Cetiosaurus

Cetiosaurus

Cetiosaurus (/ˌsiːtioʊˈsɔːrəs, ˌsiːʃi-) means 'whale lizard'. It comes from the Greek word keteios meaning 'sea monster' (later, 'whale') and sauros meaning 'lizard'. It was a genus of sauropod dinosaur that lived during the Middle Jurassic Period, about 171 to 165 million years ago. It lived in what is now Britain and probably France.

Cetiosaurus was named in 1842. This made it the first sauropod dinosaur for which bones were described. It was named by Sir Richard Owen. He thought it might have been a marine creature, like a very large crocodile, before realizing it was a land dinosaur.

Cetiosaurus walked on all four legs. It had a long neck and a small head. It ate plants. Unlike many sauropods, it had a shorter tail and neck. Its front legs were longer than usual. Scientists think it was about 16 metres (52 ft) long and weighed around 11 tonnes (12 short tons).

Discovery and species

Cetiosaurus is the first sauropod dinosaur that was found and named. It is the best-known sauropod from England. Over the years, many different species were linked to Cetiosaurus. The genus was a kind of "wastebasket taxon," meaning many fossils were grouped under this name.

The first fossils of Cetiosaurus, like vertebrae and limb bones, were found near Chipping Norton, Oxfordshire, in the early 1800s. At first, people thought they might be from a whale or crocodile. In 1841, biologist and paleontologist Sir Richard Owen named these fossils Cetiosaurus. Owen did not know they were dinosaurs and thought they were from a giant sea reptile. He named two species in 1842: Cetiosaurus hypoolithicus and Cetiosaurus epioolithicus. These names showed whether the fossils were found below or above certain rock layers.

In 1868, workers near Bletchingdon found a sauropod right femur. Professor John Phillips later found three skeletons and more bones there. In 1871, he named two species from these finds: Cetiosaurus oxoniensis and Cetiosaurus glymptonensis. In 1968, a new C. oxoniensis specimen called the "Rutland Dinosaur" was found. It is the most complete sauropod fossil from the United Kingdom. This fossil went on display in the Leicester Museum & Art Gallery in 1985.

The naming of Cetiosaurus species has been complicated. Traditionally, C. medius was thought to be the main species, but later studies showed it was not clearly defined. In 2014, scientists changed the main species to C. oxoniensis, which is the best-known and most complete species from the Middle Jurassic period.

Valid Species

The only widely accepted species of Cetiosaurus is:

• Cetiosaurus oxoniensis Phillips, 1871: type species of Cetiosaurus

Doubtful species

These species are not well-defined or are not considered part of Cetiosaurus:

• Cetiosaurus hypoolithicus Owen, 1841: not a valid name
• Cetiosaurus epioolithicus Owen, 1841: not a valid name
• Cetiosaurus brachyurus Owen, 1842: not clearly defined
• Cetiosaurus longus Owen, 1842: not clearly defined
• Cetiosaurus medius Owen, 1842: not clearly defined
• Cetiosaurus giganteus Owen vide Huxley, 1870: not a valid name
• Cetiosaurus philippsi Sauvage, 1880

Misassigned and reclassified species

These species were once thought to be Cetiosaurus but are now placed in other genera:

• Cetiosaurus brevis Owen, 1842: now Pelorosaurus conybearei
• Cetiosaurus glymptonensis Phillips, 1871: now Cetiosauriscus glymptonensis
• Cetiosaurus rigauxi Sauvage, 1874: a pliosaurid, not a sauropod
• Cetiosaurus humerocristatus Hulke, 1874: now Duriatitan humerocristatus
• Cetiosaurus leedsi (Hulke, 1887) Woodward, 1905: not clearly defined
• Cetiosaurus rugulosus (Owen, 1845) Steel, 1970: now Cardiodon
• Cetiosaurus mogrebiensis de Lapparent, 1955: not a Cetiosaurus

Description

Cetiosaurus, including the species C. oxoniensis, is known from fossils. These fossils include three skeletons found by a person named Phillips. One skeleton is from a larger animal and was selected as the main example of the species. Another set of bones comes from a smaller individual, and the third skeleton is from a young animal.

Cetiosaurus was a long-necked, four-legged dinosaur. In 2010, an expert estimated it to be about 16 meters (52 feet) long and to weigh around 11 tonnes (12 short tons). Its neck was fairly long but not longer than its body. The tail was much longer, with at least forty tail bones. Unlike some later sauropods, Cetiosaurus had solid back bones without much air space. Its forearm was as long as its upper arm, making its front legs the same length as its back legs. The bone in its thigh was about six feet long.

Classification and phylogeny

Sir Richard Owen first described Cetiosaurus. He wasn’t sure what kind of animal it was. He knew it was a reptile but thought it might live in the water. Later, scientists learned it was a land animal and a type of dinosaur.

Scientists have placed Cetiosaurus in different groups over time. Some put it in a group called Cetiosauridae. Today, we know there are many more simple sauropods than Cetiosaurus. Modern studies still aren’t sure where Cetiosaurus fits among other sauropods. Some think it belongs with dinosaurs like Barapasaurus, Patagosaurus, or Chebsaurus. Others think it sits near the base of larger sauropod groups.

Ecology

During the Middle Jurassic period, Europe had many islands surrounded by shallow seas. Cetiosaurus lived on an island called the London–Brabant Massif. This island included parts of southern Britain and nearby areas of northern France, the Netherlands, Belgium, and western Germany. It was about the size of Cuba.

Other dinosaurs that lived around the same time as Cetiosaurus in Britain included large meat-eating dinosaurs like Megalosaurus, Magnosaurus, and Duriavenator, as well as smaller dinosaurs such as Proceratosaurus.

Cetiosaurus lived in areas with floodplains and open woodlands. It likely ate plants from both low and medium heights, thanks to its long neck. The climate on the island was sometimes dry, and the plants there included different types of conifers, ferns, and other ancient plants.