A stratigraphic species series tests how bone microstructure changed during an inferred return to water.
Represented range8–3 Ma
RegionsNeogene Pisco Formation, Peru
CladesThalassocnus · Xenarthra · Pilosa
Claim ledger
ecology · medium
CT slices and thin sections across five stratigraphically successive Thalassocnus species show increasing rib and limb-bone compactness over roughly four million years, supporting progressive aquatic adaptation; hydrostatic control and marine grazing remain functional interpretations rather than observed behaviour.