Spinolestes's holotype, MCCMLH30000A', hails from Las Hoyas, Spain. The living animal was about 24 centimeters long and weighted somewhere between 50 and 70 grams. As a Konservat-Lagerstätten specimen, it is notorious for being remarkably well preserved, including not only the skeleton but also multiple soft tissues like fur, skin, internal organs and ears (both external and internal), a rarity among Mesozoic mammals. Besides soft-tissues, Spinolestes is also remarkable for its xenarthrous vertebrae, convergent with those of xenarthrans and to a lesser extent hero shrews.