H.erectus was pachy-osteo-sclerotic

[Marc Verhaegen]

Hypersalinity drives convergent bone mass increases in Miocene marine mammals from the Paratethys
Leonard Dewaele cs 2022 Curr.Biol.32:R42-44
doi org/10.1016/j.cub.2021.10.065

•Miocene marine mammals from the Paratethys Sea often have highly compact bones.
•Dense bones evolved independently in Para-tethyan whales, dolphins & seals.
•Bone mass increase may have begun as an adaptation to regional hyper-salinity.
•Paratethyan marine mammals persisted despite being isolated from the world ocean.

Pachyosteosclerosis (a condition that creates dense, bulky bones) often characterizes the early evolution of secondarily aquatic tetrapods like whales & dolphins,
but it then usu. fades away as swimming efficiency increases.

Here, we document a remarkable reversal of this pattern:
the convergent re-emergence of bone-densification in Miocene seals, dolphins & whales from the epi-continental Paratethys Sea of E-Europe & C-Asia.
This phenomenon was driven by imbalanced remodeling & inhibited resorption of primary trabeculae,
it coincided with hyper-saline conditions (the Badenian salinity crisis) that affected the C-Paratethys 13.8 - 13.4 Ma.
Dense bones (acting as ballast) would have facilitated efficient swimming in the denser & more buoyant water:
they were likely adaptive in this setting.
From the C-Paratethys, pachy-osteo-sclerosis subsequently spread East-ward, where it became a defining feature of the endemic late-Miocene whale assemblage.