Troodon
Troodon is a controversial genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period. It includes at least one species, Troodon formosus, known from Montana. Discovered in October 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877.

Montanoceratops · CC0 · via Wikipedia/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.
On record
Recorded, not inferred- Sits inside
- TroodontiniPBDB
- Diet
- carnivore, omnivorePBDB, for Troodontidae
- Life habit
- ground dwellingPBDB, for Troodontidae
- Motility
- actively mobilePBDB, for Theropoda
- Environment
- terrestrialPBDB, for Troodontidae
Time the record covers
At most 18 million years on record.
Every occurrence read is dated to somewhere between 83.6 Mya and 66 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.
103 occurrences of Troodon on record, most of them in the Late Cretaceous. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.
When
103 occurrences- Late Cretaceous100%
These are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.
Found in
15 formations
- Dinosaur Park Formation · Belly River Group23
- Oldman Formation · Belly River Group19
- Judith River Formation · Montana Group11
- Hell Creek Formation · Montana Group10
- Horseshoe Canyon Formation · Edmonton Group10
- Two Medicine Formation · Montana Group9
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The named rock units Troodon has been recovered from, largest first. Drawn where the rock is now, not where it formed.
Troodon and its relatives
Late CretaceousWhere Troodon and its relatives were recorded in the Late Cretaceous.
Found in the same rock
513 taxa- Hadrosauridae47 sites
- Theropoda35 sites
- Ceratopsidae33 sites
- Myledaphus bipartitus32 sites
- Paronychodon31 sites
- Anura30 sites
- Baenidae30 sites
- Chelydridae30 sites
- Saurornitholestes langstoni30 sites
- Scapherpeton tectum30 sites
- Opisthotriton kayi29 sites
- Teleostei29 sites
- Tyrannosauridae27 sites
- Ankylosauria26 sites
- Multituberculata26 sites
- Aves24 sites
- Coriops amnicolus24 sites
- Richardoestesia24 sites
- Champsosaurus23 sites
- Lepisosteus23 sites
- Osteichthyes20 sites
- Trionychinae20 sites
- Belonostomus longirostris19 sites
- Mammalia19 sites
The Paleobiology Database records 100 sites for Troodon, and this reads all of them. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.
This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.
Entered from
45 references- The paleogeographic and stratigraphic distribution of ceratopsids (Ornithischia) in the Upper Judith River Group of western Canada11
- Paleontology of the Judith River Formation (Campanian) of Dinosaur National Park, Alberta, Canada: evidence from vertebrate microfossil locality11
- Multivariate analyses of small theropod dinosaur teeth and implications for paleoecological turnover through time10
- Vertebrate microsite assemblages (exclusive of mammals) from the Foremost and Oldman Formations of the Judith River Group (Campanian) of southeastern Alberta: an illustrated guide6
- Fossil Vertebrate Collections5
- Vertebrate faunal changes through Lancian and Puercan time in southern Wyoming5
- Theropod teeth from the Judith River Formation (Upper Cretaceous) of south-central Montana4
- Bird-like characteristics of the jaws and teeth of troodontid theropods (Dinosauria, Saurischia)4
- Theropod teeth from the Prince Creek Formation (Cretaceous) of northern Alaska, with speculations on Arctic dinosaur paleoecology3
- Evidence for heterothermic endothermy and reptile-like eggshell mineralization in Troodon, a non-avian maniraptoran theropod2
- Diversity of latest Cretaceous (late Maastrichtian) small theropods and birds: teeth from the Lance and Hell Creek formations, USA2
- A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union2
Each of the 103 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. 33 further references are not listed. Entries link to doi.org where the Paleobiology Database holds an identifier, and to its own record where it does not. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.
Media and terms
Media content3
Picture of Troodon
- Source
- Wikipedia/Commons
- Credit
- Montanoceratops
- Licence
- CC0
- Commercial use
- the licence allows it
Structured light scan
- Source
- MorphoSource
- Credit
- Museum of the Rockies
- Licence
- not stated by the source
- Commercial use
- cannot be read from the licence given — check the record
- Specimen
- Troodon formosus · mor:MOR 553L 7-25-9-312
3D model
- Source
- Sketchfab
- Credit
- Nobilis the Palaeovespa
- Licence
- CC Attribution
- Commercial use
- cannot be read from the licence given — check the record
The description on this site
- Source
- Wikipedia, “Troodon”
- Licence
- CC BY-SA 4.0
This is what the site found, which is not the same as what exists.
Keep going
What may have been alongside itTroodontini through timeFormations of the Late CretaceousThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. Leidy 1856