left pilaster, on the inside of the façade

The large animal on top of a crown of acanthus leaves, with its head facing backwards and with whatever is coming out of its jaws being transformed into the Ionic volutes of the capital, was identified as a bear (by Gandolfo, 2003) or as the mythical chimera (by Monsignor Valente Moretti, 2004, followed by Fornasari, 2005). In reality there are elements for and against both hypotheses: the robust body is etched in such a way as to suggest the fur and massiveness of a bear, except for the form of its tail; as for a chimera, that creature’s name is derived from the Greek khìmaira (goat), and was described thus by Homer (
Iliad, VI, 180-183, trad. R. Lattimore):

a thing of immortal make, not human
lion-fronted and snake behind, a goat in the middle,
and snorting out the breath of the terrible flame of bright fire.
He killed the Chimera, obeying the portents of the immortals.

Most often the chimera is represented with a goat’s head on its back, as in the very famous Etruscan bronze statue, and, according to some, its tail had a poisonous bite. She was attacked and killed by Bellerophontes (the Homeric “hero”), who was riding on the winged horse Pegasus,.
Therefore the creature sculpted on the capital cannot be identified with any certainty as the Chimera: the volutes formed by what comes out of her mouth might symbolize flames, but there is no trace of the head or body of a goat; instead it seems to have a forked tail, the shorter part, with something like the point of a lance at its end, goes up over the animal’s back and turns towards the left, while the longer part twists around the front paws. That zone of the frieze is eroded on the surface, and it may be that the two parts formed an undivided tail. The head turned backwards might have had a symbolic meaning, since it looks towards those who enter the church, but more probably it was the result of aesthetic requirements and symmetry – so that the two volutes would begin from a point in the center of the capital.
If the animal is a bear, its Christian meaning is ambiguous: it can represent evil, crudelty, avidity, but also the resurrection, and Christianity’s power of regeneration and transformation over the pagans, because in the spring the bear emerges from the cave and from its lethargy with its newly born cub. If it is the Chimera, it also has a double meaning, either evil vanquished (in this case by God) or the seasons symbolized by its triple nature: summer in the force of the lion; winter in the serpent, a symbol of land and obscurity; autumn and spring as transitional, symbolized by the goat. This would be another case of pagan symbolism acquiring a Christian interpretation, which increases the fascination of the pieve of Gropina.
Gandolfo (2003), comparing the crown of acanthus leaves to those of some of the capitals in the apse, according to him built before the demolition of the preexisting church, attributes this capital to a stoneworker active in the first phase of the construction.