Attached is a picture of one of the bricks from the Dinosaur Set 31058. It is however not listed in the content list on lego.com, so I have not been able to find a replacement.
That's 98613c01 - Hero Factory Arm / Leg Extender with Ball Joint and Ball Socket on BrickLink.
LEGO call this item Ball Cup High Friction W. Rubber and use 74261 (design ID) and 6106472 (Element number) for latest sets.
LEGO doesn't always have full list of parts within a set as this depends on parts availability (maybe some other reasons too). You would get much better set inventory on BrickLink. Check your set - 31058 on BrickLink, where you can find the part you are looking to identify.