At the top of this page is a gallery of three different animals (you can click on each picture to make it bigger). Can you spot the odd one out?
From left to right, the animals shown are the Rock Cavy (Kerodon rupestris), the Dugong (Dugong dugon) and the Rock Hyrax (Procavia capensis). And the odd one out? It’s the Rock Cavy! But why?
Despite looking very different to one another, the dugong and the hyrax are quite closely related. They are both placed by scientists in a grouping called the Paenungulata. Along with a number of physical similarities that are not visible at first glance, they are both herbivores (meaning that they eat vegetation) and are both particularly fond of grasses. They are also both found in Africa and the Arabian Peninsula. However, unlike the fairly common hyrax, the dugong is vulnerable to extinction due to hunting and destruction of its living habitat. It does a have a few strongholds though, including the Marawah Marine Biosphere Reserve in the United Arab Emirates.
Despite looking similar to the hyrax, the unrelated rock cavy on the other hand is a type of rodent that is related to capybaras and guinea pigs. These all come from South America. So why do the hyrax and the rock cavy look so similar? This is a great example of a process called convergent evolution, where animals develop similar looks and habits because they live in similar environments, even though they aren’t related. The hyrax and the cavy lead similar lives and have become adapted in similar ways to help them make the most of this lifestyle.
One more puzzle for you – the dugong and the hyrax are also closely related to one other surprising group of land mammals. Can you guess what? The answer is here…
Cavy: By Brian.gratwicke at en.wikipedia (Transferred from en.wikipedia) [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)], from Wikimedia Commons
Hyrax: By Siegmund K. M. (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
Dugong: By Julien Willem (original photograph), Papa Lima Whiskey (derivative edit) (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons