bones- I remember them being assur medirabbanan, but I’m not holding enough.
I see from the following links that my memory is based on the shach who holds that bones with a bit of moisture in them are still assur.
The following article agrees (mods plz let it thru thx):
http://www.oukosher.org/index.php/common/article/5467
Also quotes a mishna that pigskin is considered fully edible and is a treif meat product. Chicken skin is regularly consumed as well.
The following star-k article quotes the shach that only completely dry bones are muttar but any moisture in them is assur:
http://www.star-k.org/kashrus/kk-palate-gelatin.htm
Here’s a good swipe from kashrut.com and by Rabbi Zushe Yosef Blech:
[It is beyond the scope of this article to delve into the details of the gelatin controversy, but a brief synopsis should help the reader understand the basic issues involved. Rav Chaim Ozer zt”l wrote a famous Teshuva, in which he permits gelatin based upon three considerations: (a) The hard bones from which the gelatin is produced are not considered meat, (b) because gelatin is considered a new product totally dissimilar from the original starting material (Ponim Chadashos), and (c) because gelatin is rendered inedible for a period of time during its processing (Nifsal M’Achila). The three authorities mentioned above, however, reviewed the matter and rejected this opinion for the following reasons: First, Rav Moshe Feinstein and Rav Aharon Kotler both held that bones from non-Kosher animals are not Kosher. Further, the argument is essentially academic since, even according to this approach, the bones would have to be completely clean, dry, and without marrow. Bones generally used for gelatin manufacture may have meat and marrow on them. In addition, most gelatins made today are produced from skins, which are not subject to this consideration. (Indeed, the Talmud (Chullin 122a) considers pigskins to be edible meat, and one need look no further than the snack section in the supermarket to note “Fried Pork Rinds” as proof!) As to the second consideration, the basis for the concept of Ponim Chadashos is a Rabbeinu Yonah, an opinion questioned by many authorities. Rav Moshe Feinstein further holds that Ponim Chadashos only applies to an Issur Yotzeh (an excretion from a forbidden animal) and not to parts of the animal itself. In addition, Rav Yechezkel Abramsky zt”l argues that gelatin is not even a “new creation”, but merely an edible extract that had always been present. As such, the concept of Ponim Chadashos does not apply according to these Poskim. As to the third consideration, the status of non-Kosher food that is Nifsal and then returned to an edible state is a longstanding question amongst the Poskim. Both Rav Feinstein and Rav Henkin rule that the matter remains a Safek (an unresolved Halachik issue), and one must therefore be strict in its regard. Rav Aharon Kotler argues forcefully that such material remains prohibited, and cites several additional reasons to prohibit gelatin. One is that since the processing of the gelatin was done with the intention of creating an edible product, the rule of inedible foods does not apply at all. Another is that even if the material would still be considered inedible, eating it intentionally would still be prohibited (Achshivay). He further argues that since gelatin is used to improve the food into which it is mixed, the fact that it itself may be inedible is of no consequence. It should be noted, however, that other authorities, notably Rav Tzvi Pesach Frank zt”l, and yb”l Rav Ovadia Yosef and Rav Eliezer Waldenberg shlit”a permit the use of regular gelatin based upon one or more of the above arguments. On the basis of these opinions, the Rabbanut in Israel does allow the use of certain types of gelatin produced from non-Kosher sources (primarily from dried bones). However, none of the Mehadrin Kosher certifications in Israel allow the use of this product, and the Rabbanut itself requires that products containing such questionable gelatin be clearly labeled as “permitted only for those who allow the use of gelatin”.]