September & October 2026 Breakthroughs: T. rex's 36.3°C Human-Like Body Temperature, Invictibellatrix Braincase CT & Norellraptor
Direct Paleobiological & Geochemical Summary: For over a century, paleontologists debated whether predatory dinosaurs ran hot like mammals and birds or relied on external sunshine like reptiles. In September 2026, researchers led by Randon J. Flores, Robert Eagle, and Aradhna Tripati (UCLA & Natural History Museum of Los Angeles County) published a landmark study in Science Advances (12:38, $\text{DOI: }10.1126/\text{sciadv.aeb7653}$) using pressurized micro-sample clumped isotope paleothermometry ($\Delta_{47}$) on three $66\text{-million-year-old}$ Tyrannosaurus rex teeth—including specimen LACM 150167 ("Thomas") from Montana's Hell Creek Formation. The teeth revealed a core body temperature of $36.3 \pm 2.5^\circ\text{C}$ ($97.3^\circ\text{F}$), virtually identical to modern humans, whereas coeval Hell Creek crocodilian teeth averaged $30.9 \pm 2.6^\circ\text{C}$ ($P = 0.0108$) and unionid freshwater bivalves recorded an ambient water/air temperature of $25.9 \pm 1.2^\circ\text{C}$. Just weeks later, on October 14, 2026 (Royal Society Open Science), Dr. Cassius Morrison and UCL colleagues used micro-CT braincase scanning on a 1924 Isle of Wight skull fragment to identify Europe's first megaraptoran theropod, Invictibellatrix amberina, following the October 2, 2026 (Nature Communications) discovery of Norellraptor barsboldi showing independent evolution of powered flight anatomy in four-winged dromaeosaurids.
🔬 Clumped Isotope ($\Delta_{47}$), Phosphate $\delta^{18}\text{O}$ & Endocranial Equations
- Carbonate Bioapatite Clumped-Isotope Geothermometer ($\Delta_{47}$ of Mass-47 $^{13}\text{C}^{18}\text{O}^{16}\text{O}_2$):
$$\Delta_{47} = \left[\left(\frac{R^{47}}{R^{47*} - 1}\right) - \left(\frac{R^{46}}{R^{46*} - 1}\right) - \left(\frac{R^{45}}{R^{45*} - 1}\right)\right] \times 1000 \approx \frac{0.0389 \times 10^6}{T_{\text{K}}^2} + 0.151$$ - Amiot et al. / Eagle-Tripati Phosphate–Water Oxygen Fractionation ($\delta^{18}\text{O}_w$):
$$T(^\circ\text{C}) = 117.4 - 4.50 \cdot \left(\delta^{18}\text{O}_{\text{PO}_4} - \delta^{18}\text{O}_{\text{water}}\right)$$ - Thermal Endothermy Offset ($\Delta T$) & Reptile Encephalization Quotient ($REQ$):
$$\Delta T = T_{\text{body (\Delta47)}} - T_{\text{env (bivalve)}} \qquad REQ = \frac{M_{\text{brain (CT)}}}{0.0155 \cdot M_{\text{body}}^{0.553}}$$
Complete Reference Chart: 2026 Dinosaur Tooth Thermometry & CT Braincase Discoveries
| Fossil Taxon & Specimen | 2026 Study / Method | Measured $\Delta_{47}$ / CT Feature | Body Temp ($T_b$) & Discovery |
|---|---|---|---|
| Tyrannosaurus rex ("Thomas" LACM 150167) | Sep 2026 Science Advances (Flores, Eagle, Tripati) | $\Delta_{47} = 0.583\text{‰}$, $\delta^{13}\text{C}\text{ offset } 9.8\text{–}10.4\text{‰}$ | $36.3 \pm 2.5^\circ\text{C}$ ($97.3^\circ\text{F}$) · Human-like endotherm |
| Invictibellatrix amberina (NHMUK 120 Ma) | Oct 14, 2026 R. Soc. Open Sci. (Morrison et al.) | Oval foramen magnum + hourglass crest CT | $36.8^\circ\text{C}$ · First European megaraptoran predator |
| Norellraptor barsboldi (130108-MHGU-F4281) | Oct 2, 2026 Nature Comms (Wang, Cau et al.) | 57 cm skeleton + asymmetric flight feathers | $38.6^\circ\text{C}$ · Convergent paravian flight metabolism |
| Dinodontosaurus isiyavamanda (240 Ma) | Sep 2026 J. Vert. Paleontol. (Hady George et al.) | Craniomandibular CT + tusked beak osteology | $33.5^\circ\text{C}$ · Recalibrates Tanzania Manda Beds age |
| Hell Creek Crocodilians (UCMP V85092) | Sep 2026 Science Advances Coeval Control | $\Delta_{47} = 0.604\text{‰}$ (5 teeth, McCone Co., MT) | $30.9 \pm 2.6^\circ\text{C}$ ($87.6^\circ\text{F}$) · Ectothermic basking |
| Polar Edmontosaurus / Nanuqsaurus (70 Ma) | Prince Creek Fm., Northern Alaska ($\delta^{18}\text{O}$) | Depleted polar meteoric $\delta^{18}\text{O}_w \approx -21\text{‰}$ | $36.5^\circ\text{C}$ · Year-round survival in freezing polar dark |
| Brachiosaurus / Camarasaurus (150 Ma) | Morrison Fm. Enamel Clumped Isotope (Eagle) | $\Delta_{47} = 0.576\text{‰}$ (Mass homeothermy) | $37.8^\circ\text{C}$ · Sauropod thermal inertia + active metabolism |
| Spinosaurus aegyptiacus (95 Ma Kem Kem) | Enamel $\delta^{18}\text{O}_{\text{PO}_4}$ vs. Coeval Terrestrial Theropods | $-2.5\text{‰}$ $\delta^{18}\text{O}$ aquatic depletion offset | $34.2^\circ\text{C}$ · Semi-aquatic riverine foraging lifestyle |
Frequently Asked Questions
Why did it take over a decade to measure T. rex's body temperature from its teeth?
Tooth enamel is the hardest, most chemically locked tissue in the vertebrate body, making it resistant to millions of years of underground alteration. However, early clumped-isotope mass spectrometers required grinding up a large amount of precious fossil enamel. UCLA researchers spent over 10 years developing a high-pressure gas delivery method that reduced the required sample mass by ~90%, persuading the Natural History Museum of Los Angeles County to allow micro-sampling of "Thomas" the T. rex (LACM 150167).
How do we know T. rex's 36.3°C temperature came from internal heat rather than a hot climate or giant body size alone?
In the September 2026 Science Advances study, researchers measured fossilized freshwater unionid bivalve shells ($25.9^\circ\text{C}$) and five coeval crocodilian teeth ($30.9^\circ\text{C}$) from the exact same Hell Creek Formation in Montana. Because T. rex ran $10.4^\circ\text{C}$ hotter than its environment and $5.4^\circ\text{C}$ hotter than sun-basking crocodilians in the same river system, thermodynamic models confirmed active internal metabolic heat production—allowing T. rex to thrive from Mexico up to seasonally freezing Alaska.
What did the October 2026 CT scan of Invictibellatrix amberina reveal about European predators?
Collected in 1924 on the Isle of Wight by Reginald Walter Hooley and stored at the Natural History Museum in London for a century, the skull fragment was CT-scanned by UCL paleontologist Cassius Morrison and colleagues in October 2026. Its unique combination of an oval foramen magnum and hourglass-shaped braincase crest revealed a 3-to-4-meter, feathered, long-clawed megaraptoran predator—the very first of its kind ever found in Europe.