恐龍卡第 1341 張，共 2 027 張

Pachycostasaurus

名字的意思： “thick-ribbed lizard”1

吃：肉蛇頸龍類侏羅紀中期嚴格來說不是恐龍

Pachycostasaurus was a pliosaur, a kind of short-necked plesiosaur that lived in the sea. It had very thick, heavy ribs that made its body barrel-shaped, like a fat sausage. This marine reptile was not a fast swimmer, but it used its heavy bones to stay stable underwater.1

趣味小知識：這種海生爬蟲類在海裡游泳的時候，恐龍正在陸地上走路。大家都叫牠們恐龍，但牠們其實是爬蟲類的另一個分支。

生存年代

165 到 162 百萬年前2

侏羅紀中期

化石發現地

Peterborough, England1 2

長度

3 m (9.8 ft)1

最高速度

時速約 28 公里（17 英里）

游泳, 估計值

牠生活在什麼時候？

三疊紀

侏羅紀

白堊紀

2 億 5200 萬年前20114566，小行星撞地球

牠有多大？

牠有多長？

跟 3 隻狗從鼻子接到尾巴一樣長跟 17 根香蕉頭尾相接一樣長能在 6.4 秒內游完一座大泳池（50 公尺）

Pachycostasaurus 跟「你」比起來有多大？

只是在你的瀏覽器裡算算數學。什麼都不會被儲存或傳送出去。

牠有多快？

走路的人 時速約 5 公里 (3 mph)

騎腳踏車的小朋友 時速約 12 公里 (7 mph)

Pachycostasaurus 時速約 28 公里 (17 mph)

一匹飛奔的馬 時速約 65 公里 (40 mph)

一隻獵豹 時速約 100 公里 (62 mph)

酷東西

趣味知識

Pachycostasaurus had ribs and belly bones that were so thick they looked like sausages. This condition is called pachyostosis, and it also happens in modern dugongs and manatees.1

Its flippers were small compared to its body, and its neck was short. This made it a slow swimmer, unlike many other pliosaurs.1

The only known fossil of Pachycostasaurus was found by Alan Dawn, an amateur geologist and museum volunteer, in a quarry in Peterborough, England.1

Its head was about 20% of its total body length, which is typical for pliosaurs of its time.1

Pachycostasaurus lived about 165 to 161 million years ago, during the Middle Jurassic period.2

The bones of its backbone had a large canal for the spinal cord, and some parts were not fully hardened, suggesting the animal might not have been fully grown when it died.1

Pachycostasaurus 的 AI 繪圖 — 這是電腦根據科學家目前的知識，用 AI 畫出 Pachycostasaurus 可能的樣子。這只是猜測：真正的動物可能長得不一樣，也沒有人知道牠真正的顏色。

迷思破解王

迷思： Pachycostasaurus was a fast, powerful predator like other pliosaurs.

真相： Its heavy ribs, small flippers, and short neck show it was a slow swimmer that probably stayed near the seafloor, hunting soft prey.1

給恐龍專家

學名: Pachycostasaurus
命名者: Cruickshank et al. 19962
類群: 蛇頸龍類
科 / 演化支: Pliosauridae2
分類: Plesiosauria > Pliosauridae > Sauropterygia2
岩石的年代: 165 到 162 百萬年 (Callovian)2
岩層: Oxford Clay2
國家: 英國2
化石紀錄: The Paleobiology Database 收錄 1 筆2
發現: The fossil was discovered by amateur geologist Alan Dawn in a quarry near Peterborough, England. Scientists Arthur Cruickshank, David Martill and Leslie Noè described and named it in 1996.1
仍有爭議: Scientists are not sure whether Pachycostasaurus lived in freshwater rivers and estuaries and was washed into the sea, or if it lived in the deep ocean and drifted to shallow waters.1