干旱区生态环境知识资源中心

Ammonoids occur abundantly in the Maastrichtian of the Levant, but few of the occurrences have yet been described under terms of modern systematics. We report the presence of three ammonoid taxa, one of which is left in open nomenclature. They are from the upper lower Maastrichtian (Gansserina gansseri planktonic foraminiferal zone) of the Outhriate area in the eastern desert of Jordan, ca. 20 meters below the Cretaceous/Paleogene (K/Pg) unconformity. For the first time, Baculites ovatus SAY, 1820 is identified with confidence from Jordan. In addition, Libycoceras acutodorsatus (NOETLING, 1897) is present, of which L. chargense is a synonym, and Hauericeras sp. Our records represent the youngest records of Ammonoidea in Jordan, prior to their ultimate disappearance around the lower/upper Maastrichtian transition in this region. Due to the current lack of palaeoenvironmental data, the cause for the regional disappearance of ammonoids long before their extinction elsewhere remains currently speculative and unexplained.