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Chirotherium monument with the reconstruction of a tracksite in Hildburghausen, Germany, where the first tracks were found in 1833.

Chirotherium (also known as Cheirotherium) or 'hand-beast', is the name of a creature which may be known only from fossil imprints of its tracks (trace fossils). These look, by coincidence, remarkably like the hand of an ape/human or bear, with the outermost toe having evolved to extend out to the side like a thumb, although probably only providing a firmer grip in mud. Its tracks were first found in 1833, in red sandstone in Thuringia, Germany, dating from about 243 million years ago (mya).

This creature was probably an pseudosuchid archosaur, related to the ancestors of the dinosaurs.

Cheirotherium trace fossil, displayed in Oxford University Museum of Natural History.

Tracks left by this creature were found before dinosaurs were known and initial models of the animal proposed that it was a bear or ape, which walked with its feet crossed. This proposal was necessary to explain the toe on the outside. These fossil tracks have now been found on North America, Africa, and Europe.

In reality, an external (lateral) 'thumb' was commonplace among archosauria of the creature's era, i.e. the Early Triassic Period.

Years later, the skeleton of a probably closely-related animal was found, called Ticinosuchus. It had the external toe on its hind feet but not on its front feet and was possibly a more advanced descendant, whose gait had improved enough to reduce the need for a stabilizing toe. Some have, on the other hand, proposed that it's the very same species, with what may have been a gender difference (sexual dimorphism).

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