Original paper

New finds of Halitherium (Sirenia, Mammalia) from the lower Oligocene of the Rhine area, Germany

Voß, Manja

Abstract

The morphology, stratigraphy and systematic of new sirenian finds from the lower Oligocene of the Rhine area, Germany is established. The fossil remains are disarticulated, incomplete, and partly fragmentary. All finds are assigned to the genus Halitherium based upon extensive comparative studies. One partial skeleton from the Kaiserberg in Duisburg (Lower Rhine) belongs undoubtedly to H. schinzii, known from the Mainz Basin, due to significant similarities in diagnostically important cranial elements, such as the supraoccipital and zygomatic process. Extremely fragmentary sirenian remains from Ratingen-Lintorf, north of Düsseldorf, also are allocated to Halitherium. Although specific identification remains uncertain, detailed comparative studies indicate that this specimen of Halitherium sp. might have displayed a combination of features unique among sirenians. However, the skeletal remains of Halitherium sp. that probably come from the early Oligocene "Transgressionskies" cannot be identified with certainty as belonging to a single individual. The skeletal remains of Halitherium described here show that this genus was widespread in a larger area than previously assumed. The record from Kaiserberg/Duisburg shows that H. schinzii was not only restricted to the Mainz Basin. Comparisons of the find from Ratingen-Lintorf with H. schinzii from the Mainz Basin and the Belgian Oligocene expose significant differences between both, indicating the presence of two different morphological groups.

Keywords

sireniahalitheriumlower oligocenerhine areamorphologytaxonomy