Why is Elasmosaurus not a dinosaur?

Elasmosaurus was not a dinosaur. It was a reptile that breathed air. Its neck was so long it could only lift its head above water. Mosasaurs also breathed air. They had to surface like sea turtles today. Mosasaurs were reptiles with overlapping scales, not dinosaurs.

While sharing similarities with dinosaurs, Elasmosaurus had unique traits. It was a Cretaceous marine reptile, not a dinosaur. This matters for its classification and evolution. It grew to 46 feet with half its length being its neck. It had a streamlined body with flippers suiting water movement.

In 1868, Cope first described Elasmosaurus. His early reconstruction wrongly showed it with a short neck and long tail. In 1870, Joseph Leidy noted Cope had the skull at the wrong end, on the tail not neck.

At 50 feet long, Elasmosaurus was huge. But other marine reptiles were larger, some weighing 50 tons. Its fossils were found in Kansas, which was underwater then. It mainly ate fish and ancient cephalopods.

It belongs to the order Plesiosauria, not Dinosauria. This order has plesiosaurs and pliosaurs – all ancient aquatic reptiles. Elasmosaurus platyurus is the only known species. It lived 83.6 to 72.1 million years ago. It couldn’t lift more than its small head from the waves or move its head like a snake. Its long neck alone was 23 feet.

What’s the difference between a plesiosaur and an Elasmosaurus?

Plesiosaurs had long, narrow necks, small heads, and streamlined torsos. The Elasmosaurus had the longest neck. It was half the length of its body and had 71 vertebrae. No other plesiosaur had over 60 vertebrae.

The Elasmosaurus was a plesiosaurid. It had up to 76 vertebrae in its neck alone. It reached 13 meters (43 feet) long. Half of that was its head and neck.

Measuring 10.3 meters (34 ft) long, the Elasmosaurus had a streamlined body with paddle-like limbs, a short tail, a small head, and an extremely long neck. The neck alone was around 7.1 meters (23 ft) long.

Elasmosaurs preyed on fish and ancient squids and ammonites.

The largest known plesiosaur was the 15 meter long Elasmosaurus. Half of its length was its neck, with over 70 tiny neck bones. This helped catch passing fish instantly. It may have even grabbed at flying reptiles just above the sea.

Another long-necked plesiosaur was the 3 meter Cryptoclidus. It was agile and a skilled, dangerous hunter.

The order Plesiosauria had two groups – Plesiosauroidea and Pliosauroidea. Their lifespan is unknown. They averaged 1.8-20 meters long.

Elasmosaurus platyurus is the only valid species of the Elasmosaurus genus.

The Elasmosaurus pectoral girdle appears atypical for elasmosaurids. It retains a bar connecting the coracoids. Many invalid Elasmosaurus species have been named over time.

What is the closest relative to Elasmosaurus?

Close relatives of the Elasmosaurus include the Cryptoclidus and the Styxosaurus. They shared similar long-necked, plesiosaur body plans. Its closest relative is Elasmosaurus. Both belong to Elasmosauridae family. There are six specimens on display at various U.S. museums. The Styxosaurus went extinct about 70 million years ago. The type specimen was found in Logan County, Kansas. Despite its size, Elasmosaurus was a relatively gentle creature. It focused on hunting for food and avoiding predators. Elasmosaurus had a long, flexible neck. It resembled a turtle with four large flippers. Plesiosaurs reached over 15 meters in length. They weighed upwards of 45 tonnes. The Plesiosaur is most closely related to the modern-day turtle. Elasmosaurus existed mainly in saltwater environments. It occasionally was seen in freshwater habitats. Elasmosaurus had one of the longest necks of any known animal. At the base of the jaw was a pouch-like skin. This fold of skin hung below the neck vertebra. It was beautifully sculpted with lots of wrinkles. They suggest elasticity. Most paleontologists assume Elasmosaurus would’ve given birth to live young. Elasmosaurus was a sea animal with an exceptionally long neck. It could ambush its prey. It lived 80-65 million years ago.

Why was Elasmosaurus neck so long?

Elasmosaurus was about 46 ft long. It differs from other plesiosaurs by having six teeth per premaxilla and 71 neck vertebrae. Elasmosaurus, a plesiosaurid, had as many as 76 vertebrae in its neck alone and reached 13 metres, fully half of which consisted of the head and neck.

The Elasmosaurus neck had 72 vertebrae. Its neck was estimated to be about 7.1meters (23ft) long. Along with Albertonectes, it was one of the longest-necked animals to have lived. However, its long neck was less than half the length of the longest sauropod dinosaurs necks.

Elasmosaurus spent all its time in the water, often cruising coastal waters for shoals of fish. It was a carnivorous hunter which used its long neck to get close to prey without them noticing. A swift flick could catch prey unawares. Its small head limited the size of what it could eat.

Elasmosaurus belongs to plesiosaurs, with long necks, four flippers and a streamlined body shape. Despite its long neck Elasmosaurus had a relatively small head, long snout and sharp teeth that it used to catch fish and other small prey.

The first Elasmosaurus fossil was discovered in Kansas in 1867 by Edward Drinker Cope. Elasmosaurus lived in North America during the Late Cretaceous period.

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