What does modern scholarship conclude about the shape of the cross and the method of crucifixion? I have seen a couple of articles that explain how the commonly depicted image of Jesus on the cross is not historically accurate nor physically possible.


Roman Crucifixion Methods Reveal the History of Crucifixion
Was Jesus Crucified in the Manner Shown in Paintings and Movies?


What does modern Biblical scholarship conclude about the shape of the cross and the method of crucifixion? Is there a broad consensus?
The Alexamenos Graffito - "Alexamenos worships his god".

Someone decided to mock Alexamenos with some graffiti at the Palatine Hill.  Christians, especially in the first and second centuries, were accused of worshipping a donkey, which is called "Onolatry".  Tertullian writes about this with reference to Christians.  Google "onolatry" and "Tertullian" to see what you get.  The point is, this picture is clearly intended to represent someone with a donkey's head being crucified with arms outstretched.  It is intended as an insulting parody of our Lord Jesus Christ.


  And set up over his head his accusation written THIS IS JESUS THE KING OF THE JEWS.  (Matthew 27:37).


As David Reid amongst others has pointed out, if it had been a stake then the inscription would have been put "above his hands" and not "above his head".

Again David Reid says that usually JWs portray a single nail going through both hands. But we read in John's Gospel that Thomas said:


  Except I shall see in his hands the print of the nails (John 20:25).


So there couldn't have been a single nail going through both hands.