Das coronoid der paulchoffatiidae (multituberculata; ober-jura)

For the first time the presence of a rudimentary coronoid bone in the mandible can be proved, among the Kimmeridgian Paulchoffatiidae of the Guimarota coal mine near Leiria/Portugal. In 3 specimens remains of the bone in situ are present; in others only its sutural surface is preserved. The coronoid is a small bone placed immediately posteriorly to the second molar, variable in outline. In shape and position it is more similar to the coronoid of the contemporaneous Docodonta —Haldanodon — than to that of the also contemporaneous Eupantotheria, in which it is larger and situated higher on the coronoid process. Other accessorial bones, the sulcus mylohyoideus and the Meckelian cartilage are not present. With that it is proved that in all Mammalian orders known from the Guimarota coal mine — Docodonta, Eupantotheria, Multituberculata — accessorial bones in the lower jaw persist in a more or less degree, and it seems probable that in Kimmeridgian time the presence of such reptilian bones is the normal condition in mammals.