2023-06-29 04:00:06
The ancestor of modern horses sported hoofed toes rather than a single hoof. This observation, resulting from the work of an international team of researchers, reveals how these fingers have gradually disappeared over the course of evolution.
Plantar view (underside) of the feet of a four-toed tapir (The word tapir designates four species of hoofed mammals, one in Asia and three…) and a four-toed horse (The horse (Equus ferus caballus or equus caballus) is a large herbivorous mammal and…) one-toed (right), by Nuria Melisa Morales-García.
In the middle, a reconstruction of the extinct three-toed horse Hipparion, by Karolina Suchan-Okulska.
Overall design by Morales-García. Credit: University of Bristol.
There was a time, between 60 and 45 million years ago in the Eocene era, when animals like Hyracotherium walked on feet resembling those of the modern tapir: four toes in front and three at the back, each fitted with a sabot and supported by a plantar cushion (In architecture, the cushion designates the side face of an Ionic volute capital, etc.). Today, equines such as horses, donkeys or zebras have only one toe, formerly the third of each foot, surrounded by a thick keratin hoof and endowed with a triangular structure below, serving as a damper (A damper is a system intended to limit or even eliminate the oscillations of an object or…).
Professor Christine Janis, from the University of Bristol, raises a question: where did the extra fingers go? On later horse fossils, only three toes are found front and back. Those extra toes, smaller and shorter than a tapir’s, probably didn’t normally touch the ground. However, they might have been useful in exceptional situations, such as a slip or a strong impact.
This research, published in the journal Royal Society Open Science, confirms the idea that these fingers have been completely (Completion or completely automatic, or by Anglicism completion or…) lost in evolution, without being preserved in the inside the hoof. This was suggested in a 2018 article, but the authors of the current study, including Professor Alan Vincelette of St. John’s Seminary, reject this hypothesis. The hoof structures of modern horses have evolved independently of the lateral toes and serve (Servent is a contraction of the word server and client.) both as shock absorbers and gripping devices during locomotion.
Left foreleg of a monodactyl equine with elastic hoofs (Equus burchelli) and a three-toed equine (Hypohippus equinus). Design by Nuria Melisa Morales-García.
The study also notes that the feet of one-toed horses have a different shape than the leading toe of three-toed horses, round rather than oval. , and more…). This difference could be linked to variations in the distribution of weight (Weight is the force of gravity, of gravitational and inertial origin, exerted by the…) or to adaptations to different habitats.
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