Not a Dinosaur Giraffe: The Surprising Secret Behind Diplodocus’ Long Neck

Uncovering the surprising reason behind Diplodocus’ long neck and why it wasn’t just for reaching the treetops

Giraffes have a special place in my heart, but for a reason you probably wouldn’t guess. True, they are magnificent animals with remarkable adaptations to the savannah environment, but there’s something else.

I’ve known that I wanted to be a biologist since around age five. I was fascinated with all things nature, but especially with animals.

However, my family didn’t have a scientific background, and we didn’t have good museums nearby, so I resourced to nature documentaries to learn beyond what my classroom would offer.

One day, the topic was evolution and how Charles Darwin and his colleagues reached their conclusions. They especially compared Darwinism with Lamarckism. The Lamarckist view is that giraffes had gotten long necks because they stretched them and this information was passed onto the next generation.

On the other hand, Darwinism suggested that an animal with different features was somehow born; these features made them more advantageous in their environment, and their traits were more likely to be passed on to future generations.

Be aware that when Darwin worked on his theories, they didn’t know about genetics yet. Despite that, while Darwin’s ultimate theory didn’t perfectly represent the whole picture of evolution, it remarkably got the idea quite well.

And well, a 9-year-old me found the idea fascinating. There I was, staring at a screen as if I had had the biggest epiphany of my life. I was going to dedicate my life to studying evolution, I thought!

Then, I ran into my mother and exclaimed that I knew the answer: the egg was first! Somehow, my critical thinking took me there.

But going back to today’s story. After making giraffes such an important part of my mental identity, I assumed every land animal with a long neck had evolved for the same purpose. Easy to assume, right?

Well, what if I tell you that’s not the case?

When you think of Diplodocus, the giant long-necked dinosaur, you might picture something like a giant prehistoric giraffe, wandering through ancient forests and stretching its neck to nibble on the tops of trees.

After all, with a neck that made up about a quarter of its entire body length, it seems natural to assume that’s what it was for. Right? We tend to look at the present world to understand the past.

But recent evidence tells us that Diplodocus — and its fellow long-necked sauropods — probably weren’t using those impressive necks to reach for the skies. In fact, it’s more likely they were using them to reach down low.

Really? Yes, let me explain.

Diplodocus was a true heavyweight, weighing nearly 13 tons and measuring up to 27 meters long. Yet, despite its massive size and long neck, evidence from fossilized teeth suggests that Diplodocus primarily fed on ground-level plants.

Scratches on its teeth show that it preferred to munch on soft vegetation like ferns and horsetails, not the leaves from towering trees. So why did it have such an exceptionally long neck if it wasn’t using it to reach the treetops?

To understand that, let’s zoom out and look at the bigger picture. Diplodocus wasn’t the only long-necked sauropod living during the Jurassic period, and it wasn’t the only one that kept its diet close to the ground.

Apatosaurus, another giant from the same region — now known as the Morrison Formation — also spent its time grazing on low-lying plants. Then there’s Camarasaurus, which, though a bit shorter than its cousins, still had an impressive neck. Yet, it mostly fed on ground-level shrubs and short trees, even though it stood 4 meters tall at the shoulder.

If these dinosaurs weren’t using their necks to reach high into the trees, what were they doing with them?

The answer lies in the concept of a “feeding envelope.” These dinosaurs’ long necks allowed them to cover more ground without having to move their huge bodies around as much.

I know it’s hard to picture, but follow me. Imagine a sauropod standing still but able to sweep its head across a wide area to grab food — whether from the ground or a nearby tree. This energy-saving strategy likely helped them grow to such enormous sizes.

See the image below for a more graphic representation.

But it wasn’t always that way. Sauropods had relatively humble beginnings, evolving from smaller ancestors that walked on two legs and didn’t have such long necks. As these early dinosaurs began to transition to life on all fours, their bodies started to grow larger, and their necks followed suit.

By the time of the Middle Jurassic, sauropods like Patagosaurus had doubled in length compared to their ancestors. By the end of the Jurassic, these creatures had become the giants we recognize today, with some, like Giraffatitan, weighing up to 78 tons and sporting necks up to 15 meters long.

However, the evolution of these long necks wasn’t just a quirky byproduct of their massive size — it was a key factor in allowing them to become so large in the first place. The longer their necks grew, the larger their “feeding envelope” became, meaning they could eat more without having to move.

And when you’re as big as a sauropod, moving takes a lot of energy. By being able to access food from different levels and distances while staying in place, these dinosaurs could thrive in environments where food might be spread out, helping them survive and grow in size.

Does anyone remember the Jurassic Park scene when Dr. Adam Grant and the kids are woken up by a Brachiosaurus with allergies? They perfectly illustrated this vertical movement there!

But moving on, the environments these sauropods lived in also played a role in how they used their necks. The Morrison Formation, where Diplodocus and its fellow giants roamed, was not a lush, rain-soaked forest. Instead, it was a more open, dry landscape, with seasonal wetlands fed by streams from nearby mountains.

Large trees were scarce, and the land was dotted with low-lying plants and small clusters of trees near water sources. This type of environment would have made it difficult for large dinosaurs to compete for food if they were all browsing at the same level.

However, by using their long necks to access food in different areas — like Diplodocus reaching into wetlands for soft plants, or Camarasaurus nibbling on shrubs — these giants could avoid direct competition. Genius!

However, even though their long necks might remind us of giraffes, there’s one big difference between sauropods and today’s long-necked mammals. Almost all mammals, including giraffes, have just seven vertebrae in their necks.

Giraffes stretch those seven bones to impressive lengths, but sauropods weren’t limited in the same way. They could have up to 19 neck vertebrae, allowing them to develop much longer necks than any mammal ever could.

Interestingly, the only animals that come close to sauropods in neck length today are birds — the descendants of dinosaurs. Some birds, like flamingos and herons, use their long necks in ways that would have made their dinosaur ancestors proud, reaching into wetlands or using their necks for preening.

In fact, some birds today have as many as 25 neck vertebrae, far outnumbering both mammals and their prehistoric relatives.

So, while Diplodocus and its fellow sauropods might look like the giraffes of the dinosaur world, their long necks weren’t just for high browsing.

Instead, these adaptations may have allowed them to cover more ground, save energy, and carve out their own ecological niches in a challenging environment. Long necks might be a familiar feature in the animal kingdom, but in the case of sauropods, they were the key to becoming the largest land animals that ever lived.

We’ll talk about whales another day!