Tyrannosaurus rex Substrate-Borne Wave Detection: Biomechanical Coupling, Dual-Mode Pedal Architecture, and Environmental Data Extraction

Large terrestrial theropods faced significant metabolic transport costs and atmospheric acoustic attenuation when relying exclusively on airborne sensory modalities for long-range environmental surveillance. This paper presents a theoretical framework and biomechanical model demonstrating that Tyrannosaurus rex utilized substrate-borne seismic wave detection as a primary, stationary sensory mechanism. By adopting a motionless stance, T. rex eliminated self-generated locomotor noise, maximizing the signal-to-noise ratio of incoming surface waves. Reception was enabled by a dual-mode pedal architecture: viscoelastic metatarsal foot pads matched acoustic impedance for low-frequency rumbles (1–20 Hz), while rigid, keratinized ungual claws coupled with the substrate to transmit high-frequency transients (20–100+ Hz). Static compressive loading from minor postural shifts elevated the effective Young's modulus of claw keratin and underlying bone, optimizing impedance matching and pre-straining periosteal mechanoreceptors. Vibrational energy traversed an unbroken, solid-state skeletal column—from ungual phalanx through the limbs, pelvis, and axial skeleton—directly to a heavily ossified otic capsule. Structural waves induced differential fluid inertia within an elongated lagenar duct, converting mechanical displacements into neural action potentials without middle-ear ossicle displacement. By evaluating inter-pedal time-difference-of-arrival (TDOA across a 1.0–1.5 m stance baseline), high-frequency spectral filtering, and gait cadence irregularities, a stationary T. rex could estimate source distance, trajectory, mass, and musculoskeletal injury in surrounding fauna across multi-kilometer distances. This substrate-borne sensory horizon model establishes T. rex as a high-efficiency data-processing hub, re-framing Late Cretaceous megafaunal spatial ecology, energetics, and territorial management.