Wiki on POS

[Marc Verhaegen]

Pachyosteosclerosis
Condition in which bones are effected by both Osteosclerosis and Pachyostosis
Pachy-osteos-clerosis is a combination of thickening (pachy-ostosis) & densification (osteo-sclerosis) of bones.
It makes bones more heavy, but also more fragile.
The condition often occurs in aquatic vertebrates, esp. those in shallow waters, creating ballast as an adaptation for maintaining neutral buoyancy & horizontal trim.
It is in no way pathological.
To resist bend, it frequently is found esp. in ventral bones, whereas concentration near the lungs helps in maintaining trim.
Examples of animals showing POS are seacows (dugongs & manatees), the extinct Plesiosauria & Mesosauria & extinct aquatic sloths.

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& H.erectus :-) dorsal>>ventral skull

[Marc Verhaegen]

Sorry some corrections (mostly spelling):

Pachyosteosclerosis in Wiki:
Condition in which bones are effected by both Osteosclerosis and Pachyostosis.
Pachy-osteos-clerosis is a combination of thickening (pachy-ostosis) & densification (osteo-sclerosis) of bones.
It makes bones more heavy, but also more fragile.
The condition often occurs in aquatic vertebrates, esp. those in shallow waters, creating ballast as an adaptation for maintaining neutral buoyancy & horizontal trim. It is in no way pathological.
To resist bend, it frequently is found esp. in ventral bones, whereas concentration near the lungs helps in maintaining trim.
Examples of animals showing POS are sea-cows (dugongs & manatees), the extinct Plesiosauria & Mesosauria & extinct aquatic sloths.
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POS is very clearly seen in H.erectus: it confirms H.erectus frequently dived for shellfish (stone tools cf. sea-otter, larger brain = seafood, ear exostoses = cold water irrigation, colonisations of Flores etc., Mojokerto & Trinil fossilisations amid shellfish, shell engravings google "Joordens Munro", dental micro-wear caused by shells=sand, etc.)
But in H.erectus, POS was not ventrally as in Sirenia etc., but dorsally in the skull (esp. the occiput), cf. back-floating between 2 dives for opening shells?

Ape+human evolution & speech origins, modern insights: google e.g.
- David Attenborough Marc Verhaegen
- Gondwanatalks Verhaegen
- aquarboreal
- Mario Vaneechoutte cs 2024 Nature Anthropology 2,10007 “Have we been barking up the wrong ancestral tree? Australopithecines are probably not our ancestors” open access https://www.sciepublish.com/article/pii/94