Dave Hone on Tyrannosaurs, Mass Extinction, and the Real Lives of Dinosaurs

A wide-ranging conversation with palaeontologist Dave Hone on what the fossil record actually tells us about Tyrannosaurus rex — its biomechanics, hunting strategy, ecology, and intelligence — and on the deeper questions of dinosaur behaviour, sexual selection, mass extinction, and the survival of dinosaurs as birds.

Key ideas

1. T. rex was ecologically bizarre. It stood not merely as the largest predator of its time but as a predator with no close competitor — the next-biggest carnivore in its ecosystem was roughly Velociraptor-sized. The analogy: going to Africa and finding that the only rival to the lion is a weasel. No other known ecosystem shows that degree of dominance.
2. Predators target the young, the weak, and the naive. Contrary to every dinosaur documentary, large carnivores — including tyrannosaurs — overwhelmingly took juveniles rather than adult prey. Direct evidence from bite marks and stomach contents confirms this for non-avian dinosaurs. Juveniles are smaller, inexperienced, poorly nourished, and excluded by adults from the best foraging patches.
3. Behaviour is reconstructed from independent lines of evidence. Bite-mark morphology, taphonomy (the study of what happens to a carcass between death and discovery), stable isotopes, and biomechanical modelling each constrain different aspects of behaviour. Convergent results across independent methods are the closest thing palaeontology has to a controlled experiment.
4. Sexual selection shaped dinosaur anatomy. Crests, horns, and frills across carnivorous dinosaurs are unlikely to be purely functional weapons or defences; they parallel the honest-signal and mutual-ornamentation patterns seen in living birds. The argument extends to the fused nasals and peculiar head architecture of tyrannosaurs.
5. The K-Pg extinction killed non-avian dinosaurs; birds are dinosaurs that survived. An asteroid impact ~66 million years ago caused near-instantaneous nuclear winter. Dinosaurs were the worst-placed group: large, terrestrial, and unable to disperse across geographic barriers. Their descendants — birds, roughly 11,000 species — live alongside us today.

Content

T. rex: anatomy and biomechanics

T. rex was roughly seven metric tons — heavier than a large African elephant — and bipedal. Its skull was massively overboned compared to other large carnivores: the nasal bones fused into a single solid strut, the jaw muscles attached across an exceptionally wide, robust cranium, and individual teeth could be banana-sized at the root. The bite force was correspondingly extreme, capable of crushing bone rather than merely puncturing it. Hone uses a comparison with Giganotosaurus — comparable in linear dimensions to T. rex but with a far more fenestrated, lighter skull — to illustrate just how much extra bone tyrannosaurs invested in jaw architecture.

The famous small arms were not vestigial in the sense of being purposeless relics, but evidence suggests they contributed little to prey capture: the ligamentous pits on the finger bones (the attachment sites for tendons resisting dislocation) are disproportionately small in T. rex compared with other tyrannosaurs, implying weak grip. The tail, by contrast, was integral to locomotion. A large muscle mass anchored the femur to the anterior half of the tail — in T. rex perhaps two to three metres of muscle — providing the primary driving stroke for each stride.

T. rex did not run in the biomechanical sense of having both feet airborne simultaneously; the mass loading made that mechanically prohibitive. But a stride of four to five metres at the upper speed estimate of ~25 mph (40 kph) produced effective pursuit. Hone argues for a largely nocturnal, endurance-pursuit strategy: T. rex’s giant, tennis-ball-sized eyes are consistent with low-light acuity, and the foot bones show a distinctive metatarsal locking mechanism — the arc-trochlea arrangement — that improved energy return with each step, favouring sustained distance over explosive speed.

Hunting strategy and diet

The documentary staple of T. rex bringing down an adult Triceratops is almost certainly wrong as a primary feeding mode. Hone cites predator-prey mass ratios: typical active predation across modern carnivores targets prey at 5–20% of the predator’s own mass. A seven-ton predator at the lower bound targets 350 kg prey — well below adult Triceratops or hadrosaur mass. The direct evidence supports this: healed bite marks (active predation, animal escaped) found on juvenile dinosaur bones; bite-feeding traces on carcasses indicate selective removal of muscle-rich areas using the small incisor-form teeth at the tip of the jaw, consistent with scavenging desiccated remains.

T. rex was almost certainly both active predator and scavenger — the behaviour is not mutually exclusive and both modes are confirmed by direct physical evidence. What remains genuinely uncertain is the relative proportion. Hone argues against a primarily scavenging lifestyle on energetic grounds: obligate scavengers require vast home ranges and extremely efficient locomotion (vultures exploit thermals; T. rex had no comparable mechanism for ultra-long-distance travel at low cost).

The fossil record and what it can and cannot say

A recurring theme is taphonomy — the chain of events between an animal’s death and a palaeontologist’s description of it. Bones aligned in a current, multiple carcasses in one quarry, or co-occurrence of species are frequently over-interpreted as behavioural signals. Hone gives the example of the Deinonychus–Tenontosaurus association used to argue for pack hunting in dromaeosaurs: the evidence is consistent with a predator trap (multiple carnivores attracted to a struggling prey animal, becoming mired themselves) rather than cooperative predation.

Pack hunting in dinosaurs generally is, in Hone’s view, unsupported by rigorous evidence. Even trackway evidence of multiple tyrannosaurs moving in the same direction is insufficient: solitary animals routinely follow the same game trails. He sets out what would constitute strong evidence — interlocking footprint sequences where A overtops B, then B overtops A, proving genuine contemporaneity — and notes that nothing approaching that standard has been documented.

Sexual selection and social lives

Hone argues that the near-universal presence of crests, horns, or display structures on the heads of theropod carnivores — and their presence in both sexes across many lineages — points to mutual sexual selection (where both sexes invest in offspring and both evaluate ornaments in the other). He draws an analogy with black swans: both sexes display curly wing feathers; both sexes use them in mate choice and in combat. If tyrannosaurs cooperated in rearing offspring, ornamentation in both sexes would be expected.

The difficulty is that for the vast majority of dinosaur species, specimens are so scarce that population-level analysis of sexual dimorphism is impossible. Protoceratops is the outstanding exception: more than a hundred specimens exist from a narrow stratigraphic window in Mongolia, spanning embryos to large adults. Even here, reliably separating males from females without medullary bone evidence (a calcium-deposition tissue found only in breeding females) remains intractable.

Feathers, birds, and the origin of flight

Early tyrannosaurs had feathers — simple filamentous structures, not the complex pennaceous feathers of flying birds, but confirmed from Middle Jurassic specimens roughly 165 million years old. Feathers probably evolved for two non-exclusive reasons: thermoregulation (most dinosaurs maintained a stable, elevated body temperature) and sexual display (feathers permit colour changes, erection, and patterning that scales cannot). Birds did not emerge after the K-Pg extinction; they had lived alongside non-avian dinosaurs for roughly 100 million years.

Mass extinction

The K-Pg extinction event was an asteroid or bolide impact off the Yucatan coast ~66 million years ago. The impacting body struck a particularly sulphur-rich substrate, generating an ash and aerosol cloud sufficient to cause near-instantaneous nuclear winter. All five recognised mass extinctions in Earth’s history share a common mechanism: climate changing faster than populations can adapt. Large, terrestrial animals are structurally most vulnerable — they require more resources, range further, and reproduce more slowly than small animals. Aquatic environments buffer temperature change; marine survivors fared better proportionally.

Hone thinks it probable that small, isolated populations of non-avian dinosaurs survived the initial event — analogous to the lemurs of Madagascar or the marsupials of Australia — but that the probability of such populations re-expanding globally was near zero, and the probability of finding fossiliferous rock from such refugia is negligible. The dinosaurs alive today are the birds: some 11,000 species, the direct descendants of a lineage that survived because it was small.

Jurassic Park: what it got wrong and what it got right

T. rex’s size and posture are broadly accurate in the original film; it is never shown fully airborne, consistent with power-walking biomechanics. The Velociraptor portrayal is heavily fictionalised: real Velociraptors were roughly thigh-high, narrow-snouted, and almost certainly feathered by 1993; the film’s animals are three times larger and scaled up from Deinonychus. The claim that T. rex navigated by motion is, as best as Hone can establish, invented by Crichton without a scientific basis — T. rex had enormous eyes and acute vision.

Hone’s broader point is that accuracy in popular media matters because it shapes public understanding of actual science, and that — per a creature designer he spoke to — making an animal accurate is no harder than making it inaccurate. Spielberg’s original film also established the Jurassic Foundation, which has since funded palaeontology research grants.

Related

• Dave Hone — guest
• Lex Fridman — host
• Lisa Randall on Dark Matter, Physics, and Extinction — related episode treating the K-Pg extinction from a cosmological angle