Approximately how many million years older is Xenoposeidon than the next recognized Rebbachisaurid, Histriasaurus?

10 million years older

The successful classification of *Xenoposeidon proneneukos* in 2018 as a basal member of the Rebbachisauridae family carried significant chronological implications for understanding the evolution of that group. The analysis demonstrated that *Xenoposeidon* existed approximately 10 million years earlier in the geological record than the next previously recognized member of the family, which is *Histriasaurus*. This discovery is crucial because it drastically shifts the temporal origin point of the entire Rebbachisauridae lineage much further back, anchoring it firmly in the Early Cretaceous Period, suggesting a much earlier diversification of this specific sauropod branch than was previously understood from later, more complete fossils.