|mhorn||Дата: Wednesday, 28.11.2012, 19:31 | Сообщение # 1|
|Haug J.T., Kruta I., Haug, C. (2012) A possible fossil paralarva (Cephalopoda: Coleoidea) from the Solnhofen Lithographic Limestones (Upper Jurassic, southern Germany) // Palaeontologia Electronica Vol. 15, Issue 3;28A,8p; |
Authors describe a possible fragmentary gladius of a paralarval cephalopod from the Solnhofen Lithographic Limestones, southern Germany (Upper Jurassic, Lower Tithonian). The specimen is 3 mm long and leaf-shaped, representing mainly the median field of the gladius. Faint remains indicate the former positions of the lateral fields. The median line is marked by a sharp keel. On the posterior end there is a pear-shaped structure. Anteriorly a kite-shaped area is ornamented with small pits. The principle morphology resembles, for example, certain trachyteuthidids, based on shape, presence of a keel and an ornamented anterior kite-shaped region. Also resemblances of certain muensterellid characters are pointed out. The special morphology of the here described specimen is interpreted as ontogenetically caused. This together with its small size makes a paralarval status of the specimen possible, although we cannot provide the necessary ecological evidence for this assignment. A clear ascription to any systematic group is hindered by the fact that there is no comparable material of similarly small size available.
Middle Jurassic - Lower Cretaceous ammonites & aptychi