Frogs May Have Evolved to Developing Kneecaps Before Humans Did!

Khryss | Published 2017-07-09 16:35
My life is a lie! Our science teacher may be wrong when they talk about the parts of a frog for a recent study showed that frogs surprisingly have had kneecaps! [embed]https://youtu.be/BNOYS-uPg5o[/embed] Analyzing 20 species of frog skeletons, researchers found kneecaps in eight of those species. And so, curious as they are, they then took tissue slices for analysis. Findings showed that unlike human kneecaps which are made of bone, frog kneecaps comprise dense fibrous cartilage, and are better at absorbing the stresses of leaping and jumping than ours (humans). The researchers theorized that the knees developed around 400 million years ago, when the first four-legged animals came to land. “Until now it was thought that the evolution of kneecaps coincided with the arrival of tetrapods that lay eggs on land or retain fertilised eggs in the body,” says Virginia Abdala from the Institute of Neotropical Biodiversity in Argentina, who led the study. Abdala also added that the study shows that evolution started with fibrocartilage.  “It could be related to locomotion on land, which may have required reinforcement of precise limb points,” she says. Over the millennia, tetrapods evolved to walking rather than jumping and has developed a rather bony kneecaps to handle better the stresses of walking. “The resting position in frogs is analogous to the jumping position in humans, so the knees of frogs are under constant stress, and the fibrocartilaginous kneecap might alleviate this,” says Abdala. “Bone is a good lever, better at resisting compression than fibrocartilage, so animals using their kneecaps as levers rather than cushions would benefit from bony kneecaps,” John Hutchinson, from the Royal Veterinary College says. He also added that fibrocartilage is a good cushion and that it might be what kneecaps actually looked like before the bony ones. However, not all scientists agree to the study's findings. Matthew Vickaryous of Ontario Veterinary College in Canada says, “The authors convincingly demonstrate that some frog species have one, sometimes two, fibrocartilagenous elements adjacent to the knee joint, but it’s premature to identify them as patellae”. He also pointed out that there are around 7000 species of frogs and finding eight of them seems unjustified. Well, what do you think?

Photo by Kurit Afsheen/Solent News/REX Shutterstock

https://www.newscientist.com/article/2140017-frogs-may-have-evolved-the-first-kneecaps-on-earth/
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