I'd like to get some opinions on my tentative id of this specimen as a dorsal spine from the Bullhead/Horn shark (Heterodontus sp.). I haven't been able to locate many good images of these spines and this specimen is significantly larger than the few photos I've found. Is this a dorsal spine and if so what is the normal size range? This was collected this past weekend at Ernst Quarries, Slow Curve (Sharktooth Hill), Round Mountain Formation, Middle Miocene. Any help on the id is appreciated. Also curious if the Heterodontus from that period were larger than the extant Pacific species which d