Hornung, J.J., Sachs, S. & Schwermann, A.H. (2023) The first record of sauropod dinosaurs from a palaeotopographical upland environment and its implications for megaherbivorous dinosaur faunal turnover in the Early Cretaceous of northwestern Europe. Geologie und Paläontologie in Westfalen 97, 1-34.
—A fragmentary centrum of a dorsal vertebra and a manual ungual phalanx of eusauropod dinosaurs from the Upper Barremian – Lower Aptian of Balve in western Germany are described. The dorsal centrum shares potential synapomorphies with the enigmatic genus Ornithopsis and can probably be referred to a titanosauriform. The Balve record is of significance as it represents the only known direct evidence of this clade from an upland environment in Europe, which is assumed to have reached palaeoelevations of several hundred meters above sea level. Taphonomic signatures at some of the material from this site indicate prolonged surface exposure plus various stages of wear caused by water transport. The remains were finally deposited in sediment traps within a karst cave or fissure system. The fossil record suggests a retreat or shift of sauropod habitat range from coastal plains and lowlands to hinter- and uplands during the Early Cretaceous in northwest Europe. It is hypothesized that this was linked to the faunal replacement of low- and mid-level browsing sauropods (e.g. diplodocoideans) by iguanodontian ornithopods near the Jurassic-Cretaceous boundary in this region. High-browsing titanosauriform sauropods had small overlap in the trophic niche with the ornithopods, facilitating a sympatric coexistence of both groups. However, their range was dependent on highcanopy vegetation that was probably more abundant in uplands. The previously observed “mid-Cretaceous bottleneck” in sauropod diversity may therefore be a result of partial extinction and/or a sampling bias, as the preservation of upland faunas are very exceptional. However, it is be cautioned to interpolate these regional observations to global sauropod diversity patterns.
