Dinosaurs—Living Large

Sauropods Engineered for Size by Marcus Ross

What excites you most about dinosaurs? Be honest. Surely it’s the ones that were super-sized! And the biggest of them all were some of the long-neck sauropods. But sustaining such huge bodies presented huge challenges.

If we’re honest about it, most of us think that dinosaurs are pretty cool (at least, if the box office or all those “educational” toys are any indication). How is it that dinosaurs inspire so much devotion? After all, no one makes movies about trilobites.

When most people think about dinosaurs, they think of one word: big. But dinosaurs had a wide range in size. Some, like Compsognathus, were only about a foot tall, while others, like the duck-billed hadrosaurs, were bigger than SUVs.

All told, it is difficult to precisely identify the average size of a dinosaur.¹

But it is the big dinosaurs that impress us. And the biggest of them all are found among the sauropods.

Being large had its advantages. Before Adam’s fall into sin, all land-dwelling, air-breathing animals ate plants (Genesis 1:30), and sauropods could graze on the higher vegetation. After Adam’s sin brought evil and death into the world, being big and tall had another advantage: scaring off predators.

Biggest of the Big: The Sauropods

The sauropods (“lizard feet”) included the largest land animals in history. With fossils on every continent, sauropods are easily recognized by their extremely long necks and tails, which are anchored to a huge body and held up by towering legs.

Familiar North American sauropods include Apatosaurus, Brachiosaurus, and Diplodocus. At 115 feet (35 m), Seismosaurus, the “earth shaker,” is the longest land animal ever discovered, and is even longer than a blue whale! Most massive of all is Brachiosaurus, who tipped (or broke!) the scales at around 30 tons (27 metric tons)!²

Being the biggest kid on the block has obvious advantages, but it also presents some huge challenges. For instance, how do you support and move all that bulk?

My, What Big Feet You Have! And Body, and Neck . . .

Sauropods had an enormous chest, which housed their massive lungs, heart, and stomach. To hold up these massive bodies, the legs were giant columns of bone. The femur (upper leg bone) of Camarasaurus stands over 4 feet high (1.2 m) and over 1 foot wide (0.3 m), making Camarasaurus 10 feet tall (3 m) at its hip. Not to be outdone, Brachiosaurus was over 16 feet (5 m) at the shoulder. Its head towered 40 feet (12 m) above the ground.

To help support their weight, the same bones that make up the palm of our hand (metacarpals) and most of our feet (metatarsals) were organized vertically, and in a semicircle, similar to elephant feet. In effect, sauropods walked on their toes!

Another feature that set the sauropods apart from other dinosaurs was their long neck, designed for foraging food. Most sauropods held their necks out horizontal to the ground. They could swing their necks in a wide arc, allowing them to forage large areas in front of them without moving around much.

Their necks were equal to or slightly longer than their torso. Mamenchiasaurus, a sauropod found in China, takes this to an extreme: its neck equals the length of the rest of the entire body! Other sauropods took a different approach to feeding. The neck of Brachiosaurus was angled upward, allowing it to reach high into the treetops, giving it access to food that most other animals could not reach.

Unlike many paintings and plastic toys, most sauropods did not hold their heads up high to browse on tall trees or “snorkel” under water (the pressure on their lungs and air passage would have been too great to take a breath).

The key to understanding how sauropods used their necks is their vertebrae. Think of a crane. In the center is a tower, with high-tension wires running to both ends. On a dinosaur, the tower was the hips, and muscle tendons ran from there to the head. In some species, we can see depressions in the vertebrae where they were held in place.

This design reduced the neck’s range of motion, so a sauropod couldn’t lift its head high or look directly backward, but it could gently sweep its head left and right without straining the muscles that kept its head off the ground. The long tails of most sauropods also helped to balance the weight of the head and neck.

Sauropods were the largest animals ever to walk the earth. Their amazing size and power can remind us of the power of their Creator.

From neck to tail, sauropod vertebrae are very big. So to shed a few pounds, God designed them with a lighter construction, including occasional holes or thin regions. This design is similar to modern steel construction.

What to Feed a Behemoth

One striking feature of sauropods is the small size of the head relative to the enormous body. How could they get enough to eat?

Sauropod teeth were often long and peg-like, designed to strip vegetation off plants; they did not chew their food. Instead, it would pass into their huge, vat-like stomach, where bacteria would help break down and ferment the vegetation until useful for food. Sauropods would also swallow rocks (called gastroliths) that would grind down the food. This type of digestion allowed sauropods to eat food sources (like conifers) many other plant-eaters did not.

We have little knowledge of the actual food eaten by sauropods, but the types of plants buried with them indicate low-quality, high-fiber conifers, ferns, and ginkos. One recent discovery from India gave us an unusual glimpse: some large fossilized dung (called coprolites), likely from sauropods, preserved several types of grasses.

They Grow Up So Fast

Sauropods grew to enormous sizes. But how fast?

Until the late 1990s, little was known about how sauropods had their young and how fast they grew. But the discovery of a huge nesting ground in Argentina gave paleontologists a never-before-seen view into the lives of sauropods. Many nests were found, and each had multiple layers of eggs. More amazing still was that the eggs preserved skeletons of the unhatched dinosaurs. Strangely, though, no adult skeletons were found. In other rocks where sauropods are found, there are often medium-sized juveniles along with adults. Perhaps as the Flood waters were coming closer, the parents were forced to abandon the nesting site.

Based on studies of bone structures formed while the animal grew, it took about 20 years for a large sauropod to reach maturity. Their lifespan may have been 100 years or more. So while sauropods matured slower than large whales (which require only 5–6 years to reach maturity), their growth was still rather fast when we consider how huge they became. And unlike whales, which drink up to 100 gallons a day of their mother’s milk in the first year, young sauropods dined on conifers, far less nutritious fare than milk.

Truly Gentle Giants

Sauropods were without comparison in God’s creation. They were certainly the largest animals ever to walk His creation. Their very footsteps could make the ground shake. Imagine the power of a herd! As creatures made on Day Six of creation, they truly were “behemoth” (“beasts of the field” in Genesis 1:25). Made along with us, their amazing size and power should remind us of the awesome power and glory of our Lord and Creator, Jesus Christ.

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