Many people are familiar with armored dinosaurs, such as Stegosaurus with its spiked tail, the Ankylosaurus with its back armor and clubbed tail, and of course, horned ceratopsian dinosaurs like Triceratops with its frill and three horns. Amazingly, some long neck dinosaurs also had spikes and even armored scales. It makes me wonder, what was that long neck dinosaur with spikes on its back?
There are two groups of sauropods that had spikes on their back, the dicraeosaurids and the titanosaurs. Dicreaeosaurids such as Amargasaurus and Bajadasaurus had long spikes that were part of their vertebrae, running down their necks and backs. These spikes are known as neural spines. Titanosaurs such as Alamosaurus and Argentinosaurus also had neural spines, but they were shaped like flat spiky plates and were on the neck, back, and tail.
The dicraeosaurids were:
- Noted for having elongated spikes (neural spines) on the neck and flat triangle shaped spikes down its back
- Closely related to the diplodocidae clade, which included Diplodocus and Apatosaurus
- Had characteristically shorter necks and tails compared to other sauropods
The titanosaurs were:
- Known to have spikes (neural spines) along its back in flat triangle shaped spikes, although not all species had neural spines
- Many had osteoderms (bony deposits) individually as scales with hardened points giving the likeness of armor plating on their skin
- Claimed the title of being the biggest dinosaurs ever to have existed
These giants lived during the Jurassic and Cretaceous periods of the Mesozoic Era. Carnivorous dinosaurs like T. Rex (North America) and Giganotosaurus (Argentina) are thought to have hunted these sauropods in their respective geographies.
However, with the body armor and spikes on the back, these long necks would not be an easy target. Read on to learn more about these giant sauropod dinosaurs.
More About Those Spikes on the Back – Neural Spines
The unique characteristic of titanosaurs were the spikes – termed by paleontologists as “neural spines” – and these were actually part of the vertebrae and made of bone. These distinctive spines were evident in fossil specimens on the neck and back.
They also had different shapes. Some were triangle or diamond-shaped, while in some dinosaur species like the Amargasaurus and Bajadasaurus, the neural spines were thin, long, and enhanced the tall appearance of the dinosaur. The tallest spines (longest elongated) came from the Bajadasaurus neck vertebrae fossils.
Types of Neural Spines
Paleontologists have been fortunate to have found multiple fossil skeletons of dicraeosaurids and titanosaurs on many continents. Unfortunately, some are partial skeletons that may be missing the skull or neck and tail vertebrae. When it comes to the neural spines, we are fortunate to have found skeletons clearly indicating their existence and even the positioning. The neural spines can be grouped and described as:
● Elongated spines: These were the tallest or longest spines and stuck out clearly from the neck. As mentioned, they were bone and fused as part of the vertebrae. They were visible in fossil specimens of Armargasaurus and Bajadasaurus. Some of the features of these spines were:
–a double row of neural spines down the neck
–thin and elongated (even sharp spikes)
–possibly covered by bony keratinous sheaths
–spines possibly connected by thin skin to create a sail
–dicraeosaurids were the only dinosaurs to have these types of spines
YouTube Video About Bajadasaurus And Its Neck Spines
● Bony spines (or distinctive spines)– These stood out and were clearly seen on the skeleton running in either one or two rows down the back of the sauropod, sometimes even along the tail. The shape was triangular or diamond-shaped (like the dorsal plates of the Stegosaurus).
You can see the row of spines along the neck vertebrae, back, and tail in some skeletons. In others, it is not as pronounced. Interestingly, the Amargasaurus had paddle-shaped bony spines along its back (Source).
In general, dicraeosaurids had these bony spines along their back, and in titanosaurs, they had them along the neck, back, and tail.
Purpose of the Spikes
There are a few key uses that scientists have considered as to why these dinosaurs had spikes on the back and neck. In some cases, they cross-checked with modern reptiles and birds; in others, they suggested it from current-day animal hunting habits. Here are a few of the main uses.
● Defense – The main and obvious explanation for the spikes is that titanosaurs used them for defense against predators. These body features occur mostly on herbivores, even today, to have a way to fend off carnivores.
As large as these long neck dinosaurs could be, predators could take advantage of their vulnerable rear-side if it had not been for their spikes, making it difficult to do so. If you are interested in how long neck dinosaurs protected themselves against predators, check out my article How Did Long Neck Dinosaurs Defend Themselves? 3 Key Defences.
● Species Recognition – A secondary purpose for the spikes could be for species recognition. Identifying marks like spikes could help titanosaurs identify their own – even perhaps a potential mate. From the fossils we have of the titanosaurs, the spikes are visible on reconstructed skeletons.
●Sail formation – Another explanation, though less widely accepted, is that neural spines might have provided a surface for the attachments of ligaments or muscles to form skin sails. Like those seen in crested chameleon, a neural spine sail could serve functions like thermoregulation, sexual selection, camouflage, and even food storage. (Source)
Natural History of Spiky Sauropods – Where They Lived and Common Anatomy
The sauropods were four-legged herbivorous dinosaurs, the largest dinosaurs with a stout body or trunk, neck, and tail to match. Fossils of these famous dinosaurs, some of which paleontologists have found complete skeletons, show why these types of dinosaurs claim the title of the biggest dinosaurs to have walked the earth.
When it comes to armored sauropods, the dicraeosaurids and titanosaurs had similar anatomy to sauropods like Diplodocus. The differences were not only in the neck spikes and spikes on the back. There were also differences in skull size.
Let’s take a closer look now at these dicraeosaurids and titanosaurs, starting with where they lived and then an overview of their anatomy that differentiates them from sauropods.
Where Dicraeosaurs and Titanosaurs Lived
Paleontologists have found dicraeosaurid fossils in North America, South America, Africa (Tanzania), and China. Most of them are partial skeletons, but some nearly complete fossils are found in Argentina and Tanzania.
Titanosauria which lived on all continents and their fossil remains, have mostly been found in North America (the Southwestern US states of New Mexico and Texas), South America, Argentina, China, Mongolia, and Australia. Some of the largest skeletal remains have been found in Argentina.
Paleontologists are continuously finding more fossils and reexamining previously found sauropod fossils, so there may be many more places where these armored sauropods lived.
If you are interested in knowing more about where sauropods (more than 100 species) lived around the world, check out my article Where Did Long Neck Dinosaurs Live? A Global Snapshot.
The habitats and environment of the earth during the Mesozoic era were different during the three periods. In the Jurassic and Cretaceous periods when these long neck dinosaurs lived, the habitat was dryer during the Jurassic and became sub-tropical during the Cretaceous.
If you want to know more about the habitat, environment, and plants of South America, where many of the dicraeosaurids and titanosaurs have been found, I wrote an article about South American Dinosaur Habitats which covers Argentina, where most of the sauropod fossils have been found.
The Differences in Anatomy
Dicraeosaurid differences in anatomy, besides the spiny neck and back, exhibited smaller necks and tails than other sauropods. The anatomy also showed that they had small-sized heads, similar to Diplodocus and Brachiosaurus.
Titanosaurs were considerably larger, although not all of them reached the giant sizes of titanosaurs like Dreadnoughtus and Argentinosaurus. One of the traits they all had was osteoderms, a kind of bony scale that resembled armored skin. Not all titanosaurs had spikes on their back.
Based on the size of the dinosaur compared to its small skull, both these clades of sauropods are regarded as being at the bottom of the EQ scale at an EQ of 0.2. For info about the intelligence of dinosaurs, check out my article Smartest Dinosaur Species – Hunters That Could Outsmart Its Prey.
As herbivorous dinosaurs, their teeth were flat and cone-shaped, designed for chewing and grinding vegetation. Some skull fossils of these sauropods show they had pencil-like teeth.
Here is a table that compares some of the key anatomical characteristics of titanosaurs, dicraeosaurids, sauropods, and prosauropods, giving you a comparison snapshot of these gigantic dinosaurs.
Titanosaur vs Dicraeosaur vs Sauropod vs Prosauropod
Notable Long Neck Dicraeosaurids and Titanosaurs
As little as we know about these titanic creatures, they have a way of captivating us and stirring our imaginations.
Imagining prehistoric animals that sported parallel neck sails along its sauropod neck or bone spikes down its back and tail, stomping through the vegetation starts to be more tangible when we learn about their fossil remains.
In this next section, here’s a list of notable dicraeosaurids and titanosaurs to paint a better picture of what is known.
Dicraeosaurs – Dinosaurs with Elongated Spikes (Neural Spines)
Amargasaurus – Early Cretaceous Dinosaur From Argentina
The most remarkable thing about the Amargasaurus is that they had two rows of neural spines instead of just one row running down its neck. As mentioned above, some scientists think these double rows had a type of parallel skin sails that regulated body temperature or were used in the mating attraction. Additionally, the spines were long, projecting backward along the neck.
The Amargasaurus was discovered in Argentina in 1984 by Guillermo Rougier. He was a member of paleontologist Jose Bonaparte’s fossil expedition. The fossils found in the La Amarga fossil array beds in Patagonia also held other dinosaur fossils.
An interesting and unique thing about the Amargasaurus is that it also had paddle-shaped bony spines along its back and tail in addition to the long neural spines. Other dicraeosaurids had triangular or diamond-shaped spines.
The Dicraeosaurus had thick spikes along the neck and back and shaped like a “Y,” which is how in some part, it got its name. Dicraeosaurus means “bifurcated” or “divided into two” and “lizard.” Their neck vertebrae are shaped like a “Y.”
The unique thing about Dicraeosaurus was that it had a large head, considerably larger than their relatives like Diplodocus and other dicraeosaurids.
Several mostly complete skeletons were found in Tanzania in 1914.
The Bajadasaurus Discovered by Pablo Gallina
The Bajadasaurus bears the similarity to Amargassaurus of also having elongated neck spikes. Its neural spines, fused to the neck vertebrae, were sticking out from the neck, towards the skull, instead of backward. The fossil specimen also suggests two rows of neural spines that possibly would have supported parallel skin sails.
What’s unique about the dinosaur is that the neural spine specimen measured about 1 foot and 11 inches long!
Pablo Gallina found the only fossil specimen of the Bajadasaurus in 2010. The specimen was found in the Bajada Colorada locality in the Neuquén province of Patagonia, Argentina.
Gallina and his colleagues suggest that the neural spines could have been covered with a “horny sheath,” a “sheath of keratin,” or covering made of skin and horns that effectively protected the neural spines. Additionally, scientists suggest that the spines covered with skin could help with thermoregulation, regulating the dinosaur’s body temperature.
Although only a partial skeleton was found, the skull of the Bajadasaurus shows pencil-like teeth and the shape of the skull.
Related Sauropod Articles You Might Also Be Interested In:
Sauropods Vs Prosauropods- The Surprising Differences in Sizes, Anatomy
Where Did Long Neck Dinosaurs Live? A Global Snapshot
What Are Long Neck Dinosaurs (Types, Size, List)?
North American Titanosaur – Alamosaurus
The neural spines of the Alamosaurus ran down the back of the dinosaur, and there is fossil evidence of osteoderms that resembled armor.
Dinosaur fossils of this genus were found in the southwestern US and possibly pegged as the largest land dinosaur known from North America. The gigantic herbivores could grow to 98 feet in length, weigh up to 88 tons, and sported a body covered partially in bone armor. This genus also displayed neural spines running along their necks and tails.
Interestingly, the Alamosaurus is considered the only long-necked dinosaur to have lived simultaneously and geographic region as the T. Rex during the Late Cretaceous. Amazingly, the only sauropod living with T. Rex was also a Titanosaur. If you are interested in reading more about the Alamosaurs and T. Rex, check out my article What Sauropods Lived with T. Rex? Plus, How They Coexisted.
Argentinosaurus Lived in Argentina 95 Million Years Ago
As a titanosaur, the Argentinosaurus would also possess neural spines and armored plates to protect him when he roamed around along river edges, looking out into open plains where other large carnivores will hunt.
The Argentinosaurus is a genus of titanosaurian dinosaur that lived in South America during the Late Cretaceous Period. The only known species in this genus is A. huinculensis, which Guillermo Heredia discovered in 1987 after noticing some tail vertebrae sticking out of dried mud near Huincul Neuquén Province, Argentina.
Due to its size, the Argentinosaurus has gained popularity as one of the famous dinosaurs from Argentina’s Patagonia region. It was an enormous creature with a weight estimated to be around 90 tons and about 115 feet long!
At the time of discovery and naming (1993), it was considered the biggest dinosaur ever found and held this record for nearly a decade. Paleontologists believe it lived during the late Cretaceous period, around 95 million years ago.
Chinese Titanosaur – Jiangshanosaurus
The Jiangshanosaurus, discovered in Zhejiang province, China, displays some of the key characteristics that place it under the class of Titanosauria. This genus sported neural spines, but the projections from the spines are poorly preserved.
There is evidence of osteoderm body armor scales, which fits into the definition of a titanosaur. The fossil remains found gave paleontologists a nearly complete dinosaur skeleton, including the skull, which indicates it is a titanosaur because of its smaller size compared to the body size.
The Argentinian Titanosaur – Futalognkosaurus
The spikes of the Futalognkosaurus are located on the back, neck, and tail. The spines are approximately 3.9 inches long and are triangle-shaped. About 70% of the fossil skeleton was found, making it a rather complete fossil specimen.
The unique characteristic of the Futalognkosaurus is that the neural spines were so large and ran almost the full length of its body. It weighed at least 33 tons, and its body length was 79 feet.
Sauropods are amazing to think about the way that they lived on earth. They were a wonder of the prehistoric world. As I learn more about different types of long neck dinosaurs, it becomes clear that they have unique features in their anatomy. For example, some (like the neural spines) are covered in this article.
It is interesting to think about what protection those armor plates and spikes must have against predators such as Giganotosaurus in Argentina. Hopefully, this article added to some of that wonder and maybe even sparked an appreciation of these gentle giants.