STL Science Center

STL Science Center

06 July 2019

Returns and New Beginnings

I am back to having the time to write a little bit here and there every day. There are many good animals to start with as we restart these (mostly) daily entries. I decided that, since this is the restart of this blog we should go back to the roots of the roots of the first project I worked on after the inception of this page. The only way that makes sense is to talk about an animal that is a member of the group that gave rise to the animals that I originally worked on. My first project was describing a set of plesiosaur vertebrae, and the animals that preceded the plesiosaurs were a group that we call the nothosaurs. One genus, Keichousaurus (consisting of K. hui Young 1958 and K. yuananensis Young 1965), was first discovered in China in 1958 by Hu Chengzhi and described by C. C. Young. This genus, like other nothosaurs, possess a long neck and tail, short head (relatively), and paddle-like hind and forelimbs; the forelimbs being more paddle-like were thought to be more important in locomotion than the hindlimbs. This locomotion was also thought to resemble that of plesiosaurs and has been described as "underwater flight", though this is still largely hypothetical at present. The holotype species (K. hui) is represented by numerous fossil animals, including pregnant individuals indicating live birth or ovoviviparity (hatching in the uterus and being "born" live) in Keichousaurus.

We might think these animals would be quite large, given that their plesiosaur descendants are quite large animals. However, many of these nothosaurus are extremely small, ranging from 15-30 cm (6-12 in) in length. There are individuals known to reach 2.7m. Despite the long neck and tail that we see in illustrations of Keichousaurus, that long neck is actually quite short, in respect to what we usually think of for long-necked animals (think of giraffes and long-necked dinosaurs, as examples). Of course, that neck is relatively long for these small animals!

©Nobu Tamura

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