida, attempted to answer this question by looking at the food resources available to dinosaurs.

If resources had been much more abundant in the Mesozoic era, which was when the large dinosaurs lived compared to reality, it is possible that they would have been warm-blooded.

An example of this is blue whales, which are considered one of the largest creatures that have ever lived on Earth, and which are warm-blooded. They fuel their 160-ton body from the abundant resources of the marine environment.

However, McNab concluded that this was not the case for dinosaurs. It wasn’t possible for them to have higher metabolic rates, because the resources weren’t there. For example, there were no pastures at that time which is an important source of food.

Apparently the secret lies in the fact that they took the ingested energy and invested it in growth, instead of maintaining a high body temperature.

Then, the conclusion is reached that they were not cold or hot blooded. They were actually homeotherms which included both. They did not have a high metabolic rate but their internal temperature fluctuated like those of cold blood.

Its same size kept its body temperature constant. When you’re that big you can’t cool down quickly like a small lizard would.

hollow bones

Something curious is that many dinosaur bones were hollow like those of birds. This was due to air sacs extending from their lungs, which meant they weighed significantly less than a solid-boned mammal of similar size.

It is deduced that dinosaurs could support a much larger body with their four legs. In the case of sauropods this was about 80 tons.

Feeding without chewing

According to recent research, one secret may have been that they didn’t need to chew their food as much as modern-day mammals. They cut branches, leaves and twigs, which they then swallowed whole.

This meant they could eat a large amount of food quickly. Without the need for many bulky teeth for chewing, their heads were lighter so their necks could be longer.

In turn this meant they could reach a wider variety of plants from a single location to feed.

Cope’s rule

There is a rule stated by paleontologist Edward Drinker Cope, stating that evolution tends to increase body size over geological time in a lineage of populations.

Evolutionary trends toward body enlargement are common in the fossil record. For example, the Eocene ancestors of horses were the size of a dog. Since then, in the lineages showing the greatest increases, horses have evolved to be 10 times larger.

This may also have influenced the development of large dinosaurs.