Genus
Valid Extinct

Nanotyrannus

Bakker et al. 1988
Etymology Tyran nain

Nanotyrannus is a genus of tyrannosauroid dinosaur that lived in what is now western North America during the Maastrichtian age of the Late Cretaceous, 67 to 66 million years ago. Its fossils are known from the Hell Creek Formation. It was one of the last-known non-avian dinosaurs and lived until the Cretaceous–Paleogene extinction event. The first named species, N. lancensis, was described as a new species of Gorgosaurus in 1946 by Charles W. Gilmore based on a single skull. Re-examination of the specimen in 1988 by Robert T. Bakker, Michael Williams and Philip J. Currie moved the species to a new genus of tyrannosaurid, named Nanotyrannus in reference to its small body size compared to other tyrannosaurids.

Temporal range
Triassic
Jurassic
Cretaceous
Paleogene
Neogene
252 201 145 66 0 Ma
PBDB occurrences
6
Group
Dinosaures
Carnivore Ground dwelling, solitary Terrestrial
Nanotyrannus
click to enlarge
Wikimedia
PBDB ↗ Wikipedia ↗
Classification
Dinosauria Unranked clade
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Theropoda Unranked clade
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Neotheropoda Unranked clade
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Averostra Unranked clade
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Tetanurae Unranked clade
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Coelurosauria Unranked clade
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Tyrannosauroidea Superfamily
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Eutyrannosauria Unranked clade
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Nanotyrannidae Family
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Nanotyrannus Genus
Fossil sites 6 geolocated sites
Distribution
Top countries
🇺🇸 United States
6
Geological formations
Hell Creek
4
Lance
2
Temporal distribution
Maastrichtian (72.2–66 Ma)
6
Species (2)
Nanotyrannus lancensis 72 Ma
Nanotyrannus lethaeus 72 Ma
News 3
Scientists thought this was a young T. rex. They were wrong
bone growth predator fossil juvenile +2
A long-running dinosaur mystery may finally be solved: Nanotyrannus, once dismissed as just a teenage T. rex, appears to have been its own distinct species after all. Scientists analyzed a tiny throat bone from the original fossil and discovered growth patterns showing the animal was already mature, not a juvenile giant-in-the-making. This smaller predator—about half the size of a full-grown T. rex—likely roamed alongside its famous cousin, adding a new layer of complexity to prehistoric ecosyst
16/04/2026 sciencedaily
This rare bone finally settles the Nanotyrannus mystery
bone growth museum fossil specimen +3
Scientists have confirmed that Nanotyrannus was a mature species, not a young T. rex. A microscopic look at its hyoid bone provided the key evidence, matching growth signals seen in known T. rex specimens. This discovery suggests a richer, more competitive tyrannosaur ecosystem than previously believed. It also highlights how museum fossils and cutting-edge analysis can rewrite prehistoric history.
09/12/2025 sciencedaily
Nanotyrannus: Beast of the Week
Nanotyrannus: Beast of the Week
United States Cretaceous Dinosauria Nanotyrannus
 This week we will be learning about a dinosaur who's identity has been the subject of a lot of debate or decades.  Check out Nanotyrannus!Nanotyrannus was a meat-eating dinosaur that lived in what is now Montana in the United States during the latest Cretaceous period, between 67 and 66 million years ago.  From snout to tail it measured between 17 and 20 feet (6.2 meters) long as an adult. The genus name translates to "Small/Dwarf Tyrant" because it was originally believed to be a close relativ
19/11/2025 prehistoricbeastoftheweek
Images 1
Bibliography
Original description
R. T. Bakker, M. Williams, and P. J. Currie. 1988. Nanotyrannus, a new genus of pygmy tyrannosaur, from the latest Cretaceous of Montana. Hunteria 1(5):1-30
Bibliography (5)
W. W. Stein. 2021. The paleontology, geology and taphonomy of the Tooth Draw Deposit; Hell Creek Formation (Maastrictian), Butte County, South Dakota. The Journal of Paleontological Sciences JPS.C.21:0001:1-108
K. Snyder, M. McLain, and J. Wood, A. V. Chadwick. 2020. Over 13,000 elements from a single bonebed help elucidate disarticulation and transport of an Edmontosaurus thanatocoenosis. PLoS One 15(5):e0233182:1-31 DOI ↗
M. D. Henderson and J. E. Peterson. 2006. An azhdarchid pterosaur cervical vertebra from the Hell Creek Formation (Maastrichtian) of southeastern Montana. Journal of Vertebrate Paleontology 26(1):192-195 DOI ↗
C. Lupton, D. Gabriel, and R. M. West. 1980. Paleobiology and depositional setting of a Late Cretaceous vertebrate locality, Hell Creek Formation, McCone County, Montana. Contributions to Geology, University of Wyoming 18(2):117-126
C. W. Gilmore. 1946. A new carnivorous dinosaur from the Lance Formation of Montana. Smithsonian Miscellaneous Collections 106(13):1-19