What is the Difference Between Elasmosaurus and Plesiosaurus

The main difference between Elasmosaurus and Plesiosaurus is that Elasmosaurus had a streamlined body with an extremely long neck, a small head, paddle-like limbs, and a short tail, whereas Plesiosaurus had a broad, turtle-like body with a small head, long and slender neck, two pairs of large elongated, paddles, and a short tail. 

Elasmosaurus and Plesiosaurus are two genera of the order Plesiosauria. They appeared in the appeared in the latest Triassic Period.

Key Areas Covered

1. What is Elasmosaurus
– Definition, Characteristics
2. What is Plesiosaurus
– Definition, Characteristics
3. Similarities Between Elasmosaurus and Plesiosaurus
– Outline of Common Features
4. Difference Between Elasmosaurus and Plesiosaurus
– Comparison of Key Differences

Key Terms 

Elasmosaurus, Plesiosaurus

What is Elasmosaurus

Elasmosaurus is an extinct plesiosaur that lived in North America about 80.5 million years ago. Importantly, it had a streamlined body with an extremely long neck, a small head, paddle-like limbs, and a short tail. Also, the length of the body was 10.3 meters. Its long neck was around 7.1 meters long. Also, it had the second-longest neck of an animal ever had. The number of vertebrae in the neck of the Elasmosaurus is 72. Its skull was triangular, with large, fang-like teeth at the front and smaller teeth towards the back.

Figure 1: Elasmosaurus

Furthermore, it was adapted to aquatic life, and the legs were flipper-like. They could not keep their neck above the water’s surface due to inflexibility. The function of the neck was feeding. It ate small fish and marine invertebrates. 

What is Plesiosaurus

Plesiosaurus is an extinct, large marine reptile in the early Jurassic period. It had a small head, slender and long neck, a turtle-like, broad body along a short tail. Also, it had two pairs of paddles. Additionally, the Plesiosaurus‘s skull is much narrower. The size of the Plesiosaurus is around 3.5 m long. The body mass is 185 kg. The number of neck vertebrae is 38 to 42. Further, it had 21 dorsal vertebrae, three or more sacral vertebrae, and at least 28 caudal vertebrae.

Figure 2: Plesiosaurus

Moreover, it fed on snails and clams. It ate fish and prey as well. Also, it was a marine reptile. 

Similarities Between Elasmosaurus and Plesiosaurus

• Elasmosaurus and Plesiosaurus are two genera of extinct Mesozoic marine reptiles belonging to the order Plesiosauria.
• They first appeared in the latest Triassic Period, about 203 million years ago, possibly in the Rhaetian stage.
• They were common during the Jurassic Period.
• Also, they disappeared due to the Cretaceous–Paleogene extinction event about 66 million years ago, at the end of the Cretaceous Period.
• They were distributed worldwide in the ocean and partly inhabited in freshwater environments.
• They also had broad, flat bodies, four long flippers, strong shoulder girdle, and pelvis muscles, and a short tail.
• They were warm-blooded and breathed air.
• They were carnivores. 

Difference Between Elasmosaurus and Plesiosaurus

Definition

Elasmosaurus refers to a Cretaceous plesiosaur with a long neck shaped like a swan. In contrast, Plesiosaurus refers to a large fossil marine reptile of the Mesozoic era, with a broad flat body, large paddle-like limbs, and typically a long flexible neck and small head.

Body Type

Elasmosaurus had a streamlined body with an extremely long neck, a small head, paddle-like limbs, and a short tail, while Plesiosaurus had a broad, turtle-like body with a small head, long and slender neck, two pairs of large elongated, paddles, and a short tail. 

Size

Elasmosaurus was one of the biggest plesiosaurs, while Plesiosaurus was smaller than Elasmosaurus.  

Number of vertebrae in the Neck

Elasmosaurus had 72 vertebrae in the neck, while Plesiosaurus had 42 vertebrae in the neck.

Skull

The Elasmosaurus‘s skull is triangular, while the Plesiosaurus‘s skull is much narrower than long.  

Conclusion

In brief, Elasmosaurus and Plesiosaurus are two plesiosaurs living during the Jurassic Period. Also, they lived in oceans. Elasmosaurus had a streamlined body that contained an extremely long neck. Also, they had a small head, paddle-like limbs, and a short tail. Importantly, it was one of the biggest plesiosaurs and had 72 vertebrae in the neck. In comparison, Plesiosaurus was smaller than Elasmosaurus and had a broad, turtle-like body with a small head, long and slender neck, two pairs of large elongated paddles, and a short tail. Additionally, it had 42 vertebrae in the neck. Therefore, the main difference between Elasmosaurus and Plesiosaurus is their body type. 

References:

1. Austin S.  . (2023, May 24). Elasmosaurus. AZ Animals. https://a-z-animals.com/animals/elasmosaurus/
2. Encyclopædia Britannica, inc. (2023c, August 5). Plesiosaur. Encyclopædia Britannica. https://www.britannica.com/animal/plesiosaur

Image Courtesy:

1. “Elasmosaurus platyurus (transparent) ” By DiBgd – Own Work (CC-BY SA 4.0) via Commons Wikimedia
2. “Plesiosaurus in Japan” By Kumiko from Tokyo, Japan – Own work (CC BY-SA 2.0) via Commons Wikimedia