Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations in the Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae)
Dermal fiber bundle architecture. (A) FHSM VP-401-01 showing partially degraded, longitudinal fiber bundles underlying epidermal scales. Black and white arrow indicates anterior. (B) Close-up of FHSM VP-401-04 showing superficial layers of fiber bundles with a predominantly longitudinal orientation. Note that the fiber bundles located somewhat deeper in the dermis (at the right hand side of the picture) appear to be somewhat thicker than are those immediately below the epidermal scales (at the center and left hand side of the image). (C) Longitudinally oriented and partly degraded fiber bundles located immediately below the epidermis (FHSM VP-401-04). Inset, longitudinal (arrow) dermal fiber bundles from the neck region of Eunectes sp. (LO 11215). (D) Transverse and tangential sections through helically arranged fiber bundles (FHSM VP-401-05). Arrowheads show fiber bundles that appear to be cross-weaved with those of adjacent layers, whereas arrows indicate the principal fiber bundle directions. (E) Layers with fiber bundles that extend in opposing directions (arrows) from deep within the dermis in tangential view (FHSM VP-401-04). Despite being heavily encrusted with phosphate, the fiber bundles are still readily visible. Inset (also in tangential view), a better preserved fiber bundle from the base of the section. (F) Backscatter image of an isolated fiber bundle comprised of multiple apatite aggregates (FHSM VP-401-01). Scale bars, (A, C–E) 2 mm, (B) 1 mm and (F) 30 µm.