As painters, we have a tendency to think of paintings as being as being one of the older types of art. It's easy to think in such terms when one has cave paintings in the range 20,000 years of age to point to, plus a few Egyptian efforts almost that old, coupled with some Roman painted antiquities around 2,000 years old. But the non-wall-mounted painting we think of today as "paintings" (meaning to some degree portable) are mostly less then one thousand years old. There are two reasons for this. One, those older than this were likely done on surfaces that simply couldn't survive the ages, or second, the subject matter itself was not deemed important enough to merit the care needed to preserve them. However around 1100 AD came the popularity in Italy of a type of paintings that had both of these elements going for them. They were done on smooth, nearly "grainless" poplar, well constructed, and well preserved; and the subject matter was religious. Placed as the central focal point in the many large churches springing up all over Italy at the time, they thus meriting extraordinary care in both painting and preservation. Today, we refer to them as painted crucifixes.
The earliest of these dates from around 1138, done by Guglielmo da Sarzana. Like nearly all crucifixes from the twelfth century, the crucified Christ is depicted in a rigid, standing position, in this case seeming very much alive, and one might even say looking none the worse for wear. Far from the simple Roman cross we know today, the design was really quite complex with all four points having rectangular additions and in the Sarzana example, a richly illustrated cape-like panel surrounding the body of Christ (which seems to have a rather feminine appearance in this case). By 1265 when the well-known Italian painter, Cimabue created a crucifix for San Domenico, Arezzo, the figure was much more like that which we are familiar, a definite contrapposto to the body, some attempt at anatomical rendering, and a definite lifeless quality.
Cimabue's pupil, Giotto, painting just 25 years later, rendered a crucifix for Santa Maria Novella in Florence that seems much more like a crucifixion. There is a realistic naturalism to the disposition of the dead body hanging from the cross. The panel behind the body is much reduced and is less highly decorated. There are still portrait panels of Mary and St. John on either side just beyond the hands, but they are more of the spiritual realm than merely appearing decorative. At the base is the rock of Golgotha while blood drips onto it running down over the knees from the pierced side. There is a sense of gravity, both literally and figuratively. Stylistically, the cross is quite medieval, but the figure itself very much prefigures Renaissance painting. By the end of the thirteenth century however, the trend toward naturalism in painted crucifixes also spelled their end as sculptured crucifixes came into favor as appearing more realistic to the eyes of the worshiping masses for whom they were made to impress with the horrible pain and suffering of the crucified Christ.