Regarding El Jobo, Joshua Ream - moderator of Arrowheadology forum - has possibly the best collection of El Jobo on the planet. He hand picks El Jobo in Venezuela, off of sites.
If you look closely at all of his El Jobo points, they are made from a very coarse grained material that almost resembles quartzite. I have not seen a thin finely made El Jobo, such as the basalt point found at MonteVerde.
That being said, if you look at the fluted fishtail points, they tend to be made of very fine grained cherts, and other such stones. In one case, I ran across studies of the use wear patterns of fluted fishtail points. And, it appears that they were re-flaked - just as Clovis was resharpened - while being worked down to nubs.
In the case of the El Jobo types of points, it appears that they were used to penetrate, and to kill. But, one would not need a broad bifacial head, with curved edges, simply to penetrate and to kill.
The problem that I have with views based solely on "morphology" (i.e. thick bodied versus thin bodied), is that what is not oftentimes taken into account is what the points were used for, and from what materials the points were made.
Hypothetically speaking, what if the materials that El Jobo points were made from, were so coarse that they never made good cutting implements, and could never be thinned very well? Then, why not use the materials to make bipointed penetrating killers, with stout bodies?
And, what if the materials that fluted fishtail points were made from did provide an excellent cutting edge? Then, why not make hafted fluted fishtails, that could be resharpened over and over again, until only a nub was left? If this route was taken, then wouldn't broadly curved edges lend itself to longer knife function, and longer use?
As I said, I have yet to see an El Jobo point made from a non-crude material. And, I have yet to see a fluted fishtail made from really cruddy stone, like the El Jobo points are made from.
Beyond that, modern day images of tribal people butchering elephants and such show people hacking away at the carcasses with picks, and very large steel implements that can be wielded with two hands. So, how long would it take a person to use a small Clovis/fishtail knife to cut up an elephant? Lol. It is almost unimaginable. But, how do we know that that is how the tool was being used?
I think there is a possibility that the tools were hafted, used on spears, but then detached and used as indirect percussion cutters. In other words, the early hunter could have held the tool in one hand, and rapped the back of the tool with a piece of wood, while cutting through the meat. The blows would generate a series of short bursts of movement, with greater power than can be generated via hand held pressure. When the tools became dull, they could have been re-chipped while in the haft. If a tool was used in this manner, and a bone was ever struck, then it could have produced some "impact damage" to the tool.
