Chiroterium. Saragossa (Zaragoza) Aragonen.

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The fossil record of the Triassic vertebrates (250 - 205 million years) is scarce.
However, the numerous fossil footprints (icnitas) that are known indicate an abundance of amphibians and reptiles over the continents, in this period.
However, it is rare to be able to determine with precision the author of these prints.
This is the case of Chirotherium. Icnita that raised an important polemic due to the presence of a "supposed thumb" (the first finger) in the outer area of the legs and not in the interior that is usual in the terapods.

Chirotherium

In 1925 the paleontologist Wolfgang Scergeler pointed out that this impression actually corresponded to the fifth finger, that is to say the "little finger", attributing Chirotherium to primitive reptiles from the group of archosaurs.

Chirotherium

Subsequently it has been proved that Chirotherium is consistent with the anatomy of the hands and feet of the locodont Ticinosuchus

This was a crocodile-like predator, though with legs directly below the body and an ankle joint that allows it to move more effectively than the other members of its group.

Ticinosuchus, would have measured up to three meters in length, and when moving had to exert more force on the fifth finger, which protrudes laterally, than on the others. Hence the strange disposition of "inverted hand" that so intrigues a whole generation of Paleontologists.

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