The Ancient Greeks Knew...



Prometheus chained to a cliff in the Caucasus.
This is a more modern depiction, or at least resembles it.
Source: not known.

One thing about impalement that the Ancient Greeks knew that modern scholars (at those who have studied the topic of "crucifixion") don't seem to get, is that the executioners could run a stake right through a man and he would end up in the extended struggle of a slow, lingering death. Their knowledge of this can be clearly seen both in the epigraphy and the (ableit very rare) extant writings.

First, I have found various epigraphy of Prometheus fastened to some kind of stake, or frame, or "crucified" by being chained to a cliff face.

Here are two images showing Prometheus attached to a stake.

Here we see Herakles freeing the bound Prometheus from the stake just as the appointed eagle arrives to torment him.

Herakles freeing Prometheus.
Attic black-figure cup, c. 500 BCE
Source: Bibi Saint-Pol, Wikimedia Commons.

Next we have Prometheus shown bound by his hands to a pillar whilst being tortured by an eagle pecking at his heart; his blood is falling to the ground.

Early depiction of Prometheus bound to a pillar.
Laconian black-figure amphoriskos 6th C. BCE.
Source: Vatican City Museums, Theoi.com.

Next we have images of Prometheus chained to a cliff or frame, somewhat like a crucifixion.  In other words, we're dealing with a crucifixion of a god, just like Jesus Christ (allegedly) and Julius Caesar and other deified emperors (in imagine).

In this image below, Prometheus is depicted as "crucified" though with bent elbows to a cliff. he's standing on his tip-toes and his feet appear to overlap each other, like those of "Jesus" on the Shroud of Turin.  This image is clearly congruent with the imagery depicted in Lucian's Prometheus, and it may be where Lucian got his ideas of how the god was allegedly hanged.



 Heracles freeing Prometheus, who is "crucified" to a cliff. 
Relief from the Sebasteion at Aphrodisias.1st C. CE.
Source: Source: Hans Weingartz, Deutsch (German) Wikipedia.
 

And here is Prometheus shackled to a upside-down-U-frame. His arms are spread out as if by a patibulum.

Depiction of Prometheus on a vase ca 350 bce.
Source: unknown.

 In both these depictions, Prometheus is secured to a U-frame, again, crucifixion-style.

But the next two depict (or at least imply) Prometheus as impaled.



Early depiction of Prometheus impaled on a stake.
Note the stake is absurdly flat-topped!
Black-and-white line drawing copy.
Source: not known.



Another early depiction from a plate or vase of Prometheus impaled on a stake.
Again, the impaling stake is flat-topped.
Source: Theoi.com.

In each of these two images above, the impaling stake appears to go through the rectum and out the back right behind the shoulders.  These images are essentially identical to the depictions of impalements by the Turks in Egypt and other areas they controlled, and by the Russians in about the 16th/17th Century.

Textual evidence later.