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Sauropod Characteristics and Classification

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When you look for the long neck dinosaur name, you will come across Sauropoda. It is one of the two subgroups of Saurischian dinosaurs, also known as lizard-hipped dinosaurs.  Sauropoda, which translates into lizard footed, is an infraorder of dinosaurs. Sauropods are known to be the largest land animals to ever live on Earth. These giant dinosaurs are characterized by their massive size and long neck. They ranged in size from Anchisaurus that were 7 to 10 feet tall to animals like Brachiosauridae that went over 100 feet. It is also believed that there may have been other species of Sauropods that grew up to 200 feet in size. These animals had a small brain, blunt or spatulate teeth, and long tails that provided balance. 

The four-legged or quadrupedal stance of the Sauropod group is a result of their large body structure. These animals had large guts that helped in the proper digestion of the cellulose-rich food that they consumed. Unlike their ancestors, Sauropods had nostrils that were located high on the skull, near the opening of the eye. Another distinguishing feature that appeared in Sauropods was the presence of specialized body armor for protection. Examples of these include osteoderms on the body or horny spikes to keep away danger. The nostrils of these animals were present on top of the skull, which was unlike any other terrestrial animal existing at that time. 


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The Sauropods were herbivores, but different species had varying diets. Their primary food source is assumed to be conifers. Other food sources like ferns, cycads, mosses, horsetails, and Gingkos are also believed to have been present when Sauropods existed. Some Sauropods may also have been dependent on flowering plants. 

Sauropods can be further classified into subgroups such as Cetiosaurids, Brachiosauridae, Camarasaurids, Titanosauridae, and Diplodocids. 


Origin of Sauropods 

Now that you know what is the dinosaur with the long neck called, let’s look into how they came into being. The evolution of Sauropods is believed to have taken place in the Early Jurassic period (201- 174 million years ago). The earliest members were small and bipedal. These were known as prosauropods which died by the end of the early Jurassic period. They gave rise to the more specialized, diverse, and the larger group is known as Sauropods towards the end of the Jurassic period (164-145 million years ago). It is believed that Sauropods persisted as the dominant group of dinosaurs all through the Cretaceous period (145- 66 million years ago). Their existence for more than 100 million years made them the longest-living group of dinosaurs.

The geographical distribution of these animals was widespread. This is evident from their bones and footprints, which have been recovered from all the parts of the world (except Antarctica). They are known as the largest of all the dinosaur species. The defining characteristic of these animals was their large size, long necks, counter-balancing tails with small heads. It is also believed that they had columnar legs with heavy limb bones to support their bodies. Some well-known examples of this group of dinosaurs include Apatosaurus, Brachiosaurus, Argentinosaurus, Diplodocus, etc. 

Some species of Sauropods like Camarasaurus and Titanosaurs are also believed to have been egg-laying. Fossil findings reveal that these animals lived in herds. The constitution of these herds remains unclear. Some areas have fossil evidence of animals of all groups, whereas fossil evidence from other regions suggests that age was the categorizing feature for the formation of herds, i.e. juvenile members had separate herds from the adult members of the population. Examples of such segregated herds can be seen in species like Bellusaurus. The reason for this is the difference in the dietary habits of juveniles and adults.  Such segregation must have taken place soon after the hatching of eggs. 


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Body Plan of Sauropod 

Sauropods have various defining characteristics, including their large size and relatively small heads. Even the smallest members of Sauropoda were 5 to 6 meters long. Their body is believed to have a small head, a long neck, and a giant body. Thick and strong pillar-like legs, along with blunt feet that helped in balancing and supported their body. Sauropods had a long, whip-like tail that tapered at the end. The large size is believed to be the reason why they were quadrupeds. 

Their large body consisted of a massive gut and a hip-girdle fused to the backbone. This structure helped them maintain balance and support the body. A characteristic feature of these animals is their long neck. This is believed to have been helpful in foraging, although there is little consensus on how the neck was actually postured. With the help of their long neck, the animals could get leaves present high on trees to meet their dietary requirements. The neck aided in getting access to more food for their survival. Their structural strength came from the backbone, which was hollow from the sides. The teeth of Sauropods were pencil-shaped and helped them in nibbling on leaves.

The largest terrestrial animal, Dreadnoughtus, was a Sauropod with a weight of 65 tons and a length of 85 feet. 


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The classification of Sauropod dinosaurs is provided below:


Classification of Sauropod

Kingdom

Animalia

Phylum

Chordata

Class

Sauropsida

Superorder

Dinosauria

Order

Saurischia

Suborder 

Sauropodomorpha

Infraorder

Sauropoda


Sauropods belong to the order Saurischia, which are believed to be the ancestors of birds. The Sauropoda lower classifications can be found out by studying the major sauropod families. These include:

  • Cetiosaurids-  These members had a shorter tail which brought them the name Whale lizards. Cetiosaurids are characterized by the presence of solid vertebrae. They were 30 to 60 feet long and existed until the Cretaceous period. Common examples include Cetiosaurus, Amygdalodon, Dachongosaurus, Datousaurus, Oshanosaurus, Rhoetosaurus, Shunosaurus, etc.

  • Diplodocids- These animals had extremely long necks and small heads. Their length ranged from 55 to 90 feet. They possessed extremely long whip-like tails and teeth in the front of the mouth. Diplodocids persisted from the Late Jurassic to the Cretaceous period. Examples of Diplodocids include Diplodocus, Atlantosaurus, Barosaurus, Mamenchisaurus, Seismosaurus, etc. 

  • Camarasaurids- Also known as chambered lizards, these Sauropods had smaller necks as compared to the other species.  They are known as medium-sized Sauropods. They had small hollow chambers or cavities in the vertebrae. These cavities most likely had air sacs that supported the flexible movement of the neck. The teeth of Camarasaurids were chisel-like. They were almost 60 feet long and had a relatively large head as compared to other Sauropods. Examples of Camarasaurids include Camarasaurus, Cathetosaurus, Parrosaurus, etc.

  • Brachiosauridae- These were large Sauropods that went up to 100 feet. Common examples of these animals were Brachiosaurus, Ultrasaurus, and Sauroposeidon. The animals had a giraffe-like posture along with a thick tail. They had long front legs and shorter rear legs. It is believed that the longer forelegs helped keep the neck upright when trying to secure food from greater heights. Brachiosauridae existed from the mid-Jurassic to the early Cretaceous period. 

  • Titanosauridae- The identifying feature of these animals was their armored skin. They are one of the largest dinosaur families ever and weigh almost 70 tons. It could contain spikes or bony plates etc. Titanosaurids had wide heads, and their vertebrae were not hollow. The remains of these animals indicate that they existed between the late Jurassic to the end of the Cretaceous period. A well-known example of this group is Titanosaurus. 


Posture of Sauropod Dinosaurs

Speculations have been raised regarding the rearing stance of Sauropods. Many scientists have put forward the idea that Saupods could rear up on their hind legs. This could have been supported by their tail as a third leg, giving them the stability of a tripod. To support this idea, there must have been a presence of stress fractures in the limbs of dinosaurs when they returned to their original stance from the bipedal posture, and no such evidence has been found in the fossils. 

Additionally, the flexible backbone of Titanosaurs or the center of gravity of Brachiosauridae makes it even more difficult to acquire stability while rearing on the hind limbs. On the contrary, groups like Diplodocids have the perfect body structure for rearing up. Their center of mass is positioned such that it becomes easy for them to balance their body in a bipedal position. It was, therefore, concluded that Sauropods are better adapted to a rearing stance than others.


Conclusion

The largest of all long neck dinosaur name to ever walk on Earth were Sauropods. They are also the largest land animals discovered. These animals first appeared during the end of the Triassic period and went on to increase in size and diversity up till the end of the Cretaceous period. The remains of this infraorder have been obtained from all parts of the world, which shows that they had a widespread distribution geographically. They were herbivores and walked on four legs. Many species of these dinosaurs had body armor for their protection. Although they were gigantic in size, sauropods had small brains and puny teeth. Another feature of a sauropod dinosaur is the presence of thick legs and feet with five toes, meant to support their heavy body. The basic body plan of all Sauropods was broadly the same, with some small variations. 

FAQ (Frequently Asked Questions)

1.  What Were the Dietary Habits of Sauropods?

Ans-  The exact diet of Sauropods is not known. It is believed that these giant animals required large amounts of food for sustaining themselves, but their exact preference for plants is still unknown. 


The eating habits of Sauropods can be determined by various factors such as the structure of teeth, obtained fossils such as coprolites, etc.

It is estimated that the large Sauropods fed on conifers and palm trees since any other rich source of calories or proteins did not exist during the time.  Since this diet was rich in cellulose, the animals would have required a digestive tract with crop chambers and bacteria that can break down cellulose. The Sauropods that existed in the late Cretaceous period are speculated to have eaten flowering plants for their sustenance.

2. What Type of Defensive Mechanisms Did Sauropods Have?

Ans- The large and intimidating size of Sauropods came to their advantage in protection against predatory carnivores. They also used their long tails as whips to remain protected. 


Most Sauropods developed some form of body armor for their protection. Instances of this can be seen in the spined backs of Agustinia or body protrusions of Saltasaurus. Some species also possessed clubs on their tails which they used to ward off predators. It is also speculated that these dinosaurs lived in large herds. 

3. What Was The Reason Behind The Long Necks of Sauropods?

Ans- Sauropods, known for their long necks, had varying stances. The longest neck was found in Mamenchisaurus (46 feet), which was more than half of its whole length. 

Some Sauropods like Brachiosaurus and Ultrasaurus had giraffe-like vertical necks. On the other hand, animals like diplodocids possessed a neck that was parallel to the ground. 


Although the definite reason still remains unknown, it is speculated that these plant-eaters had such long necks for foraging. They could have used their long neck to reach leaves present at great heights on trees, just like giraffes do. The long necks may also have allowed them to get access to the food present in forests, which they could not venture into, owing to their large size. 


Additionally, the long neck may have enabled the animals to browse plants in wetlands. Since the animals could not venture into the wet areas, they could reach the mosses, ferns, and other pteridophytes using their long necks. 

4. Name Some Examples of Sauropods.

Ans- Some of the most well-known examples of Sauropods include:

  • Aegyptosaurus

  • Aepisaurus

  • Alamosaurus

  • Amargasaurus

  • Ampelosaurus

  • Apatosaurus

  • Aragosaurus

  • Asiatosaurus

  • Bellusaurus

  • Brachiosaurus

  • Camarasaurus

  • Diplodocus

  • Dystrophaeus

  • Giraffatitan

  • Hypselosaurus

  • Haplocanthosaurus

  • Janenschia

  • Kumingosaurus

  • Lapparentosaurus

  • Magyarosaurus

  • Nemegtosaurus

  • Ohmdenosaurus

  • Paralititan

  • Patagosaurus

  • Protomognathus

  • Quaesitosaurus

  • Saltasaurus

  • Supersaurus

  • Ultrasaurus

  • Vulcanodon

  • Volkheimeria

  • Zizhongosaurus.